Jksimmet v6 Manual

Version 6.0

User Manual

Steady State Mineral Processing Simulator

JKSimMet - Version 6.0 Steady State Mineral Processing Simulator by JK Tech Pty Ltd

JKSimMet is a powerful tool for the analysis and simulation of mineral processing plant data. As the program developers do not control data collection, analysis or interpretation, it is the sole responsibility of the JKSimMet user to verify that the input data are accurate and that both process unit operating conditions and stream outputs are reasonable. In no event will JKTech Pty Ltd be liable for direct, indirect, special, incidental or consequential damages arising out of the use or inability to use the software or documentation. Note: The detailed descriptions of the mathematical models in this manual are provided for the information of the software licensees. These models are not public domain and they may not be used in other software without written permission from or a licensing agreement with J KTech Pt y Ltd.

JKTech Pty Ltd 40 Isles Road Indooroopilly Brisbane QLD 4068 AUSTRALIA telephone: +61 7 3365 5842 facsimile: +61 7 3365 5900 email: info@jk tech.com.au web: www.jktech.com.au

JKSimMet V6 Manual © 2014 JKTech Pty Ltd All rights res erved. No parts of this work m ay be repro duced in any form or by any means - graphic, electronic, or mechani cal, including ph otocopying, recording, taping, or information s torage and retriev al s ystems - without the written permissi on of the publisher. Products that are refer red to in this documen t may be either tr adem arks and/or regis tered trademarks of the respective owners. The publis her and the author make no claim to these trademarks. While every precaution has b een taken in the preparation of this docum ent, the publi she r and the author ass ume no responsibility for errors or om issions , or for damages resulting from the use of information contained in this documen t or from the us e of programs and s ource code that may accompany it. In no event sha ll the publis her and the author be liable for any los s of profit or any other commercial dam age cause d or allege d to have been caus ed directly or indirectly by this documen t. Printed: March 2014 in Bris bane, Qld, Australia.

Special thanks to: Publisher JKTech Pty Ltd Mana ging Edito r Chris Bailey Technical Advisors Chris Bailey Iain Crawford Chris Keenan Cover Design Andrea Evers Heather Miller Team Coordinators Rolf Fandrich Debbie Gray Principal Author Alister Grimes Assistant Author Chris Keenan

All of t he JKTech and JKMRC staff and students who have contributed in any way to the preparation of this document.

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JKSimMet V6 Manual

Table of Contents Fore w ord

Part I Overvi ew

11

13

1 About ....................... JKSimMe t....................... V6 ....................... ....................... ....................... ................ 13 General Capabilities .......................................................................................................................................................... 13 How the Program .......................................................................................................................................................... Works 14 JKSimMet.......................................................................................................................................................... Simulation 16 JKSimMet.......................................................................................................................................................... Mass Balancing 17 JKSimMet.......................................................................................................................................................... Model Fitting & Analysis 17

2 Hardware ....................... & O perating ....................... System R ....................... equirem ents ....................... ....................... ................ 17 3 Cautionary ....................... Tale s....................... ....................... ....................... ....................... ................ 18 4 JKSimMe ....................... t Structure ....................... ....................... ....................... ....................... ................ 18 5 Av....................... ailable M odels....................... ....................... ....................... ....................... ................ 18 6 JK....................... SimMet Support ....................... ....................... ....................... ....................... ................ 19

Part II Changes from Version 5

21

1 Summary ....................... of Main....................... Change s ....................... ....................... ....................... ................ 21 2 Precautionary .......................N otes ....................... on Main Changes ....................... ....................... ....................... ................ 21 3 Toolbar ....................... Changes....................... ....................... ....................... ....................... ................ 22 4 Cr....................... ea ting Projects....................... ....................... ....................... ....................... ................ 23 5 Sieve ....................... Se ries and....................... Survey D ata Ent ....................... ry ....................... ....................... ................ 28 6 The ....................... New Flowsheet ....................... Drawer ....................... ....................... ....................... ................ 31 7 Sys ....................... tem Prope rties ....................... ....................... ....................... ....................... ................ 31 8 Acces ....................... sing Mode ls ....................... ....................... ....................... ....................... ................ 33 9 Equipment ....................... Mana ....................... ger ....................... ....................... ....................... ................ 34 10 View ....................... ing and Entr....................... y of Stream Data ....................... ....................... ....................... ................ 35 11 Conf ....................... igurable St ream ....................... Overview ....................... ....................... ....................... ................ 36 12 Simula ....................... tion Changes ....................... ....................... ....................... ....................... ................ 37 13 Simulatio ....................... n Manager ....................... ....................... ....................... ....................... ................ 38 14 Change ....................... s to Reporting ....................... ....................... ....................... ....................... ................ 39 15 Change ....................... s to Graphi ....................... ng ....................... ....................... ....................... ................ 40 16 Change ....................... s to Info B ....................... locks ....................... ....................... ....................... ................ 41 17 Model ....................... Fitting Changes ....................... ....................... ....................... ....................... ................ 43 18 Mass ....................... Bala ncing Change ....................... s ....................... ....................... ....................... ................ 44

Part III Installing JKSimMet

47

1 Contents ....................... of the Package ....................... ....................... ....................... ....................... ................ 47 2 JK....................... SimMet Installation ....................... ....................... ....................... ....................... ................ 47

Part IV Learning JKSimMet

51

1 JKSimMe ....................... t Basics....................... ....................... ....................... ....................... ................ 51 JKSimMet.......................................................................................................................................................... Data Structure 51 Available .......................................................................................................................................................... E quipment Items and Associated Models 52 © 2014 JKTech Pty Ltd

Contents

5

Building a.......................................................................................................................................................... Simulation Model 56 The Mouse .......................................................................................................................................................... and C ursor 57 The JK SimM .......................................................................................................................................................... et Windows 58

2 Building ....................... a New Project ....................... ....................... ....................... ....................... ................ 58 The Steps.......................................................................................................................................................... to Simulati on 59 JKSimMe.......................................................................................................................................................... t Start Up 60 Creating the .......................................................................................................................................................... New Project 61 Adding F .......................................................................................................................................................... lows hee t Equipment 63 Add Connectin .......................................................................................................................................................... g Streams 72 Define System .......................................................................................................................................................... Properties 78 Feeder Equipment .......................................................................................................................................................... Data 81 Select E quipment .......................................................................................................................................................... Models 83 Simulation .......................................................................................................................................................... 87 Viewing the .......................................................................................................................................................... Results 89 Viewing Individual .......................................................................................................................................................... Stream Data 94 View ing D .......................................................................................................................................................... ata f or M ultipl e Stream s 97 Finishing.......................................................................................................................................................... a JKSimMet Session 99

3 Working ....................... with an ....................... Existing Project ....................... ....................... ....................... ................ 99 Selecti ng .......................................................................................................................................................... the Fl ow shee t to U se 100 Working.......................................................................................................................................................... with the Simulation Manager 101 Using M .......................................................................................................................................................... odel Ba se d Groups for Simulations 108 Simulating .......................................................................................................................................................... Changes in Operating Conditions 111 Working.......................................................................................................................................................... w ith Configurabl e Equ ipme nt Manager 116 Defining.......................................................................................................................................................... Stream Data Info B locks 120 Defining.......................................................................................................................................................... Equipment Info Blocks 125

4 Summary .................... ....................... ....................... ....................... ....................... ................... 129

Part V Using JKSimMet

131

1 JKSimMe .................... t Desc ....................... ription ....................... ....................... ....................... ................... 131 JKSimM .......................................................................................................................................................... et M odel Types 132 JKSimMet .......................................................................................................................................................... Capabilities 134 JKSimM .......................................................................................................................................................... et Constraints 135 JKSimMet .......................................................................................................................................................... Expandability 135 Definition .......................................................................................................................................................... of Term s Used in JKS imM et 135

2 The .................... JKSimMet....................... Menus and Toolbars ....................... ....................... ....................... ................... 137 The M ain .......................................................................................................................................................... J KSimM et M enu 138 The File .......................................................................................................................................................... Menu and Main Toolba r 139 The Edi t.......................................................................................................................................................... M enu 140 The View.......................................................................................................................................................... Menu 143 The Flowsheet .......................................................................................................................................................... Menu and Toolbar 145 The Balance, .......................................................................................................................................................... Fitting and Simulate Toolbar 149 Drawing .......................................................................................................................................................... Toolba r 150 The Tools .......................................................................................................................................................... Menu 152 The Help.......................................................................................................................................................... Menu 153

3 JK .................... SimMet Window ....................... s ....................... ....................... ....................... ................... 153 Configurabl .......................................................................................................................................................... e Equipment Manager 153 Config Graph .......................................................................................................................................................... Window 154 Configurabl .......................................................................................................................................................... e Stream Overview Window 157 Information .......................................................................................................................................................... Blocks 158 Model Windows .......................................................................................................................................................... 159 Property.......................................................................................................................................................... Windows 160 Reporting .......................................................................................................................................................... to Excel Window 162 Simulation .......................................................................................................................................................... Manager Window 163 Simulation .......................................................................................................................................................... Window 164 Stream Windows .......................................................................................................................................................... 165 The E quipment .......................................................................................................................................................... Window 171 © 2014 JKTech Pty Ltd

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JKSimMet V6 Manual

The Session .......................................................................................................................................................... Window 172 The Sieve .......................................................................................................................................................... Series Window 175 The Survey .......................................................................................................................................................... Data Window 175 The System .......................................................................................................................................................... Properties Window 176

4 Building .................... and Manipulating ....................... a....................... Flowshee t ....................... ....................... ................... 177 Loading.......................................................................................................................................................... an Ex isting Project 177 Creating.......................................................................................................................................................... a N ew Project 178 Loading.......................................................................................................................................................... an Existing Flowsheet 179 Creating.......................................................................................................................................................... a New Flowsheet 180 Defining.......................................................................................................................................................... the Flowshe et Name 181 Deleting .......................................................................................................................................................... a Fl ow shee t 181 Buildi ng.......................................................................................................................................................... the Flows heet - Equipment 182 Buildi ng.......................................................................................................................................................... the Flowshe et - Stream s 184 Annotat .......................................................................................................................................................... ing the Fl ows heet 187 Information .......................................................................................................................................................... Blocks 189

5 Editing .................... the Flowsheet ....................... Data ....................... ....................... ....................... ................... 191 Stream Structure .......................................................................................................................................................... 191 System .......................................................................................................................................................... Prop erties 192 Accessing .......................................................................................................................................................... the Equipment and Model Data 193 Editing the .......................................................................................................................................................... Mode l Data 194 Editing Equipment .......................................................................................................................................................... Data 195

6 Us .................... ing Simul ation ....................... ....................... ....................... ....................... ................... 199 Simulating .......................................................................................................................................................... Using the Simulation Window 200 Simulating .......................................................................................................................................................... Using the Simulation Manager 201 Access ing .......................................................................................................................................................... the Stream Data 210 Water in.......................................................................................................................................................... Simulation 212

7 View .................... ing the Data ....................... - Summarie ....................... s & Reports ....................... ....................... ................... 213 Using the .......................................................................................................................................................... Configurab le Stream Overview 213 Configuring .......................................................................................................................................................... C olumns in the Stre am Ov erview 217 Using the .......................................................................................................................................................... Reporting Feature 226

Part VI Mass Bal anci ng

230

1 Introduction .................... to ....................... Mass Bala ncing ....................... ....................... ....................... ................... 230 2 Data .................... Collection ....................... ....................... ....................... ....................... ................... 230 3

Background .................... ....................... ....................... ....................... ....................... ................... 231

4 How .................... the Mass....................... Balancing Program ....................... Works ....................... ....................... ................... 233 5 Lea .................... rning Mass ....................... Balancing ....................... ....................... ....................... ................... 235 Model Types .......................................................................................................................................................... for M ass Bal anc ing 236 Enter ing.......................................................................................................................................................... the Data 237 The SD Calcula .......................................................................................................................................................... tion Window 240 Standard .......................................................................................................................................................... Deviation Calculati ons 243 Preparation .......................................................................................................................................................... for Mass Balancing 246 Selecting .......................................................................................................................................................... Data 247 Selecting .......................................................................................................................................................... Components 251 Solution.......................................................................................................................................................... Controls 252 Water in.......................................................................................................................................................... Balancing 254 Running.......................................................................................................................................................... the Mass Balance 255 The Mass .......................................................................................................................................................... Balance Engine 259 Checking .......................................................................................................................................................... the Balance 261

6 Presentation .................... of ....................... Mass Bala nce ....................... Results ....................... ....................... ................... 262 Configurabl .......................................................................................................................................................... e Stream Overview 263 Reports .......................................................................................................................................................... Function and Printing 263 Plotting .......................................................................................................................................................... Size Data G raphs 265

7 Proble .................... ms Rela ....................... ted to Mass Bala ....................... ncing and Pos ....................... sible Sol utions ....................... ................... 267 © 2014 JKTech Pty Ltd

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The Middlings .......................................................................................................................................................... Problem 267 The Infini .......................................................................................................................................................... te Division Problem 268

8 Metallurgical .................... A ....................... ccounting ....................... ....................... ....................... ................... 268 9

References .................... ....................... ....................... ....................... ....................... ................... 269

Part VI I Model Fit ting

272

1 Introduction .................... to ....................... Mode l Fitting....................... ....................... ....................... ................... 272 2 Background .................... to ....................... Mode l Fitting....................... ....................... ....................... ................... 273 3 How .................... the Model ....................... Fitting Program ....................... Works ....................... ....................... ................... 273 4 Model .................... Fitt ing ....................... as Applied in J....................... KSimMet ....................... ....................... ................... 274 5 Prelimina .................... ry Data ....................... Setup ....................... ....................... ....................... ................... 275 Creating.......................................................................................................................................................... the Flowsheet 275 System .......................................................................................................................................................... Prop erties 275 Stream Specification .......................................................................................................................................................... 275 Data Input .......................................................................................................................................................... 276 Mas s Bala .......................................................................................................................................................... nce Prior to Fitting 276 The M odel .......................................................................................................................................................... Fitt ing Wi ndow 277 Master Slave .......................................................................................................................................................... Fitting 284 Checking .......................................................................................................................................................... the Fit 286 Prese ntati .......................................................................................................................................................... on of M odel Fit ting R esults 287 Problems .......................................................................................................................................................... Related to Model Fitting and P ossible Solutions 291 References .......................................................................................................................................................... 292

Part VI II Model Descript ions

294

1 General .................... Models ....................... ....................... ....................... ....................... ................... 294 Ore Feeder .......................................................................................................................................................... (1300) 294 Water Feeder .......................................................................................................................................................... Models (1251 & 1252) 295 Model ......................................................................................................................................................... Description - General 295 Required ......................................................................................................................................................... % Solids - Standard Model 295 Water ......................................................................................................................................................... Addition - Standard Model 296 Model ......................................................................................................................................................... Limitations 297 References ......................................................................................................................................................... 297 Hydrocyclone .......................................................................................................................................................... M odels (200, 201) 298 Desciption ......................................................................................................................................................... 298 Equations ......................................................................................................................................................... 298 Symbols ......................................................................................................................................................... 301 Restrictions ......................................................................................................................................................... 302 Printouts ......................................................................................................................................................... 305 Summary ......................................................................................................................................................... 305 Fitting ......................................................................................................................................................... the Cyclone Model (200) 306 Fitting ......................................................................................................................................................... the Nageswararao Fines Model (201) 307 References ......................................................................................................................................................... 307 Narasimha-Mainza .......................................................................................................................................................... Cyclone Model (221) 308 Description ......................................................................................................................................................... 308 Equations ......................................................................................................................................................... 308 Symbols ......................................................................................................................................................... 311 Printout ......................................................................................................................................................... 312 Restrictions ......................................................................................................................................................... 313 Summary ......................................................................................................................................................... 315 Fitting ......................................................................................................................................................... the Cyclone Model 221 315 References ......................................................................................................................................................... 317 Screen Models .......................................................................................................................................................... (215, 230 & 235) 317 Kavetsky ......................................................................................................................................................... Single Deck Screen Model (230) 317 Model Description ......................................................................................................................................... 317 Model Equations ......................................................................................................................................... 319 © 2014 JKTech Pty Ltd

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JKSimMet V6 Manual

Single Deck ......................................................................................................................................... Model Printout 321 Symbols ......................................................................................................................................... 321 Know n Restrictions ......................................................................................................................................... 322 Parameter ......................................................................................................................................... Fitting the Screen Model 322 Regression......................................................................................................................................... Model Parameters 324 References......................................................................................................................................... 325 Double ......................................................................................................................................................... Deck Screen Models (215 & 235) 325 Eff. Curves .......................................................................................................................................................... (210, 211, 212, 213, 203 & 240) 325 Simple ......................................................................................................................................................... Efficiency Curve (210, 212) 325 Model_Description ......................................................................................................................................... 325 Model Equations ......................................................................................................................................... 325 Fitting the Simple ......................................................................................................................................... Efficiency Curve 326 Simple Efficiency ......................................................................................................................................... Curve Printout 326 Simple ......................................................................................................................................................... Efficiency Curve - Water & Fines (211, 213) 326 Model Description ......................................................................................................................................... 326 Model Equations ......................................................................................................................................... 327 Fitting the Simple ......................................................................................................................................... Efficiency - Water & Fines 327 Simple Efficiency ......................................................................................................................................... Curve (Model 211) Printout 328 Splined ......................................................................................................................................................... Efficiency Curve (Model 203) 328 Splined Efficiency ......................................................................................................................................... Curve (Model 203) Description 328 Splined Efficiency ......................................................................................................................................... Curve (Model 203) Equations 328 Fitting the ......................................................................................................................................... Splined Efficiency Curve (203) 328 Splined Efficiency ......................................................................................................................................... Curve (Model 203) Printout 329 Symbols f or ......................................................................................................................................... Splined Ef ficiency Curve Model (203) 329 Know n Restrictions ......................................................................................................................................... 329 References ......................................................................................................................................................... 330 Eff. Cur ve .......................................................................................................................................................... V ariable D50 c (Mo del 251) 330 Model ......................................................................................................................................................... Description 330 Model ......................................................................................................................................................... Equations 330 Ef f iciency ......................................................................................................................................................... - Variable d50c (Model 251) Printouts 331 Symbols ......................................................................................................................................................... 331 Know ......................................................................................................................................................... n Restrictions 331 Fitting ......................................................................................................................................................... 332 References ......................................................................................................................................................... 332 Simple Combiner .......................................................................................................................................................... Model (800) 332 Model ......................................................................................................................................................... Description 332 Symbols ......................................................................................................................................................... 334 Model ......................................................................................................................................................... Limitations 334 References ......................................................................................................................................................... 334 2 Way Simple .......................................................................................................................................................... Splitter Model (810) 334 Model ......................................................................................................................................................... Description 334 Symbols ......................................................................................................................................................... 336 Model ......................................................................................................................................................... Limitations 336 References ......................................................................................................................................................... 336 2 Way Volumetric .......................................................................................................................................................... Splitter Model (812) 336 Model ......................................................................................................................................................... Description 336 Symbols ......................................................................................................................................................... 338 Model ......................................................................................................................................................... Limitations 338 References ......................................................................................................................................................... 338 Water & .......................................................................................................................................................... Solids 2-Way Simple Splitter (813) 338 Model ......................................................................................................................................................... Description 338 Symbols ......................................................................................................................................................... 340 Model ......................................................................................................................................................... Limitations 340 References ......................................................................................................................................................... 340 3 Way Simple .......................................................................................................................................................... Splitter Model (870) 340 Model ......................................................................................................................................................... Description 341 Symbols ......................................................................................................................................................... 342 Model ......................................................................................................................................................... Limitations 342

© 2014 JKTech Pty Ltd

Contents

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References ......................................................................................................................................................... 342

2 Comminut .................... ion ....................... Models ....................... ....................... ....................... ................... 342 Crushe r.......................................................................................................................................................... M odels (40 0 and 40 5) 343 Model ......................................................................................................................................................... Descr iption (A nderson/Aw achie/Whiten) 343 Model ......................................................................................................................................................... Equations 345 Ore ......................................................................................................................................................... Breakage Characterisation 346 Breakage ......................................................................................................................................................... Distribution Parameter 346 Breakage ......................................................................................................................................................... Parameters 348 Crusher ......................................................................................................................................................... Pow er Predictions 348 Crusher ......................................................................................................................................................... Model (400/405) Printout 351 Symbols ......................................................................................................................................................... 351 Know ......................................................................................................................................................... n Restrictions 352 Fitting ......................................................................................................................................................... the Crusher Model 352 Regression ......................................................................................................................................................... Modelling 354 Model ......................................................................................................................................................... Testing 354 References ......................................................................................................................................................... 354 Rod Mill.......................................................................................................................................................... Model (410) 354 Model ......................................................................................................................................................... Description 355 Model ......................................................................................................................................................... Equations 355 Rod ......................................................................................................................................................... Mill Model Printout 358 Symbols ......................................................................................................................................................... 358 Know ......................................................................................................................................................... n Restrictions 359 Fitting ......................................................................................................................................................... the Rod Mill Model 360 References ......................................................................................................................................................... 360 Perfect Mixing .......................................................................................................................................................... Ball Mill (Model 420) 360 Model ......................................................................................................................................................... Description 361 Model ......................................................................................................................................................... Equations 362 Ball Mill ......................................................................................................................................................... Model Printout 365 Symbols ......................................................................................................................................................... 365 Know ......................................................................................................................................................... n Restrictions 366 Fitting ......................................................................................................................................................... the Perfect Mixing Ball Mill Model 367 Table......................................................................................................................................................... of Appearance Functions 367 References ......................................................................................................................................................... 369 SAG Mill.......................................................................................................................................................... (M ode l 430) 370 Model ......................................................................................................................................................... Description 370 Equations ......................................................................................................................................................... - Particle Breakage 371 Equations ......................................................................................................................................................... - Mass Transfer and Discharge 374 Prediction ......................................................................................................................................................... of AG/SAG Mill Pow er Draw 376 SAG......................................................................................................................................................... Mill Printout 380 Symbols ......................................................................................................................................................... 381 Know ......................................................................................................................................................... n Restrictions 382 Fitting ......................................................................................................................................................... the Autogenous & SAG Mill Models 383 References ......................................................................................................................................................... 385 Size Converte .......................................................................................................................................................... r M odel (490 ) 385 Introduction ......................................................................................................................................................... 385 Model ......................................................................................................................................................... Details 385 Fitting ......................................................................................................................................................... the Size Converter 385 Know ......................................................................................................................................................... n Restrictions 386 Variable.......................................................................................................................................................... Rates SAG Model (435) 386 Introduction ......................................................................................................................................................... 386 Scaling ......................................................................................................................................................... Approach 386 Slurry ......................................................................................................................................................... Holdup Model 387 Variable ......................................................................................................................................................... Rates Model 387 Effect ......................................................................................................................................................... of Key Parameters 390 Parameter ......................................................................................................................................................... Fitting - Variable Rates Model 396 Variable ......................................................................................................................................................... Rates for Simulation & Design 398 Know ......................................................................................................................................................... n Restrictions 399 Variable ......................................................................................................................................................... Rates SAG Model Printout 401 © 2014 JKTech Pty Ltd

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JKSimMet V6 Manual

References ......................................................................................................................................................... 402 High Pressure .......................................................................................................................................................... Grinding Rolls (Model 402) 403 Introduction ......................................................................................................................................................... 403 Model ......................................................................................................................................................... Structure 404 Breakage ......................................................................................................................................................... Processes 405 Compressed ......................................................................................................................................................... Bed Breakage Function 407 Throughput ......................................................................................................................................................... 407 Pow er ......................................................................................................................................................... Draw 410 HPGR ......................................................................................................................................................... Model Printout 413 Fitting ......................................................................................................................................................... the HPGR Model 414 Scaling ......................................................................................................................................................... the HPGR Model 415 Know ......................................................................................................................................................... n Restrictions 417 Nomenclature ......................................................................................................................................................... 417 Ac know ......................................................................................................................................................... ledgements 418 References ......................................................................................................................................................... 418 Size Degradation .......................................................................................................................................................... (Model 480) 419 Introduction ......................................................................................................................................................... 419 Model ......................................................................................................................................................... Structure 419 Degredation ......................................................................................................................................................... Model Printout 421 Fitting ......................................................................................................................................................... the Degredation Model 421 Know ......................................................................................................................................................... n Restrictions 421

Index

4 22


Foreword

JKSim Met V6.0 Steady State Simulation Soft ware for Comminution and Classification Operations in the Mineral Processing Industry


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Part

I

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1

Ov erv iew Overview

1.1

This section provides a broad overview of the JKSimMet program and its capabilities. It includes a chap ter on the hardware and operating system requirements plus some information about program structure and the included process models.

Abou t JK SimMet V6 About this Program

1.1.1

13

This chapter covers some of the more general information relating to JKSimMet V6.

General Capabilities General Capabilities

JKSimMet V6.0.1 is a comminution circuit simulator that runs on the Intel Pentium family of com puters under Windo ws 8, Windows 7, Vista or XP. It gives engineers the ability to design and simulate comminuti on circuits. More specifically, it allows engineers to: create a circuit using a graphics based interface; enter model and stream feed data; simulate the circuit; view the results.

Main Features

JKSimMet is intended for use by plant engineers not necess arily skilled in either modelling or simulation. For that reason, it has been written to operate in a user-friendly manne r. The user selects options from menus or lists and builds flowsheets on the screen. This removes the need for specialized computer skills while maintaining flexibility. The main features of JKSimMet are: graphical user interface; flowsheet specified interactively on the graphics screen; a wide range of mod els that can be select ed from the built-in library; JKSimMet will also in the future have the ability to add new userdefined comminution circuit models to the program; model parameters that can be fitted by the user; simple data transfer b etween JKSimMet and other programs such as MS Excel for data preparatio n a nd manipulation. JKSimMet has been designed primarily as a powerful aid to engineers. The principal applica tion of JKSimMet for many users will be to carry out process analysis and optimization of existing circuit s. JKSimMet is also extremely useful for con ducting conceptual design studies, where the purpose is to a ssess the suitability of dif ferent flowsheets to a chieve a desired performance objective.

Version 6.0.1 - March 2014

14

1.1.2

JKSimMet V6 Manual

How the Prog ram Works About JKSimMet

JKSimMet is a general-purpose computer software package for the ana lysis and simulation of mineral processing operations. The package is designed to service the diverse needs of plant and development metallurgists, who need modern process anal ysis techniques to characterise plant behaviour and design engineers, who require accurate process s imulation models to facilitate the evaluation of various plan t designs. JKSimMet integrates all tasks associa ted with optimisation, design and simulation, including the storage and manipulation of models, data and results, within one packag e. It is fully interactive and operates with highresolution colour graphics capabilities. These graphics facilitate the displa y of detailed pla nt flowsheets and accompanying inform ation.

Building a Simulation Model

The engineer using JKSimMet proceeds through a series of tasks: building a flowsheet diag ram of the processing plant on the computer screen ass igning characteristics to the variou s process units and material flows of the simulation model simulating the flow of materials through the simulated plant (or a subsection of the plant). reviewing and presenting the results. Once a model has been built, the engineer can alter t he design and change the parameters as required until a satisfactory design has been achieved, or an optimum operating condition is arrived at, in the case of an exis ting plant. The resul ts may be graph ed, printed in summary for m and stored on hard disk or archived to a CD or DVD. The results can also be transf erred to other suitable programs via the clipboard. Simulation is based on the abilit y to build a model that is representative of a real system. The behavior or characteristics of the model must be similar to the characteristics of the real system. In order to build the model the engineer must analyze the ove rall plant and break it down into a number of sectio ns (circuits), in such a way that these circuits are easily understandable and identifiable. The circuits are interconnected to form the total system. The data structure within JKSimMet V6.0.1 consists of the following:

Project

A project is the cont ainer in which the user store s all of the data related to a particular body of work. The project contains one or more flowsheets (circuits) and the as sociated equipment units and stream data.

Flowsheet

A flowsheet is a graphical representation of a complete processing plant or a discrete section of that plant. The flowsheet can have inter nal recirculating streams. Howe ver, if a stream recirculates to a previous section of the plant that has been represented using a separate flowsheet, then this stream would be treated as an output stream from the current flowsheet. A flowsheet may be incre ased in size to repr esent a large, complex circuit. Either the complete flowsheet or selected sections of it may be simulated, mass balanced or model fitted. Note that this ca pability to select items for in clusion in simulation, model ling or mass-balanci ng replaces the circuit-oriented flowsheets required by the

About JKSimMet V6


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15

DOS versions of JKSimMet. Equipment and Ports

Version 5 introduced a new concept. Each flowsheet equipment icon represents a discrete proce ssing stage in your flowsheet. It can represent a single equ ipment item or several identical items in parallel. Each icon (or equipment unit) will have a single combiner or feed port plus one or more product ports. These feed and product ports facilitate the connections (by means of streams) between the various equipment icons on your flowsheet. The reason for this change in structure was to allow for the future development of amodelled dynamicas simulator a pproach a lso allows for pipes and conveyors to be pieces of. This equipment. Units and Streams still provide a convenient way of thinking about flowsheets and for practical purposes, the terms equipment and ports can be used interchangeably wit h units and s treams.

Units (Equipment Items)

A unit is any ty pe of uni t process such as a ball mill or a hydrocyclone class ifier. JKSimMet allows you to select the appropriate unit from an extensive list of processi ng unit types 18 an d to display their pictorial representations (icons) on the scree n. These units are identified within the system by a name, which is specified by the user. You can also specify the orientation of the units (i.e. whether the feed port is to the left and product port(s) to the right or vice versa) and the posit ion of units on the flo wsheet diagram.

Streams (Connectors

A stream is a description of any flow of material. The description is usually in terms of solids flow rate, water flow rate and particle size distributions (plus

between Ports)

ass ays for mass balan cing, if required). The stream connections between units are made by drawing lines connecting the appropriate f eed a nd product ports on the units. JKSimMet automatically checks to ensure that the stream connections are valid. Each stream or port is named by JKSimMet as a combination of it s equipment name and port name. The user can edit the equipment names as requir ed but the port names for each piece of equipme nt are fixed.

Specifying Flowsheet Data

Once the flow sheet has been drawn the engine er must prov ide data for each process unit and also provide raw data in the form of flows and size distributions for the streams in the circui t. This is done by stepping through the process units and the streams one-by-one, adding circuit data and building up an annotat ed description of the modelled processing circuit on the screen. The unit data for the process equipment may come from previous experience, from a design database or they may be derived from plant data. The sizing com ponent of t he stream d ata can be enter ed in one of three size distribution formats, dependi ng on the pref erences of the user. The engineer can review or correct these data at any time after making the initial entries.

Flowsheet Simulation

Once the flowsheet has been specified and the required unit and stream data have been entered, the simulation can be run. The results of the simulation are stored and can be displayed on the screen or printed as required. The following options are available for examining the results: view the detailed data in the equipment and port data windows, view summary data for equipment and ports via data information blocks, view summary data in overview tables,


About JKSimMet V6

16

JKSimMet V6 Manual

view the size dis tribution data plotted as graphs on the screen, generate configurable reports at summary or detailed level for export to MS Excel or the clipboard, copy-and-paste the data into other programs (eg. MS Excel) via the clipboard print the flowsheet to a Windows compatible printer or to a file. Recorded data include: flow rates of solids a nd water percentage solids pulp densities full particle size dis tributions. After ana lysis of the results, the user can alter the flowsheet, adjust the equipment parameters or port data and repeat the simulation process until a satisfactory result is obtained. Flowsheet Selection

1.1.3

A new capability that was introduced with V5 is that a s ubset of the flowsheet may also be selected for simulation, mass balancing or model fitting.

JKSimMet Simulation Available Process Models

JKSimMet performs steady state simulation of comminution and related operations. Process models of the following units are available: particle size reduction devices e.g. crushers, SAG mills, ball mills; particle size clas sification device s e.g. hydrocyclones an d screens separators e.g. 2 an d 3 product splitt ers; combiners e.g. pump, pump sump, sump; stream source e.g. feeder, water feeder; stream sink e.g. final product. New process models can readily be incorporated into JKSi mMet by JKTech. This is done by defining their characteristics as steady state models and creating an icon for each to represent them on the screen.

Simulation Limits

It is important at the outset to understand what JKSimMet will an d will not do. JKSimMet will predict the performance of a circuit within the limitations of the data and the mo dels selected. JKSimMet will not det ermine of its own accord the best circu it, the be st operat ing conditions or the cha nges that are requiredconstraints to ensure that a specified. circuit operates efficiently. JKSimMet does not a llow process to be Provided that the data used in the process models are relev ant to the ore being studied, JKSimMet can be used to generate detailed design information. Until experience is gained in detailed design studies using JKSimMet, it is recommended that design tasks be carried out in consultation with JKTech.

Simulation Constraints

About JKSimMet V6

The operator ha s an essential role in deciding the conditi ons to be simulat ed and in critically asse ssin g the simulation predictions. This is a deliberate result of the design philosophy of JKSimMet, which places considerable


Ove rvi e w

17

emphas is on the process experience and knowledge of the operator. This point is amplified later under the topic JKSimMet Constraints 135 , and the reader is strongly adv ised to keep these points in mind when using the system for simulation analysis .

1.1.4

JKSimMet Mass Balancing JKSimMet enables users to mass balan ce comminution circuits on both a size and ass ay basis simultaneously. It allows engineer s to: create a circuit using a graphics based interface; enter stream data and calculate appropriate standard deviations; mass bala nce the circuit; view the results. Mass Balancing Limitations

1.1.5

JKSimMet will mass balance experi mental data to produce a consiste nt data set. It will not make bad data better, but will s how the quality of the data and where more care is needed in collecting the data.

JKSimMet Model Fitting & Analysis JKSimMet allows users to perform many areas of data analysis within the program itself, rather than using external s preadsheet based applica tions. A combination of these data templates enables fitting of various model parameters to be performed. Model Fitting Limitations

1.2

JKSimMet will model fit balanced or expe rimental data to produce a set of model parameters. It will not tell the user if these values are in typical ranges or whether the values are realistic. Such judgements rely on the experience of the user, or on commu nications with specialis ts at JKTech.

Hardware & Operat ing Syst em Requi rement s Successful operation of JKSimMet requires the following: Computer System

Intel Pentium PC (or other fully compatible computer) with all of the following: Processor speed 1 Ghz recommended; 512 MB memory minimum – 1 GB recommended; CD-ROM Drive; 2 GB or larger fixed disk drive (with 100 MB free space); A SVGA or fully compatible equivalent graphics controller (minimum) – Recommended an XGA graphics controller; A suitable monitor - 15 inch minimum, 17 or 22 inch recommended.

Printer


An MS Windows 7, Vista or XP compatible printer.

About JKSimMet V6

18

1.3

JKSimMet V6 Manual

Operating System

MS Windows 7, Vista or XP

Keyboard

Standard keyboard.

Pointing Device

Microsoft Mouse or functional equivalent.

Equipment Tested

A wide range of equipment combinations h ave been successfully tested, but if in doubt JKTech will be pleased to comment on a particular combination.

Ca ution ar y Tal es Backup JKSimMet Installer

It is recommended that a backup copy of the files be made to CD. If the JKSimMet CD-ROM is damaged, a new CD-ROM can be acquired from JKTech by notifying them and quoting the version number of the copy of JKSimMet.

Learn by Example

JKSimMet is a program that is rich in capabilities and easy to operate. The simplest way to become familiar with the techniques of using JKSimMet and its capabilities is to follow a s tructured example. Such an example is provided with the package. This example assumes no experience with JKSimFloat and leads the user through a session exploring flowsheet creation, data input and the use of the simulation features of the program. It is recommended that some time be spent working through the example provided (starting with the topic Building a New Project 59 ), until the user is confident that JKSimMet can be applied to different problems. More detailed reference information on all aspects of the program is outlined under the section Using 131 JKSimMet .

Backup Work

1.4

Remember to save the work to the hard disk regu larly, for example as each section of data (say a flowsheet or a data set) is entered. Usually earlier versions will be overwritten. If this is done regularly, then when (not if), there is a power failure or other mishap, the work up to the last save will be on the hard disk; it will not have been irretrievably lost . There is an auto save function incorporated in the program that runs every 3 minutes, however regular manual saving is also recommended.

JK SimMet Struc ture Program Structure

JKSimMet consists of the following software modules: Main Program; Supporting DLL’s; Program Database; Project Da tabases.

1.5

Avai labl e Mode ls The unit models currently available for simulation include the following: Available Models

Hardware & O perating System Requir ements

Feeder

Single deck screen

Stockpile

Double deck screen

Bin

Autogenous mill


Ove rvi e w

Pump sump

Semi-autogenous mill

Sump

Rod mill

Splitters (2 way & 3 way)

Ball mill

Gyratory crusher Two rolls crusher

19

DSM Screen Hydrocyclone Spiral class ifier

Jaw crusher HPGR crusher

Rake class ifier Thickener

Degradation model Custom Models

1.6

JKTech can be contacted to add other models to JKSimMet.

JK SimMet Su pp or t Documentation

Three levels of documentation are supplied: User manual. Help files. Model instr uctions (these are include d as the final section in both the manual and the help files)

Courses

JKTech offers regular courses in simulation technology at various locations around the world. Contact JKTech for details.

Extended Support

Continuing support is provided by JKTech either through a Maintenance Agreement, telephone or facsimile contact, or through visits by JKTech to your site.

E-mail Help

JKSimMet project files can be sent electronically to JKTech via the Internet for ass istance. Send files to [email protected].

Updates

Updates and bug fixes will be supplied for one ye ar from da te of installation/ supply and are available under a maintenance agreement thereafter.

Restrictions

A stan dard licence for the use of JKSimMet permits operation of the s oftware on a single workstation only. Extension of the licence for additional workstations at a single site is a vailable for a fee. Distribution of copies of JKSimMet to other company sites is not permitted. Additional copies for other sites are available at reduced cost.

Hardware Key (Dongle)

JKSimMet will not operate without a hardware key (also called a dongle). The standard ke y is suitable for a USB port. One wor king key and one spare key are supplied with each software licence.


Avail abl e Models

Part

II

Chan ges from Ver sion 5

2

21

Changes from Version 5 JKSimMet V6 is based on the JKSimFloat architecture a nd so presents a new experience and new features to the user, while retaining the underlying JKSimMet V5 functiona lity.

2.1

Su mmary of Mai n Ch ang es Main Changes

In summary the main differences between version 5 and version 6 are: Definition of Sieve Series of up to 40 sizes and Survey Data entry Flexible flowsheet drawer

Configurable Stream Overview Simulation Manager

38

36

including data entry

for running simulations in batch mode

User editable Info Blocks

41

Size x Assay mass balancing

2.2

28

31

44

Preca utionar y Notes on Main Chan ges Overview

JKSimMet Version 6.0 represents a major shift in many respects from version 5. Version 6 is available free of charge to clients who hold maintenan ce agreements and will be available to other users for an upgrade fee. The most signif icant change is that JKSi mMet ha s been moved from the old Visual Basic/Fortran platform to the more modern C++ platform that is used by JKSimFloat. Thus, the look and feel of JKSimMet V6.0 is now quite different from older versions and is much more like JKSimFloat. This section of the help file has been adapted from two s tand-alone document s that were prepared to guide users through their early use of the new version.

Increase from 30 to 40 Size Fractions

Until now, the maximum number of size fractions available was 30. This limited the range of equ ipment that could be h andled in a single flowshe et. The range available in a series was from 2.0 m to 0.086 mm. With the extra size f ractions, that rang e is now incre ased to 2.0 m to 0.003 mm or 10 m to 0.014 mm. It is now possible to use as many as 40 size fractions in the internal series.

Single Master Sieve Series

Previous versions of JKSimMet allowed the user to specify different size distributions for each stream in the flowsheet. Internally, these were all converted to the same series but this was not easily visible to the user. This flexibility caused problems in mass balancing, where the same sieve series is required for all streams and for reporting. These problems have been overcome by using a single master series for all s treams in a flowsheet. The user is first allowed to specify the maste r series for the proje ct. Once this is done, survey sizin g data obtained using any other sets of sieves can be entered and the program will then automatically conve rt s uch data into equiv alent data for the master sieve series.


22

JKSimMet V6 Manual

Small Differences in Simulation and Fitting Results

The two chang es discussed above, 40 Size Fractions and the Master Sieve Series may mean that simulation and model fitting could give slightly different resu lts in V6.0 com pared with V5.3. Our testing has shown that these differences are insignificant except for the HPGR model – see next section.

HPGR Model

The internal structure of the HPGR model means that the change from 30 to 40 internal size fractions makes significant differences to the simulation results. Therefore, it is necessary to refit the HPGR model in V6 before conducting any simulations.

Conversion of Files from V5 to V6

V6.0 allows JKSM5 extension files to be opened and converted to JKSMX files. The conve rsion proce ss creates a new file and leaves the old file untouc hed. The flow sheets created by the conver sion process may require some work to improve them aesthetically. Extensive testing h as shown that the converted files respond corr ectly throu ghout the full range of functions, when used in V6. However, there is always the possibility of issu es that have escaped detection during testing, so please don’t h esitate to con tact JKTech if you find any items that you are concerned about. Keep in mind that after any conversion process, it is always important to check the results carefully. Note that the conversion process does NOT convert component data. This will be implemented in the next release. Also, it is not possible to convert .JKSMX files back to .JKSM5 format.

2.3

Mass Balancing

Apart from the look an d feel, one of the major changes is to the mass balance system. The old JKMBal system previously used could han dle only one dimensional data – size distributions or as says. The new JKMultiBal system, taken from JKSimFloat, is completely new for JKSimMet and uses different algorithms that can handle size by assay data. However, because the algorithms are dif ferent, the resu lts may be different. If the data are good quality and require little adjustment, the results of balancing in the two versions will be close. However, if the data are of lower qualit y, the results from the two versions may well be dif ferent. Ther e is no “right” answe r in mass balan cing and the results will be heavily influenced by the user’s choice of starting estimates and standard dev iations. Please note that in JKSimMet V6.0, a zero value for standard dev iation is not permit ted. When converting from V5 files, all 0.0 SD values will be converted to “missing”.

Installation

Instal lation of JKSimMet V6.0 will uninstall any older JKSimMet versions. After installation of V6.0, d ouble clicking on a .JKSM5 file will open V6.0 and instigate the conversion process.

Contacting JKTech

Please feel free to contact JKTech if you have any questions or problems with JKSimMet V6.0. The best contact is via [email protected].

Too lba r Cha ng es Main Toolbar

A screen grab of the main tool bar is shown belo w, with annotati on to show the names of the buttons. These na mes are indicative of their functions and are in fact th e same as the tool-tips that will appear when you hover the mouse over these buttons. Note that too l-tips for the butt ons will be switched on by defaul t when you

Precautionary Notes on Main Changes



23

first open the progr am. They can be switche d off if req uired. This is done by selecting Tools from the main menu, then Customize. For further det ails on this, see the Tools Menu topic 152 .

Side Bar

As indicated in the annotations to the screen grab above, the three buttons for entering the main a reas of JKSimMet functionality (viz. Balancin g, Fitting a nd Simulation), wer e moved after this screen shot was taken. They have now been transf ormed into large buttons in a separate toolbar located in the left panel, just above the flowsheet list. An an notated screen sh ot of this toolbar is shown below.

Note that man y of the scre en shots in this help file were taken before this change in the too lbar structure took place. These shots have generally not been updated where the difference was consi dered irrelevant to the user's understanding of the topic. Flowsheet Toolbar

2.4

The new version of the flowsheet tool-bar is shown below, a gain annotated to indicate the names of the buttons.

Cre ating Pro ject s After opening JKSimMet V6 the user may create a new V6 project, open an existing V6 project or open an existing V5 project from the file menu.


Toolbar Changes

24

JKSimMet V6 Manual

Selecting “New Project” will open a window in which the user may enter the file name for the new project and save it (a default file name is supplied).

If the user choose s “Open Project” they will be presented with a window giving them the option to open either a V5 or V6 project:

Creating Projects



25

If the user chooses to open a V5 file they will be presented with this prompt:


Creating Projects

26

JKSimMet V6 Manual

Clicking “Save” will initiate the import process. Note that the process of converting the V5 file to V6 leaves the V5 file unchanged, it creat es a new V6 file and transfers the flowsheet and data in to the new file. If the V6 file name already ex ists the user is asked if they wish to overwrite the existing file. Choosing no will return them to the save prompt screen to enter or choose another file name.

On return the user will be asked if they wish to use V5 style flowsheet icons:

After clicking “sav e” the user will be presented with a window to choose or modify the sieve series to be used as the initial “Master” series:

Creating Projects



27

The user is presented with all unique sieve ser ies defi ned in the V5 flowsheet to choose f rom. The def ault master s eries is copied from the feed in the V5 project with material in the coarsest siz e fraction. The user may modify this series as they choose. Clicking OK will generate the project and the user is advised that they may need to re-run simulation:

If the user creates a new project they will be presented with a blank flowsheet:


Creating Projects

28

JKSimMet V6 Manual

If they open a V5 or V6 project the first flowsheet in the project will be opened:

2.5

Sieve Seri es and Surv ey Dat a Entry Master Sieve Series

Creating Projects

A fundamental difference between JKSimMet V5 and V6 is the introduction of the concept of a “Master” s ieve series. In V5 the user could define individual sieve series for each port for entry of experimental data and viewing of simulated, fitted and balanced results. In V6 the user defines as many sieve series for survey data entry as they need , and a single “Master” s eries for the entire circuit to view and edit data there after. The user may define up to 40 sizes in each sieve series in V6, compare d with 30 s izes in V5. Version 6.0.1 - March 2014


29

The sieve series definition window may be opened from the FlowSheet menu or the toolbar:

The user clicks the “Insert” button (

) to insert a new sieve series. They may

then amethey it appro for the part of theeither circuit the s ieve relates to. Afternthis enterpriately the relevant sieve s eries, directly, via series copy and paste, or ente ring a new top size and generating a new roo t 2 series by clic king the “Root 2” button ( ). The new series will then be avail able for se lection against appropriate stream s in the “Stream” section.


Sieve Series and Survey Data Entry

30

JKSimMet V6 Manual

After creati ng and allocating sieve s eries against appropriate streams, the user may open the Surve y Data window and enter their experimental data obtained through plant surveys.

The user may choose to view the stream s for the whole circu it (“All Sieves”) or for specific parts of the circuit as defined by the specific sieve series selected. They may then choose to view the stream data as any of the defined sieve series (“View As”), but will only be able to edit the da ta for the streams that h ave been assig ned that siev e series. In addition they may view the data as % Retained, Cum % Retained or Cum % Passing , and choose the inte rpolation method for translating the survey data into the global Master sieve series. If the user wishes to create extra sieve series they may click the “Edit Sieve Series” button to load the Sieve Series Overview, make their cha nges then return to the Survey Data window and re-make their selections. After entering the survey data and choosing the appropriate interpolation method, the user may click the “Trans fer” button to transla te the s urvey data into the Master series for all streams. They will be prompted to confir m the a ction before procee ding a s existing data will be overwritten:

The survey data is stored so the user may later modify and re-translate the data into the master series.

Sieve Series and Survey Data Entry



2.6

31

The New Flow sh eet Dra we r The new flowsheet drawer work s in two modes – locked and unlocked. When the flowsheet is locked adding and removing icons, pasting items, moving items etc is not possible, but access to the equipment models and stream data windows is enabled by doub le click ing the appropriate icon or stream. When the fl owsheet is unlocked the user may create and modify the flowsheet by selecting equipment icons from the tree view to the left of the flowsheet and drag and drop them directly on to the flowsheet, then connect them by clicking and dragging between ports. The new flowsheet dr awer is more flexible than the V5 Version, includ ing the ability to rou te streams exactly as the user wishes, and have complete control over the placement of icons and setting of display features (colour, size etc). There is also an automatic labelling feature for units and s treams.

By default the flowsheet drawer works with vector graphic based icons , unlike the bitmap icons used in V5. However at the point where a new project is being created, the user may choose to have it use the bitmap icons (V5 style) throughout all its flowshe ets. Note however that once this initial selection has been made, you will not be able to switch icon styles for the project in question. For further information on use of the flowsheet drawer, refer to the section Building and Manipulating a Flowsheet 177 .

2.7

Sy stem Pr op er ties The System Properties in V6 s erve 2 purposes – as a place to s et properties that are global to the proje ct, and to define the elements (“components” in V5) that may be used in mass balancing. System Properties are accessed from the Flowsheet Menu or the toolbar:


The New Flowsheet Drawer

32

JKSimMet V6 Manual

The first selection in the System Proper ties is the Elements. The us er defines the Elements and display units (% or g/t) used in mass balancing:

The bul k Soli ds and Liqu id SG used in simulation and the default global size markers used in each stream windo w are defined in the Miscellaneous System Property.

System Properties



2.8

33

Acc es sing Mod els In V5 double clicking an icon takes you straight to the selected model window. In V6 when the user double clicks on an equipment unit they are first presented with a window that allows them to cha nge model s election for the unit or open the feed or product stream windows for that unit.

When the user click s on the a rrows next to the model s election they are taken into the model window, with a display very similar to V5 and identical parameters.


Acces si ng Models

34

2.9

JKSimMet V6 Manual

Eq uipm en t Man ag er In addition to individual model viewing/data entry, V6 provides the Configurable Equipment Manager that allows the user to construct summary views for all equipment using a selected model. This allows flexibility in choosing which parameters to view/edit for a selected model. To acc ess the Equipment Manager choose from the Flowsheet menu or the toolbar:

The user may construct an Equipment Ove rview for each model used in the circuit, insert columns a nd define the param eters to be displayed by clicking in the top cell of the column.

This will invoke the sele ction box from which they select the parameter for display, after which they can then view or edit data for this parameter. In addition the Overview tables can be printed, copied to the clipboard, or exported to Excel. For further infor mation on this subjec t can be found in the topic Configurable Equipment Manager 153 .

Equipment Manager



2.1 0

35

Vie wing and Entry o f Stream Data JKSimMet V6 replaces the concept of “ports” with “streams”. In JKSimMet V6 the user ente rs a nd views stream data by double clicking directly on streams, unlike V5 where t hey right clic k on a unit and choose the port . This display s a familiar window showing Totals and Sizing data:

The user may choose which data types they view in the columns for all streams by clicking the Data Type View button. An additional feature is the SD Calculator, which allows the user to make bul k changes to S Ds for a given stream or multiple stream s, and for a single data point or multiple data points.


Viewing and Entry of Stream Data

36

JKSimMet V6 Manual

Some further information on the SD Calculator is contained in the topic Viewing Individual Stream Data 94 .

2.1 1

Conf igu rable Stream Overvi ew Like V5, JKSimMet V6 provides an Overview window to view summary stream/ port data. Unlike V5, the V6 Overview provides complete flexib ility in selection of data to view, and where the data is user editable (e.g. experimental) it can be modified in this window. To access the Configurable Stream Overview choose from the Flowsheet menu or the toolbar:

The user may construct as many Stream Overviews as required, but is provided with several defaults displaying various data. The user may insert columns and define the data to be displayed by clicking in the top cell of t he column. This will invoke the selection box from which they make their selection, after which they can then view or edit the data. In addition the Over view tables can be printed, copied to the clipboard, or exported to Excel.

Viewing and Entry of Stream Data



37

For further information refer to the topic Configurable Stream Overview Window 157 .

2.1 2

Simula tion Changes The V6 simulation window may be accessed from the Flowsheet menu or the toolbar:

The V6 Simulation window largely replicate s the functionality V5 implements in three tabs:


Configurable Stream Overview

38

JKSimMet V6 Manual

V6 has intuitive equipment and stream selection via the check boxes or by clicking on equipm ent and s treams in the flowsheet, and ha s the ability to create multiple select lists which like V5 are available in model fitting. For further information on Simulation refer to the manual or help files.

2.1 3

Simula tion Manager The Simulation Manager allows users to run a batch of simulations to observe the effect of adjusting unit operating parameters in each simulation. The simulation manager may be accessed fro m either the FlowSheet menu or the toolbar:

The method for selecting parameters and calculated results to view is identical to the Equipment Manager . The user may specif y absolute or % change to the srcinal data values for each simulation.

Simulation Changes



39

For further infor mation on the Simulation Manager refer to the topic Working with the Simulation Manager 101 .

2.1 4

Changes to Report ing The repor ting funct ion in V6 is similar to V5, but there is no report preview or ability to print reports directly from the program. Instead the report is exported directly to Microsoft Excel an d opened for viewing or p rinting. Reporting may be accessed from either the FlowSheet menu or the toolbar:

In addition, to avoid the need to modify existing reporting templates when model selections ch ange, each un it’s data occupies a fixed maximum number of rows in the Excel worksheet.


Simulation Manager

40

JKSimMet V6 Manual

For further information on the Reporting refe r to the topic Using the Reporting Feature 226 .

2.15

Chan ges to Grap hing The Configurable graphing function in V6 is s imilar to V5, but the select ion an d graph display are cont ained in one tab bed window and there is no ability to print graphs directly from the program. Instead they may be copied to the clipboard and pasted to other applications for viewing and printing. The Graphing may be accessed from either the FlowSheet menu or the toolbar:

Changes to Reporting



41

The streams or equi pment to display graphs for are selecte d in the top row. The graph format options can be set by clicking the “Format” button. After all options are set, the user selects the Graph tab to view the generated graph:

The user may also change the format options in this tab, and copy the graph to clipboard for use in other applications. For further info rmation on the Graphi ng refer to the topics Plotting the Size Data Graphs 265 in the Mass Balancing section and Presentation of Model Fitting Results 287 in the Model Fitting section..

2.1 6

Changes to Info Blocks The Flowsheet Info Blocks function in V6 is an enhan ced version of V5. User s may choose any equipment or stream parameters/data to view in the Info Blocks,


Changes to Graphing

42

JKSimMet V6 Manual

and where the data is user edit able (e.g. experimental) it can be modified in the Info Blocks. The Info Blocks may be access ed from either the Flowsheet menu or the toolbar:

The user select s the number of parame ters then clicks on each cell to define the parameter or data to be displayed:

Changes to Info Blocks



43

The user the n s elects the stre ams or equi pment to a pply the info block s to a nd clicks “Add Inf o Block”. For further infor mation on the Info Blocks refer to the Information Blocks 158 topic in the section Using JKSimMet .

2.1 7

Model Fitting Changes The Model Fitting Window in V6 consolidates the five t abs in the V5 window, but provides the same functionality. Unlike V5, the parameters available for fitting are not def Fit ined throughThe theModel jkp database; rather the selection made the Model window. Fitting may be accessed fromiseither thewithin Flowsheet menu or the toolbar:

Each model fit case is represented by a user def ined circui t selection. Unlike V5, each model fit case in V6 is associ ated with unique param eter sele ction lists – they are not shared be tween model fit cases. Also it is not possible to fit model parameters for equipment that is not in the selected circuit for the fit case.


Changes to Info Blocks

44

JKSimMet V6 Manual

Mast er/Slave fitting of multiple data sets is controlled from this window. For further information on model fitting refer to the Model Fitting 272 section.

2.18

Mass Balanci ng Cha nges The Mass Balance wi ndow in V6 is quite different from V5 but provides essentially the same funct ionality, including the ability to balance flows, sizes and assays across the whol e circuit or sele cted parts of the cir cuit. The Mass Balance window may be accessed from either the Flowsheet menu or the toolbar:

Model Fitting Changes



45

In addition, V6 provides the ability to balance assays within size classes as well as total assays and sizes. Unlik e V5, the use r does not balance everything at once. The suggested proce ss to balance a whole circuit: 1.

Make selections for all required equipment, streams, sizes and elements.

2.

Set TPH Solids and Sizes to Adjust and all other components to unused, then run the balance.

3.

Then set the TPH Solids and Sizes to Fixed, the TPH Water to Adjust and % Solids to Influe nce and run the balance again .

4.

Set the TPH Water back to unused and the Elements to Adjust and run the balance again.

5.

Set the Ele ments to Fixed and Siz e x Element to Adjust and ru n the balance a final time.

For further information on mass balancing go to the Mass Balancing


230

section.

Mass Balancing Changes

Part

III

Install ing JKSi mM et

3

Installing JKSimMet Installing JKSimMet

3.1

47

This chapter provides installation instructions for JKSimMet V6.

Co ntent s of the Pac kag e Package Contents

The JKSimMet system comes either as a package containing two “HASP” keys or dongles and as a download from the JKTech web site. This manual is also available as a download. Paper copi es of the manual and the JKSimMet pdf file are on CD and can be supplied on special request. The manual (and help files) contain information on the installation and maintenance of the JKSimMet software, a tutorial guide for first-time users and a comprehensive reference chapter (Using JKSimMet 131 ).

3.2

JKS imMet Installation Hardware / Software Requirements

To be certain of a successful installatio n and of a system that works efficiently once installed, you should check that your physical system and operating system com ply with the req uirements outlined under the heading Hardware and Operating System Requirements 17 .

User Privilege Required

As JKSimMet requires several device drivers the user must have full administrator privileges to install or uninstall JKSimMet.

JKSimMet V6 Installation

JKSimMet V6 is a standard Windows program. The steps required to install the program are as follows: Step 1

If you have an earlier version of JKSimMet on your computer, make a backup copy of any existing projects

Step 2

If you have JKSimMet V5 installed already on your computer, go to: Control Panel Select Add/Remove, and Select JKSimMet V5 Uninstall


Step 3

Ensure that the hard lock key is installed in a USB port in the computer as this interferes with the installation of the hard lock drivers. If you have downloaded the program from the JKTech web site, doub le click on the approp riate .exe file. This file will have a name that is unique for your installation. It may be located in a Downloads directory o r wherever else you may h ave elected to s tore it on your hard drive following the download.

Step 4

If your copy of JKSimMet V6 is on a CD-ROM, insert the disk into your CD drive. The install program should auto start, alternatively double click on the installation .exe file. This launches the InstallShield Wizard. Follow the instructions on the screen. The install program w ill guide you through the setup process. If you are

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JKSimMet V6 Manual

installi ng from a CD and it does not auto start, go to the Windows Start Menu, select RUN and then Browse to f ind the appropriate .exe on your CD Drive. Step 5

The default location for the installation of JKSimMet is: for 32 bit computers for 64 bit computers Click on thedifferent "Change"location butt on(see if you wish to ins tall the program in a below).

Step 6

Once the installation is complete, you must then plug your protection key (dongle) into one of the USB ports of your computer or the parallel printer port ( as appropriate), in order to a llow operation of the program. Note that the prot ection key(s) provided with your copy of V5.0 or V5.1 will also work with V6.

Note: The install program may also ask to update your HTML help file viewer. This will allow full use of JKSimMet V6 help. If the default path is not chosen for installation

If the default path is not the desired installation location, click on the Change… button in the InstallS hield Wizar d and follow the instructions to s elect a new location.

Non-English Versions of Windows

If a non-English version of windows is installed, the spelling of the install path may be diff erent. If this is the case , you must mo dify the install path to the correct spelling us ing the Change… button.

Installing Additional Shortcuts

As part of the ins tallation process, a shortcut to the program will be placed on your desktop. In Windows 7 you can also pin a shortcut to your Star t Menu or to your Taskbar at the bottom of the screen. Left-click on the Start button at the bottom left of the scree n, then on Program Files and then on the JKSimMet V6

JKSimMet Installation


Install ing JKSi mM et

49

folder within the Program File sub-menu. Now right-click on the item JKSimMet V6. When the right-click menu appears it will look similar to the illustration below. Making an accessible Shortcut

From here you can s elect to either Pin to Start Menu or Pin to Tas kbar. You may find one of these shortcuts is more convenient, especially if you are going to be using the program regularly.


JKSimMet Installation

Part

IV

Lear ning JKSim Met

4

51

Learning JKSimMet Learning JKSimMet

This section (Learning J KSimMet) is designed primarily as a tutorial exercise. It is anticipated that the first time user of JKSim Met might s pend two to three hours working thro ugh this section step by ste p. In this way the new user should gain sufficient confidence and knowledge to be gin using the system in earnest. The first main heading is JKSimMet Basics. This chapter contains a general description of the procedure for building a simulation model. It also contains a list of all the available equipment items and the process models 52 associate d with each of them . This is followed by some basic instruction on operating the software under the topics Mouse a nd Cursor 57 and JKSimMet Display 58 . The topics that follo w then take the user step-by-step thro ugh the procedure for creating a new project in order to build a simulation model for a flowsheet. Techniques that apply for the manipu lation of an existing project a re covered in this section under the main heading Working with an Existing Project 99 . Given the nature and design of JKSimMet, the user will very quickly be able to learn the basic operating techniques. It is assu med that the user already understand s the techn iques of mineral processing simulation and also has some appreciation of the standard features of the MS Windows 7, XP/ NT/2000 interface.

Typical Users of JKSimMet

JKSimMet is a general purpose computer software package for the s imulation of comminution plant operations. The package is designed to service the diverse needs of: Plant and Development Me tallurgists - to apply modern process analysis techniques to cha racterize plant behaviou r. Plant Op erators - to understand the ef fect of day to day changes in circuit operation on metallurgical performance. Researchers and Academics - to test and evaluate new process models. Consultants - to develop and demonstrate process optimization and design for client operations. Once familiar with the program, you will be able to use the JKSimMet simulation engine to determine the metallurgical performance of your processing circuit under various operating condition scena rios. The ability to do this is facilitated by the ful ly inte ractive nature of the program and it's flowsheet based graphical interface.

4.1

JK SimMet Ba sics Some JKSimMet Basics

4.1.1

Before you can begin to build a new project, you need to get familiar with the basic concepts covered in this chapter.

JKSimMet Data Structure The data structure within JKSimMet V6.0.1 consists of the following:


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JKSimMet V6 Manual

Project

A project is the cont ainer in which the user store s all of the data related to a particular body of work. The project contains one or more flowsheets a nd the ass ociated equipment and stream data.

Flowsheet

A flowsheet is a graphical representation of a complete processing plant or a Section of the plant and consists of an appropriately confi gured collect ion of process units and s treams. The flowsheet can have (and usually will have), internal recirculating streams.

Equipment

Each process unit in the flowsheet is represented by an

Equipment Unit.

JKSimMet allowstythe to display select the equipment from a list of (icons) processing plant equipment pesuser a nd to their pictorial representations on the screen. This equipment is identified within the system by a name that the user can specify. The orientation of the equipment and the posit ion of the equipment on the flowsheet diagram can als o be specified. There are a numbe r of choices for the process models to be used for each equipment unit. Streams

A stream is a description of the flow of mate rial between process units. This description includes the sizing characte ristics, the SG and the water content of the stream. It contains s ufficient information to p erform simulations via the various models that are currently in use and there is virtually unlimited capacity for developing and testing new models in the future. The stre am connect ion between two equipm ent units is made by drawing a line that conne cts the appro priate fee d and product ends of the equipment units in question. On simulation, JKSimMet automatically checks to ensure that all stream conne ctions are valid. The streams are identified within the system by names tha t the user can specify.

4.1.2

Available Equipment Items and Associated Models Equipment Items

Below is a listing of the JKSimMet equipment items, showing the associate d menu icon and the process models available for each of them. Equipment Category

Equipment Item

Menu Available Models (Model ID) Icon

Stream Source

Feed (Solids Feeder)

Terminator - Solids Feeder (1300)

Water Feeder

Water Feeder - Required % Solids (1251) 295

294

Water Feeder - Water Addition (1252) 295

Crushers

Jaw Crusher

Crusher - Anderson/White n (40 0)

343

Crusher - Anderson/Whiten - Size Extended (405 ) 343 Size Converter (490) Gyratory Crusher

JKSimMet Basics

385


343

Crusher - Anderson/Whiten - Size Extended (405 ) 343


Lear ning JKSim Met

Size Converter (490) Cone Crusher

53

385


343

Crusher - Anderson/Whiten - Size Extended (405 ) 343 Size Converter (490) Rolls Crusher

385


343

Crusher - Anderson/Whiten - Size Extended (405 ) 343 Size Converter (490) VSI Crusher

385


343

Crusher - Anderson/Whiten - Size Extended (405 ) 343 Size Degradation (480) Size Converter (490)

419

385

HPGR

High Pressure Grinding Rolls (402)

Degradation

Size Degradation (480)

403

Size Converter (490) Mills

Autogenous Mill

419

385

Perfect Mixing Ball Mill (420)

360

Semi-Autogenous Mill - Leung (430) 370

Semi-Autogenous Mill - Sim/Org Scaling (435) 386 Size Converter (490) Rod Mill

Rod Mill - Lynch/Kavetsky (410) Size Converter (490)

Ball Mill

Trommel

354

385

Perfect Mixing Ball Mill (420) Size Converter (490)

Screens

385

360

385

Splined Efficiency Curve (203) Simple Efficiency Curve (210)

328

325

Efficiency Curve - Water & Fines (211) 326 2-Way Simple Splitter (810) Single Deck Screen

334


328

325

Efficiency Curve - Water & Fines (211) 326


JKSimMet Basics

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JKSimMet V6 Manual

Single Deck Screen - Kavetsky (230) 317

2-Way Simple Splitter (810)

334

Double Deck Screen (One Under Product)

Double Deck Screen Based on Efficiency Curve (215) 325

DSM Screen

Splined Efficiency Curve (203)

Double Deck Screen - Kavetsky (235) 325

Simple Efficiency Curve (210)

328

325

Efficiency Curve - Water & Fines (211) 326 Efficiency Curve - Variable d50c (251) 330


334

Water & Solids 2-Way Splitter (813) 336 // wrong Classi fiers

Air Classi fier

Hydrocyclone


328


325

Nagaswarara o Cyclone (200)

298

Nagaswararao Fines (201)

298


328

325

Efficiency Curve - Water & Fines (211) 326 2-Way Simple Splitter (810)

334

Water & Solids 2-Way Splitter (813) 336 // wrong Narasimha-Mainza (221) Spiral Classifier

308


328

325


334

Water & Solids 2-Way Splitter (813) 336 //wrong Rake Class ifier


328

325

Efficiency Curve - Water & Fines (211) 326

JKSimMet Basics


Lear ning JKSim Met


55

334

Water & Solids 2-Way Splitter (813) 336 // wrong

Splitters

O-Sepa Classifier


2 Product


Splitter

Fixed 2-Way Volume Splitter (812)


328

325

334

336

Water & Solids 2-Way Splitter (813) 336 // wrong

Storage/ Transport

3 Product Splitter


Bin

Size Degradation (480) Size Converter (490)

Size Converter (490)


Stockpile


332

385

Simple Combiner (800)

332

Size Degradation (480)

419


385

Simple Combiner (800) Thickener

332

385

Simple Combiner (800) Sump

332

385

Simple Combiner (800) Pump Sump

419

385

Simple Combiner (800) Pump

341

332


325

Efficiency Curve - Water & Fines (211) 326 Filter Model Controlled by % Solids to U/F (240) 325

Separators

Final Product

Terminator(1300)

Flotation Cell


328

Simple Efficiency Curve (210) 325 Efficiency Curve - Flotation (212)

325

Efficiency Curve - Water & Fines Flotation (213 ) 326 2-Way Simple Splitter (810)

334

Water & Solids 2-Way Splitter (813) 336 //wrong


JKSimMet Basics

56

JKSimMet V6 Manual

Flotation Column


328

325

Efficiency Curve - Flotation (212)

325

Efficiency Curve - Water & Fines Flotation (213 ) 326 2-Way Simple Splitter (810)

334

Water & Solids 2-Way Splitter (813) 336 //wrong Spiral Separator


328

325


334

Water & Solids 2-Way Splitter (813) 336 //wrong 2 Product Separator


328

325


334

Efficiency Curve - Flotation (212)

325

Water & Solids 2-Way Splitter (813) 336 //wrong 3 Product Separator

4.1.3


341

Building a Simulation Model What is Simulation

Simulation is based on the ability to build a model that represents a real system. The behavior and characteristics of the mod el must be similar to those of the real system. JKSimMet allows the user to draw the flowsheet of a comminution circuit, input and manipulate the data for a very wide range of operating conditio ns and see the predicted results of running the circuit.

Steps to Building a Simula tion Model

The user of JKSimMet proceeds through a series of tasks as outlined below.

JKSimMet Basics

1.

Building a flowsheet diagram of the comminution plant on the computer screen.

2.

Input the feed stream data in the Feeder equipment.

3.

Select the mo dels for the equipment and input the required model data.

4.

Run the Simulation of the flowsheet.


Lear ning JKSim Met

5.

57

Review the r esults of the si mulation in the Rep ort window or in the individual stream data windows.

These tasks are describ ed in more detail under the heading Building a New Project 59 , which takes the user through each s tep. Once a simulation model of a circuit has been built, the metal lurgist can use JKSimMet to assess the impact of altering various plan t conditions on metallurgical performance, until a satisfactory design or an optimum operating condition for an existing plant is achieved. The results from JKSimMet cancan be also exported to Exceltofor printing, graphin further analysis. Data be transferred other programs (such gas and MS Word), by copying them to the clipboard and pasting into the other program. Values calculated in a simulation include: flow rates of solids and water; pulp dens ities (percentage solids); particle size distribu tions (if size has been chosen a s one of the stream properties); Solids and water recoveries.

4.1.4

The Mouse and Cursor The Mouse

The standard two button mouse is used as the pointi ng device in JKSimMet. This manua l refers to ‘ left click’ and ‘right click’, which s imply means to press the left or right hand button on the mouse. Note that if the words ‘left or ‘right’ are omitted, the default is always ‘left click’. The manual as sumes that the user is familiar with comm on mouse techniques such a s double clicking and click-and-dr ag. Note that when you follow a link (unde rlined blue italics) which takes you to another topic and you then wish to return to the original topic, clicking the back button on your mouse will achieve this. That is of course assuming you have a mouse that is equipped with forward and back buttons.

The Cursor

The cursor is the visual feedback to the user of the current mouse position on screen. Any click of a mouse button will interact with the image located at that position. In JKSimMet V6.0.1 the usual form of the cursor is an arrowhead. When the cursor is over equipment in the flowsheet window and the flowsheet is unlocke d, the cur sor will change to sh ow a rrows pointing in 4 directions to indicate that the equipment item can now be moved. To achieve this you can now just hold down the lef t mouse but ton and drag the item. Releasing the mouse button will drop the item into its new location. Once the left mouse button has been clicked while hovering over an equipment unit, you will see that the item then has 8 grey squares around its periphery to indicate it is now select ed. If you then double click on the item, you will bring up the equipment properties dialog box wh ere the attributes of this equipm ent can be modified. Alternatively you can right click and select Properties from the right-click menu.

Cursor Movement


When working with a flowsheet in JKSimMet, the mouse provides the means of moving the cursor arou nd the s creen and selecting individ ual streams or equipment items as required. In the equipment, stream and model data JKSimMet Basics

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JKSimMet V6 Manual

windows, the cursor contro l keys (also known as the arrow keys) may be used to move the cursor fr om one data cell to the next. In this case, the movement will be in the direction of the arrow key used. Otherwise you can still use the mouse to hover over and click to select, any required data entry cell. To begin entering data into one of the cells, you can just begin typing once the cell has been sele cted. To edit data already existing in a cell, you must first double-click with the mouse to select the text within that cell. The text in the cell will then be highlighted with white figures on a blue background. Starting to type at this point will again just over-type the existing text. If your intention is to edit the existing text, you need to now s ingle click in the highlighted cell. You will then see the mou se cursor flashi ng as a vertical line between the characters and you can move it to the left or right via the arrow keys. In summary then, to overwrite existing te xt, just begin typing once the cell has been selected. To edit existing text, double-click and then single-click inside the target cell.

4.1.5

Appearance

As with all MS Windows progr ams, the pref erences that the user sets for the Windows deskt op will pro vide colours a nd fonts for many of the tools a nd menus within JKSimMet.

Keyboard Access

Most of the functionality of JKSimMet can also be a ccessed from the keyboard using standa rd MS Windows conve ntions.

The JKSimMet Windows The JKSimMet V6.0.1 display uses win dows to present the various types of data on the JKSimMet desktop. These windows include the following: flowsheet window equipment and port data windows graph windows data overview window the report window Users may hav e as many w indows open on the screen as they wish at any one tim e. An XGA video card and a large monitor are recommended to gain full advantage of this ca pability. Many of the windows are divided into several distinct areas that are accessed b y selectable tabs. Each area is used to convey specif ic types of information. Note that most windo ws may be minimized for convenience. However, some non-critical chang es (eg. an equipment name chang e) may require that a window be closed before other windows are updated.

4.2

Bu ilding a New Pro ject Building a Project

JKSimMet Basics

Having gained an understanding of what JKSimMet does and generally how it works, this section will take you t hrough a series of steps in order to build a JKSimMet project. A simple flowsheet will be used for learning purposes. In order to cover as many of the available techniques as possi ble though, this tutorial will take a number of diversions along the way during the process of


Lear ning JKSim Met

59

putting together this simple flowsheet. In this demonstration we will be assuming that you already have the necessary paramet ers for the main equipment items on this flowsheet. Later on in this help file , you will be shown h ow to carry out the fit ting proc ess in order to obt ains such parameters and also how to perf orm mass balancin g which is normally performed ahead of any fitting exercise.

4.2.1

The Steps to Simulation This section contains a step by step tut orial style set of instructions that is tailored for users who are still becoming familiar with the program. The following section on Using JKSimMet 131 covers all of the basic operational features of JKSimMet and is structured as a reference section. Steps to Simulation

The stages invol ved in performing a simulation are outlined below, an d the sections JKSimMet Start Up 60 thr ough to Viewing Individual Stream Data 94 are designed to guide the user through each stage. Step 1

Make a backup copy of any existing projects

Step 2

Startup JKSimMet - covered in the topic Start JKSimMet 60

Step 3

Create the flowsheet – covered in sections Create a New Project 61 through to Build a New Flowsheet - Add Streams 72 . Note that a flowsheet must have a Feed equipment unit and all equipment items (apart from feeders) must have feed streams to be valid.

Step 4

Set the System Properties in the s ection Flowsheet Data - System Properties 78 . These are global character istics that do not change during simulation. I n JKSimMet they consist of only the solids and the liquid SG values and ass ays where needed for mass balancing.


Step 5

Input feed stream data into the Feeder equipment item - see section Flowsheet Data - Feeder Equipment 81 .

Step 6

Select the models for the equipment and input the required model data – section Flowsheet Data - Equipment & Models 83 . The data for the models will usually be derived from plant or test work data. Some data may also come from previous experience. The user can review or correct the data at any time after data entry.

Step 7

Run the Simulation of the flowsheet – section Simulation

Step 8

Review the resul ts of the simulation in the Configurable Stream Overview – section Viewing Data Using Configurable Stream Overview 89 .

Step 9

Review the results of the simulation in the individual stream data windows – section Viewing Individual Stream Data 94 .

Step 10

From the Configurable Stream Overview, the results of the simulation can be copied to the clipbo ard and then exported in a printer-friendly format to other programs such as MS Excel, as required. After analysis of the results the circuit configuration ca n be altered, the capacity and characteristics of the equipment changed, the properties of the feed stream adjusted and the simulation process repeated until a satisfactory result is obtained.

87

.

Building a New Project

60

JKSimMet V6 Manual

The sectio n Working with an Existing Project work with a n existing project in this manner.

4.2.2

99

outlines how to

JKSimMet Start Up JKSimMet Start Up

The instructions for starting JKSimMet V6 are as follows: Step 1

Plug the JKSimMet protection key into the a ppropriate place in the computer.

Step 2

Left click on the Windows Start bu tton at the bottom left hand corner of the screen to open the Start menu.

Step 3

Move the cursor to select the All Programs sub-menu.

Step 4

Move the cursor to highlight the JKSimMet V6 program from the list displ ayed in this sub-menu and left clic k. You will then see two items; JKLicenseManager and JKSimMet V6. Left clic k on the latter to launch the program. The JKSimMet logo is displayed while the program is loading.

Step 5

Alternatively, JKSimMet can be started by double clicking on the JKSimMet icon on your desktop or by clicking on a Taskbar icon in Windows 7, if yo u have opted to pin a program shortcut to the Taskbar.

Having successfully launched the program the main JKSimMet sessi on window wil l open as shown below. From here , the next step is typically to open a previously saved proje ct (see section Working with an Existing Project 99 ), or to enter the data for a new proje ct (see sectio ns Create a New Proje ct 61 through to Flowsheet Data - Equipment & Models 83 ).

Changing

Note that the session window can be re-sized using the minimize and

Window Size

maximizeWhen buttons (top right corner) by border movingline the cursor to any edge of the window. it is positioned overorthe the cursor will chang e from the arrowhead to a line with arrows on each end; left click and drag with this cursor to change t he window size and release the mouse button when the window size is as required. Note also that the variou s sections of the session window can be re-sized in the sa me manner.



Lear ning JKSim Met

4.2.3

61

Creating the New Project Creating a New Project

In this exercise a new proje ct will be create d by following the steps outlined below. The proje ct you are about to create will be a simple closed circuit ball mill flowsheet.

Ne wProject

Ste p1

After starting JKSimMet click on the New Project ic on on the toolbar or select New Project fr om the File menu. This will open the New Project window.

Define Project Name

Step 2

A dialog b ox will open where you can select a suitable directory (probably somewhere within My Documents wou ld be best ) and also ente r a name for the pro ject. Note that you can create a new sub-directory for this tutorial work by clicking on the icon circled in the screen grab below.

In this case we will replace the name 'New JKSimMet Project' with ‘Learner Project’. After making this change, click on the Save button. You will then be present ed with the opti on to either use the more



62

JKSimMet V6 Manual

realistic icon style familiar to Version 5 users, or the stylised icons that have been adopted as the default for the Version 6 interface.

Note that once you make this selection, you canno t switch back again within this same project and you cannot mix icon styles within a project. Having made your selection, the new project will open. The name of the project ('Learner Pro ject' in this case) will be displa yed in the title bar of the main window. The new proje ct will have a default flowsheet called ‘FlowSheet1’, as shown below. It will initially be empty of any equipment and streams.

Define Flowsheet Nam e


Step 3

To change the n ame of the flo wsheet, right click on the flowsheet name ‘FlowSheet1’ in the left panel and select Properties from the drop-down menu. Click in the Flowsheet Name text box and type in the new name; use the name ‘Learner Flowsheet’.


Lear ning JKSim Met

4.2.4

63

Adding Flowshee t Equipment Adding Equipment to the Flowsheet

In this exercise a flowsheet for a comminution plant will be creat ed using the graphics-based flowsheet drawing tools in JKSimMet. Check that the flowsheet is not locked before you begin - the Lock b utton ( ) sh ould n ot be depressed. However, the flowsheet should be unlocked by default, after you have just created a new project.

Save the Flowsheet

As with all computer programs, your work should be sa ved regularly to avoid loss of data. To save changes to the project, click on the Save Project button or select Save Project from the File menu.

Select the Flowsheet from Left Panel

Step 1

The far left panel contains the list of flowsheets that are contained in the current project. In this case, there is only one flowsheet. This is the default flowsheet that was created along with your new project and h as now been re-named as Learner Flowsheet. Note that the project name and the flowsheet name now appear in the title bar at the top of the window.

The Learner Flowsheet will be selected by default since there are no others.



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JKSimMet V6 Manual

The avail able equipment list is displayed in the centre panel of the sessi on window. The equipment icons are grouped by equipment functionality, progressing from the feed end of the plant to the final product. An exception is that Separators are placed in a group at the end of t his lis t, since they are not so often required in JKSimMet, this program being primarily a comminution modelling tool. To the right of this list is a large blank area where you will be constructing the new flowsheet. If your project had than oneonflowsheet, to change the flowsheet selection you would need to more double click the required flowsheet in the left-panel list. The selected flowsheet's contents would then appear in the right (flowsheet display) panel.

Create New Equipment Units on the Flowsheet

The new blank flowsheet nowone ready for eq equipment to be thatFeed a flowsheet MUST have at isleast Feed uipment uni t, added. as it isNote in the equipment unit that the feed stream data are defined. So we will add this first.

Add Feed Equipment

Step 2

Double click on the Feeds Folder and then click on the Feed equipment icon from t he equipment list and then place the cursor over the flowsheet. The arrow cursor will change to the equipment placement cursor (a cursor with the equi pment icon next to it - see below).

Move the cursor to the position on the flowsheet where you require the Feed equipment to be placed and click again. You can move it later, so there is no need to be pre cise. If you chan ge your mind about adding an item you have select ed before you have placed it on the flowsheet, just right-click to cancel the placement. Add the Ball Mill


Step 3

The Ball Mill equipment item should now be added to the flowsheet in the same manner as the Feed equipment. To do this, open the Mills folder and click on the ball mill icon in the equipment list, move the cursor to the required position on the flowsheet and click again.


Lear ning JKSim Met

65

Add the Ancillary Equipment Units

Step 4

You now nee d to add the auxiliary equipment units - namely a cyclone plu s the sump/pump to feed it. When you have placed these items, your screen should look something like the one illustrated below.

Add Water Feeders to the Flowsheet

Step 5

You now need to add two Water Feeder uni ts, which should be added so that their locations are similar to those shown in the screen grab below.



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JKSimMet V6 Manual

Exercise: Adding Multiple Units

To add multiple units, press Ctrl when selecting an equipment item from the list. Instances of the select ed unit can then be placed by repeatedly left clicking on the flowsheet. The process can be discontinued by right clicking anywhere on the flowsheet, or by clicking on the arrowhead (Select) button in the toolbar ( ).

Exercise: Deleting Units

If you have multiple units on a flowsheet, some of which you don't require, deleting the surplus units is simple. Click ing on an individual unit will select it and you can select mul tiple unit s by hol ding down the Ctrl key for your subsequent sele ctions. After one or more un its have been selected, you can just hit the Delete key to remove them. Alternatively, you can select Delete from the Edit drop-down menu. A dialog box (shown below) will then be displayed, which a sks you to confirm the deletion - the purpose of this being to reduce the chances of accidental delet ion.

Note that if you press the Delete key and nothing happens, it will most likely be because the flowsheet is currently locked. In this case, click on the Lock button ( ) and try again. Add the Final Product Icon

Step 6

Lastly we will add a Final Product equ ipment icon to the flowsheet. This icon is located under the St orage / Transpor t heading and is added in the same manner as any other equipm ent unit. The Final Produ ct icon is optional but the stre am which feed s it is essential. This is where the product data are stored.



Lear ning JKSim Met

Copying Equipment Units

67

Multiple units may also be added by placing a single unit on a flowsheet in the normal manner, then selecting this equipment item by clicking once on it before copying and pasting to wherever else it is needed on the flowsheet. There are many alternative ways to achieve the copy and paste operation. Copying can be done by pre ssing Ctrl and C or by click ing the Copy butt on ( ) on the tool bar. Alternatively you can select Copy from the Edit menu or from the rig ht-click menu (with the mouse cursor placed over the equipment item in question). Multiple units may then be placed on the flowsheet by performing a paste oper ation at locations where the extra units are required. Again this can be achi eved in a number of ways; by pressing Ctrl and V, by clicking the Paste button ( ) on the toolbar or by selecting Paste from the Edit menu or from the right-click menu. Another method of copying existing u nits is to select the unit, hold down both the left mouse but ton and the Ctrl key while hovering over the unit and then with both these held down, drag with the mo use to the location where you require a copy to be placed . Letting go of the mouse button will then drop a copy into this position. Which of these methods you use is a matter of preference.

Position Equipment

Equipment units may be mov ed a round the flowsheet window, providing that the flowsheet is not lock ed. Simply place the cursor over the equipment to be moved, click & hold dow n the left mouse butt on and drag this equipment to your preferred location. Now release the mouse button to drop the equipment into its new position. If there are streams attached to the equipment, they will remain attached while the equipment is being moved. You may sometimes need to modify the route taken by the streams associated with equipment you have moved, for aesthetic reasons or to restore clarity to the flowsheet. The manipulation of streams on your flowsheet is covered under the next topic.

Change Equipment Appearance

You can also change the appearance of individ ual equipment items. Double click the equ ipment on the flowsheet or rig ht click an d select Properties from the right -click menu to bring up the Component Properties wind ow. You can then use the Line and Fill tabs, to mo dify how this equipm ent appears on the flowsheet. For instance, the fill colour, outline thickness and outline colour may all be altered using this function. You can click Apply t o check the



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appearance after your changes wh ile the Component Properties window is still open. Name Equipment

The equipment can be named and labelled for ease of identification. Steps 7 and 8 detail the procedure for naming and labeling equipment. Step 7

Ensure the flo wsheet is unlocked. Place the cursor over a n item of equipment and double click to open the Component Properties window for that equ ipment. The Name field will be activated by default on opening this window. Type in the n ew equipment name, and then click OK. For this exercise, name the equipment items as shown in the illustration be low. Remember that the Component Properties wi ndow may also be accessed by right-clicking on an equipment unit and selecting Properties from the pop-up list.

Label the Equipment

Step 8

Remove or Reposition a n Equipment

The labels for individual items of equipment may also be removed if desired by double-clicking on the equipment, selecting the ‘Auto Labels’ tab and unchecking the ‘On/Off’ check-box. This enables the user to only display selected equipment labels. In the above flowsheet we have disabled the equipment labels for the two water addition units.

Label

Once yo u have defined the names, click on the Equipment Auto Labels bu tton or select the Equipment Auto Label it em from the View menu. The labels will then appear on the flowsheet above the equipment. To remove these labels click on the Equipment Auto Labels button again or select this item f rom the View menu again. These are equivalent and both act as on-off toggles.

Auto labels may be formatt ed by selecting ‘Equipment Auto La bel Properties’ from the ‘Edit’ pull-down menu. This option allows changes to font size, style and colour, as well as allowing changes to the back ground colour and line thickness and colour of the equipment label itself. Equipment label s can be moved by double click ing on the unit or the label . In the resulting Component Properties dialog box, choose the ‘Auto Label’ tab an d change the position of the labels by select ing from the optio ns under the Auto



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Label Position heading. Change the Feed Direction (The Flip Buttons)

The orientation of equipment can be cha nged so that the feed end is facing left or right, as required. In the next step you will ch ange the feed direction for the ball mill and its pump on your Learner Flowsheet. Step 9

Ensure the flowshe et is unlocked. Place the cursor over the ‘Pump Sump’ equipment item and single click to select. Click the ‘Flip Vertical’ button on the toolbar to create a mirror image of the equipment. Repeat this sequence for the ‘Ball Mill’.

Note that the Flip Horizontal button would be used less frequently since most equipment icons are designed to look recognizable in their default orientations. However, for some icons (e.g. the wa ter feeder), flipping horizontally does not make them look odd and it may sometimes be useful. Auto Save Function

The first stage of building the flowsheet is complete and the flowsheet should look similar to the one shown below. Remember to save the project regularly. Note that JKSimMet has a n auto sa ve function that will sa ve the current project approxi mately every 3 minute s. This is done in the backgr ound and the user should not noti ce it happening. If for some reason the prog ram crash es, the auto save d project can then be opened on re-starting the progr am and saved with the appropriate file name.



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Tips for Adding Equipment

The size (and proportions) of an equipment item on a flowsheet can be chan ged if required. After clicking on the item to select it, a series of grey squares will appear around its perimeter. If the cursor is placed over one of these squar es, it will change into a short line wit h an arrowhead at each end. When this cursor appears, hold down the left mouse button and drag to change the size of the item. Note that if you drag one of the corner squares, both the height and width will be modified s imultaneousl y. Also when you use a corner square, if you hold down the Shift key while you are dragging the mouse, then the existing height/width ratio will be maintained.

Matching Equipment Dimensions

When equipment has been resized it is possi ble to match other pieces of equipment to the same size. Select the different sized pieces of equipment by holding down ‘Ctrl’ or ‘Shift’ and clicking the desired items. Once selection is completed, there are three buttons on the toolbar that can be used to resize the equipment. These are the ‘Same width’, ‘Same height’ a nd ‘Same s ize’ buttons. The selected equipment will all be resized to match the item of equipment surrounded by the grey squares. This means that the item with the requ ired dimensions has to be selected last. If selected first or anywhere else in the sequence, it wil l not have the grey square s a round it. Note however, that if you forget and select it first, you can simply select it again at the end of the sequence - without having to start the selection sequence all over again.



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Along with the ‘Flip Ver tical’ button and ‘Flip Horizontal’ buttons discussed earlier, there are a number of othe r buttons in JKSimMet that can be used to change the orientation of a particular piece of equipment. These butt ons are also located on the Draw toolbar and are the 'Rotate', ‘Rotate Left’ and ‘Rotate Right’ buttons. The Rotate Left a nd Rotate Right buttons will rotate the selected item anti-clockwise and clockwise respect ively, by 90 degrees, each time you click on them. Intermediate angles of orientation can be achieved using the Rotate button. When you click on this button and then move the mouse over selected you seehold the down cursor shown cursor to onethe end or one item, side of thewill item, the leftbelow. mouse Move butt onthis and drag around in the direction of the rotation required.

Aligning Equipment Items

If the user wants to ensure t hat several pieces of equipm ent on the flowsheet are exactly aligned with one another, ther e are a n umber of tools for doing this. There are six buttons on the Draw toolbar for aligning equipment tops, middles (horizontal), bot toms, left sides, centre s (vertical) and right sides. To use the align tools, sele ct the equipment to be aligned by press ing ‘ Ctrl’ while clicking with the mouse on the desired items. Again, the piece of equipment surrounded by grey squares is the one to which the rest of the equipment will be aligned and thus it need s to be selected last. Once your selec tion is made, press the desired align button on the toolbar.

Spacing Equipment Items

Different pieces of equipment may also be evenly spaced both horizontally and vertically from one an other. To do this, select multiple piece s of equipment in the usual way and press the ‘Space acro ss’ or ‘Spac e down’ buttons on the toolbar.



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Moving a Group of Equipment Items

If you wish to move a whole block of equipment items, you need to first select them as a group by dragging you r mouse around them with the left button depressed. Each unit inside the area you have delineated will now be surrounded by squares to indicate selection. The units highlighted in this way can be mo ved as a group by clicking and dragging any one of the selected units.

Adjusting Equipment Positioning

As an alternative to the gross movement of an equipment item that is normally achieved through clicking and dragging, very small adjustments to the location of an item can be achieved using the ‘Nudge’ functio n. Select the item and then use the appropriate ‘Nudge’ button on the toolbar to move it a very small amount in the required direction. This function is particularly useful immediately after you have a dded the connecting streams. When first added, sections of the streams may not be perfectly orthogonal. This can be rectified by nudging the equipment one or more times as required, in the appropriate direction.

4.2.5

Add Connec ting Streams Add Streams to the Flowsheet

The next ste p is to create streams to join the equ ipment units that have been placed on the flo wsheet. Note that for the flowsheet to operate correctly, all input and output ports must have feed and product streams respectively connected to them.

AddStre am s

Ste p1

The flowsheet must be unlocked in order to add streams. To begin the stream connection: Move the curso r to a position over the fee d or product port of the equipment to whic h a stream is to be connected, in this case the product port of the Feeder equipment. Note that product ports are shown as red dots and feed ports as blue dots. When the stream cursor cha nges into a circle containing a cross, click the left mo use button. One end of your stream will now be attached to this equipment item.

Step 2

To complete the stream connection: Move the cursor to the feed inlet or product outlet (as appropriate) of the equipment item that is to be at the other end of this stream. You must connect product po rts to feed ports (or vice versa). You cannot connect a feed port to another fe ed por t and the same applies to product ports. In this case you will move the cursor to the feed inlet of the pump sump. When the cursor is close enough for a connection to be made, it will change back into a circle containin g a cross. When this happens you can click the left mouse button again and the connecting stream will then be drawn on the flowsheet. Streams may be connected direct ly from an outlet to a n inlet (or vice versa) in a straight line, as would be the case following the



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instructions above. Often however, you will need to make the stream lines fol low a more complex pa th to a void drawing them over the top of other items of equipment or over other stream lines. Als o, for a neater prese ntation, you will probably want to have your stream lines generally follow an orthogonal pattern on the flowsheet, rather than being oriented at many different angles. This is easily achieved as follows: Stream

Once you have connected one end of a stream, you ca n insert points

Inflexion Points

of inflexionitem to control the route to its destination of equi pment. To dothat thisthe youstream simplytakes click the left mouse button at intermediate locations where you wish to have the steam change dire ction. Each time you do this, the stre am will be anchored at the current cursor positio n and you can then mov e the mouse in a n ew direction, either to make furt her points of inflexion (as required), or else to the connection port on the target equipm ent item. You can later move the points of inflexion, if required. When you hover the mouse cursor ove r a n inflexion point, you will see that it changes to a little square with tiny arrow heads pointing awa y from each side o f the square ( ). You can now hold down the lef t mouse button and drag to the required new location. Further points of inf lexion can also be added after the stream is completed. Start by selecting the stream and then hovering the mouse cursor over the straight line part of a stream where you wish to place the new point of inflexion. The cursor will initially ha ve the symbol that indicates the stream can now be mo ved ( ). However, when you hold dow n the Control ke y, the cursor will change to indicate a new point of inflexion can be inserted ( ). Now to complete the insertion, just left- click the mouse. You can delete po ints of inflexion if you ha ve added more than you need. This is achieved by first selecting the stre am and then holding down the Control key as you hover your mouse ove r the point you wish to delete. When close to an inflexion point, the cursor will chan ge to a cross ( ) and you can then left-click to complete the deletion. The s tream will revert to a straight line joining the points on either side of the one deleted. Step 3

Repeat ste ps 1 and 2 to cont inue connecting the streams in the flowsheet until the flowsheet looks similar to the one shown below. For the Cyc O/F stream, follow the normal procedure but simply double left click when the end of the stream is where you want it.



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Feed ports can have multiple streams connected to them. The maximum number of feed streams able to be connected to any equipment unit in JKSimMet is currently 50.

Tips for Stream Connection

Product port s can only have one stre am connection. If a product port already has a stream attached and you are attempting to connect anothe r, you will find that the cursor does not change to give it's norm al "connection available" signal a s you approach this port. Clicking the mouse over this port will not make another connection. If you have changed the locati on of a unit or a stream node and you then find that a ver tical section of stream is no longer quite ver tical, you can usually fix this by moving the equipment that it comes from slightly. The Nudge buttons 72 hav e been provided to make it easier to achieve this. If moving the equipment slightly doesn't correct the problem, a small adjustment to its size probably will. To conne ct to a unit, a stream must go all the way to the relevant product or feed port. You cannot connect a stream into another stream that is already connected to the required port. However, new streams may partiall y follow the same path to that port, giving the appearance of a stream to stream connectio n. Errors in Connecting Streams

JKSimMet will not allow connecting streams to be drawn that could not exis t in a real plant. For exam ple, JKSimMet does not allow s treams to be drawn from one product outlet to another.

Redraw

Note that streams will remain attached if equipment un its are moved a fter they have been connected by streams. Be aware howeve r that this may resu lt in an incomplete stream display upon compl etion of the move . In this case you can use the correct Redrawany button on the Flowsheet toolbar to redraw your should problem s tha t might have become evident as flowsheet. a result of This your editing.

Naming the Streams

When you create new streams on a flowsheet, they will all be allocate d names automatically by the program. However, these names may not be very meaningful to you. Thus it is recommended that you change the names so that they will be easily recognised du ring data analysis a nd later when they appear in your reports. Step 4


Double cli ck on a stream or right click on the stream and select


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‘Properties’ from the right-click menu. This will open the Component Properties window. Typ e in the new stream name then click OK. Repeat f or all streams. Rename the s treams as shown in the screen grab below. Adding Labels to the Streams

The nam es that you allocate to the str eams can be made to appear on your flowsheet as stream labe ls (see below). To do this, click on the Stream Auto Labels button or select Stream Auto Label from the View menu. Note that a gain, both the menu item and the button act as toggles, so clicking eithe r a gain will make the labels disappear. The Stream Auto Labels m ay be formatted by selecting Stream Auto Label Properties from the Edit pull-down menu. This option allows changes to font size, styl e and colour, as well as allowing change s to the back ground colour and line thic kness plus the colo ur of the stre am label itse lf. The screen grab below shows our flowsheet with both the Equipment and Stream Auto Labels switched on.

Location of a Stream Label

Individual stream labe ls can be moved to one of s everal alternative locatio ns relative to the stre am line. For instance the Cyc Feed stream labe l above has been re-set from the default location so as to be closer to the cyclone. To change a label location, first double click on the stream or the label to open the Component Properties di alog box for that stream and then select the Drawing tab. You can then change the position of the stream label by selecting from the various options under Auto Label Position.



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A further addition that can be made on this tab is to add an arrow head to indicate the direct ion of flow of a stream. If you wish to do this, click the On/ Off box in the End Arrow section and click OK after selecting the desired arrow head length and width. Hiding

Note that on the Drawing tab of this dialog bo x, there is also the option of not

Individual Stream Labels

displaying the s tream label for the selected stream . If the On/Off check box to the left of the position radio butt ons is unchecked, then the label for this stream will no long er appe ar when the Stream Auto Labels tog gle is switched on. If there are a number of stream labels that you don't wis h to ha ve displayed, then you can arrange this by first doing a multiple selection of the streams concerned. Then just select Properties from the right click menu and uncheck the On/Off check box.

Changing Stream Line Appearance

Changes can be made to both the thick ness a nd colour of s tream lines. Again double click on a stream in the flowsheet and select the Line t ab in the Component Properties dialog bo x. If you change the s election for either one of these properties, you will see that the Apply button will become activated. If you wish, you can use this button to check the effect of the change you are proposing to make , without closing the dialog bo x. Note however that pressing cancel will not undo this change. If you are not happy with the modified appearance, then you need to click on the line width or style that was srcinally selected, before you pressed the Apply button. Alternatively, if you are confident that your selection will give the desire d result, you can just click on OK to close and keep your modifications.



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Delete a Stream

Streams can be deleted in the same manner as equipment. First ensure the flowsheet is unlocked and single click on a stream. Press the ‘Del ete’ key or select ‘Delete’ from the ‘Edit’ pull-down menu. A dialog box will be displayed asking you to confirm.

Text Boxes

To add labels that are not associate d with any streams or equipment, click the Text but ton and then move the cursor onto the flowsheet. A single click will place a text box on the flowsheet. The size of the box can be adjusted by clicking on and dragging the handles, when the t ext box is selected. The text within the box can be alte red by doub le clicking the box and entering the desired text. Pressing the ‘Enter’ key completes the text addition. The appearance of a text box can be changed by rig ht-clicking on the box and selecting ‘Propert ies’. The resulting Component Properties window allows the user to change the text f ont, col our and size, as well as the box fill colo ur, line style and line thickness. Text boxes may be removed in the same manner as equipment – single click the text box to select it an d press the ‘Del ete’ key or select ‘Delete’ from the ‘Edit’ pull-down menu. The orientation of text boxes can be chang ed in the same manner as equipment by selecting the ‘Rotate’ of ‘Flip’ buttons from the toolbar. Note that if you edit the text from within the Properties window (as opposed to editing dire ctly in the text box) , when you subseq uently close the Properties window, theYou textcan box will automatically to neatly accommodate the revised text. over-ride this a uto sizresize ing h owever if you wish; just s elect the text box and drag on one of the selection handles to modify its size. Step 5


Now add a text box to y our flowsheet and edit the text so that it just contains the name of this flowsheet (Learner Flowsheet).


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The flowsheet required for this exercise is now complete. At this s tage it is advisable t o lock the flowsheet by clicking on the Lock button or by selecting Lock from the Flowsheet sub-menu. When the flowsheet is locked, addi ng and removing s treams and equipment in the flowshe et is not possibl e. Locking a flowsheet also allows users to access the equipm ent data. Saving the flowsheet at this point would a lso be advisable.

4.2.6

Define System Prop erties Once your flowsheet has been finalised with all equipment in place and connected by streams to form a circuit, the data a ssociated with this flowsheet can be entered. The first step is to define the s ystem property class es required for a particular flowsheet. Open System Properties

Step 1

Ensure the flowsheet is locked, then click on the System Properties button ( ) or select System Properties from the Flowsheet menu. Note that if the flowsheet has not been locked, then Lock should be the only available ite m on the Flowsheet menu. Click on the Lock item and then select the Flowsheet me nu again. The other items should then be available. The System Properties window when first opened, should look similar to the one sh own below.



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You will noti ce there is a Select property drop-down at the top of this w indow. The system properties are divided into two categories, Elements an d Miscellaneous. When the window first opens, Miscellaneous is selected as the default. With this item selected, the two parameters to be configured are Solids SG and Liquid SG. The se are required for the comminution modelling functions in JKSimMet. Change t he Solids SG value to 2.8 and leave the Liquid SG value on the default setting of 1.0 for water.

Close Syste m Properties

Step 3

Set the Sieve Series

Step 4

Click on the Close button to close the window. Remember to sa ve your project regularly. The next ste p is to set the series of screen sizes that will be used for this project. Again select the Flowsheet m enu and the next item down from System Properties, which is Sieve Series.

A window similar to the one shown below will then open, which will already have a default sieve series listed.



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You would normally need to change this default series into something more appropriate. You can make this change by typing in the individual values or you can copy and pa ste a series of values. Note that unless you are us ing the copy and paste method, you will fir st need to type a zero in the Size 1 cell (immediately below top-size), before typing in your new top-size value; otherwise it will just return to the default of 200 when you press the Enter button. To copy in a series of val ues from a spreadsheet or from another JKSimMet file, first select the list of values and copy them onto the clipboard. Then back in JKSimMet, select the Top-size cell and press the Paste b utton ( ) or C trl V. Th e program wi ll automatically place a zero below the last size paste d and will grey-out all sizes below this. Another alternative is to type in a top size and then press the root 2 button ( ) located in the toolbar above this li st. This will cause the program to fil l in a root 2 series below the entered top size. Note again that you need to t ype a zero into the Size 1 positi on before a new top-size value can be enter ed. Once you put in the required topsize, press the root 2 button and a root 2 sieve series will be inserted. This will extend right to the bottom of the available aperture definition rows. To complete the sieve series definition, you will now need to type a zero below the smallest aperture in your sieve series. This will once a gain grey-out all of the fields below this siz e. Note that there is space for adding as many as 40 sizes, but it would



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be rare to need anything approach ing this. You sh ould now enter the v alues sh own in the s creen grab below.

We are ju st goi ng to use the one sieve series for all streams in this case. The program does allow for you to use different s creen sets for different streams for data input but the M aster sieve series is used for balancing, f itting and simulating. The two buttons to the left of the root 2 button are for adding or deleting additional columns of sieve sizes. Note that you cannot delete the Master sieve sizes column - there must always be at least one set of sieves for any project. In cases where y ou have added an extra column of siz es, the Stream table to the rig ht allows you to select wh ich of the alternative sieve series is to be used for the different streams in your flowsheet. When you press the OK but ton, you may get a warning like the one below.

Its purpose is to rem ind you that if you did have any data already entered, changing the sieve series being used will result in the resetting of your entered data to zeros.

4.2.7

Feed er Equipment Data In JKSimMet the feed s tream data are actually entered in the feed equipment rather than as a ‘feed stream’. Note that the s ystem proper ties have a lready been defined via the System Properties window. In this section, data will be entered for the Feeder equipment



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Open Equipment Window

Step 1

Ensure the flowsheet is locked, then double click on the feeder equipment item in the flowsheet to open the Equipment window. This window will appear similar to the one illustrated by the screen grab below.

Enter the Totals Tab Data

Step 2

By def ault the Totals ta b is selected when this window opens. Enter the numb ers shown in the whit e cells of this screen grab. Don't worry about entering any data in the SD or Bal data columns at this point.

Data Field Colour Conventions

General Note: Ther e a re three different background colours used to indicate the different categories of data present in the JKSimMet windows:

Enter the Sizing Data

1.

White – the user is required/permitted to enter data (e.g. feed tonnage).

2.

Light grey – these data cannot be changed (e.g. labels).

3.

Medium g rey – user entry is not re quired but th e data will change depending on a user selec tion or calculat ion during simulation (e.g. TPH water).

Step 3

Now click on the Sizing data tab and the windo w will chang e to something like the one below; except that all the Exp column values will be init ially set to either zero or 100. Now enter the experimental values for t hese sizing data, as shown below. Note that you can enter these data using the normal Ctrl C for the copy operation in Excel, followed by Ctrl V for the paste operation in JKSimMet, on ce you have selected the top cell of the sizing data range. Note however, that in order for the data you enter to be interpreted correctly, you must ensure the appropriate butt on is selected on the main tool bar, so that it matches the fo rm of the siz ing data you are pas ting o r typing in . The alternatives are % retained (

),

cumulative % r etained ( ) a nd cu mulative % pa ssing ( ). In this case we are typing in cumulative % passi ng data, so make sure the app ropriate button ( paste operation.


) is selected before performing the


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For this exercise, there is no requirement to fill in data on the othe r two tabs. These tabs are for the entry of assay data and such data are n ot needed since here we are carrying out a comminution simulation exercise. Once more you should s ave your project at this point.

4.2.8

Select Equipment Models After the system pr operties have been defined and the feed s tream data has been entered, the mo dels for each equipment unit sh ould be selected and the relevant pa rameters entered. The Equipment and Model windows contain all of the information a bout the equipment that JKSimMet requires to perform a simulation task. As discussed in the pre vious section, the Feed eq uipment unit is a special form of equipment in which the actual feed stream data are entered. Open Equipment Window


Step 1

Ensure the flowsheet is locked then click on the Equipment icon on the tool bar or select Equipment from the Flowsheet sub- menu to open the Equipment wi ndow. This window can also be opened simply by double clicking on a ny equipment un it in the flowsheet, in which case the ite m of equipment you have clicke d on will be selected by default from the Equipment Name drop-down list.


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Select the Ball Mill

Step 2

Begin by sele cting the Ball Mill from the Equipment Name dropdown list, if it is not already selected.

Select Model for the Ba ll Mill

Step 3

Click on the Equipment Model drop-down list to access the model choices for the Ball Mill and select the Perfect Mixing Ball Mill model. See under the Model Descriptions 360 to pic for further details on the wa y this model works, including a description of the parameters as sociated with each tab.

Perfect Mixing Ball Mill Model

Step 4

Click on t he double arr ow bu tton ( ) loc ated to the ri ght of the Equipment Model drop- down list to access the data for the Perfect Mixing Ball Mill model.

The Perfect Mixing Ball Mill model data input scree n is shown in the scre en grab above. The first tab (which is selected by default when the window opens), is the Scaling tab. On this tab you enter the dimensions of the mill to be simulated, its rotational sp eed (expressed as the fraction of critical speed), the loading of the mi ll, the wo rk index of the ore being tre ated and the ball top size. Default values are prov ided for each of these items when this window is first opened. For this exercise, you should modif y the default values to lin e up with the values displayed in the white cells of the screen grab above. On this tab it is possible to scale up (or down) in cas es where the parameter fitting has been done for a different sized mill to the one that is specified in the Building a New Project


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current flowsheet. This is the purpose of the right han d table under the Original Millheading. Ball Mill Perfect Mixing Model Rate/Discharge Function Tab

Step 5

The second tab is the Rate/Discharge Function tab. The values on this tab are the fitt ed parame ters for the milling operation we are about to simulat e. In this case we will again leave these value s at their default settings. Note that you have to close the equipment a nd model parameter windows by just clicking on the cross at the top left corner . There is no Save button on these theyou enterpress ed values will remain in memory and willwindows, be saved but when the Save button on the main window toolbar or else wh en you close the file (provided you elect to save it when prompted).

Water Feed er for Ball Mill Cyclone Fee d Bin

Step 6

Double-click now on the water feeder associated with the cyclone feed sump. This will bri ng up the Equipment windo w for a water feeder. The screen grab below shows this window activated with the Equipment Model drop-down expanded.

For the mo del we will select the Required % Solids model. After you have selected this from the drop-down, click on the double arrow button beside this list to access the properties of the chosen model.



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For this model, the only value to be entered is the required % solids value. We will select 58% a s the required % solids, wh ich will then be the pul p density of t he feed to the ball mill cyclone. Close the equipment window for the wa ter feeder. Water Feed er for Ball Mill Feed Stream

Step 7

Now double-click on the Ball Mill Feed water feeder a nd perform the same sequence, this time selecting 73% as the required % solids value. With this model and this parameter value selected, the water flow will be adjusted during the simulation so as to achieve 73% solids for the pulp density of the total fee d to the mill. Close the equipment window for this water feeder.

Cyclone - Mode l Selection

Step 8

Finally, we need to select the model and set the operating parameters for the cyclone. Double click on the cyclone icon on the flowsheet and you will bring up an equipment window for the cyclone, as s hown below.

From the Equipment Model drop-down, select the Narashi ma/ Mainza mode l as the model to be used. Once you have made this selection, click again on the double-arrow button to set the parameters for this mode l. Enter the cyclone dimensions and the other operating variables on the Operating Conditiontab as shown below.



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Cyclone Mode l Setting Parameters

Then select the Model Parameters t ab and enter values as indicated in the following screen grab. Once these are entered, close the model parameters window for the hydrocyclone.

Models have now been selected for all of the equipment and the flowsheet is ready to be simulated. Remember to sa ve the project.

4.2.9

Simulation Now that your flowsheet has been set up with models assigned to all appropriate equipment items and values ha ve been entered for their relevant parameters, you can proceed with a Simulation of this circuit. Open the Simulate Window


Step 1

Ensure the flowsheet is locked and then click on the Run Simulation ic on (large icon in left panel toolbar) or select Run Simulation f rom the Flowsheet m enu to open the Simulate window. This window together with the main window behind it, is shown in the scree n grab below. All the equ ipment ite ms and


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streams a re highlig hted in heavy blue to indicate that they a re all initially selected.

You will notice that by default the Simulation Select List dropdown displays 'Whole Circui t'. Initially this is the only select list available. You can however a dd your own select lists if you wish to simulate certain parts of the circuit in isolation. For this exercise however, we will be simulating the whole circuit only. Note that the check bo xes for selecting and de-selecting individual items of equ ipment and streams can only be modified once you have defined (and selected from the drop-down), your own partial circuit for simulation. When defining a partial circuit, you will notice that as you select streams or equipment items from the list, they become highlighted on the flowsheet (in heavy blue), to indicate selection. A partial cir cuit consist ing of the cyclone a nd its feed and product streams is s hown in the screen grab be low. If you try this, be sure to select the Whole Circ uit fro m the drop down box before continuing.



Lear ning JKSim Met

Adjust the Simulation Settings

Step 2

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In the Settings region, you will see that the def ault Convergence limit is set at 0.00 000 01 a nd the default number of Iterations value is 1 000 . Both of these values can be left at their default sett ings. The Interpolation can be left as Spline and the Starting Condition as Experimental.

Run Sim ula tion

Ste p 3

Click on the Start button to start the simulat ion. It also display s the convergence value and the number of iterations that the simulation algorithm has performed to reach convergence, see below. These values are updated while the simulation is proceeding.

Completed Simulation

The iteration count will proceed until either convergence to the defined convergence value has been reached, or the maximum number of iterations has been reached , whichev er occur s first. This flowsheet should simulate to convergence in about 70 or s o steps, if set up as described.

Close Simulate Window

Step 4

The sim ulation of this flowsheet is now complete. To close the Simulate window, click on the cro ss in the top right hand c orner of the window.

4.2.10 Viewing the Results The results of the simulation can be viewed in the Configurable Stream Overview window. This window allows the user to view the s tream statisti cs calculat ed during simulation for one or more selected streams. The user can choose which data and which streams are displayed. However, when you first open this window, all the str eams in your flo wsheet will be listed by default. You can either modify this view of the data or add other alternative views that you can build to satisfy your own requirements. Open Configurable Stream Overview


Step 1

Ensure the flowsheet is locked, then click on the Configurable Stream Overview ic on or select Configurable Stream Overview f rom the Flowsheet me nu. The Configurable Stream Overview wind ow will then open. The window will look something like the screen grab below. From the Select List drop-down, you can select the type of


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data you wish to view. In this case we wish to vie w the simu lated data, so select 'Stream Data (Sim)' from the drop-down. Note that the scre en grabs below are incorrect in one respect. The grabs were taken from an earlier test version of the program and the cells in some of the simulated data columns appear white. In fact all columns containing simulat ed data should be grey , to indicate they cannot be edited.

The Func tion of the Lock Button

Adding Columns and Rows

Some aspects of this table 's layout can be modified. The Lock b utton( ) on this Window's toolbar acts as a toggle that determines the functionality of certain actions in terms of the table configuration changes that can be achieved. If the Lock button is down, you can add colum ns and rows to the tabl e. Also with the but ton in this position, click ing on a column header will bring up a dialog box for setting up the contents of the selected column. If the Lock button is up, clicking on the colum n headers does n ot ha ve the aforementioned a ffect, but it will allow you to make changes to the orde r of the columns and the same for the rows. Step 2

In this exe rcise we are going to add two extra columns. To achieve this, the Lock button needs to be in the down or locked positio n, but this should alread y be the case when you first ope n this window. First clic k somewhere within the % Solids co lumn to select this column. Note; don't click on the title of the column as this will bring up the dialog for sele cting the content s of the column. Now use the Insert Column t oolbar button ( ) to add a column. The new column will be added to the right of the currently selected column.

Adding a Column to Display Volume Flow


Step 3

Initially, the new column will just h ave 'No Select ion' as its column header. The next ste p is to set up this column with the inform ation that you req uire it to display. Clicking on the column header will bring up a dialog box where the cont ents of the new colum n can be specified.


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In this case we want a column showing the vo lume flow in each of the streams. We will leave the Selection Name set on 'Auto Generate'. Unchecking this check-box allows you to enter your own name for the column - whic h may be useful if you have lots of columns to display and want to make the headers more concise. In this case you need to select the options as per the above screen grab and then click on 'OK'. Adding a Column to Show Solids Amount Above a Selected Size


Step 4

We will add a further column now to demonstrate another feature of the Selection Options window. Click within the new volume flow column to select it, then again use the Insert Column b utton ( ) to add a further column to the right of the one selected. Again click on the tit le bar of the new column to bring up the Selection Options window. We will assum e that for some reason we want to see how much of the or e in each stream is coarser than 4.75 mm. Again click on the header bar f or the new column. When the dialog box opens, select Size for Option 1, and you will find that anot her dialo g box will appear.


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Select 4.75 mm from this dialog. When you press OK aft er this selection, the value 4.75 will be displayed in the grey box to the right of the Option 1 dro p-down and Option 2 will become available for selection. Select 'View As' from the Option 2 drop-down.

This will bring up another dialog box from which you should select 'Cum % Retained'.



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Finally, after you have selected 'Cum % Retained' for Option 2, a drop-down will become available for Option 3. Here you need to select 'Simulated' for the data type that will be displayed.

When you OK this selection, the overview will look something like thecoars one er below, a new showing is than with 4.75 mm in column each of the streamthe s. amou nt of solids that



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Stream Order and Column Order Changes

Step 5

The or der that the stream names appear in this table is the same order in which their ass ociated equipment items were added to the flowsheet when it was first drawn. To change this order, you need to first click on the Lock b utton - so that is in the up or unlocked position. In this exercise we will just move the Cyc feed Water down to the bottom of the table. Now click the left mouse button while hovering your mouse over the name cell for stream (row) that you wish to move (i.e. in this case the Cyc feed Water stream). With the mouse still over this row, hold down the left mouse button and drag this row to its new location. As you move the mouse, potential new locations will be mark ed by a red line. When you a re satisfi ed with the indicte d new positio n, let go of the mouse button and the required change will be complete d. The same method can be used to cha nge the relative location of columns in this table. The screen grab below shows the Cyc feed Water row in the proce ss of being moved.

Note that yo u can select multiple adjacent rows or columns by just clicking, holding down an d dragging - prov ided that the column or row you begin this process on has not alread y been selected. Once the req uired group of rows or columns has been select ed, you can then click, hold-down and drag a gain and this time the dragging process will move the s elected group into a new position, as indicated by the re d line. We have now set up an overview to show the results of our s imulation. For more information on the Configurable Stream Overview and its capabilit ies, go to the topic Using the Configurable Stream Overview 213 . In the real world, you would be looking at these simulation results and ass essi ng whether this circuit is achieving the required results and if not, considering what changes might be made to improve the situation. After an analysis of your simulation results, the circuit configuration could be altered and/or the capacity and characteristics of the equipment items changed before repeating the s imulation process. There may be several iterations of this sequence required before you are satisfied with the results being obtained. Finally, don't fo rget to save y our project afte r a session such as this, to protect against losing your work in the event of a power outage or other mishap.

4.2.11 Viewing Individual Stream Data A range of different stream statistics calculated during simulation can be viewed using the individual stream data windows.



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Step 1

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Ensure the flowsheet is lock ed then click on the Stream b utton ( ) or select Stream f rom the Flowsheet m enu to open the Streams window. This window can also be opened by right-clicking anywhere on the flowsheet and selecting Stream f rom the dropdown menu. All streams in the flowsheet can be accessed from the Streams window. The Streams window also shows the equipment items that the currently selected stream is flowing from and to.

Select Data to view

Step 2

The user can, from this point, choose to view the data for an y of the streams in the active flowsheet by first selecting the required stream from the Str eam Name dr op down and then clicking on the double arrow to the right of this drop-down to open the Stream Data window. An alternative method of getting at the Stream Data window for any individual stre am is to double-click directly on the line representing that stream on the flowsheet. This will open the Stream Data window for the stream dire ctly, without going first to the Streams window.

Stream Data Window


The layout of the Stream Data windo w is the same for every stream . A tabbed interface is used to display the different cate gories of stream data. The first tab shows the Total values for the stream, including the TPH Solids, the TPH Water, % Solids values and others. The other three tabs are labelled Sizing Data, Elemental assay data and Size by elemental assay data respectively.


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Click on any of the four tabs to view the data in the relevant categorie s. On each of the tab s, there are columns to show the types of data asso ciated with the parameters listed on that tab. F or example, on the Totals tab is a column for the SD (standard deviat ion) data. This is where a reliability estimate is assigned to the indiv idual parame ters that have been measured for this stream. Larger SD values indicate reduced confidence in the experimental value and allow the program to move further away from these values during balancing. Viewing the Sizing Data

Step 3

To view the sizing data, click on the second tab of the Stream Data window. The row labels will now be the screen sizes that have been previously entered. Note that at any time you can change the way the sizing data are expressed throughout the program, using the buttons on the main toolbar. The sizi ng data can b e expressed as e ither % Retained ( Retained (


) or Cum % Passing (

), Cum %

).


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On the other two tabs are the Elemental Assay Data and the Size by Elemental Assay Data. On these tabs, the data types displayed are limite d to Exp, SD, Mbal and Error. This is because in JKSimMet, none of the models deal with predictions of assay s and we are not generally dealing with processes that result in any differentiation in grade. Copying Data into Excel

Step 4

To copy data from the tab that is currently chosen, first select the required data, then cli ck on the c opy button ( ) located at the far right of the Stream data window toolbar - as shown below.

If you then open MS Excel, you will be able to paste the current data grid into the active sheet, with your chosen cursor position being the top left h and corner of the grid. Close Windows

To close the Stream data and Streams windows, click on Close( right hand corner of the windows.

)in thetop

4.2.12 Viewing Data for Multiple Streams The Configurable Stream Overview fe ature allows the user to view the stre am statistics calcula ted during simulation, mass balan cing or fitting for one or more selected streams. The user can choose which data types an d which streams are to be displayed. Opening the Configurable Stream Overview

Step 1

Click on the Configurable Stream Overview b utton ( ) to open the Configurable Stream Overview windo w. If no overview tables have been set-up previously, the window when first opened will still contain a default tab le with some flow and % solids data a nd all of the size fractions that ha ve been entered for the proje ct concerned. There are a number of pre-configured overviews with different combinations of data types. The user can select an app ropriate one of these via the Select List drop-down in the upper left-hand corner of the window. The screen grab belo w has captured this process, with the user in the process of making a selection.

If one of the pre-configured overviews does not satisfy your needs, then there are plenty of tools provided for modifying an existing overview or for creating a new overview and setting this up precisely to your requirements. Creating a New Stream Overview


Step 2

To create a new Overview, click on the New Stream Overview button ( ) w hich will bring up t he Add New Stream Overview dialog. Type a name for the new Overview here and then click on the OK button.


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The Configurable Stream Overview will then re- open with a default range of stream statistics as shown belo w. The user can then add or delete rows or columns to display only the required data for this particular overview. Note that data can be entered via the Configurable Stream Overview, in any cells that have a white background.

Remove Unwanted Streams

Step 3

Add a Data Column

Step 4

For the practi ce, we will assume t hat you don't wish to display the data for the Cyc Feed in this overview. To remove it from the display, click anywhere in this row a nd then click on the Delete Rows ( button.

)

To insert an extra column, click in any column of the table and then click on the Insert Column b utton ( ). This will add a blank column to the right of the cursor. The new column will just h ave "No Selection" a s the header and a ll of its fields will initially be grey; as illustrated in the scre en grab below. Note that you can also add a new col umn that is a replica of an existing column. To do this you click in one of an existing column's cells and then click on the Copy Column b utton ( ). Wh en you do this, a replica of the se lected column will be place d immediately to its right. This may be more efficient if the column being added is to be very similar to a n existing column, but with just the data type changed perhaps or the mode of display changed - e.g. from % Retained to Cum % Retained.

Define the Data Shown in a Column


Step 5

To de fine the data that is to be shown in the new column (or to modify what is shown in an existing column), click on the heade r row of the new column to open the Select Options dialog box. Select the required stream statistic from the Option 1 drop-down list. In this case select "%S olids", then from the Option 2 drop-down list select


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"value" and from the Option 3 drop-down list select the type of data to be displayed (e.g. experimental, simulated etc.).

Export the Configurable Stream Overview

Step 6

on the Export Overview b utton (

), or o n t he Export All button (

) if more than one stream overview exists. Alternatively, by clicking on the Copy Grid button ( ), the data can be copied to the clipboard for pasting into other documents (e.g. a Word document).

table Clone the Configurable Stream Overview table

The data presented in the tabl e can be exported to Excel by clicking

Note that the user is able to creat e clones of existing tables in the Configurable Stream Overview by clicking on the Clone Overview button.

4.2.13 Finishing a JKSimMet Session Ending the JKSimMet Session

Step 1

To qui t from JKSimMet click on the cross in the top right hand corner of the session window or select Exit fro m the File menu. A JKSimMet prompt will ask to save the changes if changes have been made and not yet saved. Click on "Yes" to sa ve any changes.

Simulation of the simple com minution circuit has been completed and the simulation data have b een examined. the next exercise operation of the circuit will be changed by varying the In parameters of somethe of the components, and then running simulations to observe the predict ed results. Before doing this, end the JKSimMet session as explained above.

4.3

Workin g with an Exi sting Proj ect About this Section


Now that a simple comminution circuit has been successfully simulated, this exercise will demonstrate how to:


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Change some of the input data and flowsheet configuration in an attempt to improve the performance. Re-simulate the circuit. View the results. The objec tive is to optimize the perf ormance of the circuit by changing key parameters. The parameters are those characteristics of the equipment or streams that can be altered . In a real plant most equipment parameters can be altered (with varying degrees of difficulty and with varying degrees of expense!). A few stream param eters such as the mass flow rate can also be varied. It is however difficult a nd costly to experiment with real equipment; simulation using JKSimMet allows the engineer to make a wide range of changes easily and then view the predicted results. The selection of these parameters is the engineer’s job and you m ay wish to experiment; this section will take you through the steps for a number of changes. The general technique is to first decide on the pa rameter cha nges you wish to make, then select the equipment concerned and make the changes, re-simulate the circui t and finally observe the result s. These result s can then be accept ed and saved as a permanent record; further changes can be made and the process of simulating and as sessin g the results repe ated.

4.3.1

Selecting the Flowshee t to Use The procedures used when working with an existing project are very similar to those outlined under the heading Building a N ew Project 59 . Sta rt JKSim Me t

Ste p 1

Start JKSimMet by following steps 1 to 4 under the heading JKSimMet Start Up 60 .

Load an Existing Project

Step 2

Click on the Open Project ic on on the toolbar or select Open Project fr om the File m enu. This will open the Open JKSimMet Project dialog, which displays the previously saved projects. Select the ‘Learner Project’ that was created while working through the Building a New Project section and then click Open.

Loading a Project when Another Project is Still Open

JKSimMet closes an open project before opening a different one. If opening a project is attempted when a nother project is still open, JKSimMet will prompt to save the open project where changes ha ve been made s ince the file was last saved. Step 3

To prevent the Learner Project from being overwritten, s elect Save Project As from the File list then type in the new project name ; for example use ‘Lear ner Proje ct – Changed Cyclone Params’ as the new name, and click OK.

Note however, that on occasions when you do wish to deal with two different projects at the s ame time, you can open a second instance of JKSimMet and then use this instance to open the second proj ect. It would be wise thoug h to avoid having the s ame proje ct open in both instance s. This could potentially result in problems - especially if you go to save data that may have been changed in both instances.

Working with an Existing Project


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Working with the Simulation Manager In this section the cyclone vortex finder diameter will be changed to see how this affects the s ize distribution of the final product from the grinding circuit . While the user can make this type of operating parameter change in the Equipment w indow or via the Info Blocks on the screen (see Defining Equipment Info Blocks 125 ), the Simulation Manager pr ovides a more convenient means of doing this, pa rticularly when several similar simulations are to be performed. Note however that with this version of JKSimMet, you cannot ch ange the feed rate to t he circuit from w ithin the Simulation Manager. This is because the Simulation Manager d eals with changes to model parameters as sociated with equipment items only. However, it is intended that in later versions the circuit feed rate will also be made available for modification via the Simulation Managerinterface. Open the Simulation Manager

Step 1

Click on the Simulation Managerbutton on the toolbar to open the configuration window for this feature. It will initially be blank as shown below and the first thing to do is to create a simulation scenario.

Create a New Simulation Scenario

Step 2

Click on the New Sim Scenario button to creat e a new simulation scenario. Type the name of the scenario into the dialog that appears and click on the OK but ton to access the blank scenario configuration screen.

When you click on OK, the initial framework for the new simulation scenario will b e set up. This will have a single column, with "No Selection" as the header. Configure the Simulation Scenario


Step 3

To begin configuring the new simulation scena rio, click on the "No Selection" header and a new dialog will open labelled Equipment/ Tab/Option/Parameter. This dialog appears as shown below.


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Selecting the Parameter to be Changed

Step 4

In this case we will select the cyclo ne from the Equipment/Group drop-down, then Operating Condition from the Tab drop-down. The Option drop -down is not rel evant in this case and will not be available. From the Parameter dro p-down we will select Vortex Finder Diameter - Do (m).

Once you have made these selections, click on the Apply button at the bottom of this dialog. The Simulation Managerwindow sh ould look similar to the image below. You will notice that now the Simulation 1 cell for the cyclone parameter we have selected is available for data entry.




Selecting the Type of Change and Specifying the Amount of Change Required

Step 5

103

The new simulation conditions can now be entered in the Cyclone column. You will see that just a bove the Original Data label, there is an other row labelle d "Type of Change". There are two choices here. You can specify the actual value for t he parameter or you ca n specify a percent age change from the original value. In this case we will reduce the vortex finder diameter by 10% for one simulation and then in crease it by 10% for a second s imulation. By default the Type of Change wil l be set to "Valu e". Clic k on the drop-down and change this to "% Chan ge". Then click in the Simulation 1 ce ll for the Cyclone co lumn and enter "-10". This simulation scenario will be automatically sa ved under the default name "Simulation 1".

Adding a Simulation


Step 6

As we are going to b e doing tw o simulat ions, we need to add an extra row - in addition to the default Simulatio n 1 row. To do this, place the cursor anywher e in the Simulation 1 ro w and press the Apply Simulation button. An extra row will be adde d below the cursor position, with the default name Simulation 2. The new simulation conditio ns ca n now be entered in the Cyclone column in this cas e we will ente r the value +10, m eaning that we will be increasing the vortex finder diameter by 10% from its original value.


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Step 7

If you now place the cur sor anywhe re in the Simulation 1 row, pressing the Simulate Select b utton ( ) will run a simulation using the parameter changes that have been specified in this row. The same would apply if you placed the cursor in the Simulation 2 row - a simulation would occur with the sett ings specified in the Simulation 2 row only. If you pre ss the Simulate All b utton ( ), t he pr ogram w ill ru n simulations consecut ively on all of the scenarios you have set up. Note that only the resul ts from the last one of these simulations will be available for plotting. Note also that you can press the Simulate Allbutton from any one of the t hree tabs. This means that you can simulate with one of the result s tabs active a nd therefore immediately see the before and after values. The result s of the simul ations just performed can be observed on the next two tabs, Results - Streams and Results - Equip. You can set up these tabs to observe any results from the simulation that you wish to monitor. This is done in a similar fashion to the way you set up the Simulation Scenariotab

Set up Columns for the Results you wish to Monitor

Step 8

Click on the Results - Streams tab, create a new column by clicking on the Insert Column button. example of the Results - Streams tab is s hown below where the user is looking at the effect of the vortex finder chang es on the solid s flow rate in the cyclone underflow and P8 0 in the cyclone under flow.




105

Notice that the buttons for adding and deleting rows from the table are not av ailable when you are on either of the results tabs. You need to return to the Simulation Scenariotab if you wish to s et up further s cenarios for simulation. The buttons for adding columns however are available and these can be used to add any characteristics of the streams or equipment that you would like to monitor following s imulations under the various scenario s. Note that yo u do need to repeat the simulations if you add further columns because the cells in any new columns will be just populated by zeros until the simulations have been re-run. Step 9


Now select the Results - Equip tab, ad d a column and click the top row of the column to bring up the dialog for selecting the equipment and equipment parameters for display. Select Cyclone from the first drop-dow n, Perform Data from the second and Op Pressure from the fourth. Notice that the third drop-down (Option) is de-activated. It is only required for a very limited number of equipment types.


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When you click on the Close bu tton, another dialog box will appear where you select the types of data that you wish to display.

Once you have made the selection and closed this dialog, you will be returned to the Simulation Manager wind ow, which will now look something like the screen grab below.




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Rename the Scenario

Step 10

You can chang e the name of the scenari o easily by pressing the Rename Scenario but ton. This will bring up a dialog box like the one shown below. Change the name to something that will be more suggestive of what the current scenario has been set up to investigate - in this cas e perhaps something like "Cyclone Vortex Finder Changes".

Run a S imulation

Step 11

To continue the exercise, now press the Simulate All bu tton to

on the Selected Row


carry out simul ations according to the conditions set up for both rows. You will see that the cyclone operating pressure data will then appear for the two scenarios that have been defined on the first tab.


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Using Model Based Groups for Simulations Groups Principles of Use

Where you have multiple equi pment items that a re using the sa me model, you can a ssign these to a group which can then be selected instead of an individual equipment item. When this is done, any changes in the settings that you make to the equipment or mod el param eters for the gro up will apply to all of the equipment items assigned to that grou p. Once you have set up groups, these will become available as alternatives to just selecting individual equipment items from the top drop-down lis t in the Scenario Manager window. Note tha t the defining feature of a Group is that all members of the Group will be using the same model, with the same parameter settings.

Edit Groups Button

Step 1

In the Simulation Managerwindow, click on the Edit Groups button to bring up the Select Equipment for Groupsdialog.

Step 2

Click on the Add Group button a t bottom left of this dialog. This will bring up an Add New Group dialog wher e you can provide a name for the new group and then select from all possible models associated with the types of equipment that exist in your flowsheet.




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In this case we do not ha ve multiple equipm ent items using the s ame model, but we will go through the exercise anyway to demonstrate how it works. Step 3

Enter a name, such as " Perf Mix BM Group". This would be a group consisting of equipment items on your flowsheet that all use the perfect mixing ball mill model.

Note that y ou do not have to assign all of the equipment ite ms that use this model to this group. Some of them could be left outside the group to be set up individually for simulations. Alternatively, you might wish to have two groups. For instance you co uld have "Perf Mix BM Group 1" and "Perf Mix BM Group 2". Both groups would nece ssarily consist of mills that use the perfe ct mixing model, but each could be set up with different pa rameter values within any given simulation. Step 4

When you close the Add New Group window , you will s ee the new group you have added in the right hand panel of the Select Equipment for Groups wi ndow. This new group will initially contain no equipment items. When you click on it however, you will be able to see in the left hand pan el, all of the equipm ent items on your flowsheet that are cur rently set up to use the model as sociated with the selected group. Now use Ctrl or Shift cli ck on the equipment items from the left panel to select all of those that you wish to include in the group and then click on the trans fer button to move these items into the selected group. In this case there is only one equipment item - the ball mill. Click on this item and then click on the transfer button to move it into the "Perf Mix BM Group". Just prior to the transfer, the window should look similar to the one shown below.



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After the transfer, the window will look like the s creen grab below, now with the equ ipment item that was selected from the left pa nel, appearing in the right panel, under the selected group.

Now when you go bac k to the Simulation Manager window and click on the top row of the table, you will find that the group you have just added will be available for selection.




111

Note that once you have assigned an item of equipment to a group, you will no longer be able to select this item of equipment individually. This is because by definition, all members of the group will have the same parameter values. Similarly, once you have set up a column with a particular parameter selected for a given item of equipment, you will n ot be able to set up another column with the same equipment and parameter selections.

4.3.4

Simulating Changes in Operating Conditions In this exam ple we wil l look at the eff ect of increasing ore hardness and how JKSimMet might be used to investigate ways to compensate for this and thus maintain throughput at exis ting levels. Open the Simulation Manager Window

Step 1

Click on the Simulation Manager b utton ( ) to bring up the Simulation Managerwindow, then click on the Simulation Scenario tab.

Step 2

Click on the New Sim Scenario b utton ( ) to create a new simulation scenario. In JKSimMet, the term scenario is used to describe a group of related simulations that have been set up to investigate the effects of changes in a particular set of model parameters. The individual s ets of parameter values are just referred to as Simulations. We will call the new Simulation Scenarioin this cas e "Compensating for Ore Hardness Changes".



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Add a New Simulation Scenario

Step 3

Now click on the "No Select ion" at the top of the default column that will be pre sent on the Simulation Scenario tab. This will bring up the Equipment/Tab/Option/Parameter windo w. Note that you must have the Lock b utton ( ) in the do wn po sition for thi s dialog to activate. From the Equipment/Group dr op-down list, select "Ball Mill".


Step 4

Select Scaling fr om the Tab drop-down and then select Ore Work Index from the Parameter drop-down.

Step 5

When you click on the Close button from the above window, a Select Properties window will open. Her e you s hould just tick the checkbox for "Sim" since the Org (o riginal) values are only rele vant for when you are fitting - not for simulating.



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On closing this window yo u will find that the Simulation Manager now looks like the screen grab below.

Simulation 1 will be present because this is a default s imulation row that is added by the system. You can change the name of each simulation if you wish to something more indicative of the parameter adjustm ents that have been applied. To do this, you just click in the relevant cell of the Simulation Name colu mn and made the required editing changes. Add Simulation Rows

Step 6

Add Colum ns

Ste p 7

Next add two more columns by pressing the Insert Column button (

Step 8

Using the same pr ocedure as described a bove for setting up the first column, set up the second column for adjusting the fraction of critical spee d that this ball mill is operating a t. Similarly, set up the third column for adjusting the load fracti on for the ball load in this mill.

Step 9

Now chang e the name s of the simulations so that they prov ide an abbreviated specification of the parameter changes involved. Also enter the new parameter val ues in the columns, as shown in the

Add three more rows to this Simulation Scenario by pressing the Insert Simulation b utton (

) three times.

) twice.

screen grab below. For the first simulation we will just be looking at the effect of harder ore on throu ghput whe n there are no compensato ry plant changes made. We will call this simulatio n "Harder Ore" a nd change the Ore Index value from the or iginal 15.3 to 17.7 kWh/t. For the second simulation we will increase the mill speed from 74% of critical to 80% of critical an d for the third we will increase the mill load from 40% to 45 %. Finally, for the last simulation we will increase both the mill speed and mill load to look at the combined effect . N ote that the



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higher ore work index should of course be entered for all four simulations. The Simulation Manager wi ndow should now look similar to the screen grab below.

Step 10

Now go to the Results - Streams t ab and set up columns for the results you wish to obse rve on running these simulations. Say in this case we are just inte rested in the cyc lone U/F solids TPH, % solids and cyclone O/F P80. There will be one column present by default so you will need to add two m ore colum ns. Set these up in the sam e way as you have done fo r the columns on the Simulation Scenario tab.

Step 11

Once the columns have been set up for the results you wish to observe, click on the Sim All b utton ( ) t o si mulate each of the plant co nditions that you defined back on the Simulation Scenario tab. The Simulation Manager sho uld now look similar to the one shown below, with simulated outcomes for each of the sets of parameter values.




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We can see from the value s obtained abov e that with both changes applied to the mill operating conditions, the simulator is predicting that production can be returned to the level that existed prior to the ore hardness cha nge. Step 12

If we now go to the Results - Equip tab, we can have a look at what effect our operating parameter chan ges have had on the power consumption of the mill. When you click on this tab, there will be a default column in place - but again it will just have "No Selection" a s the r. Click on this cell and you will again be presente d with the heade Equipment/Tab/Option/Parameter window.


Step 13

In this window, select "Ball Mill" from the first drop-down and "Power" from the second. From the Parameter drop-down, s elect the total power item for an overflow ball mill.

Step 14

Note that after you have made the selection and closed this window, Working with an Existing Project

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the selected parameter identification fields (column headers) back on the Simulation Scenariowindo w will now be populate d. However, there will be no values filled in for the results of the various simulations. To see the results, you will now need to run the simulations again, by pressing the Sim All button ( ). Once the simulations have been run, your Simulation Manager windo w will look like the one below.

So the results from this exercise have indicated that to minimise the effect of the harder or e and almost restore the circulating load and product P80 requires an 18 % increase in power.

4.3.5

Working with Configurable Equipment Manager Configurable Equipment Manager

The Configurable Equipment Manager windo w displays a summary of selected equipment unit parameters. The user can configure multiple summary tables for display and can edit the value s display ed in the table s. This window provides a simpler and more efficient alternative for reviewing and adjusting equipment information than using the individual equipm ent da ta screens. More information on the Configurable Equipment Mana ger is available under the section on 195 JKSimMet Windows 153 and in the topic Editing Equipment Data . Step 1

Ensure the flowsheet is locked ( ), then open the Equipment Manager w indow by clicking on the

Configurable Configurable

Equipment Manager b utton ( ) or by selecting Configurable Equipment Manager from the Flowsheet menu. When first opened, this window will look similar to the illustration below.




Step 2

Click the New Unit Overview b utton ( Unit Overview dialog box.

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). T his br ings up t he Add

In this case we will ente r ‘Ba ll Mill Overview’ for the na me and select 'Ball Mill (Perfect Mixing)' from the Select Model pull-down list. Since the flowsheet we h ave been dealing with for demonstration purposes has only the one item of each type of equipment, using the Configurable Equipment Manager in preference to dealing with the model by clicking on the item of equipment itself does not confer a lot of adv antages. The majo r benefits of using this option are to be had when you are dealing with multiple equipment items in your flowsheet that all use the same model. Step 3


Click ‘OK’ an d something similar to the screen below will appear.


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The Default New Overview Window

When first ope ned, the new ove rview window cont ains a single row labelled 'Ball Mill' be cause in this case it is the only equipment item in our flowsheet that uses the Ball Mill (Perfect Mixing) model. If we were dealing wit h a flowsheet that had multiple items using this model, then each of these items would have been listed on a separate row. The new overview window also contains just the one column to begin with, which is h eaded 'No Selection'. This is where we need to carry out some configuration to display the da ta that we wis h to manipulate and/or vie w in relation to the equi pment items using this model. To select the data that you wish to show in any colum n of an overview, click on the first line of the column. This brings up a dialog box where the tabs, options and parameters may be set as is appropriate to display the required data items. Step 4


Click the ‘No Select ion’ to bring up the Tab/Option/Parameter dialog box. Let's say that in this case we are interested in the effect of having a slightly larger mill. We woul d select 'Scal ing' from the Tab dropdown an d then 'Internal Length' from the Parameter drop-down.



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When you then close this dia log, the Configurable Equipment Manager should look like the image below.

Next we would like to look at the effects on the output parameters associ ated with this equipment unit such as the powe r draw of the mill. We will set up a second column to enable this to be observed. Step 5

To add an extra column, click on the Insert Column b utton ( ). Now click in the first row of the new colum n to open the dialog bo x where the contents of the new column is defined. Note that you can control t he positioning of a new column at the time of placement. A new colum n will always be placed to the right of the currently selected cell. You can also mov e a column after it has been

Positioning Columns

placed. To do this you need to first unlock the display (

), then click

on the column to select it and then click on it again, this time holding down the mouse button to drag and drop the column to its new location. Potential new locations will be indicated while you are dragging it, by a vertical red lin e between the existing columns. Don't forget you will need to click on the lock button again before continuing with other operations. Note also that is easy to eliminate columns that are no longer needed. Just click anywhere in the column in question - anywhere that is except the top header cell, because this would just open the Tab/ Option/Parameter dialog box. Havi ng one of the cells in the colum n selected is enough to ident ify this column as the one to be removed.

Deleting Columns

Then clic k on the Delete Column button ( Step 6


) to remove it.

In the Tab/Option/Parameter dialog box that will have opened after Step 5, select ‘Power’ from the Tab menu a nd ‘Total Power (Overflow kW)’ from the Parameter menu. When you click o n the Close button, the Configurable Equipment Manager should look like the one shown below.


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Step 7

Now take not e of the mill powe r reading and change the mill length from 7.3 to 9.5 m. You will need to re-run the simulation to observe the effect of th is. Back on the main window, click on the larg e Simulate button that is located just above the left (flowsheet listing ) panel and press the Start button once this window opens to run the simul ation. Now navigat e to the Configurable Equipment Manager. You will then be able to see any resultant changes to the output parameters associate d with the equipm ent items of inter est. In this case it is just the power consumption parameter that we have set up for observation. You should s ee that this will ha ve increased from around 4395 kW to 5705 kW.

Step 8

The overview may be printed directly from the dialog box, but it is also possible to copy the overview to the clipboard for pasting into Word, or export th e overview into Excel using the Export function ( ). Using these buttons a s ingle overview may be exported, or if there a re multiple overviews, several ca n be exported at once using the ‘Export All’ function (

4.3.6

).

Defining Stream Data Info Blocks Information Blocks may be added to a flowsheet to dis play certain information about streams or equipment on the flowsheet itself. Adding Stream Information Blocks

Step 1

Ensure the f lowsheet is locked (

), th en click on the

Setup Info

Blocks b utton ( ) on the toolbar. The Streams tab at the top of the Define Information Blocks window is the default active tab. Step 2

Set the Select No. Parameters v alue to 6. After you make this selection, the Information Block definition table will be generated in the area beneath the drop-downs. This table will have a cell for each of the required parameters - 6 in this case. Initially it will just display 'No Selection' in all of its cells. Note that the second drop- down is for s electing the recovery basis stream. This is only relevant where you are dealing with ass ay data i.e. in a mass balancing exer cise. As the curr ent exer cise does not involve the mass balancing of assays, it is not necessary to mak e a selection from this drop-down.




Selecting the Type of Data to Display


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Step 3

Click in the top left cell to bring up the Selection Options dialog box for choosing the data that you wish to ha ve displayed in this cell. In this particu lar cell we want to display the simulated value for the solids flow in the streams. Select the appropriate values from the drop down cells as shown below. Note that for the Streams Info Blocks, the name for the selected parameter/data type is auto generated and you do not have the optio n of modifying this name. Hence the Selection Name are a at the top does not have editable fields.

Step 4

Carry out the sa me procedure to display the simulated value for the volume flow figure in the top right cell of the table.

Step 5

Now re peat for the procedure for the next row down in the tabl e, this time selecting '% Solids (Sim)' for the left cell and 'Pulp SG (Sim)' for the right cell. The Information Block set up should n ow look like the one shown below. Working with an Existing Project

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Step 6

For the fi nal row, we wi ll displ ay the Cum % Passin g 0.15 mm in the left cell and Cumulative % Retaine d on 1.18 mm the right cell, again with both being simulated values. Click on the bottom left cell to bring up the Selection Options dialog box once more . This time select 'Size' from the Option 1 dr op down. When you do this, another dialog will open on which you select the size that you require data for.

After you have selected the size required, it will appear in noneditable form in the field to the right of the Option 1 drop down. Step 7


From the Option 2 drop down you should now select the item 'View As'. Whe n you do this, anothe r dialog box will appear on which you can select the way in which the sizing data are expressed. Select 'Cum % Passing' fro m the options presented on this dialog. The screen grab below shows the set up during this selection process.



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Your sele ction here will the n a ppear in the right hand cell next to Option 2. Step 8

For Option 3, select 'Simulated'. The set up just before you press the OK button should look like the one below.

Step 9

Set up the lowe r right cel l in a similar fashion, but this time select 1.18 mm from the Size drop-down at Option 1, Cum. % Passi ng from the View As drop-down at Option 2 and on ce more 'Simulated'

Step 10


at Option 3. You are now ready to specify which of the streams on your flowsheet are to have these info block s associate d with them. You can select streams from the availab le streams list on the left of the Define Information Blocks windo w. To do this you can use the Ctr l or Shift key with a left mouse click to select either individual streams or a continuous group of streams, respectively. In the illustration below we have just selected the feed and the two cyclone products to have info blocks on this flowsheet. Once you have made the selection, click on the Add Info Blocks button to place Working with an Existing Project

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them on the flowsheet.

Note that there is also an Update Info Blocks button. If you make changes to the info blocks definition, pressing this button will apply the changes to any info blocks already on your flowsheet. If you make changes to the definition table and then just press the Add Info Blocks button, the progr am will place the new info block but will also update exi sting inf o blocks as well as the content s of the key in the top left corner. Step 11

You can now close the Define Information Blocks window. This will return you to the main window wher e you may find that you will need to move and/or resize the key so that the text is readable. To do this you will need to unlock the flowsheet first. Remember to lock it again before continuing. Note tha t you c an re-size and move the Stream Info Blocks themselves, without first unlocking the flowsheet. The flowsheet should now look similar to the one below, shown in the process of expanding the size of the key.




4.3.7

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Defining Equipment Info Blocks As well as Stream Info Blocks yo u can also define Equipment Info Blocks to display information a bout equipment items on your flowsheet. In this exercise we will add info blocks to the ball mill and the cyclone in the Learner Project. Step 1

Again ensu re that t he fl owsheet is locked (

) before clicking on

the Setup Info Blocks t oolbar b utton ( ). T he Streams tab at the top of the Define Information Blocks wi ndow will be active by default. Now click on the Equipment tab to enter the environment for defining this type of info block. Select 'Ball Mill' from the Select Equipment li st on the left and then select 2 from the Select No. Parameters drop down on the right.

Step 2


After you have selected the 2 from this list, default parameter names will appear under Ball Mill - Parameter 0 and Parameter 1. You n ow


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need to define these parameters. So first click on Parameter 0 and a dialog box will appear where you can select from the various options available. From the Tab dr op down, select 'Scaling' and from the Parameter drop down select 'Fraction Critical Speed'. On this dialog y ou need to wr ite in your own name for the paramet er you have selected. This is entered into the Parameter Name field. This can be exactly as it ap pears in the list or your own abbrev iation of this.


Step 3

When you press close on this dialog, a further selection dialog will appear where you have a choice in this case of displaying either the simulated or original data. One would normally select simulated data to be displayed. Click on this check box.

Step 4

When you close this dialog by clicking the apply butt on, you will see that 'Parameter 0' will have been replaced by the text you entered for the fraction of critical speed parameter. Now carry out the same Version 6.0.1 - March 2014


127

procedure for the 'Paramet er 1', this time selecting 'Load Fraction' as the parameter. You should end up with the Define Information Blocks window looking like the screen grab below.

Step 5

Click on the Add Info Block button and this info block will be placed on your flowsheet, somewhere in the proximity of the ball mill. We will now add another Equipment Info Block, this time for the cyclone. The procedure will be much the same. First select Cyclone from the list of equipment on the left. In this case we will only s elect the one parameter to display. You will again s ee that by default this will be called Parameter 0 in the definition table.

Step 6


Again click on the Parameter 0 place holder to assi gn an actual parameter for this display location. In this case we will select 'Performance Data' from the Tab dr op down and then Operating Pressure, KPa (mm) from the Parameter drop down. Once more you may need to type in your own abbreviation of the parameter name.


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After you close this another will open where you sele ct the type of data that you wish to display for this paramet er. In this ca se we will assume that only t he calculated data type is to be sh own. Note that you can only make a single selec tion here. Therefore if you wanted to show say the SD fo r this parameter as well, you would have to select 2 parameters for display from the initial drop down, then go through the s ame selections until the final data type selection. Step 7

Tick the Calculated check box and then click on the Apply button.

When you clo se this dialog, the dialog for select ing the paramet er will also close and you will see the parameter you have defined now shown in the information block table. Step 8


Now click on the Add Info Block b utton and this will place an Equipment Info Block in close proximity to the cyclone. This info block will be displaying t he calculat ed D50 value for this cyclone. You can now clo se the Define Information Blocks win dow and the flowsheet should look something like the one below.



129

Note tha t you can change the size and location of the Equipment Info Blocks as well as the Stream Data Info Blocks withou t having to unlock the flowsheet first.

4.4

S u mma r y By worki ng through the topics under Learning JK SimMet, you should now have learnt how to: Create a completely new project and complete all the steps to simulate a flowsheet. Display the results of simulations a nd export them to Excel. Make changes to an existing flowsheet and re-simulate after the changes have been made. Thus if you have worked carefully through the manual to this point, you should now ha ve the abilit y to perfo rm all the basic techniques necessary to use JKSimMet and obtain useful results. The section that follows (Using JKSimMet) provides a mechanism for referring to and revising any of the skills learned up to this point.



Part

V

Using JKSi mM et

5

131

Using JKSimMet Contents of This Section

This s ection covers all the basic operational feature s of JKSimMet. While the previous section (Learning JKSimMet) was structured as a tutorial, this section is structured more as a reference guide to facilitate revision and consolidation of the knowledge gained so far . The first chapter in this section is entitled JKSimMet Description 131 and contains an over view of JKSimMet. Following this there is a topic containing some Definitions of Key Terms 135 . In the sections that follow there are descriptions of how the program interfaces with the user; the Menus and 153 Toolbars 137 a nd the various Types of Windows us ed to display information. After this there are chapters that cover Building an d Manipulating a Circuit 191 Flowsheet 177 and th en on Editing the Flowsheet Data . Finally ther e are 213 chapters on Using Simulation 199 , Viewing Summaries of Stream Data and on Using the Reporting Feature 226 .

5.1

JK SimMet De scr iption About the Package

JKSimMet is a software package for simulating mineral processing operations, particularly comminution an d class ification. It is based on more than 2 5 years of modelling and simulation research and development at the Julius Kruttschnitt Mineral Research Centre. The package has specifically been designed for eng ineers who are familiar with plant operation, but are not necessarily skilled in modelling an d computing. JKSimMet helps the user perform the following tasks: specify the flowsheet and equipment types select the necessary p rocess models specify circuit data such as stream size distributions, equipment dimensions a nd so on tune the models (using plant data) to emulate a particular operation use the models to simulate a circuit and predict the circuit performance present the r esults as annotat ed flowshe ets, tables and graphs -- on the screen or as printed reports mass balance and adjust plant data .

What JKSimMet Can Do

JKSimMet allows metallurgists to: perform anal ysis and optimisation of the performance of existing operations us ing actual circuit data pursue flowsheet design studies for new circuits mass balance and adjust data for circuit audit and metallurgical accounting run a s imulation of the plant. assess the impact on metallurgical performance of various circuit


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changes. present the data and results on the screen, copy the data to the clipboard or export results to MS Excel for printing and further analysis. Version 6 of JKSimMet is a user-friendly system that uses the Windows interface, with features such as switching between appli cations, export of data via copy and paste functions and drop-down menus for quick editing and data manipulation.

5.1.1

JKSimMet Model Type s Process Models

JKSimMet performs steady state simulation of a range of flotation circuit operations. There are eight distinct types of equipment models available in JKSimMet:

The Models

TypeofModel Feed

Example

Icon

Feed Water Feeder

Crusher

JawCrusher Gyratory Crusher Cone Crusher Roll Crusher VSI HPGR Degradation

Mills

AutogenousMill Rod Mill Ball Mill

Screens

Trommel Single Deck Screen DSM Screen Double Deck Screen (one under)

JKSimMet Desc ription


Using JKSi mM et

Classifiers

133

AirClassifier Hydrocyclone Spiral Classifier Rake Classifier O-Sepa Classifier

Splitters

2ProductSplitter 3 Product Splitter

Storage / Transport

Bin Pump Pump Sump Sump Stockpile Thickener Final Product

Separators

FlotationCell FlotationColumn Spiral Separator 2 Product Separator 3 Product Separator

There is also the facility to add new equipment models via offline compilation Model Descriptions

(contact JKTech for more information). The equipment may be combined in both simple a nd complex flowsheet circuits to enable the user to simulat e the operat ions of plants or subsections of plants. Simulation outcomes will be dependent on the selection of appropriate process models (mathematical models) for the equipment items in your flowsheet. Further contr ol is exercised through the specification of scale for the various equipment items, the selection of model parameter values and through the operating data inputs such as the feed stream properties. The algorithms for each model are outlined in under the Model Descriptions


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section.

5.1.2

JKSimMet Capab ilities Simulation Capabilities

In addition to the simulation capabilities discussed above, JKSimMet encompasse s all the fu nctions necessary for the user to use and maintain a number of flowsheets within a single project. JKSimMet provides process engineers and metallurgists with a powerful tool for conceptual design, tuning and monitoring of process plants and their elemental circui ts and equipment. It enables an almost infinite numbe r and variety of circu it designs to be simulated so that the optimal design for the task and for the expect ed range of variation of input and flow conditions may be estimated before expensive experiments with the real plant are undertaken.

JKSimMet for Metallurgists

JKSimMet allows metallurgists to assess the impact on metallurgical performance of: Plant throughput Equipment operating conditions Equipment volume Circuit layout Stream destination New equipment addition Change in plant feed sizing, floatability or mineralogy

JKSimMet for Plant Operators

JKSimMet also has the capability of a ssisting Pla nt Operators to understand the effects of day to day changes in circuit operation (e.g. equipment operating conditions, plant throughput, feed properties) on metallurgical performance. However, JKSimMet does not and cannot replace the process engineer. It facilitates the simulation of circuit and plant designs; it does not design. Like any tool, the quality of the results that it produces is directly related to the skill of the artisan wh o uses it.

Size Distribution

There is a maximum of 40 size fr actions in the size distribution for any one stream.

Number of Flowsheets

There is no defined limit to the number of flowsheet s which may be included in a project. However, the datab ase will beco me very large and may cause a decrease in machine performance.

Model Fitting Constraints

In SimMet a user is only able to simul ate one flowsheet at a time. There are n o restrictions on the number of parameters that can be fitted.

Number and Type of Models

The user cannot add new models without ass istance. However, JKTech welcomes suggested new models which will be considered for subsequent releases of JKSimMet. JKTech can also develop custom models for an individual client.

Mass Balancing

The update d SimMet mass balance algor ithm allow s the user to balance any realistic circuit, provided that they follow the correct mass balance process.



Using JKSi mM et

5.1.3

135

JKSimMet Constraints System Constraints

While JKSimMet is a powerful and flexible system there are, necessarily, some constraints. These are: Number of Flowsheets

There is no defined limit to the number of flowsheets that may be included in a project. However, the database will become very large and may cause a decrease in machine performance.

Number of Equipment Units per Flowshee t

The maximum number of equipment units that can be put into a single flowsheet is limited only by the available space on the flowsheet screen. If large numbers of equipment units are added, then the drawn circuit requirements may initially exceed the flowsheet window a rea a vailable. Howev er, a Zoom to Fitb utton ( ) is provided an d wi ll re-size your flowsheet so that it fits neatly in to the current size of the flowsheet window.

5.1.4

Number of Streams Connected to Equipment

Although the flowsheet allows an infinite number of feed stream s to be connecte d to an equipment unit, the simulation engine only recognises the first 50 streams entering an equipment unit.

Property: Size

There is no limit to the number of size classes that can be defined.

Number and Type of Models

For a list of the available models refer to Section JKSimMet Model Types 132 . JKTech welcomes suggestions for new models. Such suggestions would be considered for subsequent releases of JKSimMet. JKTech can also develop custom models for an individual client.

JKSimMet Expa ndability Package Expandability

JKSimMet is a self-contained package providing within itself all the features required to build, execute and maintain a library of projects. JKSimMet is supplied with process models for the equipment listed under the heading JKSimMet Model Types 132 . While these models cover many of the typical processes encountered in comminution plants, JKSimMet has been designed to facilitate the incorporation of new models. While the user ca nnot add new models to the system, recommendations to JKTech will be considered for inclusio n in later releases. Custo m designed versions of JKSimMet may also be considered; contact JKTech for more information.

5.1.5

Definition of Terms Used in JKSimMet A number of the te rms and n ames used within the JKSi mMet s ystem have a specific meaning, which it is important to understand. These terms are



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defined here to avoid ambiguity. Project

JKSimMet is organized and based upon the concept of a project. A project can be conside red as a portfolio in which the user stores one or more flowsheets and their related data.

Process Circuit

A process circuit is a diagram containing a set of Equipment items interconnected by Stream s, which ha s been drawn in a JKSimMet Flowsheet window to represent a particular sequence of processing steps. To be complete, a circuit m ust always have at least one Feed unit an d at least one

Flowsheet

Final Product unit. A flowsheet c onsists of one or many proce ss circuits and their related data. The flowsheet may contain one item of eq uipment or many. It can contain one complex multi-stage circuit or many circuits in parallel. While multiple circuits are acceptable within one flowsheet, ther e is no facility for linking circuits from separate flowsheets within a project. A user may cre ate a project to model several flowsheets, such as a crusher circuit and a grinding circuit. Simulation would be executed for the crushing circuit first to a defined convergence, using the equipment data and configuration supplied. The data resulting from the execution of this simulation could then be manual ly passed as input to the grinding circuit and s imulation executed through this circuit to convergence. For both circuits to be simulated at the same time however, the circuits must be contained within one flowshe et, which is probably the more s ensible approac h in this situation. When you are comparing two alternative flowsheets, you can first prepare one of them fully, including the input of the fe ed data. Then you can create a clone of this flowsheet, wit h the clone becoming your s tarting point for creating the alternative flowsheet. More detail on this approach is covered under the topic Creating a New Flowsheet 180 .

Equipment

Process equipment items are component s of the circuit. Each equipment item consists of: an icon on the flowsheet diagr am a data window that det ails the process mode l and associate d model parameters.

Streams

Streams provide the mechanism for the flow of material between equipment items. The stre ams can be named by the user and each stream cont ains the simulated stream data after simulation. The stream data for the feed s tream is entered into the Feeder equipment rather than directly into the feed stream. As well as the components outlined above , it is important to understand some concepts relating to properties and the way these are defined in JKSimMet. These concepts are described below.

System Properties

There are two default system properties available for selection in JKSimMet: Miscellaneous Elements There is also the capacity for the user to define their own properties.



Using JKSi mM et

Classes of System Properties

137

Each of the system properties has one or more classes. The user can define as many classes of the e lements property as desired but is unable to define extra miscellaneous value properties. When adding or altering an element the user can chang e the characteristic label and units value selected for the element; choosing eithe r a percentage representation or grams per ton representation. While the user cannot add to or change t he label of the miscel laneous values, they a re able to change the values assigned to them. These settings are global characteristics that are not changed during simulation.

5.2

Sieve Series

A sieve ser ies represents the ser ies of gauges used to filter material in the process circuit . JKSimMet allows the user to a dd as many sieve series a s they require to each flo wsheet in a projec t. Each serie s may contain up to 4 0 size fractions and once defined, the user is able to assi gn a particular sieve to individual streams.

Ports

Each equipment unit has one input port and up to three output ports, depending on the type of equipm ent. Only one connec tor can be attached to each output port. For the models in JKSimMet the stream charact eristics of interest are density, size distribution an d solids and liquid flow rates.

The JK SimMet Menu s an d Tool bar s JKSimMet V6 has been developed to run under the MS Windows 7/Vista/ XP(SP3) operat ing system s and makes use of the Windows interface to provide easy and flexible access to the large amount of data stored in the JKSimMet software. A typical JKSi mMet screen is s hown below with various c omponents of the screen labeled.

A Typical JKSimMet6 Window - Showing the Main Fea tures

The variou s components of the JKS imMet menus and toolbars are described in detail in the remainder of this section.



138

5.2.1

JKSimMet V6 Manual

The Main JKSimMet Menu The main menu of the JKS imMet interface follows a standard Windows menu layout, with a selection of dro p-down menus that allo w the user to access a range of com mands. Each drop-down menu is accessed by clicking on the appropriate word on the Menu bar. Menu bar

The flowsheet sy mbol ( ) at t he le ft-han d end of the Main menu provides a drop-down menu for options relating to the flowsheet window; these options are discuss ed below. The othe r Main menu items are dealt wit h in the top ics that fo llow. You can safely move to the next topic 139 i f you wish to skip the remainder of this discussion on the flowsheet symbol menu items. When you click on the flowsheet symbol, you get the drop-down menu pictured below.

Restore

Clicking on the Restore it em change s the Flowsheet window from its default maximized state into a re-sizeable window within the flowsheet area. When you do this, the flowsheet symbol ( ) will disappear from the left-hand end of the Main menu and will now be located at the left-hand end of the new resizeable Flowsheet window . Note that with a mouse you can always carry out the restore function using the Restore button, which is the middle of the three buttons at the right-hand end of the Main menu - see below.

Move and Size

The items Move and Size are de-activated in the drop-down menu that appears when you click on the flo wsheet sym bol on the Main m enu. This is because when the Flowsheet wind ow is maximized it canno t be moved or sized until after you have pressed Restore to make it a re-sizable window. These two items are therefore only activated when you click the same symbol on the re-sizeable Flowsheet wind ow. The resizi ng or moving of a window is generally best achieved by using your mouse. However, these commands are there as an alternative by which you can achieve the same result without the mouse. If you click on Move, you can then move the window using the keyboard arrow keys. If

The JKSimMet Menus and Toolbars


Using JKSi mM et

139

you click on Size, you can use the arrow keys to change the size of the window. In this case if you initial ly press the right arrow key , the chan ge in size will be achieved by movements of the right edge. Conversely initially pressing the left arrow key will adju st the lef t edge. The same principle appli es to the up and down arrows an d ass ociated changes to the ver tical dimension of the window. Minimize and Maximize

Minimize and Maximize ite ms are also present on this menu, their activation status depending on the curr ent statu s of the window. Minimize reduces the Flowsheet window to a bar at the bottom of the flowsheet area while Maximize will resize the Flowsheet wi ndow to fill the available spa ce. Both of these functions a re available to mouse users from the buttons at the end of the header bar of the re-sizeable window.

5.2.2

Close

The second last item on the menu is Close. While th is can be used to close the active Flowsheet, opening a different Flowsheet (the most likely reason to close an a ctive Flowsheet) will automatically close the active Flowsheet.

Next

The item on this menu labele d Next is currently non-functional in this version of JKSimMet.

The File Menu and Main Toolbar The File Menu

Clicking on the File menu item bri ngs up a list of options relating to the opening, saving and creat ing of JKSi mMet files. It also includes a list of the most recently opened files to provide you with quicker access to projects that you may be work ing on through a number of sessions. The File menu plus a brief explanation of the items, is shown below.

) - o pens t he N ew Pr oject w indow so t hat th e user New Project ( can create and name a n ew project. Open Project (


) - opens the Open Project windo w s o that the user


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can select an exis ting project to load from a list. Some fur ther information on the above two items is available under the Session Window 172 topic. Save Project ( ) - saves the project, including all the data associ ated with the equ ipment and streams of each flowsheet, as a JKSimMet data file (.jksf6 extension). Save Project As - allows the user to save the

current project under a

new na me. Print ( ) - prints only the flowsheet sec tion of t he se ssion wind ow. Selecting this option opens the Print window to enable the printer properties to be selected and the flowsheet to be printed. Exit - closes JKSimMet. The user is prompted to save the current project if the project has not been s aved after the most recent ch anges were made. Main Toolbar

Many of the functions that are available in the File menu can be accessed via the icon buttons on the Main Toolbar. Note that, if required, this toolbar can be moved to a more convenient place on the scre en by clic king and dragging it. When in this state the shape of the toolbar can be adjusted to personal preference by dragging the edge. The first three but tons on the Main toolbar provide shortcuts to the standard New Project, Open Project and Save Project options. The next two butt ons are the copy and pas te buttons. The final button is the Help b utton. Click on this button to access the comprehensive JKSimMet help system.

5.2.3

The Edit Menu Clicking on the Edit menu item brings up a list of options relating to flowsheet editing func tions and the sett ing of default and/or global characte ristics for various flowsheet items. A screen capture of the Edit menu is shown below, followed by a brief explanation of each of the menu items.



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Undo - reverses the last editing change. You can continue clicki ng on this to reverse a whole sequence of editing changes if required. Redo - this re verses the acti on taken when the Undo button was last pressed. Note that it is only available immediately after the Undo button was pressed. If you carry out another editing action after pressing Undo, then the Redo will no longer be availab le. Note also that it can store a whole sequence of Undo events for potential reversal, but only as far back as such events have been uninterrupted by normal flowsheet editing. Cut ( )- removes the selected item from it s original location and places it on the clipboard, ready for pasting elsewhere. Copy( ) - leaves the s elected item in its srcinal location a nd puts a copy on the clipboard, which is then available for pasting elsewhere. Paste ( ) - this has the normal paste functionality - places the clipboard contents into the current cursor location. Delete - this completely removes the selected item. Select All - this selects all of the items on the current flowsheet. Default Equipment Properties - this controls the default auto label settings for any new equipment. Default Stream P roperties - this controls variou s features of any new streams a dded to the flowshe et, including the line width and colour, the type and size of arrowheads and the auto label positions. Y ou ca n also ele ct to have new streams either always orthogonal or else free with respect to drawing direction. In addition you can change the



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colour coding if you wish, for the majo r, minor and missing stream categories (relevant only for mass balancing). Default Text Properties - you can set the charact eristics of any new text that is placed on your flowsheet, including all stream and equipment labels. Default Drawing Object Properties - here yo u can change the default appearanc e of any further drawing objects added to the flowsheet including line colour, fill colour, Equipment Auto Label Properties - the dial og box that opens when you click on this item allows you to control the colour and thickness of the equipment label outlines, the fill pattern and colour as well as the font characteristi cs of the text within the labels. Note t hat any changes made here affect all of the existing eq uipment labels, not just ones that are added after the setting has been ch anged. Stream Auto Label Properties - this provides the same controls over the appearance of the Stream Auto Labels as was described above for the Equipment Auto Labels. Port Properties - here you can (if you wish), change the colour of the ports. There are two tabs, the first is for the product ports and the second is for the feed ports. Patt ern selection is also possibl e, but not really practical in this case s ince the ports are too small for a patter n to be visible. Flowsheet Settings - this menu item allows you to change the background of the flowsheet andtothe pagethe dimensions orientation. Itcolour also provides the option toggle display ofand the icons in the soft ware between JKSimMet5 icons and JKSimMet icons as well as allowing the user to choose the number of significant figures displayed in the information blocks. Note that zooming out will better allow you to appreciate how your flowsheet is structured relative to the size and shape of the paper you have chosen for printing. You can also get to this item from the menu that appears when you right-click on your flowsheet. Properties ( ) - This menu it em al lows th e use r to v iew and alt er the properties of a selected stream or equipment item on the flowsheet. Here the user can alter the name, lab el position, line style an d fill s tyle of the selected item.



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The View Menu View Menu

The View co mmand on the Main JKSimMet Menu controls which of the available flow sheet feat ures are visible in the session window. Some of the items on this menu are also available via toolbars, but others are only available from this menu. The item s on this menu are liste d and explained below, in the order that they appear on the menu. Toolbar - when checked, the main JKSimMet toolbar is visible. Status Bar - is visible at the bottom of the JKSimMet session window when ch ecked. Workspace - this ref ers to the li st of flo wsheets contained in your project, which normally appears as the left-most panel of the session window. This panel will disappear if the Workspace item is unchecked. This may be useful if you have a large flowsheet and need more space to accommodate it. Grid - this toggles the visible grid on or off. Note that s nappin g to the grid is still possible, ev en when you have switched the grid to "off" so that it is no longer visible. Snap to Grid - this determines whether the items on your flowsheet will snap to the grid when they are mov ed. This setting provides a convenient tool for aligning the items on your flowsheet.



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Angle Snap - this applies to rotation of equipment items; when switched off, any angular position is possible whereas when switched on, the only angular posit ions possible are those in which the corners of the equipment item line up with the grid. Grid Properties - this allows adjustme nt of the grid spacin g an d other properties via the Grid Properties windows, shown below.

Vertical Rulers - this is a toggle for turning on or off, the vertical ruler along the side of your flowsheet. Note that it only applies to the flowsheet that is currently active. Horizontal Ruler - similarly, this toggles on and off the horizontal ruler at the top of your flowsheet. Again, it only effects the appearance of the currently active flowsheet. Ruler Properties - thi s brings up a dialog bo x in which you can select the colour and width of the rulers plus the colour of the ruler tracking line that appears within the rulers to indicate the current cursor position.

Equipment Auto Labels ( auto labels. Stream Auto Labels (


) - this toggles on an d off, the equipment

) - likewise, this toggles on and off, the


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stream auto labels. Note that bot h the Equipment and Stream Auto Labels ca n be also switched on or off via buttons on the Flowsheet toolbar. Port ( )- via this it em you can co ntrol whether or not the ports are to be visib le on your equipment items. It is very useful to have these switched on at least while you are constructing the flowshe et. After this, it is a matter of preference as to whether you have the ports highlighted or not. This toggle is also available via a button on the Flowsheet toolbar. Redraw ( ) - this is sometimes nee ded if yo u have a larg e flowsheet to which you have just made chan ges and immediately after making them you find that the computer is not rendering them properly. Clicking on Redraw will n ormally remedy this type of problem. Zoom Normal - this zooms back to the norm al level after you have used the other zoom functions to move away from this zoom level. Zoom Percent - this allows the user to select the zoom percent from the options 50%, 75%, 100 % (normal) and 200 %. Zoom Custom - with the Custom Zoom you can either select one of the above from the drop-down or you can type in any percent value from 50 to 500.

Zoom to Fit ( ) - this is a convenient w ay to get the w hole of your flowsheet to fit neatly into the available window size. Note that there is a button on the Flowsheet toolbar that also ach ieves this result. Zoom to Selection ( ) - i f you h ave selected par t of your f lowsheet for closer inspection, this command will zoom to the point where the selected part of the flowsheet just fits into the available window size. Again note that on the Flowsheet to olbar there is a button for this function als o.

5.2.5

The Flowshee t Menu and Toolbar The Flowsheet Menu


The drop-down menu that is triggered when you click on the the main JKSimMet Menu bar, is shown below.

Flowsheet item of


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This menu allows an alternative route into most of the functionality prov ided via the Flowsheet toolbar (see below). There are s ome differences h owever.

The Run Model Fitting item on this menu is not on the Flowsheet toolbar, but is located on the separate Model Fit toolbar. The Flowsheet Toolbar

If required, the Flowsheet toolbar can be moved to a more conveni ent place on the screen by simply clicking and dragging it. Once moved to a floating toolbar position, the shape of the t oolbar can be adjusted to your persona l preference by dragging the edges. This applies to all the other toolb ars as well. Below is a screen-grab of the Flowsheet toolbar, followed by a listing of all the buttons it contains with explanations of their functions:

Lock

The Lock button controls access to the various other functions on the toolbar.

Flowsheet

When unlocked, access is a vailable for making changes to the flowsheet's design and layout, including the addit ion or subtraction of equipment and streams, changes to the locations of equipment items and to the routes taken by connecting stre ams. In addition all propert ies ass ociated with the a ppearance of



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all flowshe et components can be accessed when this butt on is in the unlocked position. When this button is in the lock ed position, none of the abov e functionality is available. Instead, the System Properties, Sieve Series, Survey Data, Configurable Equipment Manager, Run Simulation, Configurable Stream Overview, Simulation Manager, Run Balance, Equipment, Stream, Reporting, Config Graph and Setup Info Blocksbuttons now become accessible. In fact the flowsheet must be locked before any changes can be made to the data. Requiring that the flowsheet be locked for data entry e nsures that items are not accidentally moved when you are trying t o access the data. Select

The Select button is n ormally activated by default when you first open a project. It will be de-activated however when you press the Zoom b utton( ) andyou will then need to re-activate it before you can select any items on your flowsheet. When the Select button is active, the cursor will turn back to the normal selection cursor ( ). This may look dif ferent to the illu stration here , as it will dep end on the cursor option settings on your computer. With the Select button activated you can click on any individual equipment item, stream or label on your flowsheet to select it. This is the case regardless of whether the flowsheet is locked or unlocked. The lock ing statu s just aff ects what you can do with the items once they have bee n selected. Note that you can select multiple items by holding down the left mouse butt on and dragging the mouse until the dotted line enclo ses all the items you wish to s elect. Letting go of the left-button will then select these ite ms. You can also select a ny number of individ ual items by holding down the Control key and clicking the mouse as the cursor moves over

Zoom

each of them. When you click on the Zoom button, the Select button will be s witched off a nd the cursor will chan ge to a zoom cursor ( is n ow active.

) to ind icate that th e zoom f unction

When this cursor appears on your flowsheet, you can hold down the left-button and drag your mouse to out line the area you wish to z oom into. When you let go of the mouse button, the area you h ave outlined will be expanded to occupy the whole of the current flowsheet window. Also when you have the Zoom button activated, clicking on the left mouse button will incre ase the degre e of zoom by a s et increm ent and clicking on the right button will decrease it by the same amount. To turn off the zoom facility, click again on the Selectb utton ( Zoom to Fit Zoom to Selection


).

Clicking on the Zoom to Fit bu tton will zoom in or out sufficiently to just accommodate the whole of your flowsheet. This is usually the best way to zoom back out again after you have zoomed in to a particular region of the flowsheet. For the Zoom to Selection button to be available, you first need to have selected some items on your flowsheet. When you click on this button, the program will zoom in or out a s needed, s o as to just include all of your s elected items within the boundary of the visible flowsheet.


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Auto Labels for Equipment and Streams

The Equipment Auto Labels and Stream Auto Labels bu ttons are used to add labels to the equipment and streams on the flowsheet; the labels become a part of the equipment and streams and move when the equipment or stream is moved. To change the default label, double-click on the equipment and type in the new name, see chapter on Annotating the Flowsheet 187 . Clicking on the Equipment Auto Labels button or the Stream Auto Labels button toggles between having the labels for this flowsheet either displayed or not displayed. Note that these buttons ca n be operated irrespect ive of the flowsheet locking status. As note d above, in the menu system these two functions are available via the View menu rather than the Flowsheet menu.

Ports

This button acts as a toggle for switching on and off the display of the ports for each of the equipme nt item. Feed ports a re represented by blue dots and product ports by red dots. This facilit y is normally turned on by defaul t. Note that the position of this switch does not affect functionality. You can still connect streams to port s, even when they are not displayed. However for icons with vertical a xis symmetry, s uch as the one used for flotation cells, you can't easily tell whic h side is the fe ed port unti l you turn on the por ts display. Thus it is usually better to have ports switched on, especially while the flowsheet is being constructed.

Redraw

The Redraw button is used to refresh the screen. Th is is particularly useful after equipment has been repositioned. If you have made chan ges that are not ye t a ppearing on your flowsheet, click on the redraw button and the whole flowsheet will be redrawn. It should then

System Properties Sieve Series Survey Data

Configurabl e Equipment Manager Run Simulation

Configurabl e Stream Overview

include all of your modifications. The System Properties button opens the System Properties Window 176 , where the user can add Elements to the system and alter the miscellaneous properties. The Sieve Series button opens the Sieve Series Window 175 . It is in this window that the user can add and remove sieve series, as well as assign them to individual s treams. The Survey Data button opens the Survey Data window 175 . This allows the user to input and transfer survey data into the streams, overwriting any existing experimental data. The Configurable Equipment Managerbutton brings the Configurable Equipment Manager Window 116 in to view. This window allows the user to create an overview to view and if n ecessary alter the settings for the different models used in the current flowsheet. Clicking on the Run Simulation button opens the Run Simulation 164 window, which allows the user to select the equipment and streams to simulated, set the simulation sett ings and run simulations. The Configurable Stream Overview 213 wind ow is accessed by click ing on this button. This feature allows the user to create one or more summary tables of selected stream data after simulation of the flowsheet. The data in the table can then be printed, copied to the clipboard or exported to MS Excel.



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Simulation Manager Run Balance

The Simulation Manager 201 allow s multiple simulations to be performed in a batch operation. The user can set a range of key operating parameters in the simulations and record the key performance indicators for each simulation performed. The Run Balance button brings the Input/View Mass Balance 259 windo w into view. This window allows the user to select the streams, equipment, elem ents and s izes to include in the balance and control the scope of t he fitting. The Equipment bu tton brings the Equipment Window

Equipment

Stream

Reporting

Configurabl e Graphing Setup

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193

int o view. A drop-

down list inThe theEquipment Equipmentwindow windowallows displays ll oftothe equipment on the current flowsheet. theauser select t he model to be used for the equipment via a drop-down list, and to input the parameters for the chosen model. The Equipment window also s hows the feed and product streams from the equipment; the Stream window for each of the se streams can also be accessed from the Equipment window. Clicking on the Stream bu tton opens the Stream Window user can view the stream data after simulation.

165

from which the

The Reporting but ton opens the Reporting to Excel 162 dial og. This allows the user to configure one or more repo rts by listing which stream a nd equipment data are to be exported to an Excel workbook for further analysis and printing. The Config Graph button opens the Configurable Graphing Window 154 . Here the user can create one or more graphs to view the data held in the streams and equipment on the current flowsheet. The Setup Info Blocksbutton is used to set up both Equipment an d Stream Data 120

Info Blocks

5.2.6

Info Blocks . These are configurable information blocks that can be attached to selected equipment items and streams. They are used to provi de a convenient flowsheet based readout of the results and the settings of your simulations.

The Balance, Fitting and Simulate Toolbar Toolbar for Main JKSimMet Functions

The Balance, Fitting and Simulate toolbar is located in the left side panel, just above flowsheet list.

Run Balance

The Run Balance bu tton brings the Input/View Mass Balan ce 259 window into view. This window allow s the user to select the streams, equipment, elements and sizes to include in the balance and control the scope of the balancing process.

Run Model Fitting


The Run Model Fitting button opens the window for model fitting 272 , where the user can tailor the process models associated with the various equipment items in their flowsheet, to their individual treatment characteristics based on the data that has been gathered for this circuit.


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Clicking on the Run Simulation button opens the Run Simulation 164 window, which allows the user to select the equipment and streams to simulated, set the simulation sett ings an d run simulations.

Run Simulation

5.2.7

Drawing Too lbar The Drawing toolbar contains buttons fo r all the commands ass ociated with the preparation of your flowsheet. A screen grab of this toolbar is shown below.

Note that these buttons are all de-activated once the flowsheet has been locked. The functions of the various buttons on this toolbar, going from lef t to right, are described below. Properties

The Properties bu tton gives you access to the properties dialog box for the currently selected flowsheet item or items. Properties in this context refers to the properties of the icon itself, not the properties of the physical equipment that it is representing. The later properties are associated with modelling of the equipment and are only available once the flowsheet has been locked.

Line

This button simply allows you to draw a line on your flowsheet. When click on the but ton and move the curso r down to the flo wsheet, you will see that the cursor now takes the form of a cross ( ). Click the left mouse button and drag in any direction to create the line. Let go when it is at the desired length. If you hold down the Shift key while yo u are dragg ing, the line will then snap to the grid and will be either horizontal or vertical, depending on which direction you are moving your mouse.

Rectangle

When you click on this button, yo u will again note that the cursor take s the form of a cross once the mouse is positioned over the flowsheet. Click the left button and drag in the dire ction of the diagonal of the proposed new rect angle. The proposed rectangle will be outlined b y a das hed line while you continue to hold down the mouse button. Once you let go of the button, the n ew rectangle will be placed on the flowsheet and its perimet er will chan ge to a s olid line.

Text

Clicking on this butt on followed by clicking on the activ e flowshe et will add a resizable, editable text box to the flowsheet.

Image

When you click on this button you will be pre sented with a file open type dialog box, where you will be able to select the directory where your images are stored. Click on the image file you require and then on the Open button. If the imag e you have imported initially occupies the whole of the flowsheet panel, use the zoom buttons to zoom out. This will allow you to s ee the h andles around the perimeter of your image and by using these you can re-size the image to whatever is required.

Rotate

After clicking on the Rotate bu tton, you will see that the curso r chang es once you are hovering over the selected item, to a circular arrow symbol, similar to the image on the button itself . If you then click a nd drag, the item of equipment will



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rotate. Let go when it has reached the orientation you require. Rotate Le ft & Right

The Rotate Left button rotates the selected item anti-clockwise by 90 degrees. The Rotate Right button also rotates by 90 degrees, this time in the clockwise direction. For the Rotat e Left and Right commands, the rotation is occurring about a line that is perpendicular to the plane of the computer screen.

Flip Vertical & Horizontal

The Flip Vertical and Flip Horizontal buttons effectively rotate the object concerned thro ugh 180 degrees, through a plane that is at right angle s to the screen. The rotation occurs about a line that passes through the cent re of the

Align Top & Bottom

object and lies flat on the computer screen. These but tons can be used to align eit her the tops or the bot toms of a group of objects that you have selected. First select the set of objec ts required, either by using the Cont rol key and clicking on the separate objects or else by draggi ng the mouse to encomp ass the objects with the lef t button held down. Then click on whichever of the buttons is appropriate for your purposes. Note that the alignment will be to the top (or bottom) of the last selected item. You can see which item was last selected as it will have grey rather than open selection indicator squares around its perimeter.

Align Middle & Centre

To align either the horizontal or vertical centre lines of a number of objects, you again need to fir st select the s et of objects for alignment (see above). Then just click on the appropriate button for middle or centre alignment, as required (see left). Again, the alignment will be to the centre line of the last selected item.

Align Left & Right

Left and right alignment of objects is achieved by again selecting the set of objects before clicking on whichever is required of the two buttons shown at left.Again, the last selected object will be the one that determines the alignment position.

Space Across & Down

These but tons allow yo u to evenl y space objects that you have placed on your flowsheet. Pressing the Space Across button distributes the selected objects so that the entire spac ing between the far left object and the far right object is divided evenly between entire row of selected objects. Note that the objects do not necessarily have to be first lined up in the vertical direction for this horizontal spa cing function to work. Similarly, pressing the Space Down button divides the entire ver tical s pacing between your highest and lowest object so that all the selected objects will then have equal vertical spacing between them.

Same Width, Height or Size

Using these buttons the user ca n make a s et of objects on a flowsheet all have the same widt h, height or both. Not e that the last selected object (indicat ed by the grey selection handles), wil l be the one to which the other s elected objects are matched. Use the Same Size b utton when you wish to make sure that the dimensions stay in the same ratio as they exist in your las t selected object.

Nudge Up, Down, Left and Right

There are fou r Nudge bu ttons that allow you to make small adjustments (up, down, right and left) to the positioning of objects on your flowsheet. First s elect the object to be moved a nd then click on the appropri ate Nudge button. These functions are mainly useful for adjusting the positioning of equipment units when the attached streams have gone slightly out of horizontal or vertical. You can use it to mak e the small adjust ments needed to return the streams to an orthogonal arrangement.

Front and Back

The Front and Back buttons can be used if you have overlapping ite ms on your flowsheet. Pressing one of these buttons will determine which of the



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overlapping ite ms appears to be at the front and is therefore fully visib le a nd which appears to be at the back and therefore partially obscured. When a Front or Back button is pressed, the ite m currently s elected responds by moving to the front or back as appropriate. Note that if you have sever al overlapping items selected a nd you press Front, then the ite m last selected will move to the front and the ove rlap order for the othe r items will also mirror the selection order. This means that for instance, t he second last item selected will be just under the last item selected, but will be over all of the other items.

5.2.8

The Too ls Menu

The Tools menu on the Main JKSimMet Menu allows the user to customise which tools and menus are displayed in the session window. Click on Customize then there are two tabs, Toolbars and Command. In the Toolbars tab the user can choose which toolbars appear a t the top of the JKSimMet screen. The 'look' of the toolbars can also be adjusted using the Show Tooltips an d Cool Look options. Use rs can also add and name new toolbars by clicking on the New button. Once created, the new toolbar can be populated with butt ons by either moving existing buttons from other toolbars or by moving copi es of the existing buttons from the Command t ab of the dialog box into the new toolbar..

The Command tab shows all of the buttons that make up each of the existing toolbars and the menu. Sel ecting one of the buttons will provide a description of the functionality it offers in the description box at the bottom of the window, as sh own below.



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To customize an existing toolbar users can drag any button of their choice from this tab ont o the too lbar. While this dialog box is open users can also remove or reposition buttons on existing toolbars, a llowing a large degree of customization.

5.2.9

The Help Menu Help Menu

The Help menu on the Main JKSimMet Menu allows the user to access the help files, and provides software version information: Help ( File.

) - (or pressi ng F1) takes the u ser to the c ontents pag e of the He lp

About - gives details of the JKSimMet version number, the version numbers of the databases and copyright information.

5.3

JK SimMet Windo ws Version 6.4 of JKSimMet makes full use of the Windows interface to allow users to vie w whiche ver data they choose on the scree n at any one tim e by simply opening the required windows. This section describ es briefly each of the main window types in JKSimMet.

5.3.1

Configurable Equipment Manager The Configurable Equipment Manager win dow displays a summary table of



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selected data for a currently selected model in the flowsheet. The user can configure one or many tables for display in this window. The Configurable Equipment Managerwindow can be opened by two methods: 1.

Selecting Configurable Equipment Managerfrom the Flowsheet menu.

2.

Clicking on the Configurable Stream Overview button.

Opening the Configurable Equipment Manager

The Configurable Equipment Manager feature can only be acce ssed when the flowsheet is locked. The Configurable Equipment Manager pro vides a data summary for a selected model in the flowsheet after simulation has occurred. The information display ed in the Configurable Equipment Manager window is exactly the same as the information displayed in the individual Model Data win dows. The advantage of the Configurable Equipment Manager is tha t all of the data for the equipment items that us e this model can be viewe d together, rather than having to view each equipment item in a separate window. The summ ary tab le can be printed directly from this window, copied to the clipboard for pasting into other progr ams such as Word or exported to Excel for further ana lysis or graphin g.

5.3.2

Config Graph Window The Configurable Graphing window lets the user set up and view data from streams and equipment in a graphical format . Users can open the Configurable Graphing window via the flowsheet menu or from the icon on the flowsheet toolbar.

Note that the Graphing f eature can only be accessed when the flowsheet is

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locked. Create a New Graph

To create a new graph click on the 'New' button, in the dialog that opens, the user is required to give a name to the graph (or accept the default) and to choose whether the graph will display stream or equipment data.

The user must then choose a format for the sizin g data:

They then must choose which type of data the report is going to display:

They are then required to select the stre ams or equ ipment that they wish to view:


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Viewing the Graph

The Graph tab display s the data that you have sele cted in the stream tab. To alter the settings of the graph, select the Format button (highlighted).

Formatting the Graph

The format wi ndow allows you to set the name for each axis, the range that each axis covers and h ow the data is plotted and shown to the user.

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Configurable Stream Overview Window The Configurable Stream Overview wi ndow displays a summary table of selected data for selected streams in the flowsheet. The user can configure one or many tables for display in this win dow. The Configurable Stream Overview window can be opened by two methods: 1.

Selecting Configurable Stream Overview from the Flowsheet menu.

2.

Clicking on the Configurable Stream Overviewbutton.

The Configurable Stream Overview f eature can only be accessed when the flowsheet is locked. Configurable Stream Overview provides a data summary for selected streams in the flowsheet after simulat ion has occurred. The information display ed in the Configurable Stream Overview window is exactly the s ame as the inform ation displayed in the individual Stream Data windows. The summ ary tab le can be printed directly from this window, copied to the clipboard for pasting into other pr ograms such as Word or exported to Excel for further analy sis or graphing . The Configurable Stream Overview win dow is discussed in more detail under the heading Using the Configurable Stream Overview 213 .


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5.3.4

JKSimMet V6 Manual

Information Blocks Information Blocks

Information blocks allow the user to display information about the performance and characteristics of both streams and equipment on the flowsheet. The Information Blocks window can be opened by two methods: 1.

Selecting Info Blocks from the Flowsheet menu.

2.

Clicking on the Setup Info Blocksbutton.

Note that the Info Blocks fe ature can only be accesse d when the flo wsheet is locked. Experimental or simulat ed data may be displayed, and the Info Blocks feature allows the inform ation to be displayed f or a s many s treams or equipment units as the use r wishes. Information Blocks 158 are discussed in more detail within the section Building and Manipulating a Flowsheet 189 .

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Once added to the flowsheet, the information blocks can be moved around and re-sized as the user requires. -

5.3.5

Model Windo ws The Model window colle cts data required for the selected model calculat ion and displays the equipment parameters calculated during simulation. The Model window is accessed by clicking o n the double arrow button next to the selected model in the Equipment wind ow. While the contents of the model window vary depending on the models chosen, the general layout of the model windows is common to all models; see below.


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Whilst all model options for particular equipment are accessible from the Equipment Model d rop-down list, JKSimMet can only use a model in simulation if its prerequisite stream properties have been added via the System Properties 176 table. An error messa ge will be displayed during simulation if a model has been selected for which the required stream properties have not been chosen. The data associated with a particular model are displayed on a series of tabs. Most tabs have an associate d drop-down list for the model option selection. The model window consists of: 1.

A title bar in wh ich the chosen model option is di splayed.

2.

A ser ies of tabs used t o disp lay or all ow da ta entry fo r the chosen model.

The data layouts for all of the model types, including details of prerequisite stream property requirements, are detailed in the Model Descriptions 294 section. The Model windows 193 are also discussed in more detail within the chapter on Editing the Flowsheet Data.

5.3.6

Prope rty Windo ws The properties of the flowsheets, equipment, streams and labelsProperties can be accessed in the Flowsheet, Equipment, Stream Properties and Label windows, respectively. Flowsheet Properties Window

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Right click on the flowsheet name and select Properties to ope n the Flowsheet Properties window. This window allow s the user to chang e the flowsheet name, add any comments about the flowsheet and view the last modified date. Note that there is a 50 charact er limit for the flowsheet name and comments sections.


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Equipment Properties Window

To open the Equipment Properties window unlock the flowsheet and doubleclick on the equipme nt item to be exa mined. Alternatively, you ca n right-click on the equipm ent item and select properties from the right-click menu. The Equipment Properties window allows the user t o ch ange the equipment na me and orie ntation as well as various aspects of the equipment item's physical appearance on the flowsheet.

Stream Properties Window

To acce ss the Stream Properties window for a stream, unlock the flowshe et and doubl e-click on the stream y ou wish to examine or again use the right click menu. This will open the Stream Properties wind ow in which the user can chang e the name of the stre am as well as various other characteristics affecting the streams physical appearance. Note that it is recommended streams be given meaningful name s, such as ‘Rougher Feed’, ‘Rougher Conc’, ‘Rougher Tail’, as this will enable them to be more easily recognized later, when the simulation results are reviewed.


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Repor ting to Exce l Window The Reporting to Excel w indow allows the user to select any stream or equipment data for export to an Excel workbook. Reporting is the main method for exporting data from JKSimMet, with the formatted data in the Excel workbook being av ailable f or printing and graphing as required. The user can configure multiple reporting formats. The Reporting window can be opened by two methods: 1.

Selecting Reporting from the Flowsheet menu.

2.

Clicking on the Reporting button.

Note that is the Reporting to Excel f eature can only be accessed when the flowsheet locked.

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The stream data and equipment data are exported together. Multiple report formats can be created. The Reporting feature is discussed in more detail under the heading Using the Reporting Feature 226 .

5.3.8

Simulation Manager Window The Simulation Manager window is where the user can set up multiple simulations, which can then be run in sequence as a batch operati on. The user can configure multiple scenarios for simulation an d ca n edit key operating data used in the simulations, which are displayed in the tables (e.g. Feed tonnage, % solids). The Simulation Managerwindow can be opened by two methods: 1.

Selecting Simulation Manager from the Flowsheet menu.

2.

Clicking on the Simulation Managerbutton.

Note that the Simulation Manager can only be accesse d when the flo wsheet is locked. Selected result s of the simul ations are displaye d on the stream and equipment data tabs (labelled Results - Streams an d Results - Equip), once the batch of simulations has completed. This allows the user to readily compare simulated results under the different operating conditions. The simulation operating data summary and the results of the simulations displayed on stream and equipment tabs in the window can be printed directly from the Simulation Managerwindow or copied t o the clipboard for pas ting into other programs such as Word or Excel. The Simulation Manager win dow is discussed in more detail under the heading Simulating Using the Simulation Manager 201 .


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Simulation Window Simulation Window

The Simulation window is where a simulation of the current flowsheet settings can be run, an d the controls set for t his s imulation. The Simulation window can be opened by two methods: 1.

Selecting Run Simulation from the Flowsheet menu.

2.

Clicking on the Run Simulationb utton(

).

Note that the flowsheet must be locked before the user can select the Simulation button.

Run

The Simulation window provides the selection and configuration options for running a simulation. Here the user may choose which simulation to run or to create a new simulat ion using a different selection of equipment and streams. The user can also configure the required convergence, the number of iterations, the interpolation used a nd the s tarting conditi on of the simulation.

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Simulation is discussed in more de tail in under the heading Using Simulation 199 .

5.3.10 Stream Windows Accessing the Stream Data

The Streams window provide s a ccess to the Stream Data window to view the data for each stream.

Stream Button

The Streams window for each stream can be opened by three methods: 1.

Double-clicking on a stream.

2.

Selecting Stream from the Flowsheet sub menu.

3.

Clicking on the Stream button.

All of the streams in the current flowsheet may be accessed from the Streams window via the Stream Name drop-down list. The Streams window can only be accessed wh en the flowsheet is locked.

The Stream Data window is accessed by clicking on the double arrow button next to the selected stream. Once the Stream Data window is open the user can view the stream data in a variety of ways, as required since there is considerable s cope for customising the way these data are viewed. Note that in the colum n displaying simulated data , the fields will not contain values until simulation has been completed.


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Totals Ta b

The data associated with a particular stream are displayed on a series of tabs. The tabs visible in the Stream Data window are always present. The Totals tab lists the overall properties of the stream. The default window shows various data types - s imulated, experimental, SD, mass balanced, error and fitted. The data types that are shown in these windows can be controlled by the user. If you click on the Data Type View button, a dialog box will appear where you can exercise a choice about the data types you wish to see.

Click on any of the data type headi ngs and you will be pre sented with a dropdown list containing the six available data types plus the option of selecting "none". If you chose "none", the colu mn concerned will be eliminated from the Stream Data window display. If y ou try to select any given data type twice, you will get an error message. If you are carrying out simulations only for instance, you would probably want to see the Sim, Exp an d Error dat a types and eliminate the other three. SD Calculation

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To the right of the Data V iew Type button is a button labeled "SD Calculation". This button brings up the Automatic SD Calculation window. Note t hat this is only relevant when you are carrying out mass balancing or model fitting. It is not required for simulations.


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The Automatic SD Calculation win dow allows you to set up an SD calculation method differently for each property within each stream. From the left panel containing the list of str eams, you can select either a single stream or a group of streams. To make this selection you can use the Contr ol key with a left mouse click to pick out indiv idual stream s for the group. Alternatively, you can use the Shift key and the left mouse button to add all the streams between the one initially selected and the one current ly under the cursor. Once the s tream or streams have been selected, you then select the property to which the SD method is to apply. This is done via the Property drop-down at the top right of this window. You can select All if you want this SD calculation met hod to apply to all properties of the selected streams.

Having selected the streams and the properties, you then go to the SD Calculation Option drop-down where you can now select the method of determining the SD's for this group of streams/properties.


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If you select Poor, Average, Good or Excellent, the program will use a fixed percentage of the stream. Note that you can change the percentage however, that applies to each of these selections, if requir ed. The other possible selections include "Fixed" where you can again change the value to whatever you deem to be appropriate. But in this ca se keep in mind that yo u are selecting the actual value of the SD rather than a percentage of the stream value. There are several other methods tha t can be applied for SD calculation. Whiten SD

If you select All Sizes from the Property drop- down, then there will be an extra SD calculation option available at the top of the list. The extra option is "Whiten" which is an SD calculatio n method that only applies to sizing data. This option is not visible in the screen grab above because the image was generated after selecting TPH or All from the Property drop-down. Note that Whiten is the mo st commonly used SD ca lculation method for sizing data. To app ly this to your sizin g data but still apply some other chosen method to all of your other data, you could first selectand Allapply and apply the which appropriate method". Aftermethod this youstill can in select All Sizes Whiten, would"other then leave t he other force for all of the non-sizing data.

Sizing Data

The other available tab contains the stream sizing data. These data will be displayed in the fo rmat that has been selected via the buttons on the main toolbar. The si zing data can b e expressed as either % Retained (

), Cum % Retained (

) or Cum % Passi ng ( ) . Note that this sel ection can b e chan ged at an y time, even when this stream data window is open.

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In the case of the error column you can change the form of the error that is displayed and the curr ently selected form will be s hown in the column header. This is done by clicking o n the Error Sum button, which is the button second from the right on the Stream data toolbar.

These new calcula tions are for display purposes only. The weighted e rror is used in all Mass Balance an d Model Fit calculatio ns. After pressing this button, the Error dialog box will appear where you can specify both the types of data that a re to be compared for determ ining error values and the method by which these e rrors are calculated. Fo r ins tance in the settings shown in the screen grab below, the errors will be obtained by comparing the experimental and balanced data and the method of calculation will just be a straight percentage error calculation.


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Also in thi s screen grab, you will notice there is a frame labe lled Error Sum below the drop-down selection boxes. Here there are radio buttons where you can select the errors that are to contribute to the calcul ation of the error sum fig ure that is displayed in a field (shown circled below), at the top of the Stream data window.

Note that it is only when you sele ct Exp v Bal data for comparison that all three options are available for the error sum calculation. Because JKSimMet does not contain models that predi ct element distr ibutions, the last two options cannot be selected wher e either Fit or Sim data are one of the data types to be compared. These options will be greyed-out in all but the Exp v Bal data case. Error Calculation Methods and Summing of Errors

The types of error calculation available for selection are Weighted, Percent and Absolute. Weight ed errors take account of the reliabi lity assigned to the various data points by dividing the difference by the SD value. Larg er SD values mean that the dif ferences will contribute less to the total error calculation. The other two methods take no account of the as signed SD values. The calculation methods a re: Weighted errors are calculated as [(Exp - Bal)/SD]2 Percent errors a re calculated as Abs[(Exp - Bal)/Exp] * 100 Absolute errors are calculated as just (Exp - Bal) In the case of the fi rst two error calculation methods, the individual errors are always going to be positive v alues. Thus to obtain the error sum in these two ca ses, the individual values are simply totalled. For the Absol ute error value s though, ther e will be negative values display ed for some data points and positive ones for others. To make these values all contribute to the total error and do not tend to cancel each other out , in this case it has to be the modulus of each value that gets incorporated into the Error Sum calculation.

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Accessing the Configurabl e Graphing Window

The Configurable Graphingwindow is a lso available via a butto n on this toolbar as shown below.

Changing the Column Layout

You can change the column layout of the Stream data window if required. This is achieved by clicking on the Data Type View (Dv) button - circled in the following screen grab.

The Change Data Type View window wi ll then open. The image be low shows this window with the user selecting None f rom the data type options for the last column. This action will remove the last column once the user has returned to the Data Type window. Note that selecting None does n ot delete any existing data; it merely tidies up the display.

The Streams window also lists the equipm ent from which the s tream srci nates and the equipment to which the s tream flows. Clicki ng on the double arrow button next to the From Equipment and To Equipment display panels opens the Equipment window relating to that equipment. The Equipment window 171 is discussed above. The Stream Data windows 210 are discussed in more detail within the Using Simulationchapter.

Copy Grid

The copy gri d button allows the user to copy the data from the active grid to the clipboard, from where it can be pasted into other applications as required.

5.3.11 The Equipment Window The data for the equipment can be viewed in the Equipment window. The Equipment window can be opened by three methods: 1.

Double-clicking on the equipment item itself.

2.

Selecting Equipment from the Flowsheet menu.

3.

Clicking on the Equipment button on the Flowsheet toolbar.

All of the equipment units in the curr ent flo wsheet may be accesse d from the Equipment wi ndow via the Equipment Name drop-down list. The Equipment window can only be accessed when the flowsheet is locked.


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The equipment models a vailable for the selected eq uipment unit a re a ccessed via the Equipment Model drop-down list. The Model window is accessed by clicki ng on the doub le arrow button next to the selec ted model. The Model win dow is discussed in more detail in the next topic. The Equipment window also lists the feed and product stream s of the selected equipment. Clicking on the double arrow button next to the names of the streams that are feeds or products from the selected equipment opens the Streams window. The Streams wind ow is discussed below. The Equipment and Model 193 w indows are discussed in more detail in the chapter on Editing the Flowsheet Data.

5.3.12 The Session Window The sessio n window is the driv ing seat of JKSimMet. In this window the user creates the flowsheets for analysis. After starting the JKSimMet program a blank session window a ppears as shown below.

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The use r can create a new project or load an existing (i.e. previously saved) project. Create a New Project

To create a new project click on the New Project icon on the toolb ar. In the dialog that opens, the user is prom pted to name the new project and specify its path. This loads a blank project containing a single flowsheet, a utomatically given the default name of "FlowSheet1".

Now that a flowsheet exists, the equipment list is displayed between the flowsheet list and the flo wsheet display pane on the rig ht. The procedure for


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creating a flowsheet will be discussed in more detail below. Load an Existing Project

Alternatively, the user can select a previously saved project from the list of existing projects by clicking on the Open Project ic on. This displays an Open dialog which allows the user to select the project to be opened.

The title bar in the session window displays the open project and flowsheet in the form JKSimMet - [Project Name – Flowsheet Name]. Note tha t the equipment list is not available unt il a project has been opened or created and therefore at least one flowsheet is present. Resizing the Session Window and the Internal Panels

Note that the session window ca n be resized by mo ving the cursor to any edge of the windo w. When it is positioned over the bo rder line, the cursor will change from the normal arrowhead to a thin line with an arrowhead at each end. While the cursor is in this state, left click and drag with the mouse to change the window size to whatever you require and release the mouse button when finished. Note t hat you can drag the top, bottom, sides and the corners using this method. When you drag a corner, both the height and width of the window can be chan ged simultaneously. The three main panels within the sessi on window can also be resized in a similar manner. You will see the mouse cursor turn into the double headed arrow form as you move it over one of the vertical panel dividing lines. By shifting the panel dividers, you can control how the overall window width is partitioned between the three panels.

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5.3.13 The Sieve Series Window The Sieve Series window displays a summary table of selected data for selected streams in the flowsheet. The user can configure one or many tables for displa y in this window. The Sieve Series window can be opened by two methods: 1.

Selecting Sieve Series from the Flowsheet menu.

2.

Clicking on the Sieve Series button.

The Sieve Series feature can only be access ed when the flowsheet is locked. The Sieve Series window provi des a visual display of the different sieve series available in the curr ent flowsheet and the sieve serie s that each stream in the flowsheet uses. The Sieve Series window is discussed in more detail under the heading

5.3.14 The Survey Data Window The Survey Data screen shows the surv ey size data for the sieve ser ies in the current flowsheet.


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The Survey Data window can be opened by two methods: 1.

Selecting Survey Data from the Flowsheet menu.

2.

By clicking on the Survey Data button in the toolbar area.

The Survey Data window can only be accessed when the flowsheet is locked.

The Edit Sieve Series button is used to bring up the Sieve Series

175

window.

The Transfe r button is used to transfe r the survey data into all of the streams, replacing the exper imental data. If the user has selected a s ieve series tha t is not the maste r series, the data will be transfe rred using the selected interpolation method.

5.3.15 The System Properties Window The global characteristics for the system property classe s are defined in the System Properties window. The System Properties window can be opened by two methods: 1.

Selecting System Properties from the Flowsheet menu.

2.

Clicking on the System Properties b utton (

) on the Flowsheet toolbar

The System Properties wi ndow can only be accessed when the flowsheet is locked.

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A drop-down list in the System Properties window shows the list of properties that can be defined for use by JKSimMet. The System Properties 192 funct ion is discussed in more detail within the ch apter on Editing the Flowsheet Data.

5.4

Bui lding and Manipul ating a Flo wsheet In this section we w ill go through the process of building up a new flowsheet from scratch and then examine how one can make modifications to an existing flowsheet.

5.4.1

Loading an Existing Project Loading an Existing Project


In JKSimMet V6, each flowsheet is stored as a sub-unit of a project. Therefore, to work with an existing flowsheet the user must first load the appropriate project into the session window by clicking on Open Project in the File menu or by clicking on the Open P roject ico n on the main toolbar (see topic File Menu and Main Toolbar 139 for more detail). This brings a standard Windows Open dialog into view.

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Open Project Dialog

5.4.2

Creating a New Project Creating a New Project

To create a new project select New Project from the File menu or click on the New Project ico n on the mai n toolbar. A dialog box will request a name for the new project. This n ame will be used as the file name and a s the project name.

New Project Window

To change the name of an open project, use the Save Project As from the File menu of the main JKSimMet menu. This will create an extra project with whatever new

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name you give it. You ca n delete the srcina l project if required - but remember that you will need to delete both the .jksf6 file and the .jksysdb file. To clean up completely, you will a lso have to delete the ass ociated AutoSav e files, which will have been created while you have worked on this file under its original name. There should be two of these; one for the .jksf6 file and one for the .jksysdb file. When a new project is created, it will initially be blank and will be loaded with a single blank flowshee t, which will be giv en the default na me of FlowSheet1. More flowsheets can be added to the project as required, see the Creating a New Flowsheet 180 section for further details.

Session Window Default Flowsheet

5.4.3

Loading an Existing Flowshee t Loading an Existing Flowsheet


The list of existing flo wsheets for the open projec t will be display ed in the left hand section of the session window. Double click to o pen the desired flowsheet. The flowshe et can also be opene d by right clicking on the flowsheet na me and selecting Open. The name of the current flowsheet open in the project appears in the title bar at the top of the JKSimMet session window, in the format ‘JKSimMet – [Project Name – Flowsheet Name]’.


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Session Window with Blank Default Flowsheet Loaded

5.4.4

Creating a New Flowshee t Create a New Flowsheet

To cre ate a new flowsheet ri ght click in the left hand section of the session window and select Add New from the menu that appears. Any number of flowsheets can be added in this manner. Double click on the name of a flowsheet to make it the active flowsheet.

Creating a New Flowsheet

Add New creates a new flowsheet in the current project. Open opens the s elected flowsheet in the right hand side of the session window. The flowsheet can also be opened by double-clicking on the flowsheet name (see topic Loading an Existing Flowsheet 179 ). Clone a New Flowsheet

Clone copies the flo wsheet exactly. This optio n is particularly useful to run a series of simulations while keeping the same flowsheet as a basis instead of redrawing and entering the data many times over. To clone a flowsheet, rightclick on the flowsheet and select "Clone" from the drop-down menu.



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If you need to delete a flowsheet that you h ave added by cloning or otherwise, you can do this by once again right-clicking on this flow sheet in the left hand panel listing and selecting "Delete" from the drop-down menu. Note that you will not be able to de lete the flowsheet if i t is open in the right hand pane. If you get a message that the flowsheet can't be deleted for this reason, just doub leclick on another of your fl owsheets before right- clicking again on the one you are trying to remove. The delete function from the drop-down menu should now work.

Defining the Flowsheet Name As a project can contain more than one flowsheet it is advisable to giv e each flowsheet a unique name. The list of flowsheets for a project appears in the left hand side of the session window. New flowsheets created in JKSimMet are given default names – FlowSheet1 for the first and then FlowSheet2, FlowSheet3 etc. To edit the flowsheet name, right click on the flowsheet na me and select Properties f rom the menu to open the Flowsheet Properties window.

To change the nam e of the flo wsheet the user must highlight the text in the Flowsheet Name box, type in the new name (maximum 50 characters) and press OK to register the name. The new flowsheet n ame will appear in the left hand s ide of the session window. The user can als o edit the Comments text for the flowsheet, h owever note that there is a 50 character limit for this text.

5.4.6

Deleting a Flowshee t Right clicking on the flowsheet name in the left han d side of the sessi on window opens a pop-up menu.



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The Pop-Up Menu

Delete deletes the flowsheet. An open flowsheet ca nnot be deleted. A flowsheet can be closed by click ing on the Close icon in the top right hand corner of the flowsheet window (not the Clo se icon in the top right han d corner of the session window), or by opening another flow sheet. The closed flowsheet can then be deleted.

5.4.7

Building the Flowsheet - Equipment When ‘FlowSheet1’ has been loaded, the user is presented with a blank flowsheet. The first step in entering the data for the project is to build the flowsheet. JKSimMet uses an equipment unit to represent each process on a flowsheet. The list of equipment that is available in JKSimMet is shown below in the same form as it appears in the Session window.



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The default equipment has typical values for the equipment dimensions, model parameters etc. as its default data. The user can edit these data at a ny time. Circuit Fee d

JKSimMet uses the Feed equipment unit to introduce the feed flow to the circuit. This means that the paramete rs of the feed s tream are actually defined in the Fee d equipment rather than in a ‘Feed stream’. A flowsheet therefore must contain at least one Feed equipment unit.

Adding Equipment to the Flowsheet

To place the appropriate equipment icons on the flowsheet: 1. Unlock the flowsheet by clicking on the Lock/Unlock ic on, by selecting Lock from the Flowsheet menu or by selecting Lock/Unlock from the right click menu on the session window.


2.

Click on the icon of the desired equipment.

3.

Move the cursor to where the unit is to be drawn on the flowsheet and click to place the unit. To place multiple units of the same equipment type, hold down the control key while s electing the equipment type from the equipment list, then repeatedly click in the flowsheet to place Building and Manipulating a Flowsheet

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as many units as required. Alternatively, addit ional units may be placed by placing a first unit in the usual way, pressing the Copy button and then using the Paste function to place as many units as a re required.

5.4.8

Editing Equipment on the Flowsheet

To edit eq uipment once it ha s been placed on the flowsheet, double click on the item of equipment in the flowsheet. The flowsheet must remain in unlocked mode to access the editing features. The equipment can then be moved and have its na me and orientation changed, as described below.

Moving Equipment

To move equipment to a different posit ion on the flowsheet place the cursor over the equipment and hold the left mouse button down while dragging the equipment to its new position. When the equipment is in the required position release the mouse button to place the equipment. Any streams that are attached to the equipment will remain attached after movement of the unit.

Naming Equipment

The equipment is given a default name when it is initially added to the flowsheet. To change the name of the equipment double-click on the equipment and type in the new name next to the Name i n the Component Properties window an d click OK.

Displaying Equipment Name

The Equipment Auto Labels icon can be used to display the equipment name on the flowsheet. When the Equipment Auto Labels ic on is selected an equipment label will a utomatically appear when equipment is added to the flowsheet. The equipment label takes the Equipment Name f rom the Component Properties wi ndow, as described above. The Equipment Auto Labels funct ion is discussed in more detail in the chapter on Annotating the Flowsheet 187 .

Orientation

The orientation of the equi pment can be change d so that the feed end of the equipment chan ges from left to right or vice -versa. The default orientation is the feed on the left and the prod ucts on the rig ht. Sele ct one of the ‘Fli p’ or ‘Rotate’ buttons on the toolbar to change the equipment orientation.

Deleting Equipment

To delete equipment ensure the flowsheet is unlocked and click on the equipment to be deleted. Once s elected press the ‘ Delete’ key or select ‘Delete’ from the ‘Edit’ pull-down menu.

Building the Flowsheet - Streams JKSimMet uses streams to represent the flow of material (solids and water) between the equipment on the flowsheet. Mate rial enters equipment through its feed inlet and leaves equipment through its product outlet (s). The flow of material equipment is created on the flowsheet feed andbetween product the outlets of the appropriate equipment items.by connecting the Although the drawing engi ne does not impose a limit on the numb er of feed streams that can be connected to an individual equipment unit, the simulation engine does only recognise the first 50 feed streams per equipment item. Note that there is also a limit on the t otal n umber of streams per flowsheet and this limit has been set at 999. The number of product outlets from an equipment item depends on the type of equipment; for example a flot ation cell has two product outlet s, a pump s ump



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has one product outlet. Note that there are tw o specialised eq uipment items that do not have a feed inlet. These are the Feed equipment item, which is the source of new feed to a circuit, and the Water Feeder, which is the source of wate r addition to a circuit. Adding a Stream to the Flowsheet

Streams can be added to the flowsheet in a similar manner to equipment. Once tee equipment has all been a dded to your flowsheet, it is simply a matter of using your mouse to join the appropriate output and input ports of the various equipment items. 1. Unlock th e flowsheet by clicking on the Lock/Unlock icon or by selecting Lock f rom the Flowsheet m enu. In unlock mode the flowsheet may be altered. 2.

To co nnect a pro duct ou tlet to a feed inlet, place the cur sor ov er the product outlet or feed inlet of an equipment item . When the cursor changes to a circle containing a cross, lef t click to start the connection process. T he cur sor wil l then chang e to a cross and when you now move the mouse, it will drag a line representing the stream to wherever you select as the destination.

3.

When you have positioned the cur sor over the inlet or outlet (as appropriate) of the destination equipment item, the cursor will again turn into a circle containi ng a cross. Note that this will only h appen where a connection is p ossible. If you have started at an inlet port an d you move to another inlet port, the cursor will not change because in this case the connection is not possible. W hen the cursor has changed to indicate the potential for connection, left-clicking again will complete the stream.

Streams can be connected in s traight lines in this manner, or they can be made to follow more complex paths. The above procedure will produce a connection that is just a straight line stream from one item of equipment to another. While a straight line s tream may be accept able in a very simple circuit, more often than not you will requ ire point s of inflexion so that you r streams take a less direct route to thei r destinati on. You can achieve this during the connection process if you left click at the various intermediate points where you require the stream to change direct ion. Again, you jus t terminate the s tream wh en the cursor turns to a cross within a circle over the destination port. To produce the stream connection below for instance, left-click over the outlet from the feeder, move the cursor downwards to the desired position for the right angled be nd and click ag ain. Finally , move the cursor to the right and click on the flotation cell inlet to complete the stream.



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Flowsheet with a Single Strea m Connection

Note that if you wish to abort the drawing of a stream a t a ny point during the process, all you have to do is right click and the entire stream you have entered to that point will disappear. Editing a Strea m on the Flowsheet

To edit the for matting of a stream once it has been placed on the flo wsheet double click on the stream. The flo wsheet must be in unlocked mode to access the editing features. This will open the Common Properties window for the chosen stream.

Naming Streams

The streams are given default names when they are initially added to the flowsheet. To change the name, open the Component Properties window by double-clicking on a stream. Type in the new name into the Name text box and click OK. It is recommended that the streams be given meaningful names such as ‘Cyclone O/F’, ‘Ball Mill Feed’ etc, so that they can be easily identified.

Displaying Stream Name

Labels can be added to the flo wsheet to display the stream names using the Stream Auto Labels ic on. Labels are discussed in more detail under the heading Annotating the Flowsheet 187 .

Manually Reroute Streams

JKSimMet provides a mechanism for re-routing exis ting streams in the event that you are not satisfied with your initial placement. First ensure the flowsheet is unlocked and then right- click on the s tream you wish to re-route, at the point wher e you require the point of inflexion (or stream node). The right-click menu will look similar to the image below.



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Click on the Add/Remove Stream Node menu item. This will insert a new stream no de at the curso r location. You can then move the curso r over this new node, then left-click and drag it to the location required for re-routing this stream. You can remove a stream node in a similar manner. For this you need to bring up the right-click menu while the mouse is hovering over the stream node in question. Selecting the same menu item will in this case delete the stream node. Deleting a Stream

Whole streams ca n be deleted in the s ame manner as equipment item s. Ensure the flowsheet is unlocked, then click on the stream to be deleted. Then you can either press the Delete key or s elect Delete f rom the Edit pull- down menu. Before the stream is actually deleted you will get a warning and an opportunity to cancel, so as to guard against accidental deletio n. Once all of the equipment and streams have been added to the flowsheet and the editing of names is complete, lock the flowshe et by clicking on the blue Lock icon, by selecting Lock from the Flowsheet menu or by selecting Lock from the right click menu in the session window.

5.4.9

Annotating the Flowshee t JKSimMet allows the us er to ann otate the flowsheet by adding general labels to the flowshe et or by adding equ ipment or s tream specif ic labels, as well as information blocks. There are three ways in which la bels can be added to the flowsheet : 1.

General Tex t Lab els – used to add ge neral te xt (e .g. circuit name) to the flowsheet; the labels can be moved independently around the flowsheet.

2.

Equipment Lab els – used to aut omatically add the equipment name as a label near the equipme nt on the flowsheet; the label becomes pa rt

3. Adding Gene ral Text Labels to the Flowsheet


of the equipment and moves when the equipment is moved. Stream Labels – used t o add l abels of the existing stre am name s to the flowsheet; the labels are of the same form as the Equipment Labels.

To add General Text Labels to the flowsheet: 1.

Unlock the fl owsheet by clicking on the Lock/unlock button or by selecting Lock from the Flowsheet submenu.

2.

Select the ‘Text’ icon from the toolbar. A text icon now appear s next to the cursor when it is placed over the flowsheet.


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3.

Move the cursor to the desired location and click to place the label.

4.

Double click the label and type in the desired text. Press ‘Enter’ when finished.

Editing Labe ls on the Flowsheet

To edit a label once it has been placed on the flowsheet click on the label. The flowsheet must remain in unlocked mode to access the editing features. A label can then be moved and be edited, as described below.

Moving Labels

Text labels can be moved in the same mann er as equipment. Simply place the cursor over the label and hold the left m ouse button down while dragging the label to its new position. When the label is in the required position release the mouse button to place the label.

Changing the Text of a Label

To change the text of the label, dou ble-click on the labe l and type in the new text. Press ‘Enter’ to complete.

Deleting Labels

Labels can be deleted in the same manner as equipment and streams. Ensure the flowsheet is unlocked then click on the label to be deleted. Either press the ‘Delete’ key or select ‘Delete’ from the ‘Edit’ pull-down menu.

Adding Equipment Labe ls to the Flowsheet

To automatically add the equipme nt n ame as a label above the equipment on the flowsheet click on the Equi pment Aut o Labels button. To remove the equipment name labels click on the Equipme nt Auto Labels button again. The Equipment Auto Labels function is available whether the flowsheet is locked or unlocked.

Editing Equipment

Unlike the ge neral labels, the labels added to equipment on the flowsheet using the Equipment Aut o Labels function cann ot be independently renamed.

Labels

These equipment labels become a part of the equipment; they move when the equipment is moved, are renamed when the equipment name is changed (using Equipment Properties, see topic Property Windows 160 ) and are deleted when the eq uipment is deleted. The position of the label in relation to the equipment can be changed , however. To do this, double click on the label or the equipment to bring up the Component Properties window. Select the ‘Auto Label’ tab and select an option for the positio ning of the label relative to the equipment. Note that clicki ng the ‘On/Of f’ option in this tab will mean that the labe l for this particular item of equipment will not be display ed on the flowsheet. Stream Labels may also be edit ed using the same procedure as Equipment Labels.

Adding Stream Labe ls to the Flowsheet

IMPORTANT NOTE

To automatically add labels of the existing stream names to the flowsheet: 1.

Unlock the flowsheet by clicking on the Lock/unlock button, by selecting Lock from the Flowsheet submenu or by selecting Lock from the right click context m enu in the session window.

2.

Click on the Stream Auto Labels button.

Note that if the stream names are changed subsequent to adding stream labels to the flowsheet, the stream label text automatically changes, however the stream label box doe s n ot automaticall y resize to match the size of the new stream name. To fix this, click the Stream Auto Labels button to remove the labels, then click on the Stream A uto Labels again to add the labels again.



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5.4.10 Information Blocks On opening the Information Blocks wi ndow (via the toolbar button or the Flowsheet menu) the user will be presented with a tabbed display, with one tab for setting up Stream Information Blocks and one for Equipment Information Blocks.

Stream Information Blocks

The same data is dis played for all active Stream Infor mation Blocks. You cannot tailor the block s for individ ual s treams so that they are different from those of other streams. The procedure for adding Stream Information Blocks is as follows: 1.

First ensure that the Stream tab is active.

2.

From th e first dro p-down box, select the number of parameters to be displayed in the Information Block.

3.

Select the b asis stre am for recovery calcu lations. Not e that his sele ction is only nee ded if a recovery value is to be one of the display field s and this will only be a possi bility in cases where mass balancing is being performed.

4.

Next left click on each par ameter cell in tur n to sele ct the data that yo u wish to have displayed in that cell. Each time you do this, another window labelled Selection Optionswill open. Here you specify the type of data to be display ed in more detail. A screen grab of this window is shown below.

5.


In this win dow you work your way down (st arting wit h the dr op-down at top left in Selection Options), to make a full specifi cation of the data type that is to be displayed in the sele cted cell. Note that lowe r dropdowns will become available when needed, depending on your selections in the dr op-downs above. The name that will appear in the stream information block key for this data cell is auto generated by default. You will noti ce that the re is a tick in the Auto Generate Name


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box when the window opens. If the system ge nerated name is too long however, you can manually enter an abbreviated form, after clicking to remove the tick from this check-box.

6.

Select the stream or streams for the info block – multiple sele ction can be achieved using the ‘Ctrl’ and ‘Shift’ keys.

7.

Click ‘Add Info Block’ to add the blocks to the flowsheet.

The Info Blocks will be added to the flowsheet, roughly centred on each stream. In addition there will be a key displayed a t the top left of the flowsheet that will show which parameters are displa yed in which cells of the Info Block. To modify the information displayed in the Stream Information Blocks, make the changes required and click ‘Update Selected Info Blocks’. Remember that the same data is displayed for all streams, so clicking ‘Add Info Block’ after changes have be en made in the Stream Info box tab will result in all of the Stream Info Boxes updating. Equipment Information Blocks

Equipment block s are concept ually diff erent to Stream blocks, but operate in a similar way. As each Equipment unit may use a different model and therefore different data, the information blocks are set up on a per unit basis. The procedure to add an Equipment Information Block is: 1.

Select the equipment unit or unit s for the info blo ck – multiple selec tion is a chieved with the ‘Ctrl’ an d ‘Shift’ keys.

2.

Select the number of parameters to be displayed.

3.

Left click on each par ameter cell to sel ect whic h data is to be di splayed in that cell. The selection method is the same as the Configurable Equipment Manager , except that the parameter name is also defined. Click ‘Close’ when finished.

4.

Click ‘Add Info Block’ to add the blocks to the flowsheet.

The info blocks will be added to the flowsheet, adjacent to each unit. The parameter names will be displayed in the cell next to the values.



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To modify the information shown in one or more Equipment Information Blocks, make the cha nges required in the Equipment Info box tab, s elect the Equipme nt unit or units to modify and click ‘Update Selected Info Blocks’. General Information

When the flo wsheet is unlocked, the Inf o Blocks may be moved, resized and deleted using the ‘Delete’ key. The data that is not able to be edit ed will be greyed out. Other valu es can be edited, and will update throughout the system.

5.5

Edi ting the Flows heet Data Overview

Once the flowsheet has been built comple te with equipment and connected by streams to form a circuit, t he next step is to input the da ta itself. The flowsheet must first be locked by clicking on the Lock button, by selecting Lock from the Flowsheet menu or by select ing lock from the rig ht click menu in the session window. Once locked the System Properties, Sieve Series, Survey Data, Configurable Equipment Manager, Run Simulation, Configurable Stream Overview, Simulation Manager, Run Balance, Equipment, Stream, Reporting, Config Graph and Setup Info Blocks icons are all accessib le. These tools will be described in subsequent sections.

Data Entry Conventions

There are three different background colours used to represent the different types of data in the JKSimMet windows: 1.

White – the user is required/permitted to enter data (e.g. feed tonnage).

2. 3.

Light grey – this data does not change (e.g. some labels). Medium g rey – user entry is not re quired but th e data will change depending on a user select ion or calculatio n during s imulation (eg a calculated value such as pulp volume of each cell).

These conventio ns apply to all of the data windows. Note that the exact appearance and colours of each window will also depend on the setup of the MS Windows desktop.

5.5.1

Stream Structure After input of the feed stream da ta and equipment and model data, JKSimMet predicts the sizing a nd mass flow data in the streams throug hout the circuit using an iterative technique. Comminution models are used within each of the specified comminution equipment units to dete rmine the resulting size data for the relevant output streams. A detailed explanation of the terms used to define the stream structure ha s been provi ded under the heading Definition of Terms Used in JKSimMet 135 . Remember that the feed s tream da ta a re defined in the ‘Feed’ equipme nt item rather than in the stream from this unit.



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System Properties System Properties

Click on the System Properties ic on or select System Properties from the Flowsheet sub menu to open the System Properties window. There are two system property classe s available to the user; Elements and Miscellaneous ite ms. Th e user has the opti on of def ining as many or as few elements as required, but cannot define additional miscellaneous items. The two classes of syste m properties a re accessed via a drop-down list at the top of the System Properties wi ndow, under the heading Select property. System properties must be defined for each flowsheet; they cannot be copied between flowsheets or between projects.

Miscellaneous

The first ite m on the drop down list is Miscellaneous and this will be chose n initially by def ault. Ther e are just two miscellane ous items in the system for which you need to set values; Solids SG and Liquid SG. The def ault values are 2.7 and 1 .0 (t/m3 ) respect ively. You can simply edit these values in the white cells to adjust them if required.

Elements

The othe r item on the Select property dr op dow n is Elements. In JKSimMet elements a re only neede d for the mass balancing functi on of the program. If you are not going to be doing any mass balancing, then it is not necessary to enter any elements into the system for the flowsheet in question. If you do need to specify elements, firstly select Elements from the drop-down. Once you do this you will see the appearance of the window change to resemble the screen capture below, which in this case also shows the expanded drop-down.

Adding Elements

The main difference you will notice after Elements has been select ed, is that a Delete selected row(s) button will be present at bottom left. This is to provide the option of removing mind or made an error.elements a lready in your list if you h ave changed your The table is configured such that it will always contain a blank row at the bottom where you can add further elements. When you enter an element you can either leave the units in the adjacent Units cell with the default setting of "%" or else select "g/t" (if appropriate) from the drop- down in this cell. To remove an element that is n ot required, click anywher e in the row you wish to remove and use the Delete selected row(s) button. There is no limit to the number of elements that can be added.

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The widt h of the colu mns can be changed by placing the cur sor on the right border of the colum n in the heading ro w, then holding down the left mouse button and dragging the cursor. IMPORTANT NOTE

Note that there is no internal check of consistency of these data in JKSimMet. It is up to the user to ensure that the SG values are correctly defined. When all cha nges to the System Properties window have been made, click on the Close button to close the window.

5.5.3

Accessing the Equipment and Model Data The Equipment and Model window s contain all of the information about the equipment that JKSimMet requires to perform simulation tasks. Accessing the Equipment Data

Equipment Window Layout

The data for the eq uipment can be viewed in the Equipment windo w. The Equipment window can be opened by: 1.

Double-clicking on the equipment in the flowsheet.

2.

Selecting Equipment o n the Flowsheet m enu or clicking on the Equipment icon.

There is one Equipment win dow in JKSimMet; all of the equipment can be accessed vi a the Equipment Name drop-down list in the Equipment window. The Equipment window can only be accessed when the flowsheet is locked. A typical Equipment window is s hown below.

A Typical Equipment Window

The Equipment wind ow also shows the fee d and product streams from the selected equipment. Clicking on the double arrow buttons next to the s treams that are fee ds or prod ucts from the selected equipment; opens the Streams window, which enables disp lay of stream dat a.



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Editing the Model Data The Model w indow collects the data required for the selected model calculation and displays the equipment parameters calculated during simulation. Selecting a Model

The Equipment Model drop-down list in the Equipment window shows the models a vailable for the selected equ ipment. All models for a particular type of equipment are available for selection.

Accessing the Model Window

Select a model and click on the double arrow button next to the selected equipment model to open the Model window.

Model Window Layout

The Model window for all the models h as the sa me general layout, see below. Click on the tabs at the top of the Model window to input and view the model data. The dat a layouts for all of the model types are detailed in the Model Descriptions 294 sec tion. Note that some of the calculated model data will update on input a nd s ome will update only afte r simulation.

Copy Grid

The Copy Grid button allows the user to copy the currently displayed grid to the clipboard, from where it can be pasted into other applications.

Units in Parallel

The units in pa rallel text box is used to show how many of the select ed un it in question exist a t this loca tion in the circuit.

A Typical Model Window Parameter Values


If a value is ente red for a paramet er that is outside the normal range for the parameter, JKSimMet will display a warning message. Users are given the choice of either having the valu e entered clipped to the neare st edge of the normal parameter rang e (eg, for a range of 1 to 15, an entered value of 20 would be clipped to 15) or continuing with the entered value.


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If the user needs to k now the maximum an d minimum values for a parameter value, double clicking on the cell for that item will launch the Parameter Detail window. This displays the minimum and maximum values, as well as the default value and other available information about the selected parameter.

5.5.5

Editing Equipment Data There are two options for viewing a nd editing the equipme nt a nd model da ta. The first option is to access the Equipment and Model windows for the individual eq uipment units as previously described 193 . The alter native is to use the Configurable Equipment Manager, whic h allows the user to vie w and edit data for all units of the same type in a summary table f ormat. This can be a more efficient means of a ccessing equipment data during simulation work. As its name implies, the Configurable Equipment Manager can be configured as required by the user. The Configurable Equipment Managerwindow displays a summary of selecte d equipment unit parameters. The user can configure multiple summary tables for display and can edit the value s displayed in these tables. This window provides a simpler and more efficient means of reviewing and adjusting equipment information than using the individual equipment data screens. The Configurable Equipment Managerwindow can be opened by two methods: 1.


Selecting Configurable Equipment Managerfrom the Flowsheet menu.


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2.

Clicking on the Configurable Equipment Managerbutton.

The Configurable Equipment Managercan only be accessed when the flowsheet is locked. Configurable Equipment Manager provides a summary of the equipm ent unit data for selected units in the flowsheet. The information displayed in the Equipment screens is exactlyequipment the s ame asunits. the information displayed in the modelOverview screens for the individual The summary table can be printed directly from the dialog, copied to the clipboard for pasting into othe r programs such as Word or exported to Excel for further analysis.

A Typical Configurable Equipme nt Manage r Window Configurable Equipment Manager Window

Current Overview List

Configurable Equipment Manager Toolbar New Unit Overview


The Configurable Equipment Managerwindow ha s four main components: 1.

Current Overview drop-down li st

2.

Configurable Equipment Manager toolbar

3.

Model drop-down list

4.

Data table

The user can create o ne or more Configurable Equipment Manager tables. Each table cr eated is listed by name in the Current Overview List drop-down, allowing the user to change from one table to another by selecting the required configuration from the list. The toolbar allows the user to create new configurations, delete unwanted configurations, add or delet e data columns, print, copy or export the data to Excel.

To create a new configuration the user clicks on the New Unit Overview button. This opens the Add Unit Overview dial og which prompts the user to enter a n ame for the new ov erview a nd to s elect from the Select Model drop-


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down list, a model that is to be associated with this newly configured overview.

Delete Overview

Clicking on the Delete Overview button deletes the current overview. A warning dialog asks the user to confirm that the current configuration is to be deleted as this operation cannot be undone.

Rename Overview

The Rename Overview button allows the user to rename the selected overview.

Insert Column

Inserts a blank data column to the right of the column where the cursor is currently located.

Delete columns

Deletes the column where the cursor is curre ntly located. Note that the column is deleted immediately without the user being asked to confirm their action.

Print Overview

Prints the current overview table.

Copy Grid

Copies the entire data grid for the current overv iew to the clipboard, allowing the data to be pasted into other prog rams such as Word.

Lock Cols

When this button is unlocked ( appearing as s hown in image at left) the user is able to change the position of the columns of data.

Export Overview

Exports the data for the current Equipment Manager ov erview to Excel. Clicking on the Export Overview bu tton opens the Export Report to Excel dialog where the user can enter a name for the Excel file and choose where to save the file. Note that if the file na me chosen is the same as an existing Excel workbook, the user is prompted to choose whether to overwrite the existing workbook or to append the curr ent data as a new worksheet in the exist ing workbook. The name of the Overview which has been exported is shown in the tab of the Excel worksheet.

Export All

As for Export Overview, except that in this case all of the overviews listed in the Current Overview drop-down list are exporte d to Excel, each on a separate, named worksheet in the workbook. Below is an example of a new overview that h as been created for cyclones in a flowsheet that are using the Asomah Advance Inclined Cyclone model. In this case there is only the one cyclone using this model. The overview has been configured to s how the cyclone diamete r (Dc) under the Operating Conditions category of param eters and also the var ious data types associ ated with the Water Split to Overflow parameter under the Performance Data categ ory of



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parameters.

An Example of the Default Configurable Equipment Manager Layout Configuring a New Data

When a new column is added to the Overview table by click ing on the Insert Column button, the added colu mn is headed No Selection and contains no

Column in the Overview

data. The user must select the data to be displayed in the column by first ensuring that the Lock Cols button is locke d and then clicking on the header cell for the column. This opens the Tab/Options/Parameter dialog.

The user can select the required options from the drop-down lists in the dialog.



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The selected parameters are then displayed in the overview table.

5.6

Adding or Deleting Equipment Units

The user is able to add or remove equipment units from a configuration. Data for other unit types or similar unit types tha t a re usin g a different model, must be viewed and edited by setting up another configuration for that model type.

Changing the Data Column Order

To change t he ord er in which the data columns are displayed the user must unlock the Lock Cols button, sele ct the column in the data table by clicking in the he ader cell and then dra g the colu mn to its new location on the tabl e as indicated by a red line . Two or more adjace nt columns can also be moved by selecting all of the columns together (click and drag or Shift-click) and dragging the group to their new location in the table.

Using Simu lation During s imulation JKSimMet calculat es the mass flow of the particle classes in each stream of the flowsheet. The mass in each pa rticle class in the product streams of each equipment unit is calculat ed using the mass in each particle class in the feed stream(s) to the equ ipment and the model algorithm for the equipment. These calculations are performed iteratively until the difference in the stream flows from two consecutive iterations are below a specified convergence limit. The particle class information is then combined to enable calculation of the data displayed in the Stream data an d Stream Overview windows. Various unit parameters are also calculated during simulation an d can be viewed in their as sociated equipm ent data windows. What Simulation Requires

Prior to simulation, the user must: 1.

Create the flowsheet (see Se ction 4.5). Note that eac h feed str eam to a comminution circuit (unle ss it consists entirely of water; see Water Feeder models in Appendix B3) must be preceded by a Feed equipment unit before it ca n be In ato ddition, all equipment units must have feed streams forsimulated. the flowsheet be valid.


2.

Define the char acteristics of the pro perty classes in System Prop erties (see Section 4.6.2).

3.

Input the feed str eam data in the Feed equipment uni t (see Appendix B2).

4.

Select the models for eac h equipment and input the req uired model data (see Sectio ns 4.6.4 to 4.6.6).


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Performing Simulations

5.6.1

Simulation within JKSimMet can be performed in two ways. If the user simply wants to s imulate the circuit with the current equipm ent and feed stream data values only, the Simulation window is used. Alternatively, the Simulation Manager allows one or more simulations to be performed on the flowsheet with the user being able to set selected data values (e.g. solids flow rate, % solids) for each simulation in the batch. The use of each simulation control is described below.

Simulating Using the Simulation Window Accessing the Simulation Window

To perform a simulat ion with the curre nt data in the flowshee t the Simulation window is used. The Simulation window can be opened by two methods: Selecting Run Simulation from the Flowsheet menu, or Clicking on the Run Simulation icon.

Simulation Select

The system provides a default simulation for the whole circuit; the user is then free to cre ate new simulat ions and delete or rename the simulations that they add. The whole circuit simulation cannot be renamed or deleted.

Add a new circuit

Choosing to add a new circuit brings up this dialog, where the user can choose to accept the default name or enter a name of their choice.

On returning to the main simulation dialog, the user can then choose which equipment and streams they require for the new simulation Equipment / Streams

Using Simulation

In all simulations except the default whole circuit simulation, the user can choose which equipment items and streams are to be used by the simulation.


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The optio ns in the settings area allow the user to s et the conve rgence limit, s et the iteration count, choose the interpolation method and set the starting condition for the simulation.

Interpolation options

Starting Conditions

5.6.2

Run

When the use r has selected the simulation that they wish to run, checked the

Simulation

choice of thethey selected and reviewed The the settings for the simulation, clickequipment the start butand tonstreams to run the simulation. simulation will run until either the specif ied iteration count is reached or the fitted converg ence value reaches accuracy le vel specified in the settings. As the s imulation runs it provide the user with feedback by updating the Convergence and Iteration count text boxes.

Simulating Using the Simulation Manager The Simulation Manager i s a powerful feature that allows multiple simulations to be perf ormed in a batch operation. The user can set a range of key operating parameters in the simulations and record the key performance indicators for each s imulation performed. The results of all of the simulations within a scenario can then be viewed on the same screen, allowing direct comparison of simulated f lowsheet data under different operating conditions. The user is able to vi ew any paramet er relating to stream or equipment unit data. The equipment viewing platform is similar to the Configurable Accessing the Simulation Manager


Equipment Manager viewing platform Click on the Simulation Manager icon or select Simulation Manager from the Flowsheet me nu to open the Simulation Manager wi ndow. The Simulation Manager windo w consists of the Simulation Manager toolbar and three data tabs, one for setting the simulation conditions ( Simulation Scenario) and two for viewing the simulation results ( Results - Streams and Results - Equip). When the Simulation Managerwindow is opened, the Simulation Scenario tab is a ctive.

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Simulation Scenarios

The Simulation Manager all ows the user to perform multiple flowsheet simulations varying key operat ing parameters in a batch operation called a Simulation Scenario. Any number of Simulation Scenarios may be created, however only one Simulation Scenario m ay be active at any one time. The active Simulation Scenario can be changed to another previously created scenari o by s electing the requ ired item from the Scenario Name drop-down list. Within each Simulation Scenario, the user can create a large number of simulations to investigate the eff ects on the circuit performance of a single parameter, or the effects of different values of a multiple of equipment parameters. The results of these simulations can then be viewed in the different results tabs of the Simulation Manager. The different areas of the Simulation Manager window are as follows:

Data Display Header

Using Simulation

1.

Toolbar – con tains the fu nctions to conf igure and use the Si mulation Manager. The toolbar is always visible at the top of the window.

2.

Tabbed data viewing region – each tab contains a data di splay h eader and a data display are a, and only one tab can be vie wed at any one time. The three tabs displa y the simulation conditio ns and simulation results: a)

Simulation Scenario – used to define the equipment parameters which are to be v aried in the simulations and to set the valu e of each parameter for each simulation;

b)

Results - Streams – for viewing results associate d with stre ams on the simulated flowsheet;

c)

Results - Equip – for vi ewing re sults asso ciated wit h equipment units on the simulated flowsheet .

The param eter descri ption is display ed in the data display header in each of the tabs. See further down in this topic under the heading Selecting the


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203

for the method used to select the parameters.

Note that all of the drop -down lists in the data display header list items in alphabetical order. Data Display Header: Simulation Scenario Tab

The data display header for the Simulation Scenariotab is similar to the data display header in the Configurable Equipment Manager , containing data headers to describe the selected parameter. These data headers are: Row 1 – Equipment name Row 2 – Model Tab Row 3 – Model Tab Option Row 4 – Parameter name Rows 5 to 7 – Description of property specific parameters Row 8 – Type of Change: choose either replacing the value of the parameter with a user define d value (select Value ), or increasing or decreasing the value of the parameter by a defined percentage (select % Change). Row 9 – Original Data: the ‘base case’ value of the parameter is automatically displayed when the parameter is added. This provides a reference point for comparison with the other simulations results.

Data Display Header: ResultsStreams Tab

The dat a display heade r for the Results - Streams tab is similar to the dat a display head er in the Configurable Stream Overview, containing five data headers to describe the selected stream data. Row 1 – Stream name Row 2 – Property Row 3 – Calculation Type: sele ct Row 4 – Assay Basis Row 5 – Original Data: the ‘base case’ value of the parameter is automatically displayed when the parameter is added. This provides a reference comparison point for the other simulations.

Data Display Header: ResultsEquip Tab

The data display header for the Results - Equip t ab is similar to the data display head er in the Configurable Equipment Overview, containing several data headers to describe the selected parameter. These are: Row 1 – Equipment name Row 2 – Model Tab Row 3 – Model Tab Option Row 4 – Parameter name Rows 5 to 7 – Description of property specific parameters Row 8 – Original Data: the ‘base case’ value of the parameter is automatically displayed when the parameter is added. This provides a reference comparison point for the other simulations.

Using the Simulation Manager


Using the Simulation Managerrequires the user to: 1.

Create a Scenario in the Simulation Scenariotab.

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Delete Scenario

Rename Scenario

Create a Scena rio

2.

Select the parameters to be varied for the simulations.

3.

Define different simulation conditions.

4.

Select the parameters to be displayed in the Results - Streams tab and the Results-Equip tab.

5.

Perform the batch si mulation.

The current Scenario can be deleted by clicking on the Delete Scenario button from the toolbar at the top of the Simulation Managerwindow. Click Ye s to the prompt to delete the current scenario. The current scenario can be rename d by highlighting the existing na me in the Scenario Name box and typing the new name to replace the old one.

Click on the Simulation Scenario t ab, then click on the New Sim Scenario button on the toolbar at the top of the window , type in the name for the new scenario and click OK. The Simulation Scenario ta b then displays one column in the data display area with ‘N o Selection’ in the top row of this column. Note that when selected subsequently, a particular window appears as it was las t left by the user.

Selecting the Parameters

Simulation Scenario

The Simulation Scenario wi ndows can be configured by the user to allow many parameters to be varied in the simulation. The paramete r displayed in a column can be change d by editi ng at any time. New columns can be added, and existing columns ed as required using the Insert Column and Delete Column buttons on thedelet toolbar.

Adding a New Parameter

To add a new parame ter to the Simulation Scenariotab display , first click in the data display a rea of the window then click on the Insert Column button on the toolbar. A new colum n will be added to the right of the cursor position. When a new colu mn is added to the scenario, the words ‘No selection’ are displayed in the top row of the column. This parameter descr iption can be changed as outlined below.

Changing Existing Parameters

To display a different parame ter (or to s elect a parameter for the first time), lock the columns, then click in the top row in the data display header of that column (initially this row will display ‘No selection’). A new window appears to select the parameter.

In this window the user selects the required parameter from the drop-down

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lists by selecti ng first the Equipment unit for the parameter, an d then the Tab, Option a nd finally the Parameter to be displaye d. Note that the Equipment/ Group drop-down list contains all of the equipment units in tha t flowsheet, in alphabetical order. The Tab, Optio n a nd Pa rameter are selected in an identical manner to the Configurable Equipment Overview. When parameter selection is complete click on the Close bu tton. The parameter description will then be displayed in the data display header of the Simulation Scenariotab . The Type of Chan ge and Original Data are also displayed at the bottom of the data display header. If a parameter is selected that requires further property-specific parameter selection, then a Select Properties w indow opens on top of the Simulation Manager window, as is the case in the Configurable Equipment Manager. This window opens after the user has made the Tab, Option and Parameter selections and then clicked on Close in the Equipment/Tab/Option/Parameter window.

An Example of a Select Properties Dialog

The Select All an d Deselect All b uttons can ass ist in the selection of the specific properties. When this window is closed by clicking on the Close button, the proper ty combinations that were checked are then display ed as one parameter per column under the over all pa rameter label in the Simulation Scenario tab, as sh own below.


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An Example of the Simulation Scenario Tab After Parameter Selection Delete a Parameter

Setting Up Simulations

To completely delete a parameter from a tab in the Simulation Manager, place the cur sor on the colu mn/s to be deleted then click on the Delete Columns button from the toolbar. The whole column will then be deleted from the window. Note that the deletion occurs immediately. The Simulation Scenariotab is used to defi ne the conditions for the different simulations that are to be performed in the current scenario. Place the cursor in th e dat a display area and click on the Insert Simulation bu tton on the toolbar. A new row for a new simulation will be inser ted in the row below where the cursor was placed. Each simulation is automatically given a name, Simulation 1, Simulation 2, et c. It is also possi ble for users to change the names of the simu lations. When a simulation has been inserted, ensure that the ‘Lock Cols’ button is p ressed and then double click in the cell which reads ‘Simulation 1’ (or ‘Simulation 2 ’ etc depending on the number of simulations inserted). Type in the new name for the simul ation and press ‘Enter’ when complete. A simulation can be deleted from the Simulation Scenario tab by selecting the row to be removed and then clicking on the Delete Simulations button on the toolbar.

Entering Data

Once a simulation has been cre ated as a row in the Simulation Scenario tab, new parameter values for that s imulation can be entered in to the appropriate columns. To do this, click o n the param eter cells for a given simulation and type in the Value or % Change value to be used for each parameter in the simulation. The Original Data value fo r each parameter can be seen in the bottom row of the data display header for comparison purposes. Note that oth er than the parameters selected for display in the Simulation Scenario tab, all other data used in the simulation calculations are the current data for the flowsheet. In other words, only the parameter values displayed in the Simulation Scenario t ab can be varied in the simulations – all other

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parameters remain fixed at the values that have previously been entered for each equipment unit, and the feed stream, in the respective Equipment and Stream windows. If there are no data entered on the Simulation Scenariotab for a pa rameter for a particular simulat ion (i.e. the cell is left blank), the Original Data value for that param eter will be used for simulation calculat ions. Note that the range limits for parameters a re applied when the simulation is run. Different Simulation Scenarios as well as different simulations within a scenari o may be usedFor to example, determineitthe of changing paramethe terseffect on the circuit performance. mayeffects be useful to determine on circuit performance of only one parameter at a time, in which case the Simulation Scenario w ould only have one parameter selected. A new Simulation Scenariowould then be create d to determine the effect on circuit performance of a different parameter. The Simulation Managerallows columns to be moved inside the window. To do this, ensure that the Lock Cols button is turned off, then click anywhere in the grey area at the top of the colum n to be moved in order to highlight the entire col umn. Once this is done click and drag the column to its desired location. Setting up the Results Tabs

The results of t he simul ations are recor ded on the two Results ta bs and the data to be displayed on these tabs should be set up before simulations are performed. If a simulation is run and the Results tabs have not b een set up, no results are recorded. In this case you would need to run the simulation again to see values in any new results cells you have added. The two Results tabs display the list of simulations that have been defined in the Simulation Scenariotab in the left hand column, and initially displa y only one other colu mn with ‘No Select ion’ in the top row. As with the Simu lation Scenario tab, when these tabs are subsequently opened they will appear as last left by the user. All of the cells in the results tabs are dark grey to indicate that they are calculated values, and cannot be edited by the user.

Results-Streams Tab

Parameters are added to the Results-Streams tab, and existing parameters are changed in the same manne r as for the Simulation Scenario tab. The dialog that appears and which allows the user to select the stream parameter, is shown below.

In this window the user first sele cts from drop- down lists the Stream, and then the Property, Calc Type and the Assay Basis to be displayed. Note that


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the Stream dro p-down list contains all of the streams in that flowsheet in alphabetical order. Click on Close to select the parameter. The rows in the data display header and the Original Data row are automatically filled with values once a parameter has been selected. The zero values present in some cells are replaced with simulation results after a simulation run has been performed.

The basis stream for the recovery calculat ions is selected from a drop-down list of all of the streams in the toolbar of the Results-Streams tab. Not e that if a different stream is chosen a s the basis for the recov ery calculat ion, the new recovery values calcula ted using this basis stream will only be displayed after simulation is performed again. Results-Equip Tab

Parameters are added to the Results-Equip tab and existing parameters are changed in the same manne r as for the Simulation Scenario tab. The dialog which appears and which a llows the user to select the equipm ent parame ter is the same as in the Simulation Scenariotab.

Click on Close to sele ct the param eter. The rows in the data display header and the Original Data r ow are automatically filled with values once a parameter has been sele cted. The z ero values present in some data cells are replaced with simulation results after a simulation run has been performed.

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There are two ways to perform the batch simulations: 1.

Simulate Select – used to run only the simulation selected in the Simulation Scenario tab. This feature enables the user to investi gate the s imulated data associ ated with a particular simulation in more detail. After running Simulate Select, the user can exit the Simulation Manager and the streams and equipme nt in the flowsheet will display the data asso ciated with the simulation selection. To return the program to the srcinal data, the user must return to the Simulation Manager , highlight the Original Data row, then click on the Simulate Selection button again.

2.

Simulate All - as the name implies, this option runs all of the simulations in the current scenario in the sequence listed by the user. The program always runs the Original Data simulation after performing all the simulat ions def ined by the use r. This returns the flowsheet to its baseline conditions s o that all streams and equipment within the flowsheet will have the data pertaining to its original condition, rather than that of the last simulation. The simulation scenario data a re displayed in the Simulation Manager table s.

Close Window

Click on the Close button in the top rig ht ha nd corner of the window to close the Simulation Managerwindow.

Edit Groups

The Edit Groups bu tton allows the user to com bine equipment units of the same type and same model together int o a named group. When a group has been defined, it appears in the drop-down list of equipment in the Simulation Manager , and this allows the user to select the group to change the value of a parameter for all of the equipment units in the group in one step. For example in a plant where ther e are a number of mills, the user could increase the ball loading b y 10% in each of the mill s by assigni ng them to a group and then setting the % Change for the Load Fraction parameter for this group to 10%. To cre ate a group the user clicks on the Edit Groups button to display the Select Equipment for Groupsdialog.

Click on the Add Group bu tton to open the Add New Group dialo g which allows the user to cr eate a new group and also to define the equipment an d model types to be included in the group.


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Then insert a new column in the Simulation Scenario, choose the newly created group in the Equipment/Group d rop-down list and choose the Print Scenario Grid

5.6.3

parameters in the usua l way. Click on the Print Scenario Grid b utton on the toolbar to print the data displayed on the active tab. Each tab must be printed separately.

Copy Grid

The data displayed in the current tab can be copied to the clipboard by clicking the Copy Grid button. These data can then be pasted into another program such as Excel or Word.

Lock Cols

Click on the Lock Cols button to lock the current position of the rows and columns in place. When the Lock Cols button has been clicked, the position of the rows and columns ca nnot be accidentally changed.

Accessing the Stream Data After Simulation, the data asso ciated with a stream can be viewed in the Streams and Stream data windows. The fe ed s tream data are define d in the ‘Feed’ equipment (see Appendix B2) rather than in the feed stream. This means that all of the info rmation in the Stream data windows is for viewing only; no data are entered here. Accessing the Stream Data

The Stream window prov ides access to the Stream data windo w to view the data for each stream. The Streams window for each stream can be opened by three methods: 1.

Double-clicking on a str eam in the flowsheet.

2.

Selecting Stream on the Flowsheet sub menu or

3.

Clicking on the Stream icon.

All of the streams in the current flowsheet may be accessed from the Streams window via the Stream Name drop-down list. The Streams windo w can only be accessed when the flowsheet is locked. A typical Streams wi ndow is shown below. The Streams wi ndow also shows the equipment from which the stream originates and the equipment to which the stream flows. Clicking on the double arro w buttons next to the From Equipment an d To Equipment dialog boxes opens the Equipment window relating t o that equipment. Accessing the Equipment data is discus sed under the heading Accessing the Equipm ent a nd Model Data 193 .

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A Typical Streams Window The Stream data window is accessed by clicking on the doubl e arrow button next to the selected stream. The stream name of the stream bei ng viewed is displayed in the heade r of the Stream data wi ndow. Once this window is opened, the layout and the actual data on disp lay can be chan ged to suit your requirements (see below). Stream Data Window Layout

The layout of the Stream data window is the same for every stream. A tabbed interface is used to display the different types of stream data. The Totals, Sizing data, Elemental assay data and Size by elemental assay data tabs are always displayed. The types of data available to view in each tab include simulated, experimental, balanced, SD, erro r a nd fitted, and can be selected by clicking on the Data Type View button. Unwanted data types can be turned off by selecting the selecting ‘None’ in the appropriate column.

A typi cal Stream data window is shown below. In this case, all data types other than Sim have been switched off.

A Typical Stream Data Window Totals Ta b


The Totals tab is always displayed, and lists the overall properties of the

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stream. The valu es in the Totals tab for each stream are calculated during simulation. Note that the values in the Totals tab for the feed stream are defined in the Feed equipment. The other tabs and the data displayed are: Na m eofTa b

Da taDispla yed

Sizing data

Size fractions and the proportion of the stream in each siz e fraction

Elemental assay data

Elements and the proportion of each element in the stream

Size by elemental assay da ta

Proportion of eac h size class that is made up of each element

Note that in JKSimMet, the last two tabs are not relevant for simulation. One or both of the se tabs will only become relevant and of inte rest when you are looking at the results of a mass balancing operation.

5.6.4

Water in Simulation There is a selection of models available for water feeders. To asso ciate an appropriate model with a water feeder you need to double click on the water feeder icon, just as you would do for any other equipment type. This will bring up the water feeder Equipment window. From here you select the required model using the Equipment Model drop-down.

In thi s case we will select the Req uired % Solids model for both of the water feeders. Once the m odel has been selected, you can click on the double arrow button to the right of the drop-down to set the parameters as sociated with this model.

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In the case of the Learner Project, the required % solids should be set to 75% for the BM Water feeder and 35% solids for the other water feeder (the one adding water to the cyclone feed sump). A detailed description of the Water Feeder models 295 under Model Descriptions.

can be found

Remember:

Select the two wa ter feeders from within the Select Equipment / Streams frame and then select "Adjust" for TPH water within the Control frame of the Mass Balance s heet.

5.7

Vie wing the Data - Summ aries & Report s To view the s ummary table of the str eam data the user the user will need to access and configure the Configurable Stream Overview.

5.7.1

Using the Configurable Stream Overview An alternative to entering data individually into the stream windows is using the Configurable Stream Overview. This is recommended when the data is initially conf igured, or can be config ured, into a similar style table in Excel and simply copied and pasted into JKSimMet. Configurable Stream Overview


The Configurable Stream Overview can be selected from the flowsheet menu, or launched by the icon on the flowsheet toolbar.

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Configurable Stream Overview Window

Select List

The Configurable Stream Overviewwindow has several main components: 1.

Select List drop-down list

2.

Configurable Stream Overview toolbar

3.

Data view choice drop down

4.

Button to launch the SD calculation window

5.

Data table

The user can create one or mor e Configurable Stream Overview table s. Each table created is listed by name in the Select List drop-down, allowing the user to change from one table to a nother by select ing the requ ired configuration from the list.

Configurable Stream Overview Toolbar

The toolbar allows the user to create new configurations, rename or delete existing configurations, add or delete rows and/or columns, print, copy, clone or export the data to Excel.

New Stream Overview

To create a new configuration the user clicks on the New Stream Overview button. This opens the Add New Stream Overview dialog which prompts the user to enter a name for the new configuration.

Delete Overview

Clicking on the Delete Overview bu tton deletes the current overview. A warning dialog asks the user to confirm that the current configuration is to be deleted, as this operation ca nnot be undone.

Insert Column

This button will ins ert a blank data column to the right of the colum n where the curso r is currently located. To select a column, click inside the column itself, not on the colum n header. Clicking the colum n header will open the Selection Options 217 wi ndow where you determine the contents of the column in question.

Copy Column

Pressing thi s button will insert an extra column that will be a copy of the currently selected column. You can use this if the new column is to be s imilar to the previous one. For instance you could copy a column containing experimental data a nd just switch the data type in the copy to simulated data.

Remove Column

Removes the column where the cursor is currently located. Note that the column is deleted immediately without the user being asked to confirm their

Insert Row

action. Inserts a stream data row in the overview table, in the row below the current position of the cursor. When the button is clicked the Add Stream dialog opens, requiring the user to select the stream to be added to the table from the list of streams that are not already displayed in the table.

Viewing the Data - Summaries & Reports


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If no streams a re liste d in the dialog , it means your table already cont ains all the streams from this flowsheet and therefore no further rows can be inserted in this table. Remove Row

Pressing this button removes the currently selected row from the table. If necessa ry, the deleted stream can be added back into the table usin g the Add Row button.

Print Overview

Prints the current overview table.

Copy Grid

Copies the entir e data grid for the current overview to the clipboard, allowing the data to be pas ted into other pro grams such as MS Word.

Lock Move Rows/Cols

When this button is unlocked (appearing as shown in image at left) the user is able to change the position of rows and columns of data.

Export Overview

This button export s the data for the current overview to Excel. Clicking on the Export Overview button opens the Export Report to Excel dialo g where the user can enter a n ame for the Excel file and choose where to s ave the file. Note that if the file name chosen is the same as an exis ting Excel workbook, the user is prompted to choose whether to overwrite the existing workbook or to append the cur rent data as a new worksheet in the existing workbook. The name of the Overview that you have just exported will be adopted as the name of this new worksheet.

Export All

Selecting Export All wil l export all of the overviews listed in the Select List drop-down to Excel, with each one occupy ing a separat e named sheet in the

Clone O verview

Creating a new Configurable Stream Overview


Excel workbook. Clone Overview cre ates a new ov erview, which will be an exact copy of the current overview. This optio n is useful when viewing or inputti ng data for the stre ams on a sized basis and more than one simi lar overview s creen is required. When the user clicks on the New Stream Overview button the default data table is displayed. As shown below, this lists all of the streams in the flowsheet, and displa ys the TPH Solids (Sim) and TPH Water (Sim) values for each of the streams.


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The Default Configurable Stream Overview Layout Adding Streams to the Table

To add a s tream to the overview table click on the Add Row button and select the required stream from the list shown in the dialog.

Changing the Stream Order

The order that the st ream na mes appear in the table is the order in which the streams were added to the flowsheet when it was first drawn. To change this order unlock the Lock Move Row/Cols button and then select a stream in the data table by clicki ng in the s tream name cell and then drag the row to its new location on the list as indicated by a red line. Two or more adjace nt stream rows can also be moved by selecting all of the rows toge ther (click and drag or Shift-click) and dragging the group to their new location in the table.

Removing Streams from the Table

To remove a stream fro m the ove rview table click in the row which is to be removed and click the Delete Rows button.

Setting Up to Enter Experimental Data via the Overview

It is possible to enter your experimental data via the Configurable Stream Overview window. To do this you need to select 'Experimental' as the type of data from within the Selection Options dialog box. Clicking on the header cell in each column of the Configurable Stream Overview window will bring up the Selection Options window, an example of which is shown below. In this window you need to select the parameter, the calculation type and the data type that are to be displayed in the column you are confi guring. Normally these are selected from the Optio ns 1, 2 & 3 dropdown lists respectively. The various data types a vailable (Option 3 listing) are as follows: Experimental – Displays experiment al values. Standard Deviation – Displays s tandard deviations. Simulated – Displays s imulated data. Fitted – Displays the fitted values (following the run of a simulation). Balanced – Displays mass balanced dat a following the running of a mass balance. Error – Displa ys error data.

Note that the above is the full list of data types. This will sometimes be



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reduced, depending on the selections that have been made from the Option 1 and Option 2 drop-down lists above. For preparing a column that is to be used for the entry of your raw da ta, you need to select 'Experimental' from the data type (Option 3) drop-down. The example below shows a situation where the user has chosen to display elemental assay data for coppe r and has selected experimental as the data type.

On returning to the Configurable Stream Overview, you will find that data can now be entered into this column for the various streams that you have set up in this particular ov erview and that this will also be the case for any further streams that you may later add to this overview. Configuring the Columns

5.7.2

The conf iguration of a new columns is covered in greater detail in the next topic.

Configuring Columns in the Stream Overview Configuring a New Data Column in the Overview


When a new column is added to t he Configurable Stream Overview tabl e by clicking on the Insert Column b utton the added column is headed 'No Selection' and contains no data. The user must select the data to be displayed in the column by first ensuring that the Lock Move Rows/Cols button is locked and then single click ing on the head er cel l for the column. This opens the Selection Optionsdialog.


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The user can select the required property, calculation type and data type from the drop-down lists in this dialog. You will see as you start making selections from the Opti ons drop-downs, that the items available in each will always depend on what has been selected from the preceding drop-downs. As you will soon realise, the re are a lot of per mutations possibl e, so in this topic we will just look at a couple of examples. In the exam ples selected, the user is presented with quite a few choices before arriving at the complete Option 1 Selections

Difference between % Passes and % Passing Data

specification of the data to be displayed in the column being configured. In the first drop- down list (labelled Optio n 1 ), the items available for selection are as s hown below:

If you selec t % Passing you will be present ed with a data entry dialog wher e you can type in the size (in mm ). The data will then relate to the proportion of the particles that are smaller than your chosen size. In the illustration below, the user wishes to see data relating to the % of the ore part icles that are finer than 0 .25 mm.



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If you select % Passes, then you are requ esting data in the form of the screen size that a given percentage of the particles will pass . In this case you are again presented with a data entry dialog, but this time what you are entering is a percentage value rather than a s ize.

In the illustration above, we a re setting up the overview table to display data relating to the 50% pa ssing siz e for each of the s treams in our flowsheet. Note that one of the other options in the Option 1 drop-down is P80. Selecting this item will generate the same type of data, but in this case the 50% value entered above is replaced by the standard 80% value. Ob viously in this case there is no need for the % Passes data entry dialog, so this will not appear.



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Elemental Data for the Option 1 Selection and Subsequent Choices

If you select Elemental from the Option 1 drop-down, you will then generate a further selection dia log box where you have to choose the particular element that you wish to retrieve the data for. Of course this is only relevant for mass balan cing in JKSimMet since none of the JKSimMet models deal with the distribution of elements around the flowsheet.

Once you have selected the element required, the Option 2 selection dropdown will require you to select between the options TPH, Assa y and Recovery. If you select either TPH or Recovery, the Option 3 alternatives will be Experimental, Balanced a nd Size. If you select Assay fro m the Opti on 2 drop-down, the situation becomes a little more complex, with more options available as shown below.

In this if you now select Size, yo u will get a dialog for select ing the size that youcase wish to obtain data for.



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Once this selection of the required size has been made, the Opt ion 4 dropdown will become availab le wher e you can then select which type of size related elemental data is to be display ed. In the cas e below we are selecting Error data for copper assa ys in the +0 .6 mm size fractio n.

Be Sure to Select Exp vs Bal Error Data if Elemental Data

Selecting Error fr om the above list then requires you to make another choice regarding the type of data to be compared for the error determinations. Note that althou gh at this point you can select from the 5 options available in the dialog box shown below, only the first option of Exp vs Bal will yield any data

Selected

when you return to the Configurable Stream Overviewtable . This is again due to the fact that we are dealing at this point with elemental data s o there will be no simulated or fitted data for use in the error calculations.



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Once you make this selection, another dialog will appear for selecting the error calculation method.

Here you can select whichever type of error 94 you wish see displaye d in the Configurable Stream Overview table. Assum ing in this case you wanted to display the weig hted errors, then after pressing OK, t he Selection Options dialog would look like the one shown below.



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If you select Error Sum for Option 1 (last item on the list), you will be presented with a dialog box for selecting the type of errors that are to be summed. A screen grab of this dialog bo x is below. In this instance, all 5 options are meaningful since we ha ve not at this stage narrowed the selectio n to elemental data a s we had in the case described above.

Choices

After you have selected the types of data are to be compared to give the individual data point errors, yo u will next be presented wit h a dialog for selecting the type of error calculat ion used to arrive at error values for each of these data points. The choices here are weig hted error, percent er ror and absolute error. The way these errors are calculated is explained in the topic Viewing Individual Stream Data 94 .



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If you have selected Exp vs Bal from the list of data type comparisons (see the second last screen grab), then you will be presented with a further choice regarding the circuit parameter errors that are to incorporated into the error sum.

Note however, that you will only be presented with the above selection drop-bo x in JKSimMet if your selection of data types for comparison is Exp vs Bal. The last two possibili ties for inclusio n in the erro r sum a re not relevant if you selection includes simulat ed or fitted data as the distribution of elements throughout the flowsheet is not modelled in JKSimMet. Your selections from these three dialog boxes will be concatenated into an automatically ass igned name for the overall Option 1 selection. This name appears in the display box to the right of the Option 1 drop-down. As can be seen from the scree n grab bel ow, this name can be rathe r long and in fact doesn't fit into the display area in this ca se.



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When you press OK on the above dialog b ox to close it, the column you have been setting up in the Configurable Stream Overview wil l now have thi s name as its header. The automatically generated name for the error sum makes the column a lot wider than it needs to be to accommodate the data (see below).

Modifying the Column Names


To overcome this problem, ther e is the facility to make your own abbreviation or acronym for the ty pe of error sum that has been selected. To do this you s imply uncheck the Auto Generate Name check-box and replace the auto generated name with an acronym or abbr eviated name that will make sense to you. This can be done before or after you have gone through the Options selection sequence.


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In this case one might abbre viate the above erro r sum descript ive name to ErrS (EvB W T&S) t o make the column width closer to that needed for display of the numbers themse lves. To illustrat e this, a second colum n with the same data but with the abbreviated error sum header, has been included in the screen grab above. Note that this ability t o insert your own na me for the column h eaders is available for all of the ot her data type opt ions as well. It has been illustrated for the error sum data type as this is where the auto gener ated name ends up being the longest.

5.7.3

Using the Repor ting Feature The Reporting feature is the main means for exporting data from JKSimMet. By using this feature the user can export the data to Excel for printing or further analysis Overview

The reporting functionality is accessed either from the flowsheet menu or from the reporting icon on the flowsheet toolbar.

Reporting to Excel Window

The Reporting allows the equipme nt and to streams be exported to Excel. The userfeature can select which equipment unitstream s and data which have their data exported. Each report configuration is named by the user wh en it is created and this allows the user to create multiple report configurations.

Reporting to Excel Toolbar

The toolbar allows the user to create new configurations, delete unwanted configurations, select or de-select data in the selectio n list and export the da ta to Excel.



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To create a new Report configuration the user clicks on the New Report button. This opens the Add New Report dialog , allowing the user t o n ame the new report configuration.

To generate a report the user can either choose to use an existing report, or create a new report. To create a new report the user will need to: 1. Add a report to the system

2. Select the format of the report

3. Choose whether to summarise the report data

4. Select which equipment units and streams are to be used in the report

5. Choose which da ta types to export

6. Choose whether to use a circuit select list

7. Choose to export port data



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8. Export the data

Report Name List

Each report configuration created is listed by na me in the Report Name dropdown list, allowing the user to maint ain as many report configurations as they require.

Delete Report

Clicking on the Delete Report bu tton deletes the current configuration. A warning dialog asks the user to confirm that the current configuration is to be deleted, as this operation ca nnot be undone.

Export Report

Exports the selected items on the reporting dialog to an Excel workbook.

Format of the Excel Workbook

The Excel workbook creat ed by the Reporting to Excel fe ature displays the selected data in a standard layout . The user is then free to format the data in the report as they choose.



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Mass Balancing Mass Balancing

6.1

This section provides information about the mass balancing capabilities of JKSimMet V6.

Introdu ction to Mass Balanci ng Purpose

This chapter describ es how to use the JKSimMet mass balancing component

Overview

of the software. Even the most carefully collected plant survey data are subject to many sources of variation. Some of these errors are generated within: • the natural variation in process flows, assays, etc. • sa mpling procedures or design • as saying procedures • siz ing procedures • fluctuations in plant flow rates, operating variables, feed parameters, etc. As with all data improvement processes, the usefulness of the mass balanced data will be stro ngly dependent on the quali ty of the input data. The mass balancing module can assist the user to assess data and to refine their experimental technique when problems are detected. Mass balancing will improve the quality of good data. It will not fix poor quality data or do anything more than highlight inadequate experime ntal techniques. The module is used t o mass balance sizing data, head assay data, assay data in size clas ses and flow rate data collected at steady state. The balancing process produ ces best f it estimates of flow rates, s ize and assay data which are consistent wit hin the mass balan cing constraints. The overall process is : • Collect data, using appropriate sampling methods (see Gy (1982), etc.) • Review data • Mass balance data, • Check accuracy of data fit and • Refine experime ntal technique an d ins trumentation until desired level of accuracy is obtained.

6.2

Da ta Co llect ion Good data collection procedures are essential to the success of a mass balance. While this s ection is not essent ial for lear ning how to use the mass balancing program, it should be studied in detail as poor data collection will have a s ignificant impact on the quality of mass balance tha t can be achieved. Flow Rates

Numerous flow rate measurements are very useful. Hence, calibration of all flow measurement devices (weightometers, flow meters, etc.) is important. Whenever possible, tr y for an independent flow rate check . In small or pilot plants, time and weigh a known volume of material. As a minimum


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requirement, the feed tonnage to the circuit is required. Perce nt Solids

The percent solid s of a slurry as measure d with a Marcy scale are subject to error, due to solids density variations in the circuit. Such variations are common in cyclone underf low streams. Therefore, percent s olids determined from wet and dry sample weights are preferred.

Steady State

JKSimMet is a steady state simulator. Hence, models can most usefully be fitted to data which were taken at steady state. The most common approach is to take a series of regular samples and combine them to make composite samples which covewhich r a period is to long (sev eral hours) compared with circuit fluctuations, mustwhich be kept a minimum. If circuit variations are a s erious problem, sample and fit one process unit a t a time. JKSimMet can be used to com bine the units and predict circuit steady state behaviour.

Sampling

Good sampling practices are a topic in themselves. Some useful references a re those of Gy (1982) and Lyman (1986) 269 . For a simple estimating technique for sampling requirements refer to the paper by Lyman (1986). There are well established rules for calculating the accurac y of a sampling and as say proce ss. These can be used to est ablish an error model which can then be used to provide estimates of standard deviation for each point. Alternatively, 5 to 10 replicat e sample s can be taken and processed . If these input accuracies are established, then the estimates of accuracy used for flow rates and a ssa ys will be real estimate s a nd not relative e stimates. If replicate sampl ing is carried out f or assays on a number of stream s (i.e. a range of assay values), a simple two term err or mod el can be generated by plotting rel ative s tandard dev iation against average a ssay values from each stream. The intercept and s lope of this p lot will provide fixed (minimum) a nd relative (%) error com ponents which can be used in the generalised version of the Whiten model. A sensible maximum (absolute) error will also need to be specified. Determining good estimate s of the errors as sociated with each sampling point will provide a more reliable mass balance.

6.3

Back gr oun d Mass Balancing is a type of model fitting. The models in this case are quite fundamental. Hence, they do not impose the experience knowledge (which is built into other mathematical process models) onto the data. The mass balan cing models are: a stream combiner (for example, a pump sump), a general stream splitter (for example, a hydrocyclone or a flotation cell), a unit that conserves some properties but not others (for example, a grinding mill will preserve total as says and flow rates but n ot


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size fractions). The basis of the mass balancing algor ithms is the differences in composition of various streams; that is, the differences generated by the process equipment. Consider a process with these stream s ha ving assays a, b, c:

If the solids flow rate in a stream of assa y "a" is 1 00 tph, then: (1) where x is the solids flow rate in stream o f assa y "b" and then: (2)

This is the basis of the tr aditional two- product solution, where a, b an d c may be assays for a size fraction, element or any other conserved property. It does not matter what kind of assa ys a , b and c a re, as long as there is some difference in their valu es. For exam ple, if the pr ocess is a splitter and the ass ays are all the same: a=b=c and therefore, using equation (2), then x= 0/0 which is undefined. Expressed another way, the flow rates can be estimated only if a process imposes a difference on its products; that is , s ome information is imparted by the process. If no inf ormation is imposed, as is the case with a splitter, then the information cannot be used to mak e esti mates, as it is not there to begin with. Note that the split ratio of a splitte r can be used in the mass bala nce. It follows that the most usefu l properties to use for mass balancing around a process unit will be those which have the larg est dif ference in the product streams. This means that size assays will wor k well around a size classifier such as a screen or a hydrocyclone, and elemental assay s will work well around a flotation circuit. The rev erse will generally not be true, with some notable exceptions. For example, elemental assa ys such as gold or lead are often very useful around a hydrocyclone class ifier because its density-separating characteristic will usually produce a large diff erence in these ass ays. The power of thi s program lies in its ability to use a wide rang e of assay s across a large f lowsheet. The program algorithm is driven by the ass ays with large differences but still takes account of those with small differences. Concept: Mass Balancing

The mass balancing module takes all selected streams and calculates the smallest set of data adjustme nts which will make the data consistent. If some (or all) of these streams are measured (sampled and sized, etc), the experimental measure ments can be compared wit h the data. The root mean square of the norm alised differences between measured data and adjusted

Background


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data is taken as a measure of goodness of fit of the model. i.e. Hence, the mass balancing prog ram adjusts user select ed flow rates to find a best set of flow rates which make the balance output match the experimental measurements a s closely as possible. If the precision of each data point is measured (or can be estimated from Concept: Weighted Sum of Squares

Concept: Standard Deviation

experience), then each difference between experimental data and mass balanced pred iction is normalised by div iding by its precision. That is, a small difference (or adjustme nt) between an accurate data point and its mass balanced prediction will make the sa me contribution to the weighted sum of squares as a large difference from an inaccurate data point. The usual measure of precision is the standard deviation. If repeated measurements are made of any data point, experime ntal variations will cause variations in the measured value x i . Then with many repeats, the mean the true value of x.

of the values will provide an estim ate of

Subject to a number of assumptions, the expected variations from true x can be characterized by one number - the standard deviation defined as:

Standard Deviation If the measurements are normally distributed then, out of 10 0 measurements, 67 could be expe cted to lie withi n plus or minus one standard deviation of the true v alue (as estimated by the mean), 95 within plus or minus two standard deviations and 97 within plus or minus three standard deviat ions. Concept: Estimating Standard Deviation Concept: RMS (Root Mean Square) Errors

Experimentally, 5 to 1 0 complete observations, that is , independent s ampling plus analysis, will provi de an estimate of the standard dev iation. The mean of such a set of measurements should provide a good test of sampling precision - if the test circuit was at steady state. As its name sugg ests, the RMS (ro ot mean square) error is the square root of the residual mean square error, which is the error associated with the calculated mass balanced data a nd the experimental data. A root mean s quare error of value 1 means that a ll data points were estimated with errors similar to the measur ed standard deviations of the experimental data points. Obviously, the more the RMS error varies from one, the more error is as sociated with fitt ing the data.

6.4

How the Mass Bal anci ng Prog ram Works The mass balancing program used by JKSimMet is a program called JK2DMBal written and developed by Dr Stephen Gay. Other JKMRC staff, including Michael Andrusiewicz, Jake Stoll, Ricardo Pasc ual and Robert Lasker, provided ass istance with the integration of JK2DMBal into the


Background

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JKSimMet program. The mass balancing prob lem is essentially a minimisation of s um of squares with multi-linear constraints. This corresponds to a common set of mathematical problems generally described as the ‘quadratic problem’. The algorithm is based on a Quasi-Newton approac h which means that the errors in the constraints are used to determine the changes required in calculated variables, with the amount of movement of the calculated variables controlled by the standard deviations of the experimental values. Hence standard dev iation values of 0 mean tha t a calculated value will equal the experimental value and will not change. If all the standard deviations are near 0, the program will not have enough freedom to find a solution, and therefore will not converge. The JKSimMet standard deviation interface provides formulae to allow appropriate standard deviation values to be set. When a plant is surveyed, size and assay information are often obtained, as well as percent solids. Howe ver, the solid s flow is only known for a small number of streams (and in some cases, the feed stream only). Very high standard deviation values imply that the corresponding experim ental value is unreliable. Hence, large standard deviation values are often used for the solids flow values. The main algorithm (Quasi-Newton algorithm) needs reasonab le starting values of solid a nd wa ter flow in order to converge satisfactorily . In order to estimate these flows (principally wh ere experimental values are n ot given), a second algorithm is used. This alg orithm information such as and size distribution data second to esti mate solidsuses flows. This algorithm is assays very similar to the method described as the Morrison solution in JKSimMet. The main difference is that it also use s the standar d deviations of the assay and size info rmation, and it provides an estimate of the standard deviation of the estimated solids flow. If there are many missing s treams, or missing data, the algorithm will still have some difficulty in obtaining a solution as the standard deviation values are too high. A third algorithm is used to reduce the standard deviation values as the algorithm proceeds to ensure that convergence is obtained. The three algorithms (Quasi-Newton, missing flow estimation and variable standard deviation reduction) are all integrated together within the one algorithm in terfaced to JKSimMet. Even though the a lgorithms work together it still remains that in some circumstances data reduction may be required to improve performance. For example, if there are many missing solids flow values it is best to mass balance solid s flow first wit h information such as sizes and head assays prior to mass balancing assays within size classes. JKSimFloat has a hierarchy of data associated with the mass balan cing algorithm. This hierarchy has the solids mass flow at the top, with head ass ays, size fractions and % solids all s ubordinate to the solids mass flow. The assays of size fractions are subor dinate to size fractions, and the mass flow of water is always a bottom level measurement. This can be represented schematically by the following diagram.

How the Mass Balancing Program Works


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Lea rni ng Mass Ba lanc ing The mass balancing mo dule of JKSimMet is useful in two areas. Firstly, it provides a check on data accuracy that is not mod el dependent. The mass balancin g models are corr ect (that is, they contain no built in experience). Hence, if the data balan ce well but the model fitting does not fit well, it indicates that the model is not appropriate. Where coarsely sized samples are used, as in crushing and screening circuits, the mass balanced data may be more useful as the start ing point for model fitting than the raw da ta. Secondly, mass balancing is useful for determining flow rates and recoveries around com plex circ uits. The exam ple we will use in this section, Learning Mass Balancing, is concerned with flow rates in the comminution circuit of a copper concentrator. Normal Sequence for Mass Ba lancing in a Comminution Circuit

It should be noted that JKSimMet V6 provides the abilit y to balance assays within size classes as well as total assays and sizes. Unlike V5, the user does not balance everything at once. Under the a ssumption tha t in a comminution circuit your sizing data will be the most reliable surve y data, the s uggested process to balance a whole circuit is as follows: 1.


2.

Set TP H So lids and Si zes to Ad just and all other components to Unused, then run the balance.

3.

Then set the TPH Solids and Size s to Fixed, the TPH Water to Ad just and % Solids to Influence and run the balance again.

4.

Set the TPH Water and % Solids back to unused and the El ements to Adjust and run the balance again.

5.

Set the E lements to F ixed and Si ze x Ele ment to A djust and r un the balance a final time.

The individual steps will be cov ered in more detail over the remainder of this chapter.


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Mass Ba lancing Sequence where Assay Data is the Most Reliable Data

Mass Ba lancing Sequence where % Solids Data is the Most Reliable Data

6.5.1

In cases where you r assay data is considered more rel iable that the sizing data, you would modify the above sequence as follows: 1.


2.

Set TPH Solids and Elements to Adjust and all ot her components to Unused, then run the balance.

3.

Then set t he TP H Solids and Ele ments to Fixed, the TPH Wat er to Adjust and % Solids to Infl uence and run the balance again .

4.

Set the TP H Water and % Solids bac k to Un used and th e Siz es to Adjust and run the balance again.

5.

Set th e Sizes to Fixed and Size x Element to Adjust and run the balance a final time.

In cases where y our % solids data is considered the most reliable data, you would be better using the balance sequence below: 1.


2.

Set TPH So lids and TPH Wat er to Adjust and % Sol ids to Influence and a ll other components to Unused, then run the balance.

3.

Now set th e TPH Solids to Fixed, TPH Water and % Solids to Unused and the Sizes to Adjust and run the balance again .

4.

Set the Sizes to Fixed and the Elements to Adjust and run the balance again.

5.

Set the E lements to F ixed and Si ze x Ele ment to A djust and r un the balance a final time.

Model Types for Mass Balancing In V6.0.1 of JKSi mMet the flowshe et drawing for mass balancing is the same one used for simul ation and model-fitting, with the full range of equipment icons available to draw the circuit diagram. However, no matter what equipment icon is visible, there are only two model types in mass balancing. These are: class ifier or mixer unit This un it either selects particles to go to different product ports of the unit (classifier) or adds particles from diff erent feeds (mixer). That is, particles are sorted or mixed in this type of unit, not broken down or altered. transform unit In this unit ass ays a re preserved but size structures are destroyed. In mass balancing a ll comminution devices a re transform units. The mass balance algorithm decides which type of mass balance unit is required according to the flowsheet icon selected by the user.

Learning Mass Balancing


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6.5.2

237

Entering the Data Data Entry Alternatives

The first s tep in a mass balancing exe rcise is to enter the experim ental data. This can be performed in two ways: Individual Stream data windows, or Configurable Stream Overview Both methods have their advantages and disadvantages; it is mainly dependent on what form the experimental data is in.

Accessing the Individual Stream Data

The Streams window prov ides access to the Stream data windows to view the data for each stream. The Stream data windo w for each stream can be opened by three methods: 1.

Double-clicking on a st ream in the flowsheet.

2.

Selecting Stream on the Flowsheet sub menu or

3.

Clicking on the Stream icon.

All of the streams in the current flo wsheet may be accessed from the Streams window via the Stream Name drop-down list. The Streams window can only be accessed when the flo wsheet is locked. A typical Streams wi ndow is shown below. The Streams wi ndow also shows the equipment from which the stream srcinates an d the equipment to which the stream flo ws. Clicking on the double arrow buttons next to the From Equipment a nd To Equipment dialo g boxes opens the Equipment window relating to that equipment.

The Stream data wind ow is accessed by click ing on the doub le arrow button next to the selected stream. Once the Stream data window has opened, the user can view the vari ous categories of data by selec ting the approp riate tab. The name of the stream being viewed is displayed in the header of the Stream data window. The Streams window rem ains open and accessib le after the required Stream data wind ow has opened. If you then select another stre am from the drop-down and click again on the double arrow, you will open a second Stream data window for the new stream. You can open a s many Stream data windows as you require in this way. A typical Stream data window is s hown below.



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The statu s of the stre am can be set to ‘Majo r’, ‘Min or’, or ‘Missi ng’ from the drop-down box at top right. See later 248 in this help file for an explanation of these terms. Totals Ta b

The Totals tab lists the overall prope rties of the stream . The other tabs and the data displayed are: Na m eofT ab

Da taDispla ye d

Sizing data

Size fractions and the proportion of the stream in each siz e fraction

Elemental assa y data

Elements and the proportion of each element in the stream

Size by elemental assay data

Proportion of each s ize class that is made up of each element

Data can be inserted into the indiv idual stream windows using the copy and paste functions from Excel. Sizing Data


If you click on the Sizing Data tab you will here be able to enter the sizing data for the size fractions that have been defi ned for this project and the associate d SD value s. The Stream data win dow will then look similar to the one shown below:


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The above window will also show balanced values from the most recent balance, provid ed the balancing engine has been run a t this point. Elemental Assay Data

The next tab is for the elemental assa y data and the app earance of this window will be similar to the one shown below when this tab ha s been selected.

The last tab is for size by elemental assay data and a screen grab of the appearance with this tab selected is shown below:



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In this case the num bers are all zeros since no sizing data have been entered at this point. Configurable Stream Overview

An alternative to entering data individually into the stream window s is to us e the Configurable Stream Overview. This is recom mended whe n the data has been initiall y configured into a similar sty le table in Excel. Such a table can then simply be copied and pasted into JKSimMet. Click on the Configurable Stream Overview ico n or s elect this item from the Flowsheet menu to open the Configurable Stream Overview wind ow. You may need to create a new overview that will ha ve the data in the same order as it is structured within the Excel source file. Alternatively you could manipulate the setting out of the Excel file to match a structure you have previously created within the Configurable Stream Overview. For more information on how to make changes or create new Stream Overviews, you should revise the topic Using the Configurable Stream Overview 263 .

6.5.3

The SD Calculation Window SD Calculation Window

From the Stream Data wi ndow, the Automatic SD Calculation wi ndow can be opened by pressing the SD Calculation (SD) bu tton which is the button second from the left on the Stream data window toolbar.

From here you can specify numerous different methods of automatically calculating SD values for the various experim ental data fields.



Ma ss Bal an cing

More detail on how to set the options for SD calculation are covered in the Windows 165 topic, in the Using JKSimMet section.

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Stream

The data types associ ated with the other default columns are simulated (Sim), fitted (Fit), balanced (Mbal) and the error (Err). Selecting the Type of Error

In the case of the error column you can change the form of the error that is displayed and the curr ently selected form will be s hown in the column header. This is done by clicking o n the Error Sum button, which is the button second from

Calculation

the right on the Stream data toolbar.

After pressing this button, the Error dialog box will appear where you can specify both the types of data that a re to be compared for determ ining error values and the method by which these e rrors are calculated. Fo r ins tance in the settings shown in the screen grab below, the errors will be obtained by comparing the experimental and balanced data and the method of calculation will just be a straight percentage error calculation.



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Also in thi s screen grab, you will notice there is a frame labe lled Error Sum below the drop-down selection boxes. Here there are radio buttons where you can select the errors that are to contribute to the calcul ation of the error sum fig ure that is displayed in a field (shown circled below), at the top of the Stream data window.

Note that it is only when you sele ct Exp v Bal data for comparison that all three options are available for the error sum calculation. Because JKSimMet does not contain models that predi ct element distr ibutions, the last two options cannot be selected wher e either Fit or Sim data are one of the data types to be compared. These options will be greyed-out in all but the Exp v Bal data case. Error Calculation Methods and Summing of Errors


The types of error calculation available for selection are Weighted, Percent and Absolute. Weight ed errors take account of the reliabi lity assigned to the various data points by dividing the difference by the SD value. Larg er SD values mean that the dif ferences will contribute less to the total error calculation. The other two methods take no account of the as signed SD values. The calculation methods a re:


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Weighted errors are calculated as [(Exp - Bal)/SD]2 Percent errors a re calculated as Abs[(Exp - Bal)/Exp] * 100 Absolute errors are calculated as just (Exp - Bal) In the case of the fi rst two error calculation methods, the individual errors are always going to be positive v alues. Thus to obtain the error sum in these two ca ses, the individual values are simply totalled. For the Absol ute error value s though, ther e will be negative values display ed for some data points and positive ones for others. To make these values all contribute to the total error and do not tend to cancel each other out , in this case it has to be the modulus of each value that gets incorporated into the Error Sum calculation.

6.5.4

Standard Deviation Calculations All Data Points Require Standard Deviations

Every data point must have a standard deviation entered, even if it is ‘Missing’. During the mass balan cing routine, if any data point ha s ‘ 0’ a s it’s standard deviatio n, an error message will be displayed with an option for the user to enter the correct SD. Standard deviat ions can be entered individually in the s tream data windows, or throu gh the Configurable Stream Overview 263 window. The y can also be copied and p asted from Excel. Entering a standard deviation in the individual stream data windows is particularly useful if, for instance, no experimental data for a particular stream exists. The procedure for this is outlined below.

Entering Individual Stream Standard Deviations

Ensure t he flowsheet is locke d and double click on a stream to bring up the stream window for that stream.

Setting the SD to Missing

If ‘missi ng’ is entered for the standard deviation, the mass balancer will recognise that no experimental data was recorded for this stream. However, the stream will be included in the mass balance and a balance d value will be


If the sampl e or flo w data for a particular stre am is not avail able, you can leave the experim ental value set to zero and then set the standard deviation value to ‘Missing’.


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generated using the rest of the data set. For an initial pass, the actual stream can be omitted from the balance routine, rather than setting the SD values to ‘missing’. This will not make much difference in a simple flowsheet, but may speed up the balance in a more complex one. Alternatively, if experimental data exists for that stream and the standard deviation is known, it is possibl e to enter that s tandard dev iation directly in this window. Simply click in the appropr iate cell of the ‘SD’ column and type in the standard deviation. Press ‘Enter’ when complet e. It is also possible to copy and paste standa rd deviation values from Excel into the indiv idual stre am data windows and the Configurable Stream Overview window. The Automatic SD Calculation wind ow allows the user to set SD values for multiple streams and data points simultaneously. This is accessed by the SD Calculation b utton in both the individual stream window and the Configurable Stream Overviewwindows. Entering Standard Deviations for all Streams

The Automatic SD Calculation window appears as follows.

The left-hand p anel lists a ll the streams in the current f lowsheet. Individual streams can be selected by clicking on the stream na me. Multiple streams ca n be selected in a similar mann er to the way this is achieved when using Windows Explorer. A cont iguous group of streams can be selected by holding when click ing on a stream further down the list. A selection of non contiguous streams can be made by holding down a nd clicking on the streams required. The “Property” drop-down permits the user to select the pa rameter that is to have the standard deviation formula applied to it. To select a property, click the drop-down arrow and double click on the desired property. The “SD Calculation Option” drop- down allows the user to choose from a list of mathematical formulae and other options for setting the standard deviations. This list contains the following formula options: Bounded percentage, Parabolic, SD Multiplication Factor, Exp Val Multiplication



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Factor, Replacement Value and Missing Value. If you tick the check-box labelled “Include SD values currently set to missing?” the progr am will take the experimental value for the stream and will apply the selected SD calculation to this value. If you do h ave s ome of the SD's set to missi ng, the n it is likely that the experimental values for these would have been zero. Where this is the case, the value that goes into the SD field will depend on the SD calculation method selected. If you have selected a method that involves just a fraction multiplied by the experimental value, then obviously you will get an SD value of zer o. This will mean tha t wh en you run a balance involv ing these param eters, you will get an error message and be requested to give the offending SD's some values other than zero. If you choose another SD calculation met hod (such as Whiten), where a non zero SD value will be the result, there is still a problem wit h balancing bec ause the balance engine will be try ing to accommodate a zero value wh ereas the a ctual experimental value (if a sample had been taken) would no doubt be well removed from zero. So if you are going to place a tick in this check box, make sure you have some guessed values in the experimental value fields and that you are setting a large SD on these values. There a re also some default value s that have been pre- set to enable rapid SD calculation: Fixed : SD = 0.001 Poor : SD = 20% of the experimental value Average : SD = 10% of the experimental value Good : SD = 5% of the experimental value Excellent : SD = 2% of the experimental value

These values can also be changed if necessary in the Calculationwindow.

Automatic SD

Note that although this facility allows you to use relative SD's as a quick way of setting up the balance, the ir use is not generally recommended because a balance using relativ e SD's takes most notice of the smallest a ssa y values and these are often the least well defined. Bounded Percentage

When the Bounde d Percentage option is selected, the user inputs the Upper (U), Lower(L) SD limits and the percentage error in between (P) to calculate the standard deviations for an experimental data value (x).

Parabolic

When the Parabolic option is selected, the user inputs the proportionality constant (a) which will be used to calcul ate the magnitude of the standar d deviations a ssociated with each experimental data value (x).

SD Multiplication Factor

When the SD Multiplication Factor option is selected, the user inputs the multiplication factor to be multiplied by the existing standard deviations in the system.



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Exp Value Multiplication Factor

When the Exp Value Multiplication Factor option is selected, the user inputs the multiplicatio n factor to be multiplied by the existing experimental values in the system.

Replacement Value

When the Replacem ent Value option is selecte d, the user is asked to input the value to replace selected SD values in the system.

Missing Value

When the Missing Value option is select ed the user does not enter an y value. On calculation, the selected stream and property values are assi gned as missing values. Note that the selections associate d with a particular prope rty class persist so that when the user cha nges the property class selection, the calculation option and its associ ated parameters last entered by the user for that prope rty are displayed. When the user clicks on the ‘Calculate’ button the program will calculate the SDs only for the Stream and Property Class that are currently selected and in view. Note that even a fter SDs have been automatically calculat ed, the user is still able to go to an individual experimental data point in the Stream Data window and change the SD for that data point. How ever any changes to SD values in the Stream Data window will not be reflected in the Automatic SD Calculation window. It is up to the user to decid e which standard deviation calculation method best suits the data. Click “Close” to exit the Automatic SD Calculation window.

IMPORTANT NOTE

All data points MUST have a standard deviation value associated with them or else be set to ‘Missin g’. This includes the TPH water and % solids, as well as the TPH solids, ove rall ass ays and s ize-by-ass ay data. The water balance is performed on TPH water, using the experimental % solids and TPH soli ds to calcu late the experimental values. The balanced water flow rates are determined from the % solids values.

6.5.5

Preparation for Mass Balancing Selecting Streams and Equipment

The Mass Bala nce feature of JKSimMet allows the user to select the s treams and equipment items to include in the balance, as well as selecting which parameters can be adjusted during t he mass balancing process. Open the the Mass Balance window by either pressing the Run Balance butt on on the toolbar or by selecting Run Mass Balance from the Flowsheet drop- down menu. Oncetot his is streams open, the enters mass alterations thewindow flowsheet, oruser equipment can bebalance made. mode wher e no For this tutorial, mass balancing will be performed on the Learner Project, which has already been establishe d an d has been used for examples throughout this help file. The Learner Project file will have been s upplied with your copy of the software. You can either follow along using this project, or alternatively if you have your own project with data, you can use the instructions as a general guide for mass balancing you r own flowsheet. See the section Create a New Proje ct 61 if you



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are unfamiliar with the ste ps necessary to e stablish a project and you wish to create and then loa d data into your own project . .

Opening the Mass Balance Window

Step 1

Load the Learner Proje ct an d select the Learner Flowsheet from the drop-down list. If necessary, resize the flowsheet window to view the entire flowsheet. Ensure that the flowsheet is locked.

Step 2

Click on the Mass Balance button on the main functions toolbar located in the left panel just above the flowsheets list, to bring the Mass Balance window into view.

The left-hand panel of the Mass Balance window is where you set up the conditions for the mass balance that is to be carried out on your circuit. Here you select which s treams and equipment it ems are to be in cluded in the balan ce and you specify the components including the size fractions and elements (mineral or ch emical ass ays) that will be available for the balancing procedure. At the bottom of this pan el you have the Control fields where you s elect what is to be included in the current balance and you specify values for the parameter s that control the balan ce. The right-hand panel contains all of the results for y our balance. When the mass balance is under way, you can observe its progress in the top two field s which show the number of it erations that have so far taken place plus the current convergence value . The balance will be complete when the convergence value goes below the convergence target that has been set in the Controls section.

6.5.6

Selecting Data Opening the Mass Balance Window


As is also the case for the Simulation and Model-Fitting modules, you may select a single unit or a cluster of units from your flowsheet on which to perform a mass balance. This allows you to check small parts of a circuit for data consistency. Step 1

Open the Mass Balance window by clicking on the first of the three large buttons located in the left panel, just above the flowsheet list.

Step 2

When you first open this window there will be a default Mass


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Balance Case called MBal Case 1 in the selec tion drop-down at top left. There is a Rename button that can be used to change the name of this Test Case to something more appropriate, if required. The New button can be used to create further Test Cases with different balance settings, which can then be saved and returned to later. There is also a Delete button provided so that you ca n eliminate any test cases that you have previously created but no longer need.

The default sel ection for a new Mass Balan ce Case is for all of the unit s and streams to be selected. Therefore the first stage in defining a Mass Balance Case is to exam ine the list of equipment and streams and to decide which items a re to be included in your balance. The next ste p is to re move any unwanted items by clicking on the adjacent check-box to remove the tick. Select All and Select None buttons have also been provided to speed up the process of balance configuration. In this case we will be balancing with all equipment units selected and all streams - apart from the water streams, which we will add later. Note that if you de-select an item of equipment, the input streams for that equipment will no longer be balanced with the outp ut streams, even if all of these streams remain selected on the Streams list. If only equipment ha s been s elected, it is n ot necessary to specify which streams to include in the m ass balance. The mass balan cer will automatically determ ine which streams should be included in the mass balance based on which equipment has been selected.

Designation

In the stre ams list there is a second colum n labelled "Desig nation". Ther e are three settings possible for the designation field, Major, Minor and Missing. This distinction between the different categories of streams enables selected streams to be balanced or fixed at various times throughout the mass balancing process. A ‘Major’ stream ref ers to one that can be balance d initially, for example the plant fee d, final concentrate and final tail streams,



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and then fixed with the intermediate streams subsequently adjusted within the circuit. A ‘Minor’ stream is an intermediate stream that may have some data missing, restricting it ’s us efulness in the balanc e. A ‘Missing’ stream is defined as a stream that is missing all data. These stre ams can be omitted from the balance until such a stage that th ere is enough information in the othe r streams to allow a mass bala nce to be successful. Note that streams belonging to the different categories are not treated differently in the balancing process. The categories are simply groups to which you can assig n each of you r streams and then later you can elect to keep the ir val ues fixed or adjust them during the next run of the balancin g process. There is visual fee dback provided regarding the groups to which each stream has been assigne d to. Whe n you have the Mass Balan ce window open, you will notice that all the selected streams of the flowsheet are displayed in bold black, which is the def ault for stre am designated as Major. If you chang e a stream's designation, the colour will change to bold blue for Minor or bold red for Missing. These are just the default colou rs, so they can be changed to the users preference if required. This is done via the Default Stream Properties item on the Edit m enu. These visual cues can help users identify the equipment and streams that have been selected, which can be especially useful when dealing with complex flowsheet s.

By default, all stream s are initiall y ass igned to the Major gr oup. As another example of where you might make use of this facility, you may have a complex circuit and wish to adjust valu es for a sub-section of the circuit only. In this case you could assign all of the streams that make up this sub-section, to one of the other two grou ps. You would then find that during the next run of the



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balance, all plant values would rem ain fixed at their previous balanced levels and it would be only the stream v alues for the requi red sub-section of plant that would be adjusted as a result of this balance. Note that the group ass ignation for each stream can be changed in the abov e frame. To do this you just click on the required stream and then click the appropriate button at the bottom of the list. Note that this as signation can also be changed using the drop-down list in the top right corner of the Stream Data window. Step 3

In theall Equipment / Streams frame, select all oftwo the water equipment items and streams with the exception of the addition streams. Leave all the streams with the default designation of Major.

Note that on the flo wsheet there is also visual feedback for the selec tion of equipment items, with those that have been selected be ing highlighted in bold blue.

It is possible also to select and deselect items (both streams and equipment) for your balance list, by clicking on these items on the flowsheet. You will see that the bold highlighting will disa ppear to indica te de-selection. Click ing on them performs a toggle action - so clicking again will re-instate the selection. Step 4

Now examine your Mass Bala nce Case and ensure that: all equipment units are selected all streams are selected except for the water addition streams (BM Water & Cyc Water) all s treams a re designated "Major "

Because each Mass Balance Case h as a name, you may set up several differ ent ones to exam ine different s ections of a circuit. You can select all streams a nd equipment units on your flowsheet, a single unit (together with its input and output streams) or else a selection of units and their associated streams. Note that they need to be contiguous i.e. with s treams connecting all of the selected units, to ensure that your selected sub-circuit does get balanced as a single circuit. Learning Mass Balancing


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In earlier versions all s tream data were stored in equipment ports. To balance a subset of the data, you needed to choose both equipment and ports (streams). In this versio n, the stre am data are now stored within the streams themselves, but the same rule still applies for the balancing of data sub-sets.

6.5.7

Selecting Comp onents The mass balan cing module can perform mass balan ces based on two types of data; namely elements and size distributions. These can be used individually or together to achieve the balance. If y ou also h ave assa ys of the s ize fractions, then you can add an extra dimension to your balance by allowing the size by element data to be used in the balancin g process as well. Mass balancing therefore contrasts with the model-fitting and simulation modes in JKSimMet since in the latter modes it is only ever the size distribution data that are us ed. In the nex t frame of the Mass Balan ce window, you can select the elem ents and s izes that a re to be used for the current mass balan ce case.

In the left hand sect ion of thi s frame is the list of elements that have been entered during the project configurat ion stage. At the end of this list you will see there is an element called Remainder that has been added to allow for any mass not accounted for by the sum of the defined elements. All of the elements will initi ally be select ed by def ault. If for some reason you wish to leave out one of these elements from the balancing process, then you can simply uncheck the relevant check-box. To the right of the elem ents selection area is a similar list for sizes, which shows a ll the sizes (in mm) that have been defined for this project. Again they will be all selected by d efault to begin with. In this c ase we will de-select all of the sizes since we will be b alancin g on the assays alone. Again, with bot h of the se lists, there is a check-box provided at the top to allow you to select or deselect all of them. This can be useful for speeding up the process of defining the suite o f components that are to be balanced for the balance case in question. Step 1

Ensure that all of the eleme nts ha ve been selected, but that none of the sizes are selected.

To the right of the elements & sizes selection frame is another frame with the heading "Adjust Streams". Here there are check boxes for the 3 categories 248 of streams. All three of these boxes will be checked by default. In this case we



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want the b alance to m ake adju stments to all streams in the circuit and in any case, all the s treams in this circuit have be en left in the Major category. This means that as long as the Major check-box is ticked, all streams will get adjusted. However, there is no problem with leaving ticks in the other two categories as well. Step 2

6.5.8

Leave ticks in all three category check-boxes in the "Adjust Streams" frame.

Solution Controls To perform a mass balance the next step is to set the controls for this balance. In the Control fram e there are various drop-do wn s election fields where you have the ability to choose the parameters that are to be involved in this balance. In addition, you can control the way the balance begins and concludes. Step 1

It is wise to ini tially k eep a balance as simple as possi ble, so for the first run through of the current balance we will set the TPH Solids to "Adjust" and likewise for Elements, but we will leave all the other parameter fields set to "Unused".

Click in the white cell s in the ‘Sele ct?’ colum n to change the settings on each parameter. There are a total of fou r settings that parameters may be set to, although not each setting will be available for each parameter. Adjust – The experimental values asso ciated with this measurement are included in the mass balance s um of square s calculat ion and a mass balance adjusted data value is calculated by the mass balance which is consistent with all other data in the system. Fixed – The pre viously calcul ated balance values are held at their current value and are used in the calculatio n of other parameter s selected a s ‘Adjust’. This is used, for example, to keep flow rates fixed when adjusting size so as to stabilise the convergence. Influence – The experimental values ass ociated with this measu rement influence the outcome of the mass balance (i. e. are included in the sum of squares calculation) but are not returned as an adjusted consis tent set of values after mass balancing . This means the mass balanced values for this parameter are left as zeros after balancing. The exception to this is in the cas e of % Solids, where values are retu rned during mass balancing . The objective of the Influence option is to allow the expe rimental data for the parameter concerned to contribute to a higher level balance, even though the data for this



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parameter are too sparse to allow the generation of its own set of mass balanced values. Unused – The experimental values associated with this measurement are not included in the mass balance sum of squares calculation and its mass balanced value is not changed.

If only cer tain elem ents or size fractions are to be sent to the balance, use the tick boxes provided to select the required parameter. These will then be used according to the options set in the main drop- down boxes. If an inconsiste nt selection is run. is made, an error message will be displayed when the mass balance For balancing com plex circuit s, it is suggested to select all 'Major' streams in the first instance and balance (adjust) them. Once the user is happy with this balance, set the Majo r streams to 'Fixed' and adjust the minor streams, then the missing s treams. In this way cert ain parts of the circuit can be balanced and fixed to continue balancing other parts of the circuit. The other two fields within the Control frame are "Constraint" and "Convergence". The first of these relates to how missi ng values are to be handled by the balancing engine. There are two options for this field; "Experimental" and "Balanced". If you select "Experi mental" here, any stream values that are missing will be ignored in carrying out t his bala nce. If you select " Balanced", then wherever a missing experimental value is encountered, the balancing engine will temporarily substitute the balanced value obtained from the last time the balance was run. Step 2

For the first run of thi s balance we will set the Constraint to "Experimental".

The "Convergence" field is where you determine how close the agreement between stream values has to be before the balancing engine decid es that a balance ha s been achieved. When you click on the "Convergence" drop-down, the alter natives you will be present ed with are "Average", "Good" & "Tight". The values for the convergence criterion that are ass ociated with these alternatives are 0.1, 0.01 and 0.001 respectively. Once you have made your selection, it will be the appropriate number rather than the associate d word, that will appear in the Convergence field.



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Step 3

For this balance we will set the convergence to "Good", so the number appearing s hould be 0.01.

Typically you would use either % solids or TPH water as a component when balancing a flowsheet that involv es gravity separati ons. Note that if you use % solids as a component, then you must specify appropriate water additions. For a descripti on of what happens when % solids is included as a component, see the next topic on Water 254 . It is usually a good idea to r un mass balan cing in stages however. In this case we will just the balance using the TPH solids and the eleme ass ays as we have goorun d measure ments of these on all streams except thental cyclone feed stream. After we have completed this simplified balance, we will then add in the water as an additional parameter to be balanced. After this, size distributions can be added in a s well. Some Comments on Mass Balancing

Note that it is not necessary to understand the detailed workings of the mass balance engine in order to make use the mass balance module. The following comments about its workings may be useful however. The mass balan cing algorithm runs in s everal stages. The first is the simple solution, which is analogous to multiple linear regression. Unless the data have serious problems the balance will converge in one step; that is, the s econd solution will be the same as the first. If small negative values occur, you can increase the number of steps to eliminate such values. However, recheck your data carefully. Negative values indicate measurement bias. For higher numerical accuracy you may increase the iteration limits. However, there wil l be no gain in the balance accura cy because data accuracy will be the usual limit. Hint: Read th e sec tion on problems relating to mass balancing adjusting these s ettings.

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before

The values shown above are the default values. If the adjusted data show unacceptable inconsistencies, then you must either reduce the limit or re-scale the assa ys. As a n example, if you ha ve Au assa ys expressed as a fraction (giving a number such as 1.0 E-06) this would not work too well with a converge nce criterion of 1.0 E-05. In this case it would be most sensible to re-scale the ass ay, which might involve expressin g your gold assays as Au ppm. You would of cour se then also need to specify that the ass ay total is not constrained to 100%.

6.5.9

Water in Balancing If you have selected TPH Water as a component from within the Control frame, then you will be also mass balancing any water additions to the circuit together with the water contained in all the slurry flows throughout the circuit. Note tha t you cann ot use % Solids unless you first select TPH Water as a parameter to be adjusted. Except for the water addition s treams, experimental values for water are entered by specifying the % s olids values for the streams. However, the program calculates TPH Water values from these values and it is



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TPH Water that is used by the engine as a balancin g component. The % s olids is not adj usted per se, bu t it can be used in determining the error after each iteration and this is what is meant by "influence". To allow the mass balancing engine to include water in the balance, you need to ensure that you have select ed any water feeder product s treams using the streams select list, in the Equipment / Streams frame. In the Learner Project, there are two water feeders on the Learner Flowsheet. Measured data and estimated SD's are entered in the data window associated with the water streams emanating from these water feeders.

6.5.10 Running the Mass Balance Starting the Balance

This is the simplest step. Once the components have been specified, the desired equipment an d streams selected and the bala nce controls set, the mass balancing can begin. Click on the Start bu tton which is located at the bottom right of the Mass Balance window.



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The mass balancing pro gram will run and when the balance h as completed, the results will be summarised in the righ t hand panel of the Mass Balance window. In the Results frame at the top of this panel is the a ctual convergence value. This is the value that is compared with the required Convergence value selected by the user in the bottom drop-down of the left-hand panel. The program considers the balance is complete once the actual value goes below this user specified convergence setting. The right-hand field of the Results frame is the n umber of iterations that the balance has gone through before arriving at the indicated convergence value.

The frame below the Results frame is labelled "RMS Erro rs" - s tanding for root mean square errors. In this frame you can gauge how well the data has balanced compared t o the previous balance. Smaller values of the RMS errors



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will indicate that a better balance has been a chieved. The RMS errors listed here are divided into the various areas of balancing, in line with the areas that can be selected from within the Controls frame: The Totals refers to the solids mass flows alone water.

it does not include

Flows refers to the volume flows in the various streams, consisting of the volumes of bo th the water and solids in all streams, including slurry str eams and water feeder flows. Note that balancin g on the volume flows only occurs when TPH water has been s elected as one parameters to be adjusted. Assays will have an RMS error displayed if you have selected "Adjust" in the Elements drop-down from the Control frame. Sizes will have an RMS error when Sizes has been selected for adjustment from the Control frame. Likewise Assay by Size will have an RMS error value if Size by Element has been selected for adjustment. Below the listing of the RMS error values is the Parity Graph which allows an easy visual ass essment of how good the balance has been. This graph is plotting the experimental values against the balanced values, so for a perfect balance, with no adjustments needed, all the points would be sitting on the 45 degree line. The distance that points are away from the 45 degree or parity line is a measure of how much adjustment was needed for these parameters to achieve the balance. Generalised Strategy for Mass Balancing

If you hav e assay s on mo st or all streams, the normal sequence for mass balancing would be to initially set TPH Solids and Elements to "Adjust" with all other parameters set to "Unused". Once a balan ce ha s been achieved using these parameters, you would next set both of them to "Fixed" a nd now s et the TPH Water to "Adjust" and the % Solids to "Influe nce". Then after this balance has run, the nex t step would be (if you have sizing data) , to set both water parameters to "Fixed" and set Sizes to "Adju st". Finally , if you also have Size by Element data you would set Sizes to "Fixed" and the Size by Element parameter to "Adjust". If you are work ing wit h Sizing data only and do not have any assays, you would start the process with TPH Solids and Sizes set to "Adjust". After this balance runs, you would set these two parameters to "Fixed" and set the TPH Water to "Adjust" and the % Solids to "Influence". The next step in the Learner Project is to make the TPH Solids and the Elements fixed and to balance on water, making the TPH Water set to "Adjust" and the % Solids set to "Influence. After you change these balancing settings, you should click on the Clear button prior to re-running the balance. The Mass Ba lance window will then look like the one below.



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Pressing the Start butt on will then produce a balan ce similar to the one s hown below.

Since in this case we also ha ve sizing data, t he next step is to b alance on these data. To set this up you need to click in the check-box labelled "Select/ Deselect All" above the Sizes lis t in the Elements / Siz es frame. This will select all of the sizes that are pre sent in the size analy sis for the samp les in this circuit. You then need to uncheck t he 13.2 mm size, since this con tains a value of zero for the experimental retained mass for all three products and this will cause problems for the balancing routine. In order to run the balan ce on the sizing data, yo u need to also switch the TPH Water and % Solids back to "Unused". When the balance runs, you should see the window looking similar to the screen grab below.



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In this case we do not have any size by assay data, so at this point the balancin g process is complete. If you did have size by assay data, the next step would be to set the Sizes back to "Fixed" and then the Size by Element to "Adjust". The next step is to look cri tically at the balance result s and there are various ways of do ing this. The next t opic discusse s the options here and what you need to look for in examining the balance results.

6.5.11 The Mass Balance Engine The Mass Balance Results section reports the value at which convergence occurred as well as the numb er of iter ations that were req uired to reach that value. In most cases of m ass balancing , there will be numerous missing data. The ideal s cenario of the mass-b alance algor ithm is that the user may specify all their data, press a button and have the calculated values returned in seconds. Unf ortunately the number of missi ng data points generally prevents the algorithm from being quite that accommodating. Therefore, mass-balancing needs to occur using a hierarchical approach; that is by first mass-balancing flows, then sizes and total ass ays, then ass ays within size-class es. This hierarchical approach was discussed previously 235 . The key interface is therefore the Cont rol frame in the Mass Balance window you specify which levels are to be mass-balanced. The mass balancing algor ithm in JKSimMet allows high leve l variables to be calculated using lower level results without a ctually estimating the low-level values. For example, it is possibl e to use size information to estimate flows without actually havi ng to estimate the calculated values of size. Datachecking is performed only for those vari ables that are being mass-balanced (not the values of lowe r level values used to influence the mass-balance ). However one needs to bear in mind that unrealistic low-level standard deviations will cause unreasonable weighting to the lower levels Data Checking


Data-checking is required to ensure that values are realistic.

The data-


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checking occurs for all leve ls of variables to be calculat ed, a nd assumes that higher level values have reasonably small standard deviations of the calculated values. In other words data-checking t reats upper level values as if they are fixed. Data-checking is used to check the reliability of the data. In particular, if standard deviation values are too small, the algorithm will have difficulty converging. The data-checking algorithm works by considering the difference between flow (of nt any property) going dev into iations. and out For of aexample, unit. Thefor difference shouldone be consiste with the standard a unit h aving stream in and two streams out, the to tal flow values may be represented by f1, f2 and f3 with corresponding variance values v1, v2 and v3. The flow difference is:

The expected variance of this difference value is given by:

Thus the statistic:

provides an estimate o f the reliability of these data. The expected value of r is 1. This r value is referred to as the RMS (root mean square) value. An RMS value greater than 3 usually indicates that the data contains an outlier or that the standard deviations are too small. Using the RMS Errors

The Error Analysis s ection of the Control/Run window giv es an indication of the quality of the mass balanced data through the use of RMS (root mean square) errors. As its name suggests, the root me an square error is the square root of the residual mean square erro r, which is the error associa ted with fitting the mass balanced data to the experimental data. A root mean square er ror of unit y means that all data points were estimated with errors similar to the measur ed standard deviations of the experimental data points. Therefore, when performing a mass balance, an RMS Total value of somewhere between 0.5 and 2.0 indicates that the experim ental data is good and tha t the correct standard deviatio ns have been used. Along wit h the RM S Total value it is possi ble to check the err or values (i.e. (observed – predicted)/sd) on the other pa rameters us ed in the mass balance. Click the ‘Detail’ button next to each parameter to see information about that parameter.



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This window, for instance, would indicate that particular problem s exist with the Cyc U/F and BM Product streams. Identifying particularly problematic streams allows the user to immediately focus on which data values may be less accurate than indicated by their standard deviation. It may be necessary to change standard deviation values to improve the mass balance.

6.5.12 Checking the Balance There are various ways in which the user can a ssess the results: The Overview window is probably the most useful way to check data and results. It also allows recovery of any compone nt to be displayed for all streams. See the Using the Configurable Stream Overview 36 topic for details of the Overview facility. In the RMS Errors frame of the Mass Balanc e window, the magnitude of the accumulated error values under the various parameter categories, are all indicators of how close the original experimental data were to being already balanced. Smaller values of the RMS Errors indicate less adjustment was required to produce the balance. Moreover, in the case of these fields, comparisons betwe en successive mass balan ces can be made. If these values are smaller than they were in the previous run, then the balance is getting better. If they are ge tting larg er, then the adjustments you have made are taking this balance in the wrong direction. You can also judge the relative success of mass balancing by looking at the individual stream data windows. Examine the values in the Error column. Again, smaller error values indicate less adjustment has been required. The parity graph on the Mass Balance window allows for a good visual assessm ent of the balance . The fur ther the data point s are away from the 45 degree line, the greater was the adjustme nt needed to balance the pa rameters in question. T he TPH Solid s data usually consist of numbers that are very large compared to the assay data and when the two are plotted together on this graph, th e assay data will lie in a clump near the origin, which is not very useful for assessment . To overcome this problem, you can temporarily switch



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the TPH Solids to "Unused", while leaving Elements on "Adjust". You will also have to de-select "Remainder" from the elements list, since this will be a relatively large numb er also, possibl y approachi ng 100. After you have done this, you should get a much better picture of how well the elemental data have balanced. It should be noted though that you cannot actually carry out a balance wit h the TPH Solids set to "Unused ". Note t oo that you can hover the mouse over individual data points to identify them, as is illustrated in the screen grab below. Don't be too impatient here though - you do need to have the mouse positioned over the point you wish to identify for between 1 and 2 seconds before t he data will appear.

The Configurable Graphing facilit y allows the user to plot experimental and balance d size distribution data on the same screen. Further description of this can be found in the s ection Plotting Size Data Graph s 265 . If mass balancing a large and complex circuit is proving difficult, a useful technique for tracing the source of the problem is to dissect the circuit into smaller chunks for balancing. The Mass Balancing modul e allows balance s to be carried out on a single unit or on a small set of units, isolated from the main circuit by means of the Sel ect List faci lity. This allows you to put the test data under a microscope. If circuit condi tions were changing as you did your test work, you may find that the unstable sections of the plant will have yielded unusable results. As a general principal, a good balance depends on having steady state conditions and varying conditions will usually produce nonsense.

6.6

Present ation of Mass Balance Resul ts There are two main wa ys to present the result s of mass balancing: viewing on screen via the Configurable Stream Overview window and printing or exporting via the Reports function. We shall deal wit h these in turn. For mass balanced data, graph plotting is limited to GSIM format.



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Configurable Stream Overview Using Configurable Stream Overview to View Balance Results

The Configurable Stream Overview 36 window giv es you a powerful means of summarising your data and checking it for adjustment problems. There are some built-in overviews that will already be present when you first open the Configurable Stream Overview. This includes one that contains Experimental, Balan ced and SD data. This one is all you would normally need for assessi ng the results of a mass balancing proce dure. However, as implied by the name, this overview windo w can be config ured by the user an d you can create your own overviews with additional data displayed or with just a subset of the streams in your flowsheet displayed. The best way to use the overview feature is to compare experimental and balanced values for each as say (or size fraction) across the complet e circuit. This will give a very useful picture of the accuracy of the data and the mass balance. Step 1

Left-click on the Co nfigurable St ream Overview button ( ) on the main JKSimMet toolbar. This brings the Configurable Stream Overview window into view.

Step 2

Select From the Select List at top left, select the pre-configured overview the existing Overview that is labelled "Stream Data (Exp, Bal & SD)".

Note that fro m within this window, yo u can elect to change the way you view the sizing data. The drop-down at top right contains the sizing data options of % Retained, Cu m % Retained and Cum % Passing. You can also gain access to the SD Calculation window 243 from here via the button next to this drop-down. This is provided here since after examining the most recent balance data, it will often be the case that you may need to modify certain SD values before rerunning the balance.

6.6.2

Repor ts Function and Printing Printing Mas s Balance Results

Normally for reporting the results of a mass balancing procedure you would most likely want t o show the experimental, balance d and SD values for each type of data involved and for each of the s treams in cluded in the bala nce.

Printing Individual Port Data Windows

One way to do this is via the individual stream data windows. To open a stream data window, just doubl e-click on the required stream in your flowsheet. These windows all have SD and Mbal data as pre-configured display columns. You cannot dire ctly print these wind ows, but y ou can copy the grid from them into Excel. To do this you press the Copy butt on, located top centre of the Stream Data window. As it is only the activ e tab that gets copied, you need to ensure that you


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have the appr opriate tab select ed for the type of data that you are intending to report on. This method may occasionally be useful if y ou are wishing to report the data for a particular stre am, but in general one of the other two method s below is probably more practical. Printing the Configurable Stream

Another alternative is tha t once you ha ve the Configurable Stream Overview set up according to your requirements, you can either print it directly or else export it to Excel for further manipulation before printing.

Overview

When you use the Print function directly, t he options for manipulating the format of your report are somewhat limited and it is likely to span across several pages. In most cases it is probably better to use the Expo rt fun ction and then print a report from Excel. There are two Export buttons - one is for exporting just the overview that is currently displayed, while the othe r will export all of the overviews that have been set up for this project. Note that this includes all the system configured overviews as well as any that you may have created. The expor t function will create a new Excel sheet for each of the existing overviews. The copy grid option is also available from the Configurable Stream Overview window and this may sometimes be useful as a quick way of getting the required data into Excel for further manipulation.

Configure and Print a Report

Probably the greatest flexibilit y for report production is afforded by JKSimMet's integrated Report generator. When you press the Repo rt button ( similar to the illustration below will open.

), a wind ow

From here you can create reports with complete flexibility regarding which equipment items, streams and types of data that a re to be included. There is also a drop-down to allow you to choose the way your sizing data will be expressed in the report.



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For a mass balancing report, it is recommended that you place a tick in the Summary check-box. When you do this, the formatting of the report will be modified for easier comparison of values between streams. With the Summary check-box ticked, the stream data will be arranged with the stream headings across the page and the parameters down the page, grouped by data type. If you have also s elected equipment for the report, the equipment data will still be listed down the page along the lef t-hand border, but it will have a lot less detail than in the non-summary version.

6.6.3

Plotting Size Data Graphs Plotting Graphs of the Mass Balancing Results

On the mass balancing windo w there is a graph of exper imental data versus balanced data, which provides a visual assessment of how much of an adjustment of the various data points was needed to achieve the balance.

For the sizing data it is possibl e to get a more detai led visual fee dback on h ow much adjustment was needed, by plotting a size distribution graph of both the experimental and balanced data. A drop-down is provided to allow you to select the format of the sizing data. This can be either cumulative % passing, % retained or cumulative % retained. The data can be plotted for a number of streams on the s ame chart, to allow comparisons. An example of the graphing facility with the required da ta types in the process of being selected from the drop-down, is shown in the screen grab below.

Once the str eams to be displ ayed have bee n selected and the data format and data type s s elected, you simply clic k on the Graph tab an d the requ ired chart will appear in place of the graph configuration table. The screen grab below shows a typi cal example in which the user has chosen to show the circu it feed from the Learner Flowsheet plus the two products from the cyclone.



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It is also possib le to make chang es to the way this graph appears, using the Format button near the top right of this window. I f you click on this button, a new window will open where y ou can make a number of changes to the chart formatting. An example is shown below.

Any graph that you gene rate here can be easily inser ted into an Excel or MS Word report using the Copy button at top right.



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Probl ems Rela ted to Mass B alan cin g and Possi ble Sol ution s There are, of course, many proble ms that may be encount ered during mass balan cing. It is possible however, to point out some of the more common problems and a description of these has been s et out in the remainder of this section. While the list belo w is not comprehensive, we hope that it will alert you to some of the more significant pitfalls.

6.7.1

Errors, Warnings, Faults

Some problems detected by JKSimMet can produce error messages. In version 5 the errors had error numbers and were referenced via a key that coul d be found in the hel p file. In version 6 it is no longer necessar y to refer to a key since the error explanations now a ppear in the error me ssa ge window.

Graphical Analysis

The graphing capa bility of JKS imMet is the most powerf ul way to examine your data fit. Disco ntinuities in s ize data highlight poo r data or a change in size measur ement technique. Graphic al ana lysis also highlights any bias in the data fit.

Different Sizing Techniques

Be very wary of changes in size measurement technique e.g. from screens to a Cyclosizer.

Different Assay Techniques

Where assay techniques change bet ween stream s amples, as they sometimes do for different assay ranges, ther e may be inherent biases within the as say techniques. These will lead to biases within the mass balance.

Skill versus Practice

Mass Balancing is not a cut and dried proce dure. The only way to acquire a useful skill level is to practise on a wide range of real da ta. JKSimMet offers a user-friendly environment for what are really very complex and powerful mathematical techniques.

Data

Note that it is necessary to have enou gh feed and product data to a chieve a useful mass balance. This is very important. Generally you need to have redundant dat a and the more of this you have, the better. If you have no redundant data at all, then the mass balancing exercise reduces to just a calculation – i.e. the re is only one solution to the balance. In this case the internal checking that comes from having these extra data (and is also one of the major advantages of mass balancing), will no longer be operating. Without redundant data, the re could well be a very large error in one of your data points and you would have no way of ever being alerted to it.

Common Mass Balancing Pitfalls

There are a couple of sim ple traps which can appear in many guises. If you become aware of the se now you may recog nise them more easily when you encounter them in the future. These are discussed in the two sub-topics that follow.

The Middlings Prob lem The Middlings Problem

Below we have a single unit flow diagr am for a separation n ode wher e there is a middlings s tream of assa y m.

In this situation there are not enough assa ys to go around. However, if we have two assa ys in each s tream, we would write them out as


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simple equations and solve for two unknowns. However, if m really is a middlings stream, it will be close to a in composition and very often recycled back to it. In this case, no matter how accurately we can sample and assay the stre ams, we can only find out: the ratio between flows b & c (if m goes elsewhere) or the flows in b and c if m is recycled. The actual flow rate in m can be anywhere between zero and infinity. However, there is a straightforward solution. Measure (or estimate) the flow rate in stream m and input this flow rate as data. The mass bala ncing module allows you to do this.

6.7.2

The Infinite Division Problem The Infinite Division Problem

If one wishes to extract maximum inf ormation from a survey , it is not unusual to assay on a two (or even three) dimensional matrix, for example , assay by size or assay by size by specific gravity. This subdivides the stream into even smaller sub-groups. Each sub- group has an extra step of processing and an increased relative error. Hence, we tend towards trying to solve for (0 - 0) / (0 0). This is not a useful numerical exer cise. The solution to this problem is straightforward, however. You should the total assay where there are you large differences, to calculate thefirst massuse balance flow rates solutions. Once have these flow rates, fix them by selec ting "Fixed" from the TPH Solids drop-down (in the balance controls fram e) and only then add in all of the smaller fraction a ssa ys to the mass bala ncing problem. Once the flo w rates have been defined, the mass balancing mo dule will be more easily able to allocate the minimum adjustme nts required to make all of the fractional assa ys consistent.

6.8

Meta llurgi cal Accou nting Use in Metallurgical Accounting

The day to day data collected from a mineral processing plant are rarely consistent and will almost always con tain redundant information. In general, any two methods of calculation will yield different results. The challenge for metallurgical accounting is to produce adjusted data that are both selfconsistent and as accurate a representatio n of plant performance a s poss ible. Consider a typical bas e metal concentrator with several products from s everal circuits,

At each point mark ed , we h ave Au, Cu, Fe, Pb and Zn Assays. For the feed,

Problems Related to Mass Balancing and Possib le Solutions


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we have weightometer readings and for the conce ntrates we have load out weights with stockpile surveys. If we select an accounting period that is large compared with the circuit residence time, we can carry out a mass balan ce over this complete data set. If large adjust ments are req uired, these may be an indication of problems in either samp ling or assay techniques. In this case you may need to select smaller circuits for mass balancing in order to isolate and identify these problems. Once a consis tentsets set of adjuste d data is produced for each accounting period, the sums of these will also be consistent. If assays and flow rates a re availabl e on a short tim e s cale, e.g . several times per shift , these data can be balance d for each time period, printe d to a file or exported to most Wind ows spreadsheet or word processing packages using copy and paste. JKMetAccount

For users with a serious interest in metallurgical accounting, the JKMetAccount program was created to enable the Metallurgist or Plant Manager to track the performance of a mineral processing plant over time.Changes to a plant flo wsheet, which can so often cause problems for a spreadshe et based system, are easily accommodated by the JKMetAccount software. The majo r s trength of this program comes from h arnessing the power of the JKMBal mass balan ce engine (and more recently a model based mass balan ce engine), within a rigorous data mana gement environment that is accessed via a user frie ndly graphical interf ace. JKMetaccount also still provides for very flexible reporting, as it utilises the formatting power of Excel within its report production module. With its rigorous data manageme nt advantage over a spreadsheet s ystem, we believe that JKMetAccount will in time become regarded as an indispensable tool for modern mineral processing plants. At the end of 2006, all right s to the JKMetAccount program were sold to the large Brisbane based software development company Mincom, whom were considered better able to handle the furt her development and marketing of this produ ct. Mincom have since be en taken ove r (in July 2011) by ABB and are now part of the ABB owned company Ventyx. If you are interested in finding out more about JKMetAccount, further information can be obtained either from the JKTech website ( http:// www.jktech.com.au/commercialisation-case-studies ) or directly from Ventyx, whose contact details can be obtained from their website at http:// www.ventyx.com/ .

6.9

Refer en ce s LYNCH, A.J., 197 7. Mineral Crushi ng and Grinding Circuits, (Elsevier, Amsterdam), Chapter 7. LYMAN, G.J., 1986. Application of Gy's sampling theory to coal, International Journal of Mineral Process ing, Vol 17:1-22. GY, P.M., 1982 . Sampling of particulate materials: theory and practice, 2nd Ed,


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(Elsevier, Amsterdam), p 431. MORRISON, R.D., 1976. A two stage least squares technique for the gener al material balance problem, JKMRC Internal Report No 61 (unpublished)

References


Part

VII

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Model Fitting Model Fitting

7.1

This section provides information about the model fitting capabilities of JKSimMet V6.

Introdu ction to Model Fitting Purpose

This ch apter describes how to use the JKSimMet model-fitting mode. Model fitting allows JKSimMet to be fine-tuned to each specific plant and operating condition, or even to part icular ore typ es. It does so by adjusting selected model paramet ers on the basis of system atic differences between measured product data and simulation predict ed product data. The model fitting proced ure can take into a ccount any measured flow rates and es timates of their accuracies. Previously the determination of the model parameters was performed in spreadshe et-based programs, involving complex formulae. This has been very time consuming and potentially prone to error . As more companies are becoming skilled in developing models, JKSimMet enables the fitting routines to be standard ised. The abilit y to use JKSimMet to fit the model parameters greatly increases the efficiency and level of confidence in developing the models; although a high degree of training is still required to ensure reasonable results are obtained.

Overview

For both plant designer and plant operator, model fitting is primarily concerned with the collection of accurate experimental data, at either pilot or full plant scale. The model fitting process provides a powerful means of data examination or a ssessme nt as well as the compression of thousands of data points into a few parameters. The parameters characterise how a particular ore behaves in a particular plant. This characte risation can be used to find the optim um plant settings with respect to v arious criteri a, or even to find a n optimal plant configuration to achieve stated objectives. As with all data a nalysis or predic tion processes, howev er, the qualit y of the output is strongly dependent on the quality of the input. The computer ja rgon for this phenomenon is GI GO or GARBAGE IN – GARBAGE OUT. A serious difficulty with a ll realistic simulation systems like JKSimMet is that they will produce very plausible looking nonsense from rubbishy data. Hence, just as the spreadsheet is not a replacement for the accountant, JKSimMet is not a replacement for a metallurgist or process engineer. There is no substitute for professi onal expertise or experience, especially in the collection and ana lysis of large quantities of data. JKSimMet provides s uch a professional with a tool of enormous power. The general procedure for model fitting is: Collect data; Analyse data; Optimise pla nt usin g models; Adjust plant;


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Collect data to confirm And start the cycle again.

7.2

Back groun d to Model Fitting Default Parameters

The JKSimMet models are provided with a set of default parameters and, in most cases, a range of parameter values. For any real mineral processing operation, the best-fit parameters will almost certainly be different from the default values provided with the system. There are several cla sses of parameters used a s model inputs:

Machine Parameters

Firstly there are the machine dependent parameters. These are typically dimensions and key operating adjustments.

Ore Parameters

Then there are the ore dependent parameter s. For example, the work index or specific gravity or appear ance function for a particular ore at a particular energy.

Operating Parameters

There are also the calculated or measured operating parameters. These usually depend on a combination of machine and ore dependent parameters and ore feed rates, etc. Examples a re cyclone feed pressure and crusher power draw.

Circuit Flow Rates of Solids and Water

Process instrumentation often p rovides an estimate of solids and liquid flow rates in the circuit. An example m ight be the solids mass flow rate to a cyclone classifier. In some cases, such a flow can be treated as data. If it is unmeasured, it may beeffectively varie d until a best afitparameter. to the other data is achieved. In this case, the flow rate becomes

Model Parameters that can be Fitted.

7.3

Each mode l has a list of paramet ers that can be fitted. Each parameter to be fitted is selected from a menu for that model. These menus are listed for each of the models within the Model Descriptions 294 section.

How the Model Fitting Program Works The model-fitting program works by ca lculating the differences between the predicted and experimental data, and then deriv ing from these differences a weighted sum of squares value (WSSQ). On its first iteration (step), the program makes a small adjustment to each parameter in turn, with each adjustment followed by an internal simulation to determine its affect on the weighted sum of square s value. This s tep is used to estim ate the magnitude and direction of the adjust ments to the parameters required to minimise the WSSQ. On subsequent iterations, the program varies a ll the fitted parameters simultaneously , noting the effect of the adjustme nts. This process is repeated until the program is stopped for one of the following reasons: A minimum WSSQ has been reached; The maximum number of steps set by the user has been reached; The adjust ments made to the parameters are having no significant effect on the weighted sum of squares value; Operator intervention. Whereas simulation uses given feed data and given model parameters to


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predict the product data, the model-fitting program uses the sum of the squares of the differences between the predicted and the actual product data to adjust the model parameters. The difference between simulation and model fitting is represented schematically below:

Schematic to Illustrate Difference between Simulation and Model Fitting

7.4

Model Fitting as Appl ied in JKSi mMet Model fitting allows the simulation models present in JKSimMet to be tuned to specific real world operating conditions. To do this, the user collects experimental (stream) data and periodically engages in model fitting to update parameters.

How the Model Fitting Program Works


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Model fitting consists of adjusting the model parameters so that the model predictions line up a s closely as possibl e with collected experimental data. These data are collected from the real plant or circuit, and they are mostly data associated with the circuit product stream or streams. Any parameter within the comminution models can be incorporated into the fitting routine. In general, the model paramete rs a re within the comminution machines themselves, while the data to be fitted against are within the streams.

7.5

Pre liminar y Da ta Set up The initial step s in performing the mod el fitting data analysis are similar to those required for all previous functions.

7.5.1

Creating the Flowshee t To create a new project, follow the procedure discussed earlier under the topic Creating a New Project 178 . This wil l load a new project wit h a blank flowsheet called FlowSheet1. Lock the flowsheet once the f lowsheet has been drawn, including labels given to equipment and streams.

7.5.2

System Properties The fi rst ste p in model fitting for a given flowsheet is to check the system properties defined for that flowsheet. First make sure that you have selected the flowsheet you wish to deal with. Remember that you need to double-click on a flowsheet from the list in order to s elect it. Next you should click on the System Properties icon or sele ct System Properties fr om the Flowsheet submenu to open the System Properties window. System Properties

In JKSimMet there are only two classes of system properties: Elements Miscellaneous In JKSimMet there are no predictive models that deal with the dispersion of elemental flows around flowsheet nodes. Any elements tha t you enter a s part of the system properties will only be used within the mass balancing function. For the miscellaneous category, there are two built-in properties solids SG and water SG. Both of the se will have relevance for a number of the predictive models. Generally the water SG will not vary greatly, but solids SG will have more variation and cha nges here could have a s ubstantial effect on the output from models where gravity effects are important, such as the cyclone model. Other aspects of the System Properties chapter on Editing the Flowsheet Data.

7.5.3

192

wi ndow are discussed in the

Stream Specification Click on the Stream icon or sele ct Stream from the Flowsheet menu to open


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the Stream window. From here you can select individual streams. See Entering the Data 237 unde r the chapte r Learning Mass Balancing for more detailed information. For model fitting within JKSim Met, the user must ensure that sizing data has been entered as part of the stre am data for all streams associ ated with the equipment item or items concerned. For the models a ssociated with these equipment items, the default values for the parameters being fitted can be used as starting values.

7.5.4

Data Input Feeder Units

JKSimMet requires the user to enter data into the Feeder units, even though this data h as been previously used in the streams for t he mass balance. Ensure the following data has been entered for the feed stream(s): TPH solids % solids Size distribution

Configurable Equipment Manager

In a similar manner to setting up the flowsheet for simulat ion, the user must enter starting point parameter v alues for the equipme nt units. The addition of these data can be achiev ed via the Configurable Equipment Manager 153 or be entering the data directly into the individual unit windows. The Configurable Equipment Manager can be particularly useful where you have multiple equipment units with the same associated process model.

Survey Data

7.5.5

If you have survey data that has been entered into the survey data screen, the task of getting your data into the various flowsheet streams can be efficiently accomplished via the Trans fer button on this Survey Data 175 window.

Mass Balance Prior to Fitting It is generally recommended to balance experimental data prior to moving into the model fitting routine. See the sect ion on Mass Balan cing 230 for more details Ensure the following steps have been performed: Experimental Data Specification – check to see that you have size fraction data entered for all streams involved with model fitting. Enter data in either the Configurable Stream Overview or the individual stream windows. Calculate ALL standard deviations, either by using the Automatic SD Calculator or by manual ly entering values. The Automatic SD Calculator is accessed from either the Configurable Stream Overview or from individual stream windows. Ensure standa rd deviations are present in the s ystem for: TPH Solids TPH Water

Preliminary Data Setup


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% solids ALL size fractions Where no experimental data is present, ensure the s tandard deviation value is set to ‘Missing’. Run the mass balance using the hierarchical structure as discussed in the Mass Balancing 230 section: Adjust TPH solids and elements first until reasonab le values have been obtained, keep these as fixed for subsequent runs; Adjust TPH wat er, using % solids as influence, then leave a s unused for subsequent runs; Adjust size fractions (wt %) Review results using the parity graph, Configurable Stream Overview and individual stream windows to ensure realistic values.

7.5.6

The Model Fitting Window Opening the Model Fitting Window

Step 1

Open the Model Fitting window.

The Model Fitting windo w within JKSimMet contains several frames. When first opened, either by clicking on the Model Fitting b utton ( ), or by selecting Run Model Fitting fr om the Flowsheet menu, a window similar to the one shown below will appear. At the top left is aa system drop-down selection boxfitfor selecting Model Fit Case. By default, ther e is generated model case calledthe Whole Circuit , which as the name implies, encompasses all the equipment items in your flowsheet that have as sociated models, plus their connecting stre ams.

The Whole Circuit mo del fit case cannot be deleted. However, you can add (and/or delete) as many mor e model fit cases as you wish, so as to enable the fitting of either individual equipment items or sections of the plant that encompass any number of connected items.



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Creating a New Model Fit Case

Step 2

Add a new model fit case for the ball mill only.

To add a new model fi t case, you first click on the button at the end of the dropdown (circled in the screen grab below).

After clicking on this button, a window labelled Simulate will open containing a similar dro p-down list at the top , this time labelled Simulation Select List. From this window you can add new model fit cases as well as make any changes needed to ones you have previously added. A screen grab of this window is s hown below.

Beneath the drop- down list ther e are two panels, the left -hand one showing a list of e quipment item s and the righ t-hand one showing a list of the stre ams. You will notice that when Whole Circuit is selected from the drop-down list, all the equipment items and s treams will be selected by d efault and you will not be able to deselect any of them. To create a new s elect list (mode l fit case), click on the New button (circled above) and then enter a name for the new list in the dialog box that will then have opened (see below).

Setting up the

In this case we will elect to fit the ball

New Mode l Fit Case

model fitting the items on this flowsheet, so you could enter something like 'Ball Mill Only' for the name. As a general principal, it is usually best to model fit the equipment items individually before attempting to carry out model fitting on the entire circuit. That said, in the case of a closed circuit ball mill configuration, it is often better to fit t he ball mill concurrently with the associate d cyclone (see ball mill model description 361 ). However, since our purpose in this example is to demonstrate the more normal sequence, we will fit the ball mill first, followed by the cyclone and finally the whole circuit.


mill in isolation as our start ing point for


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After pre ssin g OK to name the new model fit case, you will be back on the Simulate window where you can specify the equipme nt a nd streams that are to be include d. Here you will find that in addition to the Whole Circuit model fit case, Ball Mill Only is now an additional option for selection from the dropdown list. If you now selec t this item, you will see that initially there are no equipment items or streams selected. To set up the new model fit case, you sh ould now select Ball Mill from the lefthand pane l. Af ter doing this you will find that all of the input and output streams for the ball mill will be automatically ch ecked in the right-hand s tream selection panel. You can modify this selection if required. However, bear in mind that the only streams you will h ave available in the Model Fitting window when this mode l fit case is selected, will be the ones have been checked in the Simulate window. After setting up the model fit case, you should return to the Model Fitting window. You do this simply by clo sing the Simulate wind ow - via the corne r closeb utton ( ).I f Ball Mill Only wa s selected when you closed the Simulate wi ndow, then this will also be selected on returning to the Model Fitting window. The model fitting window should now look similar to the screen grab below:



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Selecting Equipment Items with Associated Models and Showing their Parameters

We will use the Ball Mill Only case for initial model fitting. However, to illustrate a point we will now select Whole Circuit agai n. You will notice that the parameters appearing in the centre panel list will be appropriate for whatever equipment item you have clicked on in the equipment selection list at left. Note that when you click on a grey Equipment cel l (or on a Model cell) you will bring up the list of the appropriate parameters for the selected item of equipment - you don't have to put a tick in the ch eck-box n ext to the equipment item for it to be selected and to see the associated parameters. The check-box is there simply to provide a means of quickly selecting the ap propriate stream s in the Stream Error Selection list . When you place a tick in one of the equipment item check-boxes, the appropriate streams will a lso be ticked. The s treams that get selected for error assess ment by default will be the product streams from the selected item of equipment. You are not bound by this stream selection, but it does represent what would be the normal choice of stre ams for use in assessing the veracity of the parameter values, after each round of simu lation. You can remove the tick for instance from one of the product streams if you don't want the error in the simulated values for this stream to influence the parameter fitting.

Selecting the Streams for Fitting Error Assessment

Step 3

Select the streams that are to be used for the fitting process.

If you now select Ball Mill from the Equipment Selection frame and place a tick in its check-box, the program will automatically s elect the BM Product from the Stream Error Selection frame. By default this frame shoul d contain all of the streams associated with the ball mill - the feed plus the water addition. However, the defaul t s election for s tream error assessment will always be just the product stream (or streams) from the selected item of equipment; in this case the BM Product. This means that fitting of the ball mill parame ters will take place by minimising the difference between the simulated values and the experimental values associated with the BM Product stream.

Selecting Parameters for Fitting

Step 4

Select the parameters to be fitted.

Next you need to select from the central parameters list, the ones that you intend to be dealing with for this round of fitting. As you select each pa rameter from the top centre s election list, you will s ee that the chosen parameters will immediately appear in the Parameter Selection frame below. By default, each of the paramete rs that is added into the lis t in this frame will have its check- box in the lower fr ame ticked, which means that it is selected for fitting. You c an however, uncheck these check boxes. If you elect to do this, the pa rameter concerned will not be fitt ed, but the guessed value will be used as a fixed value for the parameter concerned through each simulation cycle of the fitting process. If on the other hand you were to de-select this parameter from the top parameter list, then whateve r value h as been entered for the parameter in the equipment model window will be the one us ed as the fixed value through each round of simulation. JKSimMet automatically inserts your initial estimate of the parameter value from the equipment data window into the Guessed Value column. The Scale Factor is also autom aticall y set at 10% of the initial estimate. If you wish, these values can be changed by highlighting the existing value and over-typing it with a new one.



Model Fitting

Creating Parameter Lists

281

For each model fit case, a parameter list will autom aticall y be saved and this will consist of whatever pa rameters you ha ve chosen while this model fit cas e was select ed. Howe ver, in addition to this first paramet er list, you can create any n umber of extra pa rameter lists that you can then return to a s required. Any such lis ts you create will be aut omatically saved and they will be specif ic to that particular model fit case. Note that the definition of the parameter lists also includes the specification of which streams are to be used for the model fitting error assessment.

Fitting the Ball Mill Model

You next Ball Only from(Knot the Model Fitare Case drop-down then should select all butselect the last of Mill the parameters 4), that associated withand the ball mill mod el. Note that the ball mill model is actuall y s et via the equipment window and in this case the pe rfect mixing model is the one that has been selected. There should now be 3 pa rameters listed in the lower Parameter Selection table. Deselect the last of these three (Knot 3 ) by removing the tick from its ch eck-box. Then place a value (say 2 for example), int o the Guessed Value fi eld for this parameter. This is not necessarily a realistic numbe r to use for this parameter just an example to illustrate the principal.

Adjust Model Fit Settings

Step 5

Adjust the settings for model fitting.

The next step is to adjust the simulation settings for model fitting, if required. The Settings frame looks like the screen grab below.

The Size Interpolation re fers to how data assoc iated with intermediate sizes; that is sizes other than those actually ent ered, are to be calculate d. The default setting is Linear, bu t Spline interpolation may give better results under some circumstances. The Starting Conditiondrop- down is where you select the type of data that are to be use d for the fee d to the circu it during each round of the fitting process. Normally you woul d s tart fro m the experimental data but if you have doubts about how representative the samp le was and if balancing has chang ed the values for this sample significantly, then you might want to start from the balanced values. Again, for the Error Condition, there is a choice of the data typ e with which to compare the simulated values after each round of simulat ion. Once more the first choice should prob ably be to use the expe rimental data, but if there are doubts about the sample s (in this case the product s from the selected circuit), then balanced data may be a better choice. The Max Iterations figure here refers the maximum iter ations allowed for each round of simu lation during the model fitting sequence. For simulations of a circuit where the re is no circulating load , (as is the case here, where we are



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fitting the ball mill alone), only one or two iterations for each round of simulation would be needed. The maximum iterations limit only becomes important whe n you are fit ting a larger circuit where there are one or more circulating loads. Norm ally the default lim it of 100 will be s ufficient, but if your circuit is having problems converging, then you may need to increase this limit. Convergence refers to how close the simu lated values have to be to whichever data type has been chosen for the error condition, before the model fitting process has deemed to have converged. The convergence limit value can normally be left at the default setting. Run the Ball Mill Model Fit

Step 6

Create A

Step 7

Model Fit Case for the Hydrocyclone

Now that model fitting has been run for the ball mill by itself, you s hould create another Model Fit Case, this time for the cyclone (call it Cyclone Only), using the same procedure as was outlined above. After you have created this, select Cyclone Only from the Model Fit Case drop-dow n. On doing so you will s ee that there is now an item in the Equipment Data Selection fram e (far right), which was emp ty when we were fitting the ball mill parameters. This frame has an item in it be cause the cyclone is selected and a cyclone is an example of an equipment item that has an operational character istic which can be measured and is a lso predicted by the model. The characteristic we are talking about here is the cycl one oper ating pressur e. This means that in the case of a cyclone, the difference between the measured and simulated cyclone pressure can be used in the same way as the difference between measured and simulated stream characteristics, to tune the parameters associated with the cyclone model.


Run model fitting.

Leave the defaul t settings in place and press the Start button to run the model fitting. A summary of the results will be shown in the Model Fitting Results frame, which is immediately below the Settings frame.

Set up a model fit case for the cyclone.


Model Fitting

Run Cyclone Model Fitting

Step 8

Run Fitting for Whole Circuit

Step 9


283

Run model fitting for the cyclone.

After selecting the cycl one U/F and O/F streams plus the cyclone operating pressure for the fitting error comparisons, you can again leave the settings at the default value s and run another fit . A screen grab of the Mode l Fitting window after fitting the cyclone is shown below.

Run model fitting for the whole circuit.

Once the ball mill and the cyclone have be en fitted s eparately, you can then run the fitting process for the whole circuit. A screen grab of the Model Fitting window after fitting the whole circuit is shown below.


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Master Slave Fitting Master/slave mod el fitting a llows the same parameters to be fitted to two or more units in a s ingle test. The parameters fitted will have the s ame values for the mast er and all the slave units. Master/Slave fitting can be used when fitting survey data collected simult aneously from parallel units with the same operating conditions. Alternatively, it can be used for survey data collected sequentially from a single process unit, where it is expected that model parameters will not be affected by any change in operating conditions.

Equipment Selection

The Master/Slave functionality is available in the model fitting dialog when two or more of the same equipment items use the same model, as shown below.

In this ca se the eight cone crushers have the sa me model. The choice of which equipment item to use as the maste r is not impo rtant as all units will finish with the same parame ter values. For this example Te st 1 is



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the maste r equipment. The first step is to select the parameters in the master equipment that yo u wish to use in the s lave equi pment. In this example the parameters K1 - Constant, K1 - CSS(mm), K1 - Feed TPH, K1 - F80(mm), K2 Constant, K2 CSS(mm), T10 - Constant and Pow Prod Fact have been chosen, as s hown below.

Selecting Test 2 in the equipment list and then select ing Test 1 in the Master drop down control gives the following selection options in the equipment parameter list:

The user can now select the parameters chosen for fitting in the master equipment as parameters for the slave equipment, in effect replacing those parameters in the slave equipment.

As selected above, Test 2 will use the parameters from the master equipment and none of its own.

Parameter


With the eight paramet ers already chosen the paramet er s election grid will


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selection

display the following:

The equipment parameters listed are the selected non slave parameters for each equipment item. The equipment that uses the selected parameter as a slave parameter is listed in the final column. Once a piece of equipment has been set as a slave it cannot act as a master to another equipment item. However, any equipment not set as a slave can be a master to many other piece s of equ ipment as shown below where Test 1 is also the master of Test 3, 4, 5, 6, 7 a nd 8.

7.5.8

Chec king the Fit During the execution of the fitting program the Model Fitting Results frame of the Model Fitting wi ndow is continually updated as the iteration count progresses. Assuming that the fitting reaches a satisfactory conclusion, the standard dev iations (SDs) of the param eters will be updated to their final values when the fitting program stops. There are var ious ways in which the user can judge whether the results are good or bad: One method is to compare the s ize (order of magnitude) of the parameter SDs with that of their associated values. When the SD is small compared with the value as a ratio, it is a good fit, when large, it is a poor fit. The summary val ues in the Model Fitting Results fr ame also indicate the success of the fit . Low values in the Residual, Error Sum, and Errors SD fields indicate a good fit; large values, a poor fit. Moreover, in the case of these fields, cross comparisons between fittings can be made. If these values are smaller in the most recent run of the fitting than they were in the previous run, the fit is getting better. If they are getting larger, you are going in the wrong direction.



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The engineer can also judge the relative success of the fitting by looking a t the stream data windows, with Weighted Error and Percentage Error versions of the difference between calculated and experimental data being the most useful indicators. These are displayed by selecting the appropriate item from the Error drop-down list. The graph plott ing facili ty of JKSimMet allows the engineer to plot raw and fitted sizing data on the same g raph, as detailed in next s ection - Presentation of Model Fitting Results. The facility of sJKSimMet allows experimental and calculat ed dataoverview for mult iple stream to be viewed in a key summary table. These overviews are configurable by the user (see the topic under the JKSimMet Windows section 157 for details).

7.5.9

Presentation of Model Fitting Results There are two main ways to present the results of model fitting: Printing data Plotting graphs We shall deal with these in turn. Printing Mode l Fit Results

Given that model fitting concer ns the experimental (raw) data and the predicted (fitted) data for streams (mainly), the re sults p resentation s hould displa y these two types of data for the stre ams concerned, in a manner that facilitates easy comparisons. The easi est met hod of print ing data for the indiv idual streams is to go to the relevant stream data window and follow the steps below. Step 1

Open the relevant stream data window by double clicking the stream.

Step 2

Left-click on the Copy Grid ic on in the top centre portion of the stream data window to copy the required data.

Step 3

Open Excel, select an appropriate positio n for the top left corner of the data grid to be pasted and then press the Paste button to insert the data.

Step 4

Repeat Steps 1 to 3 for all the other streams whose data you want to print.

These steps also apply to any other window that contains data you woul d like to print , such as equipment data. In this case you would doub le-click on the equipment item rather than on a stream to open the appropriate window. Once these data have b een inserted into an Excel s preadsheet, just use the Excel facilities for setting out and printing a report. The Configurable Stream Overview Window


The Configurable Stream Overview window provides a convenient means of looking at experimental and model fitted data on the scree n and enables the user to de sign the layout so that it only shows the data that is currently of interest and only for the stre ams that the user has selected. Thes e overviews can also be print ed, using the Print Overview button located on the Configurable Stream Overview w indow toolbar. For more information on using the Configurable Stream Overview, see under the to pic heading Viewing the Data -


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Summaries and Reports

213

.

The Reporting Feature

The Reporting feature provides a means of printing both stream and equipment data. The use r can configure the report to s how experimental and fitted data, SDs and errors for any streams. (See the s ection Using the Reporting Featur e 226 for more information on the this feature).

Plotting Graphs of the Model Fitting

The graphs presenting model fitting results are once a gain, of stream data. They involve experimental (raw) data, and predicted (fitted) data. The graphs are configured on the Configurable Graphingwindow, which is opened by pressing

Results

the Config Graphb utton (


).

Step 1

Left-click on the Config Graph button on the main JKSimMet toolbar to bring the Configurable Graphingwindow into view.

Step 2

For this exe rcise, you will create a new graph so click on the New button (circled in screen grab below). Note that the default setting for the graphing facility will normally have some data pre-selected, so at this point you can either adjust the settings for this graph or else create a new one.

Step 3

When you click on the New but ton, a dialog will open where you can type in a n ame for your graph and a lso specify the type of graph you require. For the type there are only the two options; Equipment or Stream. In this case we will create a graph showing the new feed plus the cyclone products.

Step 4

Move the cursor t o the top row (w here the row heading is Stream).


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289

When you click on this cell, (which s hould initially contain the word "None"), a drop-down list will appear with all the available streams from your flowsheet. Select Cyclone Feed from this drop-down.

Once you have selected the stream, you will find that all of the previously grey cells below the stream selection cell will now be white and editable. In fact they all contain drop-down lists through which you can select the typ e of data to be plot ted and also set up the characteristics of the display for this data s et.


Step 5

Select Cum% Passing from the drop-down list in the Format cell, immediately belo w the cell for stream selection. Leave the Display cell on the default of Show. The option of Hide is available to provide you with the ability to temporarily remove a ny of the data sets you have configured for plotting on the current graph.

Step 6

The cell in the Data row allows you to select indiv idual data types or combinations of data types. Select Exp & Fit from the drop-down lis t to compare your fitted results with the experimental data.

Step 7

Leave the display cha racteristics of Line, Point and Colour at their default settings.

Step 8

You can then s elect Cyc U/F for the next column and Cyc O/F for the third column.


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Step 9

Note that when you hav e multiple columns set up, you can set all the Format and Data fields to the same values using the drop-down lists immediately above the tabulated data.

Step 10

Once the columns of the gri d have been set up, you can view the graph by simply switching from the Stream tab to the Graph tab.


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7.5.10 Problems Related to Model Fitting and Possible Solutions There are of course many probl ems that may be encount ered during model fitting. It is poss ible, however, to point out some of the more common mistakes, so that you are aware of them. Errors, Warnings, Faults

Some problems detected by JKSimMet will produce error messa ges. Generally these error messages will have a description of the problem that has occurred.

Skill versus Practice

Model fit ting is not a cut and dried procedure. The only way to acquire a useful skill level is to practice on a wide range of real da ta. JKSimMet offers a user-friendly environment for what are really very complex and powerful mathematical techniques.

Initial Parameter Estimates

As with all non-linear least squares programs, Model Fitting is sensiti ve to initial parameter estimates. The default values and the supplementary information provide a useful guide. However, trial and error may be necessary to find the best estimates to use with a new circuit or new data.

Graphical Analysis

The graph capability of JKSimMet is the most powerful way to examine your data fit. Discont inuities in size distrib utions highlight poor data or a change in measurement technique. Graphical analysis also highlights any bias in the data fit.

Different Size Measurement Techniques

Be very careful of changes in size measurement technique, such as from s ieves to Cyclosizer.

No Apparent Progress

When nothing much seems to be happening in model fitting, a simple fir st check is to ensur e that yo u have a reasonab le Maximum Number of Steps setting, and that the stre ams and para meters that you intend to include in the fitting are select ed with a tick in the Parameters section of the Model Fitting window.

Data

Note that it is necessary to have as much feed and product data a s pos sible for each of the unit Mode ls to be tuned. Simulat ion requires only feed data, but fitting must have some product data as well.

Not Enough Data

Even when you have the necessary data to perform model fitting, it is essential



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to ensur e that the re are enough readings to be useful for fitting; in general terms, the more data the better. SDs and Emphasis

The SD settings in the stre am data window may be set s o that they can cause such an over-emphasis on one parameter that the potential of the fitting is compromised. Always try to make the SDs as good an estimate as possible.

Scale Factors

The Scale Factor in the Parame ters section of the Model-Fit window can also be a source of pr oblems. If the scal e factor is too big the fitting may stop, because any adjustme nt in the paramete r produces such a la rge change that it steps over the minimum of the the sumfitting of squares. On the other hand, however, if the scal e factor is too small, may stop because any adjustment produces a chan ge of so small a scal e as to be judged insignificant, even though you may not be close to a minimum point . So, be very careful with scale factors. A s a guide, perhaps a scale factor one-tenth of the magnitude of the parameter estimate would be a reasonable place to start.

Parameter Problems

The last chapter 294 contains model descriptions, default values and a section on fitting for each specific model. The comm ents contained in these sections may help to ove rcome any misunderstandings or other problems you may have with the model parameters.

Large Weighted Errors

Examine the weighted errors carefully. These often indicate suspicio us data points. A typical exampl e is a screen top size that contains s everal times the predicted weight, because the laboratory scree n s tack did not extend to a large enough top size. Set the error to missing for this fraction to fix the problem.

Knot Positions

Where spline functio ns are used, the knot v alues can usually be fitted, but not the knot positions. These models provi de a fairly smooth response because of the use of s pline functions. A simple guide to knot positioning is that knots should be selected wherever a bend is needed. After all, the spline function is a mathematical model of a draftsman’s spline curve - a thin s trip of steel with screw p ositions which a re equivalent to spline knots.

7.5.11 References GY, P.M., 1982. Sampling of Parti culate Materials: Theory and Practice, 2n d Ed. Elsevier, Amsterdam. LYMAN, G.J., 1986. Application of Gy's Sampling Theory to Coal, International Journal of Miner al Processing, 17, p p 12 2. LYNCH, A.J., 197 7. Mineral Crushing and Grinding Circuits, (Elsevier, Amsterdam). NAPIER-MUNN, T.J., MORRELL, S., MORRISON, R.D., & KOJOVIC, T. 1996 . Mineral Comminution Circuits – Their Operation and Optimisation. JKMRC Monograph Series in Mining and Mineral Processing 2. Series Editor T.J. Napier-Munn, Julius Kruttschnit t Mineral Research Centre, University of Queensland.



Part

VIII

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Model Descriptions In this chapter, detai ls are prov ided for a ll of the models that are availabl e in JKSimMet. The models are grouped and described under the major plant section headings. This chapter contains: •

A description of each model available in JKSimMet

•

Instructions for the use of each model

•

Key equations that constit ute the mathematical basis of the m odels

•

A list defining the symbols used in the model equations

•

Any known limitations and restrictions

•

Any relevant references where the user could go for further information

•

Typical model parameter values, where appropriate.

There are a number of generic models included in JKSimMet which can be used to describ e the behavio ur of a wide range of processes. For example the mass re-all ocation model can be used to describ e any sort of device in which the ore feed properties are changed, such as a reagent additio n point or a ball mill. Selection of parameters for these models will depend entirely on the type of process being modelled. Most of the process units available to the user when drawing the flowsheet can be described by a number of models. Typically, a process unit will have a specific model, developed for that particular device, and a number of generic models. Selection of the appropriate model is at the user’s discretion and will often depend on the available test data.

8.1

Ge ne ra l Mod els General Models

This topic contains a description of all the g eneral process models available in JKSimMet that do not fit in one of the more specific process type category headings below. The splitter models described here provide splitters of varying complexity, from a simple mass split into two product s (810) or into three product s (870), independent mass splits of solids and water (811) and a split generating a specific volume flow rate to one of the products (812).

8.1.1

Ore Feed er (1300) Ore Feeder

The ore feeder (called Feed) is a specialized piece of equipment that has a single product. The feed unit allows you to set up the flowsheet ore SG and the starting size distribution. The size m arkers, i.e. the percent passing a particular size and the size at a particular percent passing, can be set by double clicking on those fields in the Totals tab. Note that while the f lowsheet properties dialog allows you to set global properties for Data Information blocks and for the tools such as Simulation and Model Fit, these properties for the feeder and ports may be set at different values for each.


Model Descriptions

8.1.2

Water Feeder Models (1251 & 1252) Water Feed er Models

8.1.2.1

295

This topic contains a description of the Water Feeder models available.

Model Description - General Equipment

The Water Feeder is specialized equipment that is the source of water additions to a flowsheet. The Water Fee der is characte rized by the fact that it has no feed streams and one product stream that is made up of water only. The Liqu id Feeder replaces the "Unit Feed Density " section of each model in JKSimMet Version 4. The three models provided with the Liquid Feeder are functionally identical to the three options for "Unit Feed Densi ty". The functioning of these models is described below. There are two ways in which the Water Feeder can be defined: 1.

Water Feeder – Required % Solids – Standard.

2.

Water Feeder – Water Addition – Standard.

These model choices are only available for the Water Feeder equipment. After opening the Equipment window for the Water Feeder equipment, click on the Equipment model drop down list to access these choices. Then click on the double arr ow button to the right of the drop down list to open the model window pertaining to the selected model. 8.1.2.2

Requir ed % Solids - Standar d Model Model Overview

The Water Feeder – Required % Solids – Standard model is used when wa ter is to be added so that the stre am perc ent solids feeding a piece of equipment equals that specified by the user. This option allows the user to set a maximum % solids for the total feed to the connected equipment. If the feed % solids is higher than the "Required % Solids" then the liquid feeder adds additional liquid to achieve the required % solids. If the % solids value is already lower than required, the liquid feeder adds no liquid. It does NOT remove liquid to achieve the required value.

Model Data Input

Double click on the appropriate field in the table and type in the required value for the parameter: •

Required Percent Solids (%)

During simulation, JKSimMet calculates: •

New Water Addition (m3/h)

such that the percent solids of the combined streams flowing into the equipment to which the water is added, equals that specified by the user. The other valu es in the table a re a lso calculat ed by JKSimMet during simulation and relate to the combined stream that flows into the equipment:


•

Solids Flow (tph)

•

Water Flow (m3/h)

•

Percent Solids (%) General Models

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•

Volume (m3/h)

If during simulation the new wa ter addition ca lculated by JKSimMet would be negative, the new water addition value will be set to zero. A typical Required % Solids tab for the Water Feeder is shown below.

Water Fee der – a typical Required % Solids – Standard tab 8.1.2.3

Water Addition - Standard Model Model Overview

The Wat er Fe eder – Water Addition – Standard model is used when a user defined volume of water is to be added. Liquid Addition is the recommended mode for comm on use. The user s pecifies the required liquid addition rate in cubic metres per hour. This option ha s two more uses. The experi mental liquid additi on may be used as a parameter in model fitting. That is, a model f it may use liquid addition as a parameter when liquid flows were not measured or the measurement was dubious. The "exp Liquid Addition" is subject to optional update after the model fit, as are all other parameters. Note that % solids or water flo w from the circuit should be constr ained by a small SD value to provide a constraint on total water addition. The third use of this option is for mass balancing of liquid additions. The user prov ides the "exp New Liquid Add ition" and an SD estimate for this model. The other requirement is that the Liquid Feeder and Liquid are selected on the Select Tab of t he Mass Balance Tool. The balanced liquid addit ion is returned to the Calc* field of the Liquid Feeder. If you wish to use this value for fitting or simulation, copy it into the appropriate Exp value.

Model Data

General Models

Double click on the appropr iate field in the table and type in the required value Version 6.0.1 - March 2014

Model Descriptions

Input

297

for the parameter: •

New Water Addition (m3/h)

The other values in the table are calculated by JKSimMet during simulation a nd relate to the com bined stream that f lows into the equipment unit to which the water is added: •

Solids Flow (tph)

•

Water Flow (m3/h)

•

Percent Solids (%)

•

Volume (m3/h)

A typical Water Addition tab for the Water Feeder is shown below.

Water Feede r – a typical Water Addition – Standard tab 8.1.2.4

Model Limi tation s

Two Water Feeders with the Required % Solids – Standard model selected cannot be used to add wate r to a single wat er addition point on a flowsheet. This is because the Required % Solids model calculate s the volumetric flow of water to be added by taking into account the percent solids of all of the streams that com bine to flow into the equipment to which the water is added. If there are two Water Feeders with the Required % Solids mo del adding water to one equipment item, the amount of wat er a dded by each water feeder to obtain the required percent solids of the combined equipment feed cannot be calculated. 8.1.2.5

Referen ces

No relevant references.


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298

8.1.3

JKSimMet V6 Manual

Hydrocyclone Models (200, 201) Hydrocyclone Models (200 and 201)

8.1.3.1

This topic contains a description of t he Hydrocyclone models 200 and 2 01.

Desciption

The model is based on the concept of a reduced efficiency curve, which in turn is developed from the actual efficiency curve and the corrected efficiency curve for the classifi er treating a particul ar ore. The important concept is that the reduced efficiency curve is a characteristic function of an ore and is independent of the dimension or operating cond itions of the cyclone. A typical s et of efficiency curve s for a cyclone is shown in the first figure 298 of the next section. The mo del consists of a series of equations which are descr ibed bel ow. At least one cycl one test on a particular ore is required to provide data for the calculation of constants in the equations. 8.1.3.2

Equations

The model consists of a series of equatio ns, which are described be low. Pressure Throughput Relationship

The pressure-throughput relat ionship can be expressed as: Q = KQ2 Dc2 (P/ p)0.5 (Do/Dc)0.68

(M200.1)

where KQ2 = KQ1 (Di/Dc)0.45 ( )-0.1 (Lc/Dc)0.2 The proportionality constant, K

Q1

(M200.2)

, is a function of the fee d material and the

diameter of the cyclone. For cyclones of Krebs design, treating identical feed solids, the dependence on cyclone diameter may be empirically represented by the equation KQ1 = KQ0 Dc-0.1

(M200.3)

where KQ0 depends on feed solids characteristics (eg. specific gravity) only. Classification Size Relationship

For normal industri al operation, the classifi cation size can be relat ed to the variables according to the equation d50c /Dc = KD2 (Do/Dc)0.52 (Du/Dc)-0.47

0.93

(P/{

p

g Dc})-0.22

(M20 0.4)

where KD2 is related to the minor design variables D i, Lc and q by KD2 = KD1 (Di/Dc)-0.5 (Lc/Dc)0.2 ( )0.15

(M200 .5)

and K D1 may be written as KD1 = KD0 (Dc)-0.65

General Models

(M200


Model Descriptions

299

.6) KD0 depends on feed solids characteristics only (such as size distribution and specific gravity). (Note that the classification sizes for specific minerals within the feed stream can be estimated using the following formula:

where FeedSG is the mean feed solids density, d 50c is the overall corrected d 50 , MineralSG is the density of the specific mineral of interest, and d 50c (m) is the corrected d50 of the mineral of in terest.) Recovery to Underflow Relationships

Water recovery (Rf) and volume pulp recovery (R v) to un derflow are related to the major variables by: Rf = Kw2 (Do/Dc)-1.19 (Du/Dc)2.40 (P/{

p

g Dc})-0.53 ( )0.27

(M200.7)

p

g Dc})-0.31

(M200.8)

and Rv= Kv2 (Do/Dc)-0.94 (Du/Dc)1.83 (P/{

Further, the effects of inlet diameter, cone angle and cylinder length have been evaluated as Kw2 = Kw1 (Di /Dc)-0.50 ( )-0.24 (Lc/Dc)0.22

(M200.9)

and Kv2 = Kv1 (Di/Dc)-0.25 ( )-0.24 (Lc/Dc)0.22

(M200.10 )

Here Kw1 and K v1 are constants also depe nding on feed solids c haracteristics. The current data indicate that K

w1

a nd Kv1 ar e independent of cyclone

diameter for geometrically similar cyclones treating identical feed solids. Small quantities of viscosity modifiers such as clay, can have a marked effect on these variables. Efficiency Curve Relationship

The efficiency curve used in this model is given below: Eo(d/d50c ) =

(M200. 11)

C.(1+ . *.d/d50c ) (exp( ) - 1)/(exp( . *d/d 50c ) + exp( ) - 2) When is 0, * is 1 the above equation reduces to Eo(d/d50c ) = C.(exp( ) - 1)/(exp( .d/d 50c )+exp( )-2)

(M200.12)

The shape p arameter determines the initial rise, while determines the slope at lar ger values of d (d d 50c ). Bot h and are normally constant for given feed solids, while C and d

50c

vary with cyclone dimensi ons

and

operating conditions. The parameter * is determined, for given values of and , by the condition that


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EoC/2 .(1) =

(M200.13)

* is calculated iteratively in the model. The first two figures below sh ow the effects of efficiency curve. Modified Efficiency Curve

and

on the shape o f the

An alternative to the standard efficiency curve is available with the Nageswararao Fines hydrocyclone model. With this model the user can specify the value of the reduced efficiency curve (ie. fraction reporting to overflow) at 33% and 66% of the d 50c size. The cur ve is fix ed (by definition) at the 100% point for zero size and at the d50c . A cubic spline curve is used to desc ribe the ef ficiency curve for sizes below the d 50c point. For sizes larger t han the d

50

, a log-normal distribution

curve is used. The log-normal curve is determined so that there is no discontinuity in slope at the d 50c point. The third figure below shows h ow the modified efficiency curve works. The user needs to specify (or model fit) the values of the curve at 33% and 66% of the curve only. The other parameters used by the mod el are used in the same way as the standard Na geswararao model . The Nageswararao-Fines mode l is useful for describing a symmetric efficiency curves where a long 'tail' exists for either coarse or fine material. Interactions Scaling

The interactions of variables within a cyclone are com plex. Refer to Summary Table 305 section for a summary of interaction dependencies. Facilities for scal ing the operation of the hydrocyclone are built into the model.

Figure M200 .1 - Effect of Alpha on Reduced Efficiency Curve

General Models


Model Descriptions

301

Figure M200 .2 - Effect of Beta on Reduce d Efficiency Curve

Figure M200.3 - Efficiency Curve for Nageswararao-Fines Model 8.1.3.3

Symbo ls

Symbols

Symbol

Meaning

reduced efficiency curve s harpnes s parameter reduced efficiency curve h ook parameter *


reduced efficiency curve calculated parameter

C

R 100 -

f or recovery of water to overflow, %

Dc

cyclon e diameter, m

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Di

diameter of circle with the same area as cyclon e inlet, m

Do

diameter of circle with the same area as vortex finder, m

Du

diameter of circle with the same area as spigot, m

E (d) o

percentage of feed material of size d reporting to overflow

g

gravitationalacceleration

KD

cons tant in the classification s ize relations hip

KQ

cons tant in the volume pulp recovery relati ons hip

Kv


Kw

cons tant in the water recovery relations hip

L c

length of cylindrical section, m

P

feedpressureatinlet,kPa

Q

3 cyclone throughput, m /hr

R f

recovery of water to underflow, %

Rv

volumetric recovery of feed pulp to underflow, %

d

meansizeofparticle,mm

d50c

size of a particle in feed which has equal probabi lity of going to underflow or overflow, due to centrifugal action, mm

Cv

volumetric fraction of so lids in feed slurry Cv

p

Cv

density of feed pulp, tonnes/m 3 cone full angle, degrees

8.1.3.4

Restrictions

Restrictions

As the feed becomes coarser, d 50c tends to decrease eve n when all the other variables are kept constant. The effect of size distribution of the feed material becomes insignificant when the feed consi sts of mainly –53 mm particles, and also when the pro portion of –53 mm par ticles is less than 25% of the feed solids. The ana lytical form used does not provide a perfect representation for the reduced efficiency curve. As a result the model often tends to predict fewer coarse particofles the overflow than tooccur in real operation, however, the magnitude theinerror is considered be small. Viscosity variations due to change s in pulp density are largely accounte d for by the model. Viscosi ty vari ations caused by variable quantities of slimes affect the parameters in quite a systematic way. As viscosity (or slimes fraction) increases, the cut size becomes coarser, the water split to overf low is reduced, and the cyclone pressure drop becomes larger. However, the reduced eff iciency curve rem ains relatively constant until the onset of roping.

General Models


Model Descriptions

303

The model may be used to estimate operation during roping: o

the cut size will become 5 to 10 times larger (ie. multiply K

D0

by 5 to 10

times o

the efficiency curve will become an “inefficiency” curve with an typically of 0.1 - 0.2.

value

o

water split and pressure drop are relative ly unaffected although a small drop in pressure is often claimed. This may result from a reduced volume of solids to overflow.

The onset of cyclone roping is difficult to predict. In general 50% solids by volume is a practical underflow limit. However, very coarse underflow may achieve higher density a nd finer ones somewhat lower density as detailed below. JKSimMet will warn you that roping is likely if either of the density limits (detailed below) are exceeded. Cyclone Roping Constraint

If the cyclone feed density is less than 35% solids by volume, the SPOC constraint (Laguitton 1985) is claimed to predict onset of roping. Vol % solids in U/F = Limiting Vol % solids (~56) + 0.2 (Vol % Solids in Feed 20) The limiting % solids is defined as the onset of roping at a volumetric feed density of 20%. In tabular form: Table M2 00.1 - Cyclone Roping Conditions

atsg2.7 Feed Density

Underflo w Density

%byVolume

Empirical Constraint

Feed Density

atsg4.0 Underflo w Density

%byWeight

Feed Density

Underflow Density

%byWeight

5

53

12.4

75.3

17.4

81.8

10

54

23.1

76.0

30.8

82.4

15

55

32.3

76.7

41.4

83.0

20

56

40.3

77.5

50.0

83.6

25

57

47.4

78.2

57.1

84.1

30

58

53.6

78.8

63.1

84.7

35

59

59.2

79.5

68.3

85.2

Industrial experience demonstrates that a coarse underflow will remain in spray discharge at a higher density than a fine underflow. This is intuitively reasonable in terms of slurry viscosity but difficult to predict. Plitt et al (1987) have developed an empirical relationship based on Lynch (1965) data an d others.


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Vol % Solids in U/F = 62.3 * This appro ach puts a 50% solids by volu me limit on an underflow with 50% passing 100 µm and 60% at a P50 of around 200 µm. This functio n decreases sharp ly with size dro pping t o 45% solids by vol ume at a P50 of 80 µm and 40% at a P50 of 60 µm. In tabular form: Table M20 0.2 - Cyclone Roping Conditions - Accounting for Coarsen ess

Roping onset

Underflow

% Solids

% Solids

% Solids by Vol.

50% passing (mm)

at sg 2.7

at sg 4.0

35.2

50

59.4

68.5

39.0

60

63.3

71.9

45.9

80

69.6

77.2

50.5

100

73.4

80.3

53.9

120

75.9

82.4

58.6

170

79.3

85.0

60.0

200

80.2

85.7

61.3

250

81.0

86.4

The two effects are probably competitive to some degree. Further, each operation has a 'comfort limit' on cyclone underflow density which may be a good deal lower than the above limits.

General Models


Model Descriptions

8.1.3.5

305

Pri ntouts Nageswararao (Model 200)

Nageswararao Fines (Model 201)

8.1.3.6

Summar y

Summary of the Effects of Variables on Cyclone Operation


Table M200.3 - Effects of Variables on Cyclone Operation Variable Increased

Resultant Effect on Parameter Q

d

50c

R f

R v

Dc

increase (0.57)

increase (0.82)

decrease (-0.4)

decrease (-0.55)

Di

increase (0.45)

decrease (0.5)

decrease (-0.5)

decrease (-0.25)

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JKSimMet V6 Manual

Do

increase (0.68)

increase (0.52)

decrease (-1/19)

Du

-

decrease(-0.47)

increase(2.4)

increase(1.83)

Lc

increase (0.2)

increase (0.2)

increase (0.22)

increase (0.22)

p

increase (0.5)

decrease (-0.22)

decrease (-0.53)

decrease (-0.31)

-

increase(0.93)

increase(0.27)

decrease (-0.5)

increase (0.22)

increase (0.53)

increase (0.31)

decrease ( -0.1)

increase ( 0.15)

decrease ( -0.24)

decrease ( -0.24)

p

decrease (-0.94)

-

Note: The numbers listed in brackets are exponents for dependence of the parameter on the variable. Examples of the effects of and on reduced efficiency curves are given in the figures in the Model Equations 298 topic. The * parameters used in the model are calculated. 8.1.3.7

Fitting the Cyclone Model (200)

Parameter Menu

Pressure Data

If you wish to predict cyclone pressure accurately at other conditions you will need at least one accurate pressure measurement and a set of at least two out of three of the feed, underflow an d overflow samples. If pressure data are not available, an approxi mate pressure can be estimated from the manufacturers published data. The calcul ated pressure is used in the equ ations for classi fication size and recovery to underflow. Hence, the cyclone pressu re is an important measurement. The measured or as sumed pressure data must be entered on the Performance Data tab o f the cyclone equipment data window. If an accuracy esti mate is available, use it to calcul ate the standa rd dev iation. If not, use 10% of the pressure value. The capacity constant K

QO

can be calculate d from the cyclone flow rate and

the cyclone dimensions. (Refer to equations M200.1-M200.3). Typical values of K QO are in the range 300-600. The scale f actor for fitting should be 100. To make the pressure obser vation available to the fitting calculat ion, it must be selected with a tick on the Equi pment Data tab of the Model Fit dialogue window Classification Size (KDO)

General Models

Equations M200.4 to M200. 6 define the cut size. K

DO

is typically a small

number - say 0.001 to .00001. Therefore, a scale fac tor of 0.0001 is usual ly suitable.


Model Descriptions

Water Split % to O/F (Cal WS)

307

The actual water split to overflow (Cal WS) is fitted rather than the two parameters, KV1 and K W1, which a re defined by a sin gle water split. When model fitting a single set of cy clone data, ALWAYS fit Cal WS. A good starting point is 50% with a scale factor of 5. After fitting, the calculated values of K V1 a nd KW1 ar e displayed on the cyclone equipment data window (Model Parameters tab).

Efficiency Curve

The reduced efficiency curve is an "S" s haped function as shown in the figure

( a nd )

in the Model Equations topic. Typical values of range from 0.5 to 4. Beyond 5, the efficiency curves become very sharp and la rger numbers are not significant. A good initial estimate is 2.0.

298

The factor modifies the "S" curve to add an additional "hook" - or a negative portion to the actual ef ficiency cur ve. A typical value is zero. However, a poor fit at fine sizes can be tested by trying values of of 0.01 to 0.5. Fitting of is avail able but not recommended. A s cale facto r of 0.1 is suitable once a good initial estimate has been found by trial. If the efficiency curv e is a poor fit at coarse sizes, try the alternative fines modified or spline efficiency curve models. Master/Slave Fitting

Multiple sets of cyclone data can be model-fitted using the Master/Slave facility, wit h one impo rtant provision. The wate r split (Cal WS) canno t be fitted using Master/Slave fitting. Fit KD0 , KQ0 ,

and Cal WS for each data set independently, and determine the

average values of KV1 and K W1 for each cyclone data set from the fit. Use the average values of KV1 and K W1 in each cyclone data set. Use Maste r/Slave to fit KD0 , KQ0 , 8.1.3.8

and (if required) , over all data sets.

Fitting the Nageswararao Fines Model (201)

Parameter Menu

The comments in the topic above apply equally to Model 2 01 except for the Efficiency Curve parameters a and b which are replaced by Eff @ 0.33 (of d50c) and Eff @ 0.66 (of d50c). Typical values are 0.85 and 0 .65 respectively. 8.1.3.9

Referen ces

DE KOOK, S.K., 195 6, Symposium on recent developments in the use of hydrocyclones - a review J. Chem. Metal. Min. Soc. S.Afr., Vol. 56:281-294. KAVETSKY, A., 197 9. Hydrocyclone modelling and scalin g. JKMRC report to AMIRA, November.


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KELSALL, D.F., 1953. A further study of the hydraulic cyclone. Chem. Eng., Sci., Vol. 2:254 -273. LAGUITTON, D. (Ed), 198 5. The SPOC Manual Simulated Proce ssin g of Ore and Coal, CANMET EMR Canada, Ch. 5.1 (Part B). LYNCH, A.J. 196 5. The characteristics of hydrocyclones and their a pplication as control units in comminution circuits, AMIRA Progress Report No. 6, University of Queensland (unpublished). LYNCH, A.J. and RAO, T.C., 1965.

Digital computer simulation of

comminution systems. Proc. 8th Comm. Min. Metall. Congr., Aust., N.Z., Vol. 6:597-606. NAGESWARARAO, K., 1978. Further developments in the modelling and scale-up of industrial hydro cyclones. Ph.D. Thesis (unpublished). University of Queensland. PLITT, L.R., FLINTOFF, B.C. and STUFFCO T.J., 1987. Roping in hydrocyclones. 3rd International Confe rence on Hydrocyclones, Oxford England, Elseveir, pp21 -23. YOSHIOKA, N. and HOTTA, Y., 1955. Liquid cyclone as a hydraulic class ifier. Chem. Eng. Jpn., Vol. 19:63 2-640.

8.1.4

Narasimha-Mainza Cyclone Model (221)

8.1.4.1

Description

Like the Nagesw ararao model, the Narasimha-Mainza model is based on the concept of a reduced efficiency curve, which in turn is developed from the actual efficiency curv e and the corre cted efficiency curv e for the classifi er treating a particular ore. The model consists of a ser ies of equations wh ich a re described below. At least one cyclone test on a particular ore is required to provide data for the calculation of constants in the equations. The form of the equations was given by Na rasimha (2009). The exponents differ slightly from those reported in his thesis, as the mode l has since been refitted with a la rger data s et. 8.1.4.2

Equat ion s

The model consists of a series of equatio ns which are described below. Pressure Throughput Relationship

General Models

The pressure-throughput relat ionship can be expressed as:


Model Descriptions

309

( M 2 2 1 . 1 )

where (M221.1)

The proportionality constant , K Q0 , is a function of the feed material and depends on feed solids characteristics (e.g. specific gravity) only. fv is the volume concentration of solids in the feed.

Classification

For normal industri al operation, the classifi cation size can be relat ed to the

Size Relationship

variables according to the equation (M22 1.3)

where:


and:

(M22 1.4)

f38 is the mass percentage of -38µm particles in the feed.

(M22 1.5)

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Recovery to Underflow Relationships

Water recovery (Rf) to underflow is related to the major variables by:

where:

and:

Efficiency Curve Relationship

The efficiency curve used in this model is identical to that used in the Nageswararao model ( equations M200.11, M200.12 and M 200.13 ), but with the

General Models

given by:


Model Descriptions

8.1.4.3

311

Symbo ls

Symbols

Symbol

Meaning

reduced efficiency curve s harpnes s parameter reduced efficiency curve h ook parameter *

R 100 -

d

meansizeofparticle,mm

d50c

size of a particle in feed which has equal probability of going

D c



C

f

or recovery of water to overflow, %

underflow or overflow, due to centrifugal action, mm cyclon e diameter, m

D i

diameter of circle with the same area as cyclon e inlet, m

D o

diameter of circle with the same area as vortex finder, m

Du

diameter of circle with the same area as spigot, m

E (d) o

percentage of feed material of size d reporting to overflow

f38

mass percentage of -38 µm particles in the feed

g

gravitationalacceleration

i

angle of inclination of the cyclone, degrees

Kd0

cons tant in the classification s ize relations hip

KQ0


K 0

cons tant in the

K w0

cons tant in the water recovery relations hip

Lc

length of cylindrical section, m

relationsh ip

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P

feedpressureatinlet,kPa

Q

cyclone throughput, m 3/hr

Re

ReynoldsNumber

f p s R

f

dens ity of feed fluid, tonnes /m3 density of feed pulp, tonnes/m

3

density of feed solids, tonnes/m

3

recovery of water to underflow, % cone full angle, degrees

Vi 8.1.4.4

inlet velocity

Pri ntout NarashimaMainza (Model 221)

General Models


Model Descriptions

8.1.4.5

313

Restrictions

Restrictions

· For the Nageswararao model, as the feed becomes coarse r, d tends to 50c decrease even when all the other variables are kept constant. The effect of size distribution of the feed material becomes insignificant when the feed consists of mainly –53 mm particles, and als o when the proport ion of – 53 mm particles is less than 25% of the feed solids. For the Narasim ha/Mainza model, it is not know n if this effect exist s. However, it is likely that there is still a feed size effect on d . 50c · The anal ytic fo rm use d does not provide a perfect representation for the reduced efficiency curve. As a result the model ofte n tends to predict fewer coarse part icles in the overflow than occur in real operation, however, the magnitude of the error is considered to be small. · Viscosi ty variations due to cha nges in pulp density are larg ely accounted for by the model. Viscosi ty var iations caused by vari able quantities of slimes are also accounted for by the model. · The model may be used to estimate operation during roping: –

the cut size will become 5 to 10 times larger (i.e. multiply K

D0

by 5 to 10

times – the efficiency curve will become an “inef ficiency” curve with an a val ue typically of 0.1 - 0.2. – water split and pressure drop are relatively unaffected although a small drop in pressure is often claimed. This may result from a reduce d volume of solids to overflow. · The onset of cyclone roping is difficult to predict. In general 50% solids by volume is a practical underflow limit for vertically mounted hydrocyclones. However, very coarse underflow may achieve higher density and finer ones somewhat lo wer density as detailed b elow. The Narasimha/Mainza model does incorporate t he effect of angle of inclination and this will affect the roping point. JKSimMet will warn you tha t roping is likely if either of the density limits (detailed below) are exceeded.

Cyclone Roping Constraint

For vertically mounted hydrocyclones, if the cyclone feed density is less than 35% solids by volume, the SPOC constraint (Laguitt on 19 85) is claimed to predict onset of roping. The effect of angle of inclination incorporated in the model is NOT included in this prediction of roping. Vol % solids in U/F = Lim iting Vol % solids (~56) + 0.2 (Vol % Solids in Feed -20) The limit ing % solids is defined as the onset of roping at a volumetric feed density of 20%. In tabular form: atsg2.7


atsg4.0

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Feed Den sity

Underf low Densit y

%byVolume

Empirical Constraint

Feed Densit y

Underfl ow Density

%byWeight

Feed Densit y

Underf low Densit y

%byWeight

5

53

12.4

75.3

17.4

81.8

10

54

23.1

76.0

30.8

82.4

15

55

32.3

76.7

41.4

83.0

20 25

56 57

40.3 47.4

77.5 78.2

50.0 57.1

83.6 84.1

30

58

53.6

78.8

63.1

84.7

35

59

59.2

79.5

68.3

85.2

Industrial experience demonstrates that a coarse underf low will remain in spray discharge at a higher density than a fine underflow. This is intuitively reasonable in terms of slurry viscosity but difficult to predict. The effect of angle of inclination incorporated in the model is NOT included in this prediction of roping. Plitt et al (1987) ha ve developed an empirical relationship based on Lynch (1965) data and others.

Vol % Solids in U/F = 62.3 This a pproach puts a 50% s olids by volume limit on an underflow with 5 0% passing 100 µm and 60% at a P50 of around 200 µm. This function decreases sharply with siz e dropping to 45% s olids by volume at a P50 of 8 0 µm and 4 0% at a P50 of 60 µm. In tabular form:

The two effects are probably competitive to some degree. Further, each operation has a 'comfort limit' on cyclone underflow density which may be a good deal lower than the above limits.

General Models


Model Descriptions

8.1.4.6

315

Co mp aris on wit h Na ges

In preparing the Narasimha/Mainza model for inclusion in JKSimMet, JKTech has conducted a series of comparisons with the older Na geswararao model. In most cases, the response s to changes in operating variables are similar between the two models. However, the effect of D on d is quite i 50c different. The reason for the difference is that in Narasimha/Mainza, the major effect of on D on d is in the calculati on of Reynolds Number (Re) i 50c which depends on inlet velocity (Vi) which depends in turn on D . i Nageswararao does not consid er Re, the eff ect of which is very strong in

wa rar ao

Narasimha/Mainz a a nd outweighs the direct ef fect of Di which is s imilar in both models. The valid ity of this major change in response is currently being investigated by CFD modelling.

Summar y

Summa ry of the effects of variable s on cyclone operatio n

Examples of the effects of a and b on reduced efficiency cur ves are given in the attached Figures A2.1 and A2.2. The b* parameters used in the model are calculated. 8.1.4.7

Fitting the Cyclone Model 221

Parameter Menu


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JKSimMet V6 Manual

Pressure Data

If you wish to predict cyclone pressure accurately at other conditions you will need at least one accurate pressure measurement and a set of at least two out of three of the feed, underflow an d overflow samples. If pressure data are not available, an approxi mate pressure can be estimated from the manufacturers published data. The measur ed or assumed pressur e data must be entered on the Performance Data tab of the cycl one equ ipment data window. If an accuracy estimate is available, use it to calc ulate the standar d deviation. If not, use 10% of the pressure value. The capacity constant K

can be calcula ted from the cyclone flow rate a nd the Q0 cyclone dimensions. (Refer to equations A2.14-A2.15). Typical values of K

Q0

are in the r ange 100 - 600. The scale fact or for fitting

should be 100. To make the pressure obser vation available to the fit ting calculation, it must be selected with a tick on the Equipment Data tab of the Model Fit dialog window Classification Size (KDO)

Equations A2.16 to A2.18 def ine the cut size. K DO is typically a small numb er

Water Split % to U/F (KW0)

Equations A2.19 to A2.21 define the recovery of water to the underflo w. K

- say 0.001 to .05. Therefore, a scale factor o f 0.001 is usually suitable. W0 is typic ally –in the range 0.01 – 4.0. Therefore, a scale fact or of 1.0 is usually suitable. The mod el is particularly sensi tive to this parameter so it may be necessar y to try several different starting estimates for model fitting to be successful.

Efficiency Curve ( a nd )

The reduced efficiency curve is an "S" s haped function as shown in the figure M200.1. Equation M221 .9 defines the alpha pa rameter. Ka is typicall y –in the range 1 0 to 80. Therefore, a sca le factor of 1.0 is usually suitable. Typical val ues of a a range from 0.5 to 4. Beyond 5, the efficiency curves become very sharp and larger numbers are not significant. A good initial estimate is 2.0. a is ca lculated from Equation M221 .9. The b factor modifies the "S" curve to add an additional "hook" - or a negative portion to the actual efficiency curve. A typical value is z ero. However, a poor fit at fine sizes can be tested by tr ying val ues of b of 0.01 to 0.5. Fitting of b is available but not recommended. A scale fact or of 0.1 is suitable once a good initial estimate has been found by trial. If the efficiency curve is a poor fit at coarse sizes, try the alternative models.

Master/Slave Fitting

Multiple sets of cyclone data can be model-fitted using the Master/Slave facility. Use Master/Slave to fit K

D0

,K

Q0

,K

W0

K and (if required) b, over a ll da ta a0

sets.

General Models


Model Descriptions

8.1.4.8

317

Referen ces

LAGUITTON, D. (Ed), 1985. The SPOC Manual Simulated Processing of Ore and Coal, CANMET EMR Canada, Ch. 5.1 (Part B). NARASIMHA, M., 2009. Improved Computational And Empirical Models Of Hydrocyclones, PhD Thesis, University of Queensland (unpublished) PLITT, L.R., FLINTOFF, B.C. and STUFFCO T.J., 1987. Roping in hydrocyclones. 3rd International Conference on Hydrocyclones , Oxford England, Elseveir, pp21-23.

8.1.5

Screen Models (215, 230 & 235) Screen Models

8.1.5.1

This topic con tains a description of the various screening models.

Kavetsky Single Deck Screen Model (230)

Kavetsky Model

This topic contains a description of the Kavetsky Single Deck Screen model.

8.1.5.1.1 Model Description

Mechanist ically a screening process can be reg arded as a series of tri als, as a result of which parti cles of a particular s ize have a probability of entering the fine produ ct. This conce pt of defining the screening efficiency in terms of a number of trials (or bounces) is the basis for a screen model. A typical efficiency curv e for a vibrating screen is shown in the figur e below. There are three regions on the curve:

A Typical Efficiency Curve for a Vibrating Screen

the region describing the above-aperture size material (region A),


General Models

318

JKSimMet V6 Manual

the region describ ing the belo w but near aperture size material in which the probability of pas sing through the aperture is directly dependent on particle size (region B), the region describing the ultr a-fines that a dhere to the coa rse particles (region C). Region B of the eff iciency curve is the important region for modelling purposes, and it ca n be described by the equation (Whit en and White 1977). E(x) = exp[-TRN.fo.(1-x/d)k]

(A3.1)

where E(x) is the fraction of particles in the feed of s ize x which enter the coarse product, d is the screen aperture; fo the fraction open area, TRN is the efficiency parameter and k is a minor parameter used for precise fitting purposes. Typically, the value of k is about 2. The performance of the screen in region C can only be determined experimentally since it will be dependent on local conditions such as the moist ure conte nt of the ore which causes small particle s to adhe re to large particles. For design purposes it is necessar y to make a reasonable ass umption about the sha pe of the curve in region C and this ass umption is made by the design engineer based on knowledge of local conditions. The typical depende nce of the efficiency parameter, TRN, which is analogous to the number of trial s, on the feed rate is shown in the figure below for different materials used for the screen deck.

The depe ndence of the screen efficiency parame ters on the feed rate for rubber and steel decks

The expl anati on of the abo ve fig ure is that when the fee d rate to screens with rubber decks is low the particles move independently, accumulate energy, take large bounces and have little opportunity to pass through the screen aperture. An increase in fee d rate causes an increase in inter-particle collisions, reduction in particle energy and bounce lengths, and an increase in number of trials. Hence, the scre en efficiency incre ases. A further increase in feed rate causes more particle interference, a decrease in the number of trials due to particles n ot

General Models


Model Descriptions

319

reaching the screen s urface, and a decrease in screening efficiency. With steel screens, however, the coefficient of restitution is low a nd particles do not accumulate energy. Particle bounces are small and high efficiencies occur at low feed rates. As the feed rate increases the in ter-particle interf erence increases and this reduces the number of trials and the screening efficiency. A better underst anding is required of the relationship between particle shape, aperture shape and screen efficiency, a nd also of screening performance in the difficult area between dry and wet screening. The first is a problem of

Model Limitations

optimization of existing s creens, the s econd is a problem of plant operation. 8.1.5.1.2 Model Equations

Region B of the screen efficiency curve

317

318 is described by equation A3.1

E(x) exp = TRN (- P/T) *

.

(A3.2)

where P = fo*((1-fs) (1 - x/d)2 + fs*(1 - x /d))T

(A3.3)

and (W/L) - 1 = fs

(A3.4)

In region A 1.0 =E(x)

(A3.5)

In region C an adjustment is made using the submesh factor (SF). This adjustment the submesh material undersize stream to the submeshtransfers fract ionsome of theo foversize stream, that isintothe a ccount for the s mall particles that adhere to the larger ones. The important oper ating parameter is feed rate per unit screen width (FW) and this function is approximated by sev eral straight lines as shown in Figure A3.2. The number of trials TRN is related to operating parameters by a set of regression equations of the following form. Ln(TRN) = A + B * FW + U * P1 + V * P2

(A3.6)

FW < FW1 Ln(TRN) = C + D * FW + U * P1 + V * P2

(A3.7)

FW1 < FW < FW2 where C=A+(B-D)*FW1bycontinuity and

(A3.8)

Ln(TRN) = C + D * FW2 + U * P1 + V * P2

(A3.9)

FW > FW2 SF is also related to operating parameters by a regression equation PSF SF *F+ E = TSF G + * Fines Factor


(A3.10)

The fines facto r is used to describe the "piggyback" effect of fines on coarse

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320

JKSimMet V6 Manual

material. The material coarser than the "fine s critical size" is considered in terms of its notional surface area.

and SF* Area is the t/h of fines which are carried into the oversize product. Moisture Behaviour

For damp ore s, the behavio ur of moisture can be very important. There are sometimes several kinds of moisture. The only one of interest to this model is in the fines, that is , fractions finer than the "Moisture Split Crit ical Siz e XM". All of the feed moisture is assumed to be carried in material finer than this size. It is then allocated across the coar se and fine prod ucts in proportion with how the material finer than XM is a llocated.

Scaling

The model allows scaling of s creen length by linear s caling of the n umber of trials parameter, TRN. Scaling of screen width is a ccomplished within the normal mo del s tructure a s FW is feed rate per unit width. Aperture, fraction open area and slot shap e are also included as normal model parameters.

General Models


Model Descriptions

321

8.1.5.1.3 Single Deck Model Printout

8.1.5.1.4 Symbols


Sym bol

Mea ning

xi

size of particles in the ith s ize fraction

E(x)

fraction of particles in the feed of size x w hich enter the coarse product

X1, X2

lower and upper screen si zes at fraction being considered

X3

a critical size - if required - close to screen aperture. However V is usually zero

X4

sub-mesh screen size, i.e., the smallest sieve in the series

TRN

efficiency parameter (number of bounces or trials)

fo

fractionopenarea

T

totalareaofscreen

W

widthofapertures

L

lengthofapertures

fs

fractionslot=1-(W/L)

d

maximum size of particle than c an p ass t hrough t he s creen, i e.

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JKSimMet V6 Manual

aperture siz e FW

solids feed rate/unit width of screen

P1

% offeed ofsizex such thatX1 < x < X2

P2

%offeed
SF

submeshfactor

PSF

%offeed
TSF

tonnes/hourfeed ofsize,X4

XF

fines factorcriticalsize

XM

moisturesplitcritical size

A

Regressionconstant

B

Regressionconstant

C

Regressionconstant

D

Regressionconstant

E

Regressionconstant

F

Regressionconstant

G

Regressionconstant

U

Regressionconstant

V

Regressionconstant

8.1.5.1.5 Know n Restrictions

Accurate applicat ion of the scree n model requires data from the screen to be simulated for parameter fitting. For simulation of screens for which data a re not avail able, data for a similar scree n type with similar feed may be used. using data from operations with markedly dif ferent screens or feeds will not provide useful results. The same square roo t of two serie s of scre en sizes should be used for both fitting and simulation. The regression equations of the screen mode l make it quite complex and more difficult to handle than most JKSimMet models. For most processing plants only the tonnage dependence is required . That is the values of U and V can be left at zero. For wire mesh screens often equation A3.5 is adequate on its own. Where there are large variations in the fitted submesh factor (SF) try the dependencies of equ ation A3.9 as detailed in Sub Mesh Factor Modelling. However, a constant SF is often adequate. In a situation where yo u really want to tun e a screen and are prepared to collect a lot of accurate data, cont act JKTech for ass istance with the pa rameter and regression fitting. 8.1.5.1.6 Parameter Fittingthe Screen Model

Parameter Menu

General Models


Model Descriptions

323

Ap Length Ap Width OA % A int (TRN) B*FW (TRN) D*FW (TRN) U*P1 (TRN) U*P2 (TRN) E int (FF) F*PSF (FF) G*PSF (FF) XF XM The basic con cept of a number of trials is quite simple. However, the extensive correction factors and sectionalised curves make this quite a difficult model to fit. The model fitting program can process only one set of flowsheet data at a time. However, one flowsheet may contain many measured sets of screen data. Clearly, the flow rate and near size dependencies require several sets of data to define the screen efficiency v feed rate curves 318 . To descr ibe any parti cular set of scree n data, only a number of trials TRN (parameter 22) and a submesh factor SF (par ameter 23) need to be found. Good initial estimates for these parameters are 5 and 0.1 respectively. However, both TRN and SF are calculated variables in this model. Therefore, we need toE fit them asset regressi on parameter (Ln anticip TRN) ated and regressi on parameter with FW1 to a larger value thanAany screen feed rates per unit of width and with B, V, U, D, F and G all set to zero. Master/Slave Fitting

Master/Slave model fitting allows the secondary dependencies on the parameter menu to be establi shed when multiple s ets of data are a vailable. Setting up Master /Slave fitting is detailed in section 5.6.5. Parameter dependencies are discuss ed in A3.7. However, fitting of multiple data sets is complex and assistance from JKTech consultants is s trongly recommended if you intend to tackle this aspect of the fitting process.

Aperture Length and Width

Where screen data do not provide precise aperture and wire dimensions, the screen aperture can be fitted to the data. Note that for slotted screens, effective aperture length depends on the shape of the particle because the siz e data are measured using square mesh screens.

Selection of Feed Size Parameters X1 to X4

Screen performance can be aff ected by the fee d size distr ibution. This is usually a secondary dependence compared with feed rate. However the model does allow it to be i ncorporated. X1 and X2 are the upper a nd lower sizes of a critic al size fract ion (or fractions). If a pa rticular range of sizes in your feed data is highly variable use X1 and X2 to bracket it. Set X3 to the screen aperture; or the average screen aperture, if you are going to fit several screen mesh s izes. Set X4 to say - 2 or 3 times the sub mesh top size . The f iner part of a size distribution has most of the surface area and will tend to dominate surf ace


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carryover. Traditional screen design te chniques relate a differ ent “ fines factor” to ha lf of the screen aperture. You can use X3 set to half the screen aperture to approximate this dependence if there are large variations in fines in the feed. Similarly, a traditional approach would use a “near size” dependence of aperture size to half aperture size and X1-X2 can be set to estimate this dependence. 8.1.5.1.7 Regression Model Parameters

Trials versus Feedrate

This is the important dependence. Fit each of the data sets avail able. This will giv e you a set of TRN values at each fitted feed rate. You may als o ha ve a s et of fractions between P1 and P2 at each TRN value. The next step is to plot up (TRN) ver sus feedrate. Any graphing package eg MS Exc el, can be use d. Select FW1 and FW2 to let you describe the curve accurately in three sections. An alternative method is to print out your graph (with a full grid) and rule o n several line sections to suit. Their slope s and intercepts will provide B and A and D and C respectively. A multiple linear regression program can a lso be used - if you are a dept with such programs. Most spreadsheet programs (eg. Lotus, MS Excel) have builtin multiple linear regression functions).

Critical Size

If your Trials (TRN) versus feedrate data are erratic and your data are a good

Dependencies

fit than 2 stream SD with White n weights), then it is worth trying P1 and P2 (less dependencies. Use a multiple linear regr ession progr am to fit ln (TRN) against feedrate, P1 and P2 and divi de into sep arate data sets using you r estimates of FW1 and FW2. You can impose the cont inuity constraint by correcting equations 6 and 8 ln(TRN) values by equation 7. If you have a constrained non-linear fitting program which can han dle multiple equat ions, you can fit FW1 and FW2 as well. However, you will need lots of good data.

Submesh Factor Modelling

This is the other im portant dependence. For many operations, SF is small a nd more or less constant. However, for operations with damp ore, it can be crucial to a good model. Once again, plo t your best fit SF values against the calcul ated PSF and TSF values from the param eter scree ns and draw a linear regression line against any one variable. Print out the graph with a fine grid for this slope (for G) and the intercept E. points.

Running the Screen Model

Input your estimated values back into the screen menu and import to each of your data set s. Try a simulat ion and check agr eement on product stre ams. Expect to make errors in this procedure the first few times.

Master/Slave Fitting

For up to 10 data sets, Master/Slave fitting provides an excellent way of estimating these dependencies for good data. You can add secondary dependencies one at a time to test for a significant re duction in the sum of squares.

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325

Hint : Only the undersize and a flowrate is needed for a full screen fit. 8.1.5.1.8 References

WHITEN, W.J . and WHITE, M.E ., 1977. Modelling and simulation of high tonnage crushing plants, XII International Mineral Processing Congress, Brazil, Volume II, 148-158. WHITEN, W. J., 1984. Models and control techniques for crushing plants, Control 84 , Mineral/Metallurgical Processing, (Edit or, J A Herbst), Publishers - AIME, New York, 217-225. 8.1.5.2

Double Deck Screen Models (215 & 235)

The Double Deck Screen models (215 & 235) are simply two consecutive applications of the Single Deck Screen models. Model 215 consists of consecutive applicati ons of the Simple Efficiency Curve Model (210) while model 235 consists of consecut ive applicatio ns of the Kavetsky Single Deck Screen Model (230). The operation of the Kavetsky Single Deck Screen Model is described fully in the previous topic.

8.1.6

Eff. Curves (210, 211, 212, 213, 203 & 240) Efficiency Curves

These models (210, 211, 203) use simple efficiency curves to describe the operation of any classi fication device. For the filter model (240), the user simply sets the U/F pul p density and the mode l redirects all the remaini ng water out in the effluent stream.

8.1.6.1

Simple Efficiency Curve (210, 212)

Simple Efficiency Curve

This topic contains a description of the Simple Efficiency Curve model.

8.1.6.1.1 Model_Description

The model is simply an efficiency cur ve with a fixed d50c and a fixed water split to fine product. Refer to the figures in the Hydrocyclone model description 298 for efficiency curv e shape s. A typi cal DSM scree n has an value of 4 and a value of zero. The model can be used to approximate many classifiers. Therefore the default parameter values should be us ed with caution. 8.1.6.1.2 Model Equations


The efficiency curve used in this model is given below: Eo.(d/d50c ) = C.(1+( . *d/d50c )) (exp( ) - 1) / (exp( . *.d/d When


50c

) + exp( ) - 2)

is 0, * is 1 and the above equation reduces to:

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Eo.(d/d50c) = C.(exp( ) - 1) / (exp( .d/d 50c ) + exp( ) - 2) The shape p arameter determines the initial rise, while determines the slope at larger values of d (d » d50c). Both and are normally constant for given feed solids . The parameter * is determined, for given values of and , by the condition that: Eo(1) = C/2 * is calculat ed iteratively in the model. C is the fractional water split to the fine product. Scaling

This form of the model does not permit scaling.

8.1.6.1.3 Fitting the Simple Ef f iciency Curve

Parameter Menu

This is a simp le model to fit as it has no scali ng capabi lities. Fit the water split, alpha an d d50c. See the comments regarding fitting Beta in the cyclone model description 306 . For DSM Scre ens, initial esti mates of 4 for alpha and 5 0% for the water split should be adequate for most data sets. An initial d50c estimate of half of the actual screen a perture is appropriate 8.1.6.1.4 Simple Ef f iciency Curve Printout

8.1.6.2

Simp le Efficie ncy Curve - Wa ter & Fine s (211, 213)

Simple Efficiency Curve - Water & Fines

This topic contains a description of the Simple Eff iciency Curve - Water & Fines model.

8.1.6.2.1 Model Description

The model is also an efficie ncy curve with a fixed d50c as described a bove for Model 210 with the added feature of allowing the fines and water splits to be different.

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8.1.6.2.2 Model Equations


The efficiency curve used in this mode l is the sa me as that described in A4.2.2 above except that C (fr actional water split to fine product ) is replaced in the equations with a separate parameter F (fractional split of fines to fine product): Eo.(d/d50c ) = F(1+( . *.d/d 50c )) (exp() - 1) / (exp(*d/d50c ) + exp( ) - 2) When


Eo.(d/d50c ) = F(exp( ) - 1) / (exp( .d/d

50c

) + exp( ) - 2)

The shape param eter determines the init ial rise , while a determines the slope at larger values of d (d d 50c ). Both and are normally constant for given feed solids . The parameter * is determined, for given values of and , by the condition that: Eo.(1) = F/2 * is calculate d iteratively in the m odel. F is the fract ional fines split to the fine product. The water split is calculated direct ly from C, the fractional water split to fines product. Scaling


8.1.6.2.3 Fitting the Simple Ef f iciency - Water & Fines

Parameter Menu

This als o is a simple model to fit as it has n o scaling capa bilities. Fit the wa ter split, the fines split, alpha and d50c. See the comments regarding fit ting Beta in the cyclone model description 306 .


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8.1.6.2.4 Simple Ef f iciency Curve (Model 211) Printout

8.1.6.3

Splined Efficiency Curve (Model 203)

Splined Efficiency Curve

This topic contains a description of the Splined Efficiency Curve model.

8.1.6.3.1 Splined Ef f iciency Curve (Model 203) Description

The mod el is also a simply an efficiency curv e but the analyt ic form of the curve used in Models 21 0 a nd 21 1 is replaced by a four k not spline curve. 8.1.6.3.2 Splined Ef f iciency Curve (Model 203) Equations


The ef ficiency curve in this model is provided by specifying four pairs of coordinates through which a smooth curve (piecewise cubic spline function) is cons tructed. Fine end of the curve is specified by the water split as in Model 210.

Scaling


8.1.6.3.3 Fitting the Splined Ef f iciency Curve (203)

Parameter Menu

This als o is a simple model to fit as it has n o scaling capa bilities. Fit the wa ter split and the four efficiency v alues at the knots on the spline curve. It is important to reme mber to set the size values for the knots before attempting model fitting. Even though it seems inc orrect, it is possible for the fitted efficiency values to be greater than 1 or less than 0. Sometimes, model fitting arrives at values at the ends of the curve which are outside the 0 – 1 range in order to achieve the best shape for the curve inside the 0 – 1 range. This is due to the properties of

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329

the spline curve f or which the values at the ends of the curve have an effect on the shape of the curve in the centre region. The sim ulation model code truncates the efficiency values to be less than 1 and greater than 0 . The combination of these two fe atures, control of the shape of the centre of the curve and truncation at 0 and 1 ensures that the model predictions are sensible. 8.1.6.3.4 Splined Ef f iciency Curve (Model 203) Printout

8.1.6.3.5 Symbols f or Splined Ef f iciency Curve Model (203)

Sym bol

*

Me a ning

Equivale nt JKSimMet Parameter

Reduced efficiency curve sharpn ess parameter.

Alpha

Reduced efficiency curve dip parameter.

Beta

Parameter for describing the reduced efficiency curve.

Beta*

C

Watersplittofinesproduct.

WS%Fines

F

Finessplittofinesproduct

FI%Fines

Size of particle in the feed which d50c

has equal probability of going to fine or coarse product.

D50c

8.1.6.3.6 Know n Restrictions

Range of Validity


The highly simplified form of these models means that extrapolation away from the conditions at which the parameters were determined will significantly de crease the accuracy. If a wide range of data is available, it may be possible to use Model 25 1 330 which ha s a variable cut point .

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8.1.6.4

JKSimMet V6 Manual

Referen ces LYNCH, A. J., 1977, Mineral crushing and grinding circuits, (Elsevier, Amsterdam), pp 124-126.

8.1.7

Eff. Curve Variable D50c (Model 251) Efficiency Curve

This chapter describes the Efficiency Curve Variable D50c model.

- Variable D5 0c 8.1.7.1

Model Description

This model is an extension of the Efficiency curve (Fixed D50c) model to include a regression relationship for d50c. The water s plit to the fine product remains fixed. 8.1.7.2

Model Equat ion s

d50c Relationship

For normal operation the class ification s ize d 50c can be related to the operating variables according to the equation: Log10 (d50c ) = W * log10 (SW) + X * FW * C / 100 + Y * FPS + Z

(A5.1 )

Efficiency Curve

The efficiency curve used in this model is given below:

Relationship

Eo.(d / d50c ) = 100 .C.(1+( . *.d / d 50c )) (exp( ) - 1) /

(A5.2)

(exp( . *.d/ d 50c ) + exp( ) - 2) When


Eo.(d/d50c ) = 100.C.(exp( ) - 1) / (exp( .d / d

50c

)+exp( )-2)

(A5.3)

The shape p arameter determines the initial rise, while determines the slope at larger values of d (d close to d50c ). Both and are normally constant for given feed solids. The parame ter * is determined, for given values of and , by the condition that: Eo.(1) = 100.C / 2 * is calculated iteratively in the model. Scaling

General Models



Model Descriptions

8.1.7.3

Efficiency - Varia ble d50c (Model 251) Printouts

8.1.7.4

Symbo ls

Sym bol

331

Mea ning

reduced efficiency curve sharpness parameter reduced efficiency curve dip parameter *

8.1.7.5


W,X,Y,Z

regression constants in the d

d50c

size of particle in the f eed which has equal probability of going to fine or coarse product

C

%watersplittofineproduct

SW

slotwidth(mm)

FW

volume flow rate of water in the feed (m3)

50c

equation

Known Restrictions

As Model 251 is based on a regression equation, extrapolation beyond the scope of the data us ed in the regression will decrease a ccuracy significantly. Effect of the Log Relationship

The relationship between d

50c

and Slo t Width is def ined in Log space . This

means that the multiplier coefficient W will have a different effect for slot widths less than and gre ater than 1.0 mm. For slot widths less than 1.0 mm a multiplier greater than 1 will make the calculated d 50c value smalle r than the slot width. However, for slot widths greater than 1.0 mm, the effect is reversed.This ca n caus e unexpected results when ch anging slot width.

Screen Wear


DSM screens are sensit ive to wire wear condi tion. The scree ns are usuall y reversed on a regular basis. If possible, test data should record the wear condition. If this is not possibl e, test at both new a nd worn to obtain a range of likely operation.

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8.1.7.6

JKSimMet V6 Manual

Fitting

Parameter Menu W * Slot X * FPS Y * FdWater Z (int) Sharpness Dip C This is a simp le model to fit as it has no scali ng capabi lities. Fit the water split, and d 50c . See the comments regarding fitting in the cyclone model description (Appendix A2). Initial estimates of 4 for a and 50% for the water s plit should be adequate for most data sets. An initial d 50c estimate of half of the actual screen aperture is appropriate. Multiple Da ta Sets

If the data cover a range of feed rate s, feed perc ent solid s, slot widths and screen widths, proceed as follows: Fit each data s et for a, C an d d 50 . Refit with average a and C set constant. That is, force all the variation in to the cut size. Use Master/Slave fitting to fit the s eparation siz e equation (A5.1) for W, X, Y and Z. Note: If the slot width does not have a strong effect on d 50c , then the data are

very questiona ble. 8.1.7.7

Referen ces LYNCH, A. J., 1977, Mineral crushing and grinding circuits, (Elsevier, Amsterdam), pp 124-126.

8.1.8

Simple Combiner Model (800) Simple Combiner Model

8.1.8.1

This topic contains a description of the Simple Combiner model.

Model Description Equipment

The Simple Combiner model is available for selection for the Pump, Pump Sump, Sump, Ball Mill, Tower Mill and Stockpile equipment. After opening the Equipment window for the equipment, click on the Equipment model drop down list to access the model options. Next click on the double arrow button to the right of the drop down list to open the model window pertaining to the selected model.

Model Overview

For the Simple Combiner model, the mass in the pa rticle class es of two or more incoming feed streams is combined to produce the mass in the particle classes in a single product stream of the combiner (Equation M800-1):

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333

(M800-1) The mass of water in the feed streams is also combined to produce the mass of water in the Simple Combiner product stream. Prerequisite System Properties

There are no prerequisite system properties for this model for the Standar d input option, however the Volume output warning option requires the Mineralogy system property to be added as a property in the particle class definition table in Stream Specification.

Model Data Input

The information required by JKSimMet to calculate the mass in a single product stream using the Simple Combiner model is outlined below. There are two options for the Simple Combiner model accessed via a drop down menu on the screen: 1. Standard 2.

Standard Option

Volume Output Warning Option

Volume output warning

The Standard model option requires no parameter input and has no prerequisite stream properties, (see window below). The number of particle classes in all feed and product streams is equal and the mass of a particular particle class is conserved across the equipment unit.

Simple Combiner Model – Standa rd Option The Volume output warning op tion alerts the user when the flow rate of the streams entering the comb iner equipm ent exceed the volume capacity of the equipment. When using this option, JKSimMet will repor t a warning to the user at the completion of s imulation when the Simple Combiner output flow exceeds the Maximum Product Volume flow (m3 /hr) specified.

The Volume output warning option for the Simple Combiner model is shown below.


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Simple Combiner Model – Ex ample of Volume O utput Warning Option 8.1.8.2

Symbo ls S ymbol

Mp

feed stream s

Mp product 8.1.8.3

Meani ng

mass in particle class p in an incoming feed stream, s, to the combiner mass in particle class p in the single product stream of the combiner

Model Limi tation s

No relevant limitations. 8.1.8.4

Referen ces


8.1.9

2 Way Simple Splitter Model (810) 2 Way Simple Splitter Mode l

8.1.9.1

This topic contains a description of the 2 Way Simple Splitter model.

Model Description Equipment

General Models

The 2 Way Simp le Splitter model is available for selection for the 2 Product Splitter, Hydrocyclone, Flotation Cell, Flotation Column and Jameson Cell. After opening the Equipment window for the equipment, click on the Equipment model drop down list to access the mo del options. Next click on the double arrow button to the right of the dro p down list to open the model window pertaining to the selected model.


Model Descriptions

Model Overview

335

The feed to this model is split into two streams with size distributions, pa rticle classes and pulp densit ies identical to the feed. The controlling paramet er is the Fraction Split to Top Product. The top product is the upper product on the equipment icon and is marked with a T. The parameter range is 0.0 to 1.0. The 2 Way Simple Splitter model in JKSimMet combines the mass in the particle classes of the feed stream and splits this mass according to a defined ratio into the particle class es of its product streams. A splitter is characterized by the fact that its combined feed composition is equivalent to the composition of each individual product s tream, that is, the ratio of parti cle classes in the feed and product stre ams is equal, and the total mass in a particular particle class is conserved acro ss the unit.

Prerequisite System Properties

This mode l can be used re gardless of the properties that have been added as properties in the particle class definition table in Stream Specification.

Model Data Input

The infor mation required by JKSimMet to calculat e the mass in each particle class in each of the product streams using the 2 Way Simp le Splitter model, and the models used to perform these calculations, are outlined below. The user defines the fraction of the feed stream split to the top product, α. Double click on the appropriate field to input the required value for Fraction sp lit to top product. This fraction is used during simu lation to determine the mass in each pa rticle class in the product streams, M pproduct stream 1 or 2 (Equations M810-1 and M810-2). This ratio is used in a similar manner to det ermine the mass of water in the two product streams. (M810-1) (M810 -2) The 2 Way Simple Splitter model is shown below.


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Example of 2 Way Simple Splitter Model 8.1.9.2

Symbo ls S ymbol

Mp

mass in each particle class in a feed stream s

Mp

product stream

mass in each particle class in a p roduct stream

α

8.1.9.3

Meani ng

feed stream s

fraction of the feed stream split to the top product

Model Limi tation s

This mode l makes no assumptions about the proc ess used to separate. It is a splitter onl y; the frac tion split data must be ente red by the user. There is no relationship between feed or equipment unit conditions and the model output. 8.1.9.4

Referen ces


8.1.10 2 Way Volumetric Splitter Model (812) 2 Way Volumetric Splitter Mode l

This topic contains a description of the 2 Way Volumetric Splitter model.

8.1.10.1 Model Description Equipment

General Models

The 2 Way Volumetric Splitter model is a vailable for selection for the 2 Product Splitter, Flotation Cell, Flotation Column an d Jameson Cell. After opening the Equipment window for the equipment, click on the Equipment model drop down list to access the model options. Next click on the double arrow button to the Version 6.0.1 - March 2014

Model Descriptions

337

right of the drop down list to open the model window pertaining to the selected model. Model Overview

The fe ed to this model is split into two streams with size distributions and particle class es identical to the feed. The controlling parameters are the Fraction Split to Top Product (Water) and Fraction Split to Top Product (Solids). The top product is the upper product on the equi pment icon and is marked with a T. The parameter range is 0 .0 to 1.0. The 2 Wa y Volumetric Splitter model in JKSimMet combines the volume in the particle classe s of any feed streams and splits this volume into the particle class es of its product stre ams. Instead of ente ring a split ratio, in this model the user defines the volumetric flow to the top product. A splitter is characterized by the fact that its combined feed composition is equivalent to the composition of each individual product s tream, that is, the ratio of parti cle classes in the feed and product stre ams is equal, and the total mass in a particular particle class is conserved acro ss the unit.

Prerequisite System Properties

This mode l can only be use d if the Mine ralogy property has been added as a property in the p article class definition table in Stream Specification.

Model Data Input

The information required by JKSimMet to ca lculate the volume in each particle class in each of the product stre ams usin g the 2 Way Volumetric Splitter model, and the models used to perform these calculations, are outlined below. The user defines the volumetric flow rate to the top product. Double click on the appropriate field to input the required flow rate for Volumetric flow rate to top product (m3 /h). This value is used during simulation to det ermine the volume in each particle class in the prod uct stre ams (see Equations M810-1 and M810-2 334 ), wher e the split ratio, α, is equivalent to the defined top stream volume flow divided by the s tream volume flow in the combined feed streams. If the defined top stream volume flow is greater than the combined feed stream volume flow, JKSimMet sets the s plit ratio to 1.0. This ratio is used in a similar manner to determine the mass of water in the two product streams. The 2 Way Volumetric Splitter model is sh own below.


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Exa mple of 2 Wa y Volumetric Splitter Model 8.1.10.2 Symbo ls S ymbol

Meani ng

α

split ratio, equivalent to the user defined top stream volume flow divi ded by the stream volume flow in the combined feed streams

8.1.10.3 Model Limit ations

This mode l makes no assumptions about the proc ess used to separate. It is a splitter only; the volumetric flow rate to the top product must be entered by the user. There is no relationship between feed or equipment unit conditions and the model output. 8.1.10.4 References


8.1.11 Water & Solids 2-Way Simple Splitter (813) Water and Solids 2-Way Simple Splitter

This topic contains a description of the Water and Solids 2-Way Simple Splitter model.

8.1.11.1 Model Description Equipmen t

General Models

The Water and Solids 2 Way Simple Splitter model is available for selection for the DSM screen, 2 Product Splitter, Rake Classif ier, Spiral Classif ier, Spiral Separator, Hydrocyclone, Flotation Cell and Flotation Column. After opening the Equipment window for the equipment, click on the Equipment model dro p down list to access the


Model Descriptions

339

model options. Next click on the double arro w button to the right of the drop down list to open the model window pertaining to the selected model. Model Overview

This model is a variatio n on the 2-way simple s plitter model. The feed to this model is split into two streams with size distributions and particle classes identical to the feed but the water in the feed is split in proportions different from the solids split to the two products. The controlli ng parameters a re the Fraction Split to Top Product (Solids) a nd Fraction Split to top product (liquid). The top product is the upper product on the equipment icon and is marked with a T. The parameter range is 0.0 to 1.0. The water and solids 2 Way Simple Splitter model in JKSimMet combines the mass in the particle classes of the f eed stream and splits the solids mass according to a defined ratio into the particle class es of its product streams and the liquid .. ratio.

Prerequisi te System Properties Model Data Input

This model can be used regardless of the properties that ha ve been added a s properties in the particle class definition table in Stream Specification. The infor mation requi red by JK SimMet to calculat e the mass in each particle class in each of the product stre ams using the wate r and solids 2 Way Simpl e Splitter model, and the models used to perform these calculations, are outlined below. The user defi nes the fraction of the fee d s tream solids split to the top product, α and the feed stream liquid to the top product β. Double click on the appropr iate fiel d to input the required values for Fraction split to top product solids and liquid. These fractions are used during simulation to determine the mass in each particle class in the product streams, Mpproduct stream 1 or 2 (Equations M813-1 and M813-2) and the mass of liquid in the product streams. The liquid ratio is used in a similar manner to determine the mass of water in the two product streams. (M8 131)

( M 8 1 3 2 )


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JKSimMet V6 Manual

The Water and Solids 2 Way Simple Splitter model is shown below.

Example of 2 Way Simple Splitter Model 8.1.11.2 Symbo ls S ymbol

Meaning

Mps feed stream s

mass in each particle class in a feed stream s

Mps product stream

mass in each particle class in a product stream

α


Mpl

feed stream l

Mplproduct stream ß

liquid in feed stream s liquid in p roduct stream fraction of the feed stream split to the top product


This mode l makes no assumptions about the proc ess used to separate. It is a splitter onl y; the frac tion split data must be ente red by the user. There is no relationship between feed or equipment unit conditions and the model output. 8.1.11.4 References


8.1.12 3 Way Simple Splitter Model (870) 3 Way Simple Splitter Mode l

General Models

This topic contains a description of the 3 Way Simple Splitter model.


Model Descriptions

341

8.1.12.1 Model Description Equipment

The 3 Way Sim ple Split ter model is available for selec tion for the 3 Product Splitter equipment item. After opening the Equipment window for this item, click on the Equipment model drop down list to access the model opti ons. Next click on the double arro w button to the right of t he drop down list to open the model window pertaining to the selected model.

Model Overview

The feed to this mode l is split into three streams with size distributions, particle classes and pulp densities identical to the feed. The controlling parameters are the Split Top Product ndthe theequipment Fraction Split Bottom Product. The top Fraction product is thetoupper produ ctaon icontoand is marked with a T. The parameter range is 0 .0 to 1.0. This model can be used regardless of the properties that have been added as properties in the particle class definition table in Stream Specification.

Model Data Input

The information required by JKSimMet to calculate the mass in each particle class in each of the product streams us ing the 3 Way Simple Splitte r model, a nd the models used to perform these calculations, are outlined below. The user defines the fraction of the feed stream split to the top product, αtop, and the fraction of the stream split to the bottom product, αbottom. Double click on the appropriate fields to input the required values for: •

Fraction split to top product

•

Fraction split to bottom product.

On data input, JKSimMet calculates: •

Fraction split to middle p roduct.

These fraction split ratios are used during simulation to determine the mass in each particle class in the product stre ams (Equations M870 -1, E870-2 an d E8703). The fraction s plit ratios are also us ed in a similar manner to det ermine the mass of water in the three product streams. (M870-1) (M870-2) (M8703) The 3Way Simple Splitter model is shown below.


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Example of 3 Way Simple Splitter Model 8.1.12.2 Symbo ls S ymbol

Meani ng

Mp

feed stream

mass in each particle class in an incoming feed stream

Mp

product stream

mass in each particle class in the product str eam

α

α


top

fraction of the feed stream split to the bottom product

bottom


This mode l makes no assumptions about the proc ess used to separate. It is a splitter onl y; the frac tion split data must be ente red by the user. There is no relationship between feed or equipment unit conditions and the model output. 8.1.12.4 References


8.2

Co mminu tion Mode ls This s ection describes the various comminution circuit mode ls a nd contains : a description of each comminution model available in JKSimMet key equations forming the mathematical basis of the models known limitations an d restrictions some guidance and restrictions for parameter fitting

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343

typical model parameter values, where appropriate There are a number of generic models included in JKSimMet that can be used to describe the behaviour of a wide range of processes. For example, the simple efficiency curve model can be used to describe any sort of classification device, such as a cyclone or a spiral classifier. Selection and fitting of parameters for these models will depend entirely on the type of process being modelled. Most of the pro cess units available to the user when drawing the flowshe et can be described byeloped a number of models. Typically, process unit will have a specific model, dev for that pa rticular devicea, an d a number of generic models. Selection of the appropriate mo del is at the user's discretion and will often depend on available test data. Note that all model paramet ers have defau lt values and a permitted range. The default value and range can be viewed by double clicking on the parameter value. These values are not currently editable by the User.

8.2.1

Crus her Models (400 and 405) Crusher Models

8.2.1.1

This ch apter describes the crusher mode ls.

Model Description (Anderson/Awachie/W hiten)

The crusher mode l considers the crushin g process as two components: the selection of particles for breakage, and the breakage of the particles so selected. Selection

Clearly, whether or not a particle is selected will depend principally upon its size relative to the close d-side sett ing (CSS) of the crushe r and the exte nt of choke feeding. The size distribut ion of the daughter products of breakage will depend principally upo n the init ial s ize of the parti cle and upon its physical properties. New feed entering the crusher is classi fied (or selected). Some material, predominantly the finer fract ion, bypasses the breakage process entirely and reports directly to the product. The rem ainder is broken, and the daughter fragments are then recycled to the classificat ion s tep. The new fine fraction exits via the product, and the coarser material is re-broken.

Perfect Mixing Model


If we think of a crusher as a s tage-wise breakage process, then we ca n model it in terms of a steady state balan ce.

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Schematic Representation of the Crusher Model

A schemati c representation of the crusher mo del is given in the above figure. Mass bala nce equations may be writ ten about each node as: ACx + f = x

(A6.1)

x = p + Cx

(A6.2)

where x is a vector representing the amount in each siz e fraction in the crusher f

isthefeedsizedistributionvector

p

is the product size distribution vector

C

is the classification function, a diagonal matrix describing the proportion of partic les in each size interval entering the crush ing zon e

A

istheappearancefunction,alower triangular matrix giving the relative distribution of each size fraction after breakage.

Combining (A6.1) and (A6.2) results in the Whiten crusher model equation: I-AC p(*= I-C )-1 (f)*

(A6.3)

where I is the unit matrix. Since the feed and product are expressed as size distributions, and the properties of the internal classification and breakage mechanisms are expressed with respect to particle size intervals or mean sizes, it is convenient to represent these quantities as vectors and matrices respectively. Since f is known andofpCisand the desir output, themachine problemand resolves itself into obtaining est imates A fored a particular feed material. These valu es can then be manipulat ed by simulat ion to explore the effects of changing machin e parameters, material chara cteristics or operating conditions upon the p roduct size distributio n. An important lim iting facto r in crusher operat ion is the power drawn by the machine. This model permits estimates of power draw to be made for a given condition, so that the s imulations can be constrained by power requirements (by the user ). The pow er draw can be norm alised to experimental data or estimated from data for similar crushers in the Supplementary Parameters

Comminution Models


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345

Manual. Note: a single part icle breakage test of the ore is required for either type of power estimate. 8.2.1.2

Model Equat ion s

p = (I - C) * (I - A * C)-1 * f Selection

Where C is the cla ssification function (a diagonal matrix) and where C(x) is the probability of selection for breakage of a particle of size x and is defined as: 1 =C(x)

(A6.4)

for x > K2 i.e. all particles are broken C (x) = 1 - [ (K2 -x)/(K2 -K1 ) ] ^ K3

(A6.5)

for K1 < x < K 2 0 =C(x)

(A6.6)

for x < K1 i.e. no particles are broken (x = mean particle size) An example of the classification functions is given in figure A6.2.

Classification Function, c

The model equations are developed by non-linear regression anal ysis of survey data collected over a wide range of operating conditions, followed by multiple linear regression of the fitted parameters against the operating conditions. The general form of these relationships is : K1 = A0 * Crusher gap - A1 * Throughput + A2 * Feed coarseness K2 = B0 * Crusher gap - B1 * Throughput + B2 * Feed coarseness K3 = C0 (generally held constant at a value of 2.3) First Approximation


For many crusher ty pes perf ormance can be estimated by setting K1 to the closed side setti ng, K2 to the open side setting (or K1 plus eccentric throw). Both K1 and K2 will decrease with particle interference as the crusher throughput increases to choke feeding.

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The breakage severity (t10) will also increase (see A6.6 and equation A6.11). The model allows for inclusion of minor variables where more detailed data are available The equations in the model are of the form: K1 = A0 * CSS + A1 *TPH + A2 * F80 + A 3 LLen + A 4

(A6.7)

K2 = B0* CSS - B 1 * TPH + B2 * F80 + B 3 * LHr + B4 * ET + B5

(A6.8)

(usually 2.3) K3 = C0

(A6.9)

Where: CSS

Closed sidesetting

LLen

LinerLength

ET

EccentricThrow

LHr

LinerHours

TPH

CrusherFeed Rate

F80

Crusher Feed 80% passing size

P 80

Crusher Product 80% passing size

Note that only cl osed side setti ng and crusher throw will normall y be used. The other relationships require a very detailed experimental database. 8.2.1.3

Ore Breakage Characteri sation

Andersen Breakage Model

The Andersen model uses the results of JK breakage testing of coars e pa rticles to pre dict both bre akage and crusher powe r consumption. This model has been extensively tested on cone crushers (mostly operating as secondary crushers) ove r a broad range of ore types. When the model was developed, only the pendulum device was available for single particle breakage tests. However, the JK Drop Weight test is now used as it provides for a wider range of energies and pa rticle sizes. The first step is to use the JK breakage test to characterise ore breakage over a range of input and absorbed energies. The absorbed energ y (per unit mass of particle) is referred to as the specific comminution energy.

8.2.1.4

Breakage Distribution Parameter

A typical size distribution of product from the JK breakage tester is given in the figure below. This product size distrib ution may be adequately described by a one parameter (t) family of curves (Awachi e (1983); Narayanan and Whiten (1983)). The paramete r t10 is defined as the cumulative percent passin g one tenth of the geometric mean size, Y, of the test particle. The parameter is shown in the figure below, together with other tn value s - t2 and t4,- which are defined in a similar manner to t10. Using the tn values (n= 10, 2, 4, 25, 50 and 75), the whole of the size distribution may be fully described.

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347

Typical pendulum product size distribution

The tn valu es (n = 10, 2, 4, 25, 50 and 75) for the prod uct size distributions for nine pendulu m tests on hard rock ores from four major crushing operat ions at different sites were det ermined an d a 'best-fit' s pline curve was drawn through all of the tn data using a JKMRC multiple spline regression package, MSR. This breakage distribution information may be conveniently stored as a three dimensional spline relationship between the breakage distribution parameter, t10 ( a measure of the amount of breakage or reduction), the cumulative percent passing a particular rel ative size, and the relative size, tn, of the particle being broken. Using th e t10 spline kno ts 10.0, 20.0 and 30.0, Table A.6.1 gives the cumulative percent passi ng the rel ative sizes t75, t50, t25, t4, and t2 i.e. the cumulative percent passing the Y/7 5 s ize (etc), where Y is the size of the srcinal particle being broken as shown in Figure A6.4. The distribution for any intermediate value of t10 is determined by spline interpolation. SIZE RELATIVE TO INITIAL SIZE T75 Breakage Parameter t10

T50

T25

T4

T2

Cumulative Percent Passing

10.0

2.8

4.0

5.5

22.2

51.4

20.0

5.6

7.2

10.7

43.4

80.8

30.0

8.9

11.3

16.4

60.7

93.0

Appearance Function Data


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The relatio nship between t10 and the rem ainder of the product size distribution

8.2.1.5

Breakage Paramet ers

Breakage param eters can be estab lished fro m regression an alysis of the same data as the classification equations. t10 = D * Crusher Gap + D * Throughput – D * Feed Size (F80) + D 0

1

2

3

(A6.10 )

This equation shows the intuitively expected dependence on the crusher gap, throughput and feed size distribution. The "feed coarse ness" factor is somewhat applicat ion depende nt. That is, it will be influenced by crusher liner profile a nd effective slope as well as closed side setting and gap. First Approximation

8.2.1.6

Typical cone crusher oper ation for secondary and ter tiary crushers will be at a t10 of 15 to 20. For a lightly loade d crusher (size cont rol on a primary jaw crusher) will operate at a t10 of 5-10. A high reduction crusher (toothed roll or choke fed tertiary) may achieve a t10 up to 25.

Crusher Power Predic tions

Energy - Size Reduction Relationship

The JK breakage test also provides important information on the specific comminution energy (kWh/t) required for a fixed size reduction, quantified by the breakage distribution parameter t10, for each particle size broken. The specific comminution energy, Ecs, defined as the amount of energy available for breakage, is derived as the energy a bsorbed from the drop weight on impact. This energ y has been found to have a linear re lationship with the breakage distribution parameter, t10, but is also dependent on the test particle size. This relationshi p is ore-specific and is used to characterise ores and compare the crushing energy requirements of different ores. Figure A6.5 shows the energy - s ize - size reduction relationship derived from a JK breakage test for a fine-grained, siliceous copper ore.

Comminution Models


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349

Energy size reduction relationship

This infor mation as used in the crushe r model program in the spline form is tabulated below. The ener gy required for a given reduction increases with a decrease in particle size. In Model 400, provision is made f or data for three particle sizes. In Model 40 5, the matrix is extended to accept data for fiv e particle sizes to match the data available from the JKTech Drop Weight Test.

Reduction parameter

Particle size mm

t10

14.50

%

SpecificcomminutionenergykWh/t

10.0

0.35

0.30

0.25

20.0

0.80

0.70

0.50

30.0

1.2

1.0

0.80

20.63

28.89

Energy-Size Reduction Relationship (Spline Form) – Mode l 400


Reduction parameter

Particle size mm

t10

14.50

%

SpecificcomminutionenergykWh/t

10.0

0.35

0.30

20.0

0.80

30.0

1.2

20.63

28.89

41.10

57.80

0.25

0.20

0.15

0.70

0.50

0.40

0.30

1.0

0.80

0.60

0.40

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Energy-Size Reduction Relationship (Spline Form) – Mode l 405 Power Pre diction Method

A power prediction method has been developed using energy – size-reduction information from the pendul um test (Andersen & NapierMunn, 1 988) and is also applicable to the Drop Weight test. Using the ore-specific energy-size-reduction relationship from the pendulum test, the breakage functio n, B the classificat ion values Ci (from the parameter fitting or model regression equations, the model calculates the total energy required to reduce the feed size distribution to the product s ize distribution a s if all the feed was broken in the pendulum or drop weight testing device, i.e. it defines the ene rgy which would have been used by the breakage device to achieve the s ame degree of breakage observed in the crusher. The sum of the products of the amount of material selected for breakage in each size fraction, Ci*xi (tonnes) (from equation (A6.3)), and the Ecs (kWh/t) for each size at the breakage parameter value t10 (determined from the parameter fitting or model regression equation (A6.11)), is the total comminutio n energy calculated by the model, Pcalc (kWh). This total model-calculated energy is then regressed against the actual power draw observed during the plant s urveys on a particular crusher using multiple linear reg ression analysis, resulting in a simple equation of the form given below. Pobs = E1 * Pcalc + E 2

(A6.11)

where Pobs

is the observed crusher power draw (kW)

Pcalc

is the model calculated comminution energy(kWh)

E1

is a constant dependent on the efficiency of the crusher

E2

is a constant of similar value to the 'no-lo ad' power draw

The constant included in the regression equation adequately a ccounts for the crusher machine power draw (the power required to overcome machine frictional losses), or 'no-load' power draw as it is commonly termed. This 'noload' power appears to vary slight ly with throughput and is a function of both plant power factor and drive motor efficiency. Feed rate (t/h) and feed coarseness are usually less significant variables and a satisfactory model can be obtained by a bsorbing these effects into the constant term. These variables are implicitly included in the pendulum power calculation. The power regressions developed may be used to predict the power requirements of crushers operating on different ores after determining the relationship between the break age paramet er, t10, test pa rticle size, and the specific comminution energy, Ecs, for the ore under investigation. The pendulum test s hould be conducted on representative ore particle s over the range of the crusher feed size. Where a specific mathematical performance model of the form of equations A6.7 to A6.10 has been developed from extensive plant surveys, the power draw may then be predicted for different operating conditions. In a design s ituation, given the feed and the desired product siz e dis tributions, the t10-size-Ecs relationship for the ore to be processed must be obtained from the pendulum test and this information used in the model to ca lculate the total comminution energy req uired. The crushing power requirements can then be

Comminution Models


Model Descriptions

351

determined for a similar crusher from a power regression of the form of equation A6.11 obtained from another site. 8.2.1.7

Crusher Model (400/405) Printout

8.2.1.8

Symbo ls

Sym bol


Me a ning

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352

8.2.1.9

JKSimMet V6 Manual

f

feed sizedistribution (vector)

p

product size distribution (vector)

A

appearancefunction (matrix)

C

classification function (diagonal matrix)

I

unitmatrix

K1

size below which C = O

K2

size above which C = 1

K3

exponent in the equation for C

CSS

closed side setting (mm)

TPH

tonnes/hourfeed

F80

coarseness of feed, e.g. 80% - 25.4mm

t10

breakage distribution factor

Pcalc

total power consumed in size reduction using the pendulum (from laboratory tests results)

Ai

regressionconstant

Bi

regressionconstant

Ci

regressionconstant

Di

regressionconstant

Ei

regressionconstant

Known Restrictions

This is the most ge neral of the crusher models developed a t the JKMRC. It has been extensively tested for large (7ft) cone crushers. The model provi des an excellent description for indiv idual results for many types of crusher, e.g., jaw, roll, toothed roll, hammer mill etc., but has not been extensively tested on these other crusher types. The feed coarseness relationships are usually based on scalped feed oversize variations. They could well be dif ferent from variations in scalp ing screen aperture. This interaction is a subject for continuing in vestigation. For power calculat ions large particles a re apparentl y softer (see Table A6.2). The drop weight t est is not s uitable for particles of diameter larger than 63mm. Hence, using specific comminut ion energies derived on smaller particles will tend to overestimate required pendulum power. There iscause alsoaaconsiderable physical flo w limit for st types crushers. For crushers which increase in mo volume, thisoflimit is important. Hence for cone or 'Gyra disk' types, check the simulated flowrates against the design tables for that type of crusher and the corresponding bowl and mantle. Typical flo wrates are available fro m s tandard ref erences such as Mular and Bhappu (1978 ), Chapter 11. 8.2.1.10 Fitting the Crusher Model

The model fitting subsy stem only analyse s one data s et at a time. Hence the actual parameters adjusted are the constant terms in each of the equations Comminution Models


Model Descriptions

353

A6.7, A6.8, A6.9 an d A6.10. Thatis,

A

and

4

for

K1

B5

for

K2

D3

for

t10

Parameter Menu

There are two di stinct le vels of use of the crusher model. The diff erent uses require different fitting strategies. Limited Data

One data set allows a (somewhat approximate) estimate of product size for small variations in clos ed side setting. For one data set: fit A4 and B 5 with A 0 = 1.0, and B 0 = 2 .0 and (for cone crushers) K 3 = 2.3. Set other A and B values to zero. Similarly for the breakage function: fit D3 D0, D1 and D2 are set to zero. Note that one data set does not provide useful information about power dependencies.

Extensive Data

The model is much more useful with a ran ge of data. This means 5 to 10 data sets covering a range of crusher settings, feed rates and (if possible) feed sizes. JKTech can undertake breakage tests to characterize an ore as shown in Figure A6.3 and Table A6.1 an d to determine the s ize single particle breakage /power as s hown in Figure A 6.5 an d Table A6.2.


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HP Grinding Rolls (and Others)

Note that the value of K

3

is generally 2.3 for cone, jaw and gyratory crushers

only. For other types of crushe rs, such as grinding rolls and hammer mills, it is advisable to fit K3 also, with 2.3 a s a good initial estimate

8.2.1.11 Regression Modelling

The procedure is very similar to that for the screen mode l. Hence, an efficient test program can be designed to gather screen and crusher data together. Fit each test using only constant ter ms, A 1 , with all of the other regression terms s et to zero. Use the ore Specific Appearance and Power Data measured by JKTech, or use the defaults (average of 4 ore types). Measured oretype data should give more accurate results for breakage and are essential for realistic power estimates. Each da ta set produces estimat es of K 1 , K2 , K3 and A and B. Set K3 = 2.3 Use a multiple linear regr ession package to fit each estimate to the measured variables. If any coefficients plus or minus their estimated errors bracket zero, try a refit without that var iable included . If the error of prediction improves (i.e., gets smaller), omit the variable by setting its model coefficient to zero. 8.2.1.12 Model Testing

Import each feed and product into the model and simulate to check each set. This is quite a complex model and it is not difficult to make errors. If any data sets are seriously in error, tr y to track down the reason. Check the calculated K1, K2, and t10 agains t your fitted estimates. When a ll else fails (or much earlier, if you prefer), ask JKTech, who will be happy to assist. As soon as you have reasonab le parameter estimates, you may use Master/ Slave fitting on up to ten data sets at a time to test secondary crusher model dependencies. 8.2.1.13 References

ANDERSEN, J. A., 198 9. M.Sc. Thesis, University of Queensland, (unpublished). ANDERSEN, J .A. and NAPIER-MUNN, T.J., 19 88. Power predict ion for cone crushers, Mill Operators' Conference, Cobar. AWACHIE, S.F.A., 1983, Development of crusher models using laboratory breakage data, PhD Thesis, University of Queensland. MULAR A. L. & BHAPPU, R. B. 197 8, Mineral Processing Plant Design. WHITEN, W.J., 1984, Models and control techniques for crushing plants, Control 84, Minl./ Metall.Process (Am.Inst.Min.Engrs. Annual Meet., Los Angeles, USA, February), 217-225.

8.2.2

Rod Mill Model (410) Rod Mill Model

Comminution Models

This chapter describes the workings of the Rod Mill model.


Model Descriptions

8.2.2.1

355

Model Description

The rod mill model is based on the concept of stages of breakage. A stage of breakage has three components: selection appearance classification. That is, each s tage is equivalent to b reakage, screening and recirculation. The mill is consid ered a s a number of segm ents in order. Each segment is a stage of breakage. 8.2.2.2

Model Equat ion s

Diagrammatically a stage of breakage may be considered as:

A representation of the breakage process in a rod mill

Eliminating m and q by matrix algebra yields pj = (I-C) . (A.S +I-S) . [I-C(AS+I-S)]-1 . fj or pj = X . fj since AS and C a re assumed constant for all stages. Stages of Breakage


If there are v stages of breakage in the mill then:

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JKSimMet V6 Manual

p = (X) v f

(A7.1)

or p = XXX ... f

for v times

Non-integer numbers of stages can only be calculated by interpolation. Once A, S and C are known, any particular operating condition can be represented by a value of v. Feed Rate

The key dependence is the variati on of stages of breakage v with mill feed rate F. Experimentally: F (v)1.5 = MC where MC is the mill constant. The mill constant can als o be scaled as detailed later.

Appearance Function

The default Appearance Function is the modified Rosin-Rammler equation: A(x,y) = (1-e-x/y)/(1-e-1 ) Where A(x ,y) is the pro portion after breakage of particles of initial size y which are smaller than size x. The appearance A is made up of vectors of the differences in x for the specified screen interval. For specific ores, JKTech can measure the appearance function. A range of appearance functions for various ores is given with the ball mill model description in Appendix A8.

Classification

The classific ation functi on C is a diagonal matr ix which provides a simple

Function

classifi er. Each diagonal elem ent gives the propor tion of that size fraction returned to the breakage stage for rebreakage. The usual values are (for a v2 siz e distribution) 1.0, 0.5, 0.25, 0.125, 0.063 and so on. Hence, each stage of breakage in a rod mill will eliminate the top size fraction from the product.

Selection Func tion

The sele ction func tion, S is a diagonal mat rix. It gives the proportions of each s ize fractions which are selected for breakage. S is represented by three parameters XC, SL an d IN a s shown in the figur e below, and is ca lculated by: Si = SL * Size + IN

for Size i > XC

Si = SL * XC+ IN

forSizei < XC

and limited if Si > 1.0 then Si = 1 .0 and if Si < 0.0 then Si = 0.0 An example of a selection function is given in the figure below.

Comminution Models


Model Descriptions

357

Graph of a rod mill selection function Scaling

The rod mill model is scaled by modifying the mill constant according to dimensions and operating conditio ns described below:

Mill Size

FACTA = (DSIM /DFIT )2.5 * LSIM /LFIT These scale factors only a pply for rod mill s with normal length to diameter ratios, that is, 1.2 < simulated L/D < 1. 6 and L 7m.

Media Load

Load Fraction ( i.e. volume of mill occupied by cha rge and media at rest after grinding out) FACTB = [(1 - LFSIM ) * LFSIM ] / [(1 - LFFIT ) * LFFIT ] Note 30% < LF < 45%

Critical Spe ed

Fraction Critical Speed FACTC = CSSIM /CSFIT Note 50% < CS < 80% These factors are appl ied to the Mill Constant MC of the original mill to estimate the mill constant of the simulated mill. MCSIM = MC * FACTA * FACTB * FACTC The required number of stages of breakage is VSIM = (MCSIM /FSIM )2/3

Feed Size

Coarseness of feed (90% pass ing size) FACTD = ln (F90 FIT /F90 SIM ) / lnv2 VSIM = (MCSIM /FRSIM )2/3 + FACTD

Ore Hardness

Work Index FACTE = - 0.8 ln (WISIM /WIFIT ) FACTF = ln [(S(I)FIT /(1-S(I)FIT )] + FACTE


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JKSimMet V6 Manual

FACTG = exp (FACTF) S(I)SIM = [FACTG/(1+FACTG)] 8.2.2.3

Rod Mill Model Printout

Rod Mill Printout Showing Default Values 8.2.2.4

Symbo ls

Comminution Models

S ymbol

Meaning

f

feed size distribution (vector)

p

product size distribution (vector)


Model Descriptions

A

appearance function (step matrix)

C

class ification function (diagonal matrix)

S

selection function (diagonal matrix)

Si

element of selection function S from size i

v

number of stages of breakage of srcinal mill

vSIM

v for simulated mill

F90FIT

90% passing size for fitted mill feed

F90SIM

90% p ass ing size for simulated m ill feed

MCSIM

mill constant for simulated mill

MC

mill constant for srcinal or fitted mill

SL

slope of selection function

IN

intercept of selection function

XC

Size below which selection functio n is constant

DSIM

diameter of simulated mill

DFIT

diameter of fitted mill

LSIM

length of simulated mill

LFIT

length of fitted mill

LFSIM

load fraction of simulated mill

LFFIT

load fraction of fitted mill

CSSIM

fraction critical speed of simulated mill

CSFIT

fraction critical speed of fitted mill

WISIM

work index of ore for simulated mill

WIFIT

work index of ore for fitted mill

359

Note: The fitted mill is the rod mill which provided the experimental data. 8.2.2.5

Known Restrictions

Scaling

Note the restrictions for scaling in the s ection on Model Equatio ns.

Change in Feed Pulp Density

The numb er of stages of breakage is calculated from the feed solids mass flow. No account is taken of wate r in the feed. It is assumed that ro d mills operate at 75 to 85 percent solids in the feed.

Effect of Feed Size

There is some doubt about the a djustment of n umber of s tages of breakage according to fee d coarseness. Data fro m some oper ations exhibit an effect while dat a from others do not. If the partic les are large enough and strong enough to resist a rod impact, the depe ndence is reasonable. The scaling effect can be eliminated from open circuit operation by s etting F90FIT (parameter 16) equal to F90SIM (parameter 80).

Mill Spee d


This dependence is reasonab le from 50-80% of crit ical speed at industrial mill feed rates.

Comminution Models

360

8.2.2.6

JKSimMet V6 Manual

Fitting the Rod Mill Model

Parameter Menu

Because the rod mill model is dependent on feed conditions, it is difficult to fit in closed circuit until the parameters are very good estimates. Therefore, mass balance a closed circuit rod mil l first. Then fit the discharg e using the mass balanced feed rate and sizing . (Use Whiten SDs for the prod uct size distribution). If an ore specif ic breakage function is available, it should be used. the mill constant (MC) and the three select ion function parameters can be fitted. For fitting, set the simulated and original mill dimensions etc. to the same values. Check the experimental feed 90% passing size a nd input it. Use a measured work index if available - an approximate one if not. This mode l is fussy a bout initial estim ates and some trial and error may be needed. These guidelines will help for many cases. If you are new to the rod mill mod el use the rod mill example in Chapter 3 and graph the output to g et a feel for how XC, SL and IN interact a nd change the shape of the product curve. Set XC to about half of the top size of the mill feed and MC to 2000. Assume a selection value of 0.1 at XC and 1.0 a t the fee d top size. Calculat e slope an d intercept to suit. Try a simulation with these values. If the product distribution is approximately the right shape, (plot as cumulative percent pass ing both simulated and experimental products) fit the rod mill constant. If the shap e is very different, increase the assu med selection value for a steeper product slope and proceed when the slope is similar. If the fitting program finds a reasonable minimu m, - that is, the mill constant error is less than 2 0% - change the MC estim ate to the new value an d fit the slope. If the sum of squares decreases, update the SL guess to the fitted value and fit XC and IN also. 8.2.2.7

Referen ces

LYNCH, A.J., 197 7. Mineral crushing and grinding circuits, (Elsevier, Amsterdam), 51-60.

8.2.3

Perfect Mixing Ball Mill (Model 420) Perfect Mixing Ball Mill Model

Comminution Models

A new feature introdu ced with Versio n 5.2 was the extension of the ball mill model to include a grate discharge optio n. Ball mill power is now calculat ed for both overflow and grate discha rge options (using the Morrell Power Model) and is displayable in an information block.


Model Descriptions

8.2.3.1

361

Model Description

This model considers a ball mill as a perfectly mixed tank with contents described by a vector size distribution s. The product vector p is produced by a disch arge rate di for each size fraction, where D is a diagonal matrix of rate s, that is: s

*

D =

p

(A8.1)

Within the mill, two factors control bre akage. The first is the rate of selection of each size for br eakage. The second is the way in which the selected particles are broken (or appear) in the mill contents. Selected = R * s where R is a diagonal matrix of rate s. Appearance = A * s where A is a triangular matrix of breakage (appearance) functions (distributions). At steady state, the m ill feed minus the material selected for breakage plus the material from breakage minus the material disch arged must equal zero. This can be written a s: s+ R -s*fD -R = A **0 Discharge Rates

(A8.2)

For overflow mills an d most of the operational range of grate discharge mills, the discharge elements can be approximated by: 2

(A8.3)

Di = Di* 4 * v / (d * l) where Di* is close to unity v is the total volumetric mill feed rate d and l are mill diameter and length A typical discha rge function is given in Figure A8.1.

Typical graph of m ill discharge function Breakage Rates


Breakage rates tend to increase rapidly with particle size, with the increase tapering off at the feed top size.

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Typical graph of breakage rate factor Appearance Function

8.2.3.2

The appear ance function A is ore dependent, a nd can be measur ed using the drop-weight testing technique developed at the JKMRC. A table of appearance fu nctions for a variety of ore type s and the associate d operating work indices is given in section A8.7. The standard Broadbent-Calcott appearance function is also included.

Model Equat ion s

Considering equation 8.1 as the elements of each vector and matrix yields: ( A 8. 4 )

i

ARij s-j D j

fi - Ris i +

=i0 si

j=1

and: p i = Di s i

(A8.5)

Substituting for si yields: i

A ij fi - pi + j=1

Rj

pj- pi = 0

(A8.6)

Dj where feed and product are related by R/D for a particular breakage function. Equation A8.3 can be used to scale for feed rate and mill dimensions. In general, the mi ll content s s is not know n and it is not possibl e to separate the R/D* ratio into its components. The R/D* function is represented internally by a cubic spline function (t hat is, by a smooth curv e). A n umber of spline knots (generally between 2 and 4) on the 1n(R/D*) function are fitted. Scaling

Scaling of the ball mill model is achieved by modifying the fitted R/D* function according to dimensions and operating conditions as described below.

Mill Diame ter

The mill diameter d is scaled.

Comminution Models


Model Descriptions

363

FACTA =

Note: This factor is in addition to a direct vo lume effect which is built into the model. Load Frac tion

The load fr action LF is the volume of mill occupied by charge and media at rest when the load is ground out. FACTB =

Fraction Critical Speed

(1 - LFSIM ) . LFSIM (1 - LFFIT ) . LFFIT

Fraction critical speed is scaled by:

FACTC = 55% < CS < 78% Work Index

The Work Index is scaled by: FACTD = 0.8

Ball Size Scaling

By assuming that the reductio n mechanisms of impact an d attrition occur in a ball mill, the following relationships can be derived from theoretical considerations. Impact breakage Attrition breakage

Db3 1/Db

where Db = ball top size diameter. Impact breakage is assumed to predo minate above a certain size xm whilst attrition is the main reduc tion mechanism at sizes below xm . The size xm is ass umed to be equivalent to that at which maximum breakage occurs. Size xm can be related to ball diameter as follows: xm

= K * Db2

where K is the maximum breakage rate factor. The va lue of K has been found to be of the or der of 4.4 E-04. K can be calculated from the formula above if the value of x m is known. The graphing facility within JKSimMet allows easy graphing of the breakage rates to determine this value. xm (fit) and xm (sim) are both calculated. The smaller of the two is denoted xm (small) and the larger as xm (large) . The abov e relati onships are used to s cale R/D* value s at each spline knot to account for ball size effects. The sca ling factor for ball siz e effects depends on the knot position size. for knot position size < xm (small)


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1 FACTE

Db SIM 1 Db FIT

Db

FIT

Db

SIM

for knot position size xm (large)

FACTE

2

Db

SIM

Db

FIT

For knot positions betw een xm (small ) and xm (large) linear interpolation is used. The effect of ball size is shown in the diagram below.

R/D* Relationship with Ba ll and Particle Size Scaling Calculation

These factors are applied to each fitted 1n (R/D*) knot as follows: R/D*SIM = R/D* FIT • FACTA • FACTB • FACTC/FACTD • FACTE

Scaling Using Breakage Functions

Comminution Models

Where characteristic br eakage functions h ave been measured (i.e. pendulum tested) for both ores, these breakage functions may be used to predict performance. Note that it is not val id to scale this way fr om the default breakage function.


Model Descriptions

8.2.3.3

365

Ball Mill Model Printout

Ball Mill Model Printout Showing Default Values 8.2.3.4

Symbo ls


Sym bol

Mea ning

f

feedsizedistributionvector

p

product s ize distribution vect or

s A

millcontents size distribution vector appearance function lowermatrix

R

breakage rate function diagonalmatrix

D

breakage discharge function diagonal matrix

D*

normalised discharge function

* R/D SIM

normalised R/D ratio for simulated mill

R/D* FIT

normalised R/D ratio for fitted mill

dSIM

diameter of simulated mill

dFIT

diameter of fitted mill

LSIM

length of simulated mill

v

volumeflowrateoffeed

LFSIM

load fraction of simulated mill

LFFIT CSSIM

load fraction o f fitted mill fraction critical spe ed of simulated mill

CSFIT

fraction critical sp eed of fitted mill

WISIM

work indexof ore for simulated mill

WIFIT

work indexof ore for fitted mill

Db

balldiameter(topsize)

DbSIM

ball diameter for simulated mill (top si ze)

DbFIT

ball diameter for fitted mill (top s ize)

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K

8.2.3.5

maximumbreakage rate factor

Known Restrictions

Change in Coarseness of Feed

It is known that the coar se end of the R/D* function does vary with gross changes in the amount of coarse material in the fe ed stream. As the a mount of coarse material in the feed is decreased, the relevant R/D* values increase. This limit ation is not conside red significant for change s of less than plus or minus 50% in the amount of coarse material in the feed.

Critical Spe ed Range

The critical speed dependence is approxi mately valid for 55 -78% of critical speed and incorrect outside of that range.

Predicting Rates at 'Missing Sizes'

If the ball mill model does not produce any of a coarse fraction (i.e. none in the mill dischar ge) then the eff ective rate of grinding is 'infinite'. One way to overcome this problem is to size the mill contents and expand to the perfe ct mixing model used for the SAG mill model. This is usually not experimentally convenient. approaches a re to:

Some more practical

Test the m ill at maxim um tonnage with coarse f eed. If there is any coarse material in the discharge, the actual rates c an be estimated. Use a s et of rates and knot values from the supplementary information for a similar mill feed sizing and fit with Work Index alone the first time. Transfer the coarse rate value s from calc to exp, ret urn the Work Index to its original value and ref it the two smalle r rates. This procedure should give reasonable answers wit h a coarser feed. Work is proceedi ng on improving High Mill Viscosity or Pulp Density

the ball mill model in this area. The perf ect mixi ng mill mode l only take s account of pulp density variations as variations in mill volume. Therefore, highe r pulp density will always predict highe r grinding rate s. In pract ice, the rates do improve until pulp viscosity begins to interfere with ball action and rates decrease rapidly. This onset is difficult to predict as it is highly ore type dependent. However, effective mill operation of greate r than 50% solids by volume is unlikely an d improbable at greater than 60% solids by volume.

Ball Size Scaling

The ball size scaling relie s on the R/D* funct ion exhibit ing a maximum. If there is no maximum in the fitted R/D* function, increasing the ball size will give optimistic results.

Wide Range Size Data

The mill model ass umes a constant break age functio n for all size fractions. This assumption simplifies the model but experimental evidence suggest strongly that partial breakage increases in severity with decreasing size down to some limiting size. Therefore, if more than (say) twenty size fractions are considered, an apparent minimum rate may be produced in the finer ranges. This phenomenon is more likely to be an artefact of an incorrect ass umption than to have any physical signif icance. Research work continues in this area.

Comminution Models


Model Descriptions

8.2.3.6

367

Fitting the Perf ect Mixing B all Mill Model

Parameter Menu The ball mill model is well-behaved for model fitting. It can be fitted in closed circuit with the cyclo ne model with generally better results than by fitting each model to mass balance d data. Hence a goo d closed circuit fit will also provide a good mass balance estimate of circulating load. R/D* Spline Knots

Use thre e knots for normal grinding conditions and four knot s for a wider than us ual siz e range (such as SAG mill discharge or a very f ine product).

Knot Positions

To determine an appropriate set of knot positions divide the number of size fractions covering the feed size distributio n by the number of knots plus one. This will give about equal log size s paces from both ends and between knots.

Knot Estimate s

Estimates for the functi on values at the knot positi ons are prov ided as ln(R/ D*) values. A simple ascendi ng series provides a good first estimate, for example: 0.5, 1.5, 2.5

Work Index, Load Frac tion

If you have several sets of data, use an operating Work Index for each (calculated fro m mill fee d rate, mill power, feed and product 80% passing sizes). If the major v ariation is hardness only, the n the average knots can be used. The calculated R/D* values are displayed on the unit data entry screen. There should be a smoo th increase with size. Sometimes the curve will h ave a maximum at the coar se end. If the re are any sudden changes or ups and downs, try adjusting the knot positions. There will often be a bump at a change in size measurement techniqu e, such as the trans ition from screen sizing to Cyclosizer sizing. Systematic deviations can sometimes be removed by a djusting a knot towards the largest deviation.

8.2.3.7

Graph Cumulative Simulated a nd Experimental Product

When nothing else work s, plot the experimental feed and product on a coarse scal e (say 0-30 %) pe rcent retained against log size. If there are any large discontinuities, check you r data very carefully, a nd repeat your sampling if possible.

Master/Slave

The perfect mixing ball mill model is well suited to fitting of multiple data

Fitting

sets. The ln(R/D *) knot values can be fitted simul taneously for a number of surveys. Ensure that yo u use the same knot posit ions, and number of knots, for each mill in your master/slave fitting test.

Table of Appearance Functions

This table sh ows ore-specific appearance function values determined from single parti cle break age tests using JK breakage testers – pendulum or dropweight.


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Ball milling circuits from which the samples were collected

Size Interval

Massiv e Sulphid e (Ni)

Massiv e Sulphid e Coarse

Porphy ry Hard

Porphy ry Soft

(Cu)

(Cu)

Massive Sulphid e Fine (Pb-Zn)

(Pb-Zn) 1

0.0591

0.0505

0.08586

0.05220

0.1128

2

0.1052

0.0974

0.1248

0.09919

0.1490

3

0.1318

0.1276

0.1387

0.1288

0.1497

4

0.1295

0.1278

0.1278

0.1284

0.1250

5

0.1127

0.1128

0.1076

0.1129

0.09885

6

0.0927

0.09469

0.08722

0.09423

0.07866

7

0.07486

0.07810

0.06960

0.07727

0.06289

8

0.06082

0.06428

0.05540

0.06339

0.04943

9

0.05005

0.05316

0.04428

0.05239

0.03842

10

0.04166

0.04424

0.03574

0.04364

0.03003

11

0.03462

0.03666

0.02899

0.03623

0.02376

12

0.02723

0.02880

0.02278

0.02847

0.01865

13

0.02054

0.02171

0.01743

0.02146

0.01448

14

0.01537

0.01623

0.01325

0.01604

0.01120

15

0.01144

0.01207

0.01004

0.01192

0.00864

16

0.00849

0.00894

0.00758 1

0.00883

0.00664

9.0

13.6

12.2

15.9

Operating Work Index 12.8

Ball milling circuits from which the samples were collected Size Interval

Quartzit e Sulphide Low Grade (Cu)

Comminution Models

Porphy ry Soft USA (Cu)

Massiv e Sulphid e (Cu, Pb, Zn)

Massive Sulphid e (Pb, Zn, Cu)

Standar d Functio n


Model Descriptions

369

1

0.09514

0.0501 3

0.1171

0.1081

0.193

2

0.1322

0.0970

0.1537

0.1442

0.157

3

0.1417

0.1273

0.1522

0.1472

0.126

4

0.1267

0.1276

0.1247

0.1253

0.101

5

0.1049

0.1128

0.09723

0.1006

0.082

6

0.08477

0.0948 1

0.07685

0.08050

0.066

7

0.06778

0.0783 2

0.06131

0.06444

0.053

8

0.05371

0.0645 1

0.04810

0.05076

0.043

9

0.04244

0.0533 6

0.03729

0.03958

0.035

10

0.03379

0.0443 8

0.02911

0.03103

0.028

11

0.02709

0.0367 7

0.02303

0.02459

0.022

12

0.02127

0.0288 8

0.01810

0.01929

0.018

13

0.01637

0.0217 7

0.01407

0.01496

0.015

14

0.01254

0.0162 8

0.01089

0.01155

0.012

15

0.009565

0.0121 1

0.00841 3

0.00888 8

0.010

16

0.007279

0.0089 68

0.00648 3

0.00682 5

0.008

10.2

14.1

13.5

Operating Work Index 14.1

8.2.3.8

Referen ces

LYNCH, A.J., 1977. Mineral crushi ng and grinding cir cuits, Amsterdam), 309 -312.

(Elsevier,

WHITEN, W.J., 1976. Ball mill simulation using small calculators, Proc. Australas. Inst. Min. Me tall., 258, 47 -53. MORRELL, S. 1992. Ball size effects in ball mills. Chapter 2, End of project


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report, AMIRA/JKMRC Project P9J. "Simulation and Automatic Control of Mineral Treatment Processes".

8.2.4

SAG Mill (Model 430) AG and SAG Mill Models

8.2.4.1

This ch apter contains a description of the AG and SAG Mill models.

Model Description

The JKMRC h as been involved in the development of a model of autogenous and semi-autogenous grinding for many years. The first model to provide useful predictions was the Leung mode l (Leung, 1987). It used ore- specific breakage functions obtained off-line using a laboratory test procedure. It has largely been superseded by the Variable Rates model( see Appendix 11). However, because of its relative s implicity, the Leung model provide s a good introduction to SAG mill modelling. Caution: The Leung model scales on volume. This is irrelevant for optimisation but is important for scale up from pilot to full scale mills of more than 8 to 9m in diameter. The power model (Morrell, 1991 ) was a dded in 19 92. The Leung model has the general structure shown in Figure A9.1. appearance function has two components:

The

high energy corresponding to impact breakage, determined from the twin pendulum single particle bre akage apparatus, a nd low energy correspond ing to an abrasion mechanism, determined from laboratory tumbling tests. In both cases the functions are obtained off-line on representative samples of ore and do not rely on being simultaneous ly back-fitted to operating data. The energy levels a t which the high energy appearance function is determined are based on the mean energy in the mill, which is related to mill diameter. Discharge rates are determined as the product of the rate at which the load is presented to the grate, dmax, and the classi fication at the grate (which is represented by a simple classification functio n). The model iterates to s elect a value of dmax equal to the fraction of mill occupied by material of a size less than the grate size, which in turn is a ssumed to be a simple power function of feed rate expressed as a proportion of mill volume. The model predicts produ ct size distrib utions and mill loads from a known feed size and tonnage for a given mill and feed ore. Ball charge is incorporated through the assumption that balls are equivalent to mill load particles of equal mass. Average breakage rates are provided as defaults for both the autogenous a nd SAG mill models. Note that the se rates are different and are based on a limited data set. Usually, breakage rates will be model fitted to plant data. Limitations / Cautions

Comminution Models

This model is a significant development of earlier models, and has been shown to be successful in describing operating data on full scale autogenous


Model Descriptions

371

and SAG mil ls. Its scale -up capab ility is limited to mil ls up to 8 to 9m in diameter from pilot mills of up to 2m. The dependency of the model parameters on operating conditio ns such as mill s peed, percent solids, grate open area, liner charact eristics and pulp rheol ogy was not well establ ished when this model was developed. Most of these issues are addre ssed in the Variable Rates model(A13) The Leung model is based on data from mills operating at approximately 70% of critical s peed and 60 -70% solids by weight in the feed.

Autogenous Mill Model Structure 8.2.4.2

Equatio ns - Partic le Breakage

Particle Breakage

This description follows the s tructure shown in figure A9.1. The model assumes that each size fraction experiences only one energy level of breakage. (The reality will certainly be a distribution of energy levels).

High Energy

The rel ationshi p between the amount of breakage and the input energy is

Breakage

described by t10 = A (l - e- b Ecs )

(A9.1)

where t 10 is the perce ntage of t he broken pa rticle which will pas s through a screen of one te nth the size of the original particle, and Ecs is the energy absorbed per unit mass during breakage measured in kWh/t. A and b are the parameters which charact erize this equation for a particular ore. A is usual ly taken as 50. Parameter b is derived from a drop-weight breakage test of clo sely sized ore particles. Required sample size varies


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according to or e variability. However, as a guide, about 50 kg of 50 mm material is needed. Low Energy Breakage

One or more 3 kg samples of 50 mm natural ore are tumbled for 10 minutes in a s mall dry m ill at 70% of critical spee d. The prod ucts of each run are sized and t 10 is measured for each run. Where 50mm material is not available, other sizes are used and adjusted using a simple linear model. The t10 data are fitted to t10 = a0 + a1 *mean size+ a2 *samplemass + a3 *time.

(A9.2 )

The actual value of the abrasion pa rameter ta is one tenth (scale factor only) of t10 : based on top size of 50 mm, mass 3 kg and time 10 minute s. Low Energy Appearance Function Abrasion

The size distributions produced by ore s tested to date have a similar shape. This shape can be scale d to the ta factor that is the per centage passing one tenth of the srcinal particle size. A cubic spline function is used for smooth in terpolation. A 100mm particle is chosen as an example as particles of this size will typically under go abrasion rather than crushin g breakage. Parameter ta is taken as 1 .0 to make the scaling obvi ous. size(mm) value t

scale*

%passing

100

100

t

1.25

2.687*ta

80

2.687

t

1.5

1.631*ta

67

1.631

t

10

1.0*ta

10

1.0

t

100

0.9372*ta

1

0.9372

t

250

0.8070*ta

0.4

0.8070

t

500

0.6365*ta

0.2

0.6365

The example shows that most of a 1 00 mm particle remains unbroken. This value of t is as sumed to be equal for all s ize fractions. Breakage Energy

As the charge provides the grinding media, the level of available energy is related to the coarse fraction of the mill charge. The av erage size of t he top 20% of the charge is used as the highe st energy reference level. S20 = (p100 * p98 * p9 6 ... p80)

1/11

(A9.3)

and the potential energy at the full height of the mill E1 = 4/3 .

Comminution Models

. (S20 )3 g D

(A9.4)


Model Descriptions

373

where D is mill diameter in metres. An a ssumption due to Austin et a l (198 4) is used to relate o ther energy levels to E1. Austin et al prov ided a rationale for energy levels in mills to be related by E particle

1/(x) 1.5

(A9.5)

where x is particle diameter. Hence, the energies experienced by smaller sizes are scaled using this relationship. This allows an Ecs to be calculated for each size and t calculated from equation (A9.1). High Energy Appearance Function (Crushing Breakage)

Once the energy of breakage is known, the distribution the particle breaks into can be described by a cubic spline surface. splineknotst =

0.0

10.0

30.0

50.0

function values for t2

0.0

50.53

92.49

96.47

t4

0.0

23.33

61.58

82.86

t10

0.0

10.00

30.00

50.00

t25

0.0

4.975

15.62

25.88

t50

0.0

3.064

9.412

14.71

t75

0.0

2.325

6.893

10.32

For example, for a 50 mm particle, a t of 30 would produce this distribution. %passing

Combined Appearance Function

Size(mm)

50

100

t2

25

92.49

t4

12.5

61.58

t10

5

30.00

t25

2

15.62

t50

1

9.412

t75

0.67

6.893

As noted earlier, the abrasion distribution does not vary with particle size while the crushing breakage is h ighly dependent on particle size. Hence, abrasion will tend to dom inate for coarse particle s and impact for fine particles (from equation (A9.5)). To generate an a ppearance function for e ach size fraction, the high and low energy appearance functions are combined proportionally. a=(tLE*aLE+tHE*aHE)/(tLE+tHE)


(A9.6)

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JKSimMet V6 Manual

where aLE and aHE = low and high energy appearance functions, tLE and tHE = low and high energy t values Equations (A9.1) to (A9. 6) combined with the two tables of spline knots yield a complete appear ance function (that is how each component will break) for each size in the mill load. Breakage

To predict a product from the mill content s and the appearance function

Rates

requires only a rate of selection for breakage for each size fraction of the mill load. These rates will be inherently scaled because the mill load will be constrained by mill dimensions and the mill diameter (if the energy versus breakage assumpt ions are correct). These rates will cert ainly vary if mill speed is ch anged but this dependence is not included in the Leung model. To describe these rates, a five knot spline function is used. Best fit values to data are tabulated. Splineknots(mm)

ln(Rateof Breakage) Autogenous

ln (Rate of Breakage) SAG

0.250

2.63

2.176

4.00

4.04

4.444

16.0

3.32

3.577

44.8

1.98

2.753

128

3.37

4.082

These are the default values in each model. These rates are fitted to customize the model to an y particular operating mill. The ball charge is approximated by a distribution of equivalent weight particles added to the mill load for the high energy breakage calculat ion (equation (A9. 3)). That is, only the a ppearance funct ion will be varied by the addition of balls.

SAG Mill Modification

This completes the description of the Breakage area of the model. 8.2.4.3

Equations - Mass Transfer and Discharge

The mill grate is mod elled as a very s imple classifi er. When this model was developed the relationship between the classi fication, discharge and the operating conditions was not well defined. Hence, the clas sifier/discharge is assumed to b e const ant- for other than minus grate size hold up. A simple form is used.

Classification

1

=

D

x

<

x

D = [ ln(x) - ln(x g) ] / [ ln(xm) - ln(xg) ]

Comminution Models

m

(A9.7)

xg > x > x m


Model Descriptions

375

where x m is the particle size be low which it will always pass through the grate if pre sented to it - that is, behave lik e water. x g is the size of the grate through which the largest particle s will p ass through. Pebble Port Modification

Pebble port allows a small discharg e rate of substantially coarser pa rticles. This modification aff ects the clas sification curve as s hown below.

Pebble Port Effect on Classification Curve

xp is the notional size of the pebble port fp is the noti onal fraction open area of the pebble ports compared with the fraction of grate open area. Typical values for fp are 2 to 5% ie. 0.02 - 0.05. While this modification gives a good description of pebb le product, the areas are notional only and in fact reflect relative discharge rates. Discharge Rate

The quantity of pulp discharged will depend on the quant ity per unit tim e presented to the grate multiplied by the classification function. d = dmax * D where dmax is the fraction of the load presented to the grate per unit time and D is the clas sification function. The water is a ssumed to follow the sub mesh particles. The actual value of D is found iteratively. The required value satisfies the following empirical mass trans fer law (Austin, 197 6).

Mass Transfer "Law"

The value of dmax is adjusted until the model prediction matches the required one. That is, until it lies on the operating line of L = m1 Fm2

(A9.9)

where m1 = 0.37 m2 = 0.37 L is the fraction of the active volume of the mill occupied by minus grate size material and F is the total volumetric feed rate per minute divided by the


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active volume of the mill. Perfect Mixing Mill Model

The perfect mixing model at steady state provides the structure to combine the various components of the model. It relates the different parts in the following manner.

fi - ri si +

( A 9. 1

- di s i = 0

0) (A9.11)

pi = di * si

where fi, si, ri, di and p i are feed rate, contents, breakage rates, disch arge rates and p roduct rate vectors a nd a ij is the combined appearance function. The form of equat ions (A9.10) and (A9.11) allows both the mill load and the product to be calculat ed for any mill load and discharg e rate adjuste d until equation (A9.9) is satisfied. Calculation s equence: 1. Calculate breakage rates 2. Calculate volume of below grate size mater ial in the mill, L 3. Calculate discharg e rate 4. If error is acceptable exit else m ake correction to Dmax

8.2.4.4

Mill Load

This model is unusu al because it uses an internal port to descr ibe the mill contents. This port is acces sible from the model properties drop down or from the model window. It does not appear as stream equipment.

Scaling

This model is inher ently scaled for mill diame ter and volume. This scaling optimistic in capacity as mill diameter is in creased. It is reasonable for mills of up to 8 to 9 m diameter.

Predic tion of AG/SAG Mill P ower D raw

The Grinding Mill Power

The gross power draw of the mill is that drawn by the mill motor(s), ie metered power. It is assumed that this has two components, viz net power, ie. the power delivered to the charge no-load power, ie. the power to overcome drive train and bearing losses. The gross power can, therefore, be represented by the following equation Gross PowerDraw =No-LoadPower+NetPower

(A9.12)

The gross power draw is calculat ed from the fraction critical speed, ball SG and b all and ro ck por osity. These data are provided by the user. The calculations us e pulp load data generated by t he model calculations. The model data entry screen section for the power calculations include the 'net powe r adjust ment fac tor'. This is a calibration constant which varies slightly from mil l to mill depending on mill liner configuration and other factors. Users are strongly recommended to leave this value set at 1 .21. Other values

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377

should not be used unless a comprehensive range of load vs power data are available. Net Power Draw

From photographic evide nce, the cha rge shapes shown in Figure A9.2 were ass umed to occur in grate discharge mills.

Simplified AG/SAG Mill Charge Sha pe

By considering an ele ment in the c harge of cross sectional area r ds d and Len, the to rque inertia of the element can be represented by the following equation. Torque Inertia of Element = g Len

r2 c os d dr

(A9.13)

Power can be def ined in terms of t orque ( ) and rotational rate (N) as follows: N Power 2 =

(A9.14)

For grate discharge mills, by integrating bet ween the limits

s

and

T

and

between ri and r m the net power (P net) is given by: rm

S

N r r 2 cos d .dr

Pnet = 2 gLen ri

No-Load Power

(A9.15)

T

The no-load power draw (i.e. t hat drawn by the mill when completely empty), is associated wit h various electrical and mechanical energy losses. The main ones are mot or, gearing and bearing losses. None of the se are fixed over the full mill operating range. Some, however, may have a fixed com ponent. For example, bearing losses due to friction will be dictated by the mill's dead weight (though even this will vary as liners and lifters wear), and the mill charge weight which will clearly vary with grinding condition. To determine the relationsh ip between no-load power and mill design parameters, data from pilo t a nd industrial mills ranging from 1.7 to 7.2 m in diameter wer e analysed. However, these no-load powers are difficult to measure preci sely. The probl ems are power fact or effects at low loads an d achieving a completely empty mill. The parameter Diam3Len N was


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regressed against no load power and found to provide a good fit (Figure A9.3). The relationship developed was as follows with N converted to the fraction of control speed: No Load Power (kW) = 2.62 (Diam2.5 L en )0.804 Hence, this equation estimates the likely indicated no-load power for an installed mill.

Indicated vs Fitted No-Load Power Power Calculation Accuracy

The most recent JKMRC database currently includes power data from 63 different mills. Details are shown in Ta ble A9.1.

Ball Mills Diameter(m)

0.85-5.34

AG Mills

1.80-9.59

1.8-9.50

Belly Length Inside Liners (m)

1.52-8.84

0.59-7.95

0.59-5.18

Length/DiameterRatio

1.00-1.83

0.33-1.50

0.33-1.0

PercentofCriticalSpeed(%) BallFilling(Vol%)

60-83 20-48

TotalFilling(Vol%)

Number Mills of Number of Data Sets PowerDraw(kW)

48-89 0

7-38

2.6-4.6 38

10-31

2.6-4.1 20

41

2.7-4.6 5

28 6.8-4100

72-75

3-25

20-48

SpecificGravityofOre

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SAG Mills

7 14.8-7900

12.55500


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379

The pow er model has been applied to this database and was found to giv e excellent results. The standard deviation of the relative error of the model was calculated to be 6.5% for gross power.. The model therefore requires a knowledge only of mill dimensions and speed, ball charge, volume occupied by balls and pulp, and the ore specific gravity. Full details of the model are given in Morrell (1991). Because of the industr ial database, the prediction of gross power is the most reliable. Restrictions


This power m odel ass umes the SAG mill grate and pulp lifte rs do not limit pulp thro ughput. For a large diameter mill (say > 7 m) in closed circuit with hydrocyclones or fine screens, this as sumption may not b e justified. A build up of fine slurry in the mil l will remove some of the charge imb alance and reduce the actual power draw.

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8.2.4.5

JKSimMet V6 Manual

SAG Mill Printout

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SAG Mill Printout

Model Descriptions

8.2.4.6

381

Symbo ls

Sym bol

Me aning

aij

fraction of s ize j which breaks into size i

A

Ecsmodelparameter

b

Ecs model parameter

dmax

discharge rate at xm

di

discharge rate of size i

fi

feed rate of size i

Ecs

Energy absorbed per unit mass during breakage in each size fraction

E1

particle potential energy at full height of mill

F

volumetric feed rate/mill volume

HE

High Energy

LE

Low Energy

L

mill volume fraction of minus grate size

m1, m2

mass transfer parameters

si

mill contents of s ize i

r j

rate of breakage out of size j

S 20

average size of top 20% of mill load

t10

percentage which passes through a screen aperture of 1 0% of the srcinal size.

tp

percentage which will pass through a screen of aperture srcinal s ize /p

t

abrasion parameter

a

x i

particle size

xg

grate size (mm)

xm

size below which all will pass through the grate (mm)

g

gravitational cons tant charge density

r

radial position of element angular position of the element

Nr

rotational rate at a radial distance r

rm

mill radius

r i

charge surface radius (see Figure A9.2)

s


angular position of the shoulder

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r

angular position of the toe

Diam

mill dia meter (m)

Len

mill length (m) fraction of critical speed.

8.2.4.7

Known Restrictions

The model is not valid out side a range of 55% to 75% solids by weight in the feed. Mill speed is a ssumed to be 70% of critical or clo se to it. However for small changes in s peed (~ ± 5%) a good a pproximation can be made by multiplying the rate at each knot by the relative change. That is, for +5% (ie. 70% increas ed to 73.5% critical) multiply by 1.05 or add ln (1.05) to the logarithm of the knot value. This assu mes the number of im pacts per mill revolution will not change. In reality more speed will give more lift and a slightly higher breakage energy. The classification model is ve ry simple and only depe ndent on grate size. The xm parameter is driven by slurry viscosity. For viscous ores, xm may be up to 1mm. For clean ores (hard rock, clay free) 0.1-0.2mm is typical. This model has been tested against a large number of full-scale operations and a very wide range of pilot plant test data. The model has p rovided good predictions for design (Morrison, Kojovic and Morrell 1989) over a wide range of ore types. Detailed comparison with pilot plant data has highlighted areas where the model ass umptions a re not a sufficie ntly good approximation. Known areas to treat with caution are as follows. The assum ption that gr inding rates are const ant at a given ball load is not true when there are large v ariations in mill feed sizin g the mill is taken from open circuit to closed circuit. Opera ting Limits

The model is numerically stable at any mill load (equation (A9.9)). Real world mills typically operate with maximum loads of 30 to 35% by volume of charge. However, they may be limited by motor power a t much lower loads. There is usually a limit on ball load of 5 to 10% because of me chanical or power constraints. It is the engineer's responsibility to check these parameters against the limits for a particular mill.

Feed Sizing

The auto/S AG model 'forms its load' from the mil l feed. If the mill feed size distribution is smooth (ie. a reasonably straight line on a Rosin-Rammler plot), simulated variations in feed s izing give sensible result s. If the coarse end of the feed distribut ion is artificially a djusted for the feed is preclassified in some way, then the S20 assumption that the load can be treated as a single number becomes unjustified. Hence artificially adjusted to p sizes will c ause the model to predict wide variations in performance. (While these var iations are excessiv e, it should be n oted that real auto mills are also sensitive to feed top size).

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383

Similarly, if those fract ions that limit throug hput (notional critical size) are prescreened from mill feed, the model will be optimistic about increased throughput. (Once again, real SAG mills will also achieve much higher throughputs). However, predictions for recycle crusher are quite realistic. If mill operation is closed with a fine classifier (D SM s creen or hydrocyclones) there is usual ly an increase in the observed grinding rat es at 4mm. This means a typical SAG mill m ay have some 'free ' grinding capa city for particles acircuit few millimetres in diameter. Where the simulated mill is operating with a screen, the cir culating load will tend to vary more (and in theclosed mill load less) with changes in hardness and feed sizing than the real mill. However trends will be correct and overall product sizing should be close. Mill Power

Accurate measurements or estimates of mill dime nsions, s peed and ball and pulp load are r equired for the power calculat ion. Ensure that a ll data used are accurate.

Ball Size Effects

Ball effect is estim ated by ge nerating an equivalent load of ore particles. As the top 20% of t his load is used to find S20, only the top one or two ball sizes can have any 'imp act' on this calculat ion. Manipulating the finer ball s izes (ie. < half top s ize) have v ery little effect. In practi ce, it does change the fine grinding rates.

Ball Load Effects

These have bee n investigated in s ome detail at pilot scale. In general, the harder the ore (low b and low ta) the less the grindi ng rates are affe cted. A soft ore howev er follows the accepte d wisdom that increasing ball load will produce a coarser prod uct. This may well be b ecause the increased n umber of balls are now breaking the ore particles in the load which were doing the fine grinding.

Discharge Rates

Considerable work has been carried out by Morrell (1990 ) on factors affecting discharg e rates. These ef fects are also summarised in Morrell and Morrison (1989). See A11 for details. Overall, discharge rates will only become a limiting effect in very high viscosity ores. In this case, operation at a lower pulp density is recommended. The SAG mill is an effective pump and the charge will remain relatively 'dry'.

Mill Liner Effects

The SAG mill model is valid for correctly designed traditional 'high/low' lifter type action. Wave liners or sh ort lifters do n ot provide enough lift to achieve the default rates. If poor lift is combined with poor discharge , the mill only produces abrasion with a very fine product at a correspondingly low throughput.

Further Developments

The JKMRC now has a substantial database of SAG/auto mill surveys and breakage characte ristics. This data base has been used to develop the wider

Mill Load Limits

8.2.4.8

range variable rates AG/SAG model described in Appendix 11 The autog enous and SAG mill model does not include an explicit maximum for the mill load. However, a warning will be flagged if the total load (ie. balls and pulp) exceeds 40 % by volume. If the total load exceeds 60% by volume an error will be flagged and the model calculations will be stopped.

Fitting the Autogenous & SAG Mill Models

XG


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XM Rate Rate Rate Rate Rate

1 2 3 4 5

Parameter Menu These models are complex and calculation intensive. However, any computer which is suitable for MS Windows 95/98/NT should be adequate for AG/SAG model fitting. In the unlik ely event that the fit is slow, the Sel ect list may be used to restrict the scope of calculation or to fix recycle streams as “feed” streams. Initial Va lues

Use the grate wi dth and 100 µm as initial estimates fo r x g and x m. The default breakage rat es for auto and SAG will provide a good guess for each knot value.

Ore Type Parameters

For accurate results, these are best derived from tests carried out on representative samples at JKTech. For an existing operation, the values provided in the volume of supplementary information provide some guide to possible values.

Mill Load

If a reasonable estimate of load mass and sizing is available, then fitting with a range of A and b values may provide a way of estimating these values - that is - use the values which give the best fit for ratio work. Mill Load is fitted by input ting it as raw data into the dummy produ ct stream. If you only have a total mill load estimate (e g. from bearing pressure), set the size fraction SDs to zero and the load SDs appropriately. Subtract the weight of balls from this load for a SAG mill and in put it on the mode l screen.

Closed Circuit Operation

If the mill is being operate d in closed circuit with hydro-cyclones, it is better to re duce m1 from 0.37 to 0.25. This seems to provide a better approximation of the mass transfer respo nse for a large recirculation of material finer than grate size.

Knot Positions

The spline knot posit ions are better left where they are for the 'n ormal' range of SAG mill feed sizings, 80mm < F80 < 250 mm. However for very fine auto mill feeds, the limiting size fracti on will als o be finer and it may help to scale down all the knots. That is, reduce them by the same ratio. An alternative is to simply fix the larger knots at their default values. Hint: If the closed circuit simu lation gives a very different circulating load, check carefully for size biases in the fit or in the data itself.

Master/Sla ve Fitting

Comminution Models

The Maste r/Slave fitting can be used with multiple sets of SAG/auto data. Ensure that you are using the same knots positions for each mill in the test. Similarly, each survey data set to be fitted simultaneously should ha ve been collected with the same grate and pebble port size, and ball load.


Model Descriptions

8.2.4.9

385

Referen ces

AUSTIN, L.G., LUCKIE, P.T. and KLIMPEL, R.R., 1984. The process engineering of size reduction: Ball Milling, S.M.E/A.I.M.E., NEW YORK: 561pp. AUSTIN, L.G., WEYMONT, N.P., PRISBREY, K.A. & HOOVER, M., 1976. Preliminary results on the modelling of autogenous grinding. 14th Int. A.P.C.O.M. Conf. The Penn. State Uni.: 207-226pp. LEUNG, K., 1987. An ener gy base d ore specific model for autogenous and semi-autogenous grinding. Ph.D. Thesis, unpublished, University of Queensland. LEUNG, K., MORRISON, R.D. and WHITEN, W.J., 198 7. An energy based ore specific model for autogenous and semi-autogenous grinding. Copper 87. Chilean Institute o f Mining Enginee rs, Santiago, Chile. MORRELL, S. 1990 . Simulation of bauxite grinding in a semi-autogenous mill and DSM screen circuit. MEng Thesis, University of Queensland (unpublished). MORRELL, S. and MORRISON R.D. 1989. Ore charge, ball load and material flow effects on an energy based SAG mill model. SAG Conference, University of British Columbia, Vancouver. MORRELL, S., NAPIER-MUNN, T.J. and ANDERSEN, J. 199 2. The prediction of power draw in comminution machines. Comminution-Theory and Practice, K. Kawatra (ed), SME, Chapter 17, pp. 2 35-247, 1992 .

8.2.5

Size Conve rter Model (490) Size Converter Model

8.2.5.1

This chapter contains a description of the Size Converter model.

Introduction

The model provides a product size distributio n with a us er specified P80. This is achieved by adjusting the feed size distribution finer or coarser as required. The model is useful when there is no process knowledge of upstream comminution devices, or when a size distribution of a particular size is required for sensitivity analysis. 8.2.5.2

Model Details

The feed to the model is adjusted by mov ing it sideways on a Cum % Passin g v size plot until the product P80 matches the specified P80 as closely as possible. 8.2.5.3

Fitting the Size Converter

There are no fittable parameters in this model.


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8.2.5.4

JKSimMet V6 Manual

Known Restrictions

The model is limited in its ability to generate a product which is coarser than the fe ed by the coarsest scree n available in the feed combiner and product ports. It is always wise to plot and inspect the graph of the feed and product to ensure that the sh ape of the distribut ion is reasonable.

8.2.6

Variable Rates SAG Model (435) Variable Rates SAG Model

8.2.6.1

This ch apter contains a description of the Variable Rates SAG mode l.

Introduction

The Leung AG/S AG model (A9) typ ically re quires a full scale plant or pilot mill survey combined with ore breakage test ing to generate a set of grinding rates. However research in the mid 1990’ s using a large database of pilot and full scale milling tests ha s lead to the development of a correlation between model grinding rat es and mill operating conditi ons. A further correlation between mill feed sizing and ore breakage characteristics has also been developed. These two correlations now allow mill performance to be predicted for a wide range of mill sizes and operating conditions. Hence the model can be used to evaluate optimisation strategies in existing plants and to investigate (and compare) grinding circuit configurations at the pre-feasibility stage thus reducing the cost of pilot testing. The under lying mod el is still identical with that developed by Leung et al (1987) except that grinding rates ha ve been related to mill diameter a nd operating conditions, and A model that includes grate geom etry (but does not incorporate pulp lifter capacity) now describes s lurry holdup. This a pproach was reported by Morrell and Morrison, 199 6. If you are new to SAG mill modelling, it is strongly recom mended that you work thro ugh Appendix 9 (the Leung model) before attempting to use the Variable Rates model. The VR model inter face has been s lightly revised for Version 5 mostly to make recycle effects easier to specify. 8.2.6.2

Scaling Approach

A large propor tion of AG/SAG model users either carry out pilot s cale tests and wish to predi ct full scale operation or carry out full- scale tests a nd wish to predict perf ormance at different operat ing conditions. The variable rates model has been implemented to facilitate this scali ng process as in the rod and ball mill models. The variations in rates also depend on recycle and feed sizing. Hence, this model allows the user to s elect appropr iate stre ams for recycle data. For model fitting, the original a nd simulated cases will usually be identical. This is considered in detail in section A11.6.

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Model Descriptions

8.2.6.3

387

Slurr y Holdup Model

The transp ort of slurry through the mill is described by a function which relates the h old-up of slurry, grate de sign, grate open area a nd mill speed to the volumetric discharge rate through the grate (Morrell and Stephenson, 1996): Jp = k Q 0.5

-1.25

A-0.5

0.67

D-0.25

(A11.1)

where Jp

fractional slurry hold-up

D

mill diameter (m)

A

total area of the grate apertures (m2 )

f

fraction of critical speed

Q

volumetric flowrate out of the mill (m3 /hr) mean relative radial position of the grate apertures ri ai

= rm

ai

ai

open area of all holes at a radia l position ri

rm

radius of mill inside the liners

Classi fication by the grate is related to the effective grate aperture by a simplified classification function. For illustrative purposes a conceptual view of the weighted radius model is shown in Figure A11.1.

Weighted Radius For Two Grate Designs 8.2.6.4

Variab le Rates Model

Relationships between the operating conditions and changes in the breakage rate distributions within the JKMRC’s pilot mil l database (Mutambo, 1993) were developed. These results were augmented with results from full-scale mill data in cas es where the pilot mil l database contain ed little or no variation in the parameter of interest e.g. mill speed. To indicate the extent of the pilot


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mill database, Table A11.1 summarises its details. Range NewFeedF80(mm) Ball load (%) Recycleload(%) No.differentores No. tests

35-140 0-12 0-500 16 52

Pilot Mill Database Details The breakage rate distribution is described within the model using cubic splines (A hlberg, 1967). This gives rise to five breakage rate value s each of which relate to a particular partic le size and which toge ther cha racterise the entire breakage rate distribution. The five standard particle sizes chos en are 0.25, 4, 16, 44 and 128mm which have associ ated with them breakage rate s which are labelled R1, R2, R3, R4 and R5 respectively.

Characterisation of the Breakage Rate Distribution These rate curves exhibit a characteristic shape. The coarser (R5 an d R4) rates relate to abrasi ve breakage whil e the fi ner rates R1 and R2 exhibit similar characteristics to those of coarse ball milling, ie. predominantly impact breakage. The pronounced dip in the r ates at R3 is a ssociated with the critical size which may lim it mill throughput by building up to excessive levels. Typically it is in the 25-75mm range and varies with particular combinations of feed sizing , breakage characteristics and the magnitude of the breakage energy developed in the mill. To determine the relationship betwee n operating conditions and the breakage rate distribution, the break age rates R1-R5 were regressed against operating conditions. The resultant equations were of the following form:

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Ln (R1) = (k11 + k12 Ln(R2) - k13 Ln(R3) + JB (k14 - k15 F80) - DB )/Sb

(A11. 2)

Ln (R2) = k21 + k22 Ln(R3) - k23 Ln(R4) - k24 F80

(A11. 3)

Ln (R3) = Sa + (k31 + k32 Ln(R4) - k33 Rr ) /Sb

(A11. 4)

Ln (R4) = Sb(k41 + k42 Ln(R5) + J B (k43 - k44 F80

(A11. 5)

Ln (R5) = Sa +Sb(k51 +k52 F80 + J B (k53 -k54 F80) - 3DB )

(A11. 6)

where: Sa

rpm scaling factor = Ln (simulated mill rpm/23.6)

Sb

fraction of critical speed sca ling factor = simulated mill fraction of critical speed/0.75

DB

ball diameter scaling factor = Ln (simulated ball diameter/90)

JB

% of total mill volume occupied by balls and associated voids

Rr

recycle ratio (tph recycled material_-20+4mm) / (tph new feed + tph recycled material -20+4mm)

F80

80% passing size of new feed (mm)

kij

regression coefficients

The regression coefficients for equations (A11.2) - (A 11.6) are given below and are base d on the JK MRC cur rent dat abase at mid 1996. As more data are collected and our understanding of the various factors increases, these coefficients are likely to be modified.

j

k1j

k2j

k3j

k4j

k5j

1

2.504

4.682

0.397

0.468

3.14 1

1.057

2

1.89 4

3 4

0.597 0.192

5

0.002

0.327 0.008 5 --

0.40 2 4.63 2 ---

0.333 0.171 0.001 4 --

0.01 4 0.47 3 0.00 2 --

Regression Coefficients


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It can be seen fro m the equat ions that the finer size rates are funct ions of the rates of the coarser sizes. Hence R1 is a functi on of R2 and R3 etc. The rates can be considered as falling in to 2 groups wh ich represent the grinding me dia and prod uct size fr actions. Hence the grinding media group contains the rates R4 and R5 (related to particle s >30mm) the magnit ude of which affect the throughput. The product group incorporates rates R1, R2 and R3 (related to particles < 3 0mm) and the magnitude of these a ffects the final product size. It is of part icular note that the r ates are interrelated in a complex manner a nd are best understood by graphing the entire breakage rate distribution. 8.2.6.5

Effect of Key Parameters

The variable rate m odel allows the eff ects of a number of key pa rameters to be considered independently. It is wort h mentioning that ‘src inal’ does not provi de a basis for scaling in this model as it doe s in rod and ball mi ll mo dels. It provides a marker to allow the user to see how much the rates have varied from the srcinal case. Ball Load

The effect of changing ball load on the breakage rate distribution is illustrated in Figure A11.3.

Effect of Ball Load on Brea kage Rate Distribution

The resulting re lationship is as expected in tha t by increasing the ball load the breakage rates increase at coarser sizes but reduce at finer sizes. This has the effect of predicting hi gher throughputs at coarser grinds as the ball load is increased. However, it is commonplace to operat e at too high a ball charge often because of historical experience with softer, oxidised, surface ore. As the ore becomes harder it may well be possible to replace balls with ore as grinding media for more power effective operation.

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Model Descriptions

Makeup Ball Size

391

No significant depe ndence of the breakage rates on ball s ize wa s found in the pilot mill database. The sag model does account for ball size chan ges in terms of the ene rgy provided during im pact. It does this by chang ing the mean grinding media-size, which in turn changes the ‘energy level‘ of the mill. This ‘energy-level‘ term is us ed to determine the specific energy of im pact. As the ball size is increased, there fore, the specifi c energy increases an d hence for a given impact event a finer product size distrib ution occurs. However, as the ball size is increased the number of grinding me dia per tonne of charge will decrease. As the breakage rate is related to the number of impacts provided by the grind ing medi a then a reduction in the breakage rate may be expected to occur. To account for this a ball scaling factor is used. Figure A11.4 illustrates the effect of the ball size correction factor on the breakage rate distribution. It should be emphasised that it is usually argu ed that a coarser ball size will give a higher throughput but with a coarser grind. In practice, exper iments with full-scale mills are sometimes inconclusive and mill operators see little or no effect when experimenting with ball size. This may be due to the countereffect of reduced numbers of balls providing higher breakage energies when increasing bal l size. The mod el pred icts such a response by increasing the breakage energy and reduc ing the br eakage rate. In some instance s the one effect may out weigh the other , in which case a response will be noted . Over some ranges of ball sizes, however, little or no effect will be seen.

Predicted Effe ct of Changing Ball Size


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Feed Size F80 Effects for SAG Milling

The effect of F80 was found to be the most dif ficult one to evaluate as it interacted with the ball charge lev el. At relatively high ball charges (10% or more) high F80 values were detrimental as evidenced by the reduction in the breakage rates illustrated in Figure A11.5.

Effect of F80 on Brea kage Rate Distribution - (SAG mill)

Feed Size F80 Effects for Autogenous Milling

However in the case of autog enous grinding the patte rn is different. In this case a higher F80 promotes breakage in the coarser size fractions (Figure A11.6). This is to be exp ected when it is considered that in autogenous milling large rocks are required to break ore in the R5 size range (128 mm). As the F80 increases, t his will typical ly result in more coarse rocks in the charge able to break R5-size or e and hence R5 will incre ase. In SAG mills running with higher ball charges, the roc k component of the grinding media plays a lesser rol e in dictating the breakage rate and contributes more to the rock ‘burden’ whic h has to be gro und down. Feeds with F80 value s and hence more coarse feed rocks, can thus be expected to reduce the breakage rate. Caution needs to be exe rcised, however, as it has been found that the F80 is not always a good indication of the feed size distribution. This is particularly noticeable with autogenous mills whose performance may cases fluctuate considerably ye t maintain a reasonably constant F80. In such the distribution changes systematically with performance and that typically higher proportions of 25-50mm material in the feed result in lower feedrates, ie. less sub-grate size mat erial is present in the feed and more near size material has to be broken.

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Effect of F80 on Brea kage Rate Distribution - (AG mill)

Effect of Recycle Load

Recycle loads broadly fall into 2 categories viz.: 1. Coarse recycles from trommels, vibrating screens and recycle crushers which typically comprise only -20 + 4 mm material and have P80 values of the order of 8 - 12mm, 2. Fine recycles from hydrocyclones and DSM screens which are predominantly –4 mm mate rial and h ave P80 values of the or der of 0 .2 - 0.5 mm. It has been found that the amount of recycled material in the -20 + 4 mm size range is inversely related to the amount of breakage that this material is subjected to. This can be exp lained if one considers that these roc ks are broken by coarser rocks and balls whose frequency does not appreciably change with changes in r ecycle load. However as the amount of recycl ed -20 + 4 mm rock increases, the amount of thi s size material in the load will increase. As the breakage rate in a given size clas s is related to the ratio of the number of coar ser rock s and balls to the number of rock s in the giv en size class , thenrate increasi ng size the ran -20 ge + 4(R3 mmsize recycle a drop in in the breakage in this = 16 will mm).result Theinchanges the breakage rate distribution as the coarser recycle increases is illustrated in Figure A11.7. Interestingly, recycle of fine material ie. –4 mm did n ot correlate with any of the bre akage rat es. This may be relat ed to the breakage mode of this material which is believed to be dominated by attrition. Where the mate rial has been recycle crushe d, it is considered to h ave similar properties to new feed and is not included as -20 +4 mm recycle.


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Effect of Recycle Load on Bre aka ge Rate Distribution

Recycle Control in V5

For the most part , the Ver sion 5 model is identical with the Variable Rates SAG model in Version 4. There are, however, a couple of important differences which relate to cont rol of rec ycle of –20 +4mm material on the grinding rates. As for V4, t he User inputs new fee d rate tonnes per hour and 80% passing size for Simulate d an d “Original” mills. Recycle Options – In Version 4, there are two implied switches.

The first is “Fixe d Recycle”. If the User inputs a Fixed Recycle tonnage , all simulations will use this value to calcula te the recycle ratio. Version 5 uses this implied switch as well i.e. the fixed recycle tonnage value is set to zero to allow for simulated recycle. The second implied switch in Version 4 is to select one (or more) recycle streams from the flo wsheet. In version 5, this switch is now explici t as “Use Recycle in Calculations”. If this switch is set to one, the actual recycle is now calculated by the model as the difference between –20 +4mm in new feed (specified by the user) and in the total feed to the SAG mill. Hence the User uses the Ore Feeder s ize marker to estimate % -20mm and % 4mm and enters the difference into the appropriate field on the SAG model. Comment. The effect of recycle has a lways been difficult to model and it als o the subj ect of curr ent rese arch. It provides some compensati on for recycle material ‘survivors’ being likely to be somewhat ‘harder’ than new feed particles in the sa me size fraction. Comminution Models


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However, if the recycle stream is crushed, new flaws will be generated and the original feed prope rties retained. Therefore it is recommended that ‘Use Recycle …. ‘ be turned off when a recycle crusher is used, with the following note of caution. If K1 is larger than 4mm, a proportion of recycle crusher feed will not be crushed. The by pass ed –20 +4mm can be compensated for by iteratively adding the ‘new’ –20 +4mm in the crusher product to the new feed % of –20 +4mm. Excess ive fine recycle may make this model unstable. However, excessive fine recycle will often make real AG/SA G mills unstable and it a consequence of a realistic model. Mill Speed/Mill Diameter

The breakage rate is related to the number of size reduction events per particle, per unit t ime and is hence a frequency. This in turn must be rel ated to the frequency with which the mill rotates (rpm). A scali ng factor is therefore applied to account fo r changes in the rotational rate . For a given fraction of critical speed the rpm decreases with mill diameter0.5 and hence this scaling factor will also change with mill diameter. All else being equal, therefore, a larger diameter mi ll will have a lower breakage rate than a smaller unit. However it is pointed out that the JKMRC model inherently scales on the basis of breakage ener gy which it relate s to mill diameter. Therefore, whereas a larger diameter mi ll will have a lower breakage rate it will have a higher breakage energy. In a given mill as the rpm changes, apart from the rotational rate, the s hape of the grinding charge will also change in line with the fraction of critical speed (Morrell, 1996). Typically as the fraction of c ritical speed increases the cha rge is s ubjected to increase d lift and h ence impact breakage is enhanced. It is at the expense of attr ition breakage which is normally associated with casca ding motion and which is prevalent at lower speeds. To account for these effects a further scal ing factor is applied which is based on the fraction of critical speed. Figure A11. 8 illustrates the predicted changes in the breakage rate distribution as s peed is changed.


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Predicted Effec t of Changing Spee d on the Brea kage Rate D istribution Mill Power

8.2.6.6

The variable rate s model allows the user to specify the conical slope ins ide the liners of each mill end. The mil l power esti mate inclu des the coni cal ends (Morrell, 1996).

Parameter F itting - Variable R ates Model

Parameters Fitting Single Data Sets

Model fitting the variable rates model is quite similar to fitting the Leung model (A9). The defaults for the original mill grinding rates are a ll set to zero, ie. the intercepts of the rate equations (Table A11.2) are included in the model. Hence the fitted rates indicate how far the measured mill is operating from “typical” condit ions. The recommend strate gy is to first fit xg and xm with the grinding rat e intercepts set to zero. If the mil l has pebble port s, set the initial pebble port size to the largest measured particle in the mill discharge. If

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the xg and xm fit is plausi ble, add the pebble port size (PPSize). Use the measured open areas for pebbl e ports and grates and the measured weighted radius/mean relativ e radial position for the gr ates. Note that the grate open area include s grates a nd pebble ports. The recy cle stre ams are selected from the unit menu. The measured recycle rate (-20 +4 mm) should also be ente red as data. (When this field is zero, the calculated recycle is used. This is appropriate for simulation). The new feed size should d and entered fordata. both Sim(ulated) and Org(inal) mills as (F80) should all of be thenote other measured mill If the xg, xm and PP (pebble port) size fit is plausible, adjust the scale factors on Breakage Rate “Constants” to 0.1 and in clude them in the next fit . The open area fractio ns (Grate OA) can be selected to fit. They a re only suited to matching wear condit ions a nd s hould not be fitted together with grate or pebble port sizes as the parameters are likely to interact quite severely. Given good data and ore characterisation this model will often predict the measured results quite well and model fitting is very simple. Remember – xg, xm and PP size are all square mesh equivalent sizes. Therefore, apertu re shape and particle shape will inter act. A slabby particle will appear much larger to a square mesh screen than to a slotted grate aperture! Fitting Multiple Data Sets

A comprehensi ve pilot test program will produce data over a range of operational conditions. For sophi sticated users, the variable rates model allows s everal s ets of pilot data to be ana lysed simultaneously. The first step is to analyse eac h set by using its own select list. This should identify any data pro blems. Then add each data s et onto a combined select list for master slave fitting. One of the pilot data sets is selected as a base cas e. For this set, s imulated a nd original inputs are the same. For the othe r sets, change the simu lated mill conditions as required (e g. Ball load) and use the base case original mill conditions in all tests. Add all of the measur ed load and product str eams to the model fit data list. Use the master/slave capability t o simultaneously fit , xg, xm, PPort size a nd grinding rate intercept s to a ll data sets at once. Notes: a fast computer (Pentium 166 or better) is required for three or more SAG data sets Multi-fit capab ility is not available in Version 5. However, the n umber of fittable sets of port data will be expanded in later releases. This approach can also be used to simultaneously anal yse several sets of operating plant data, even between different sizes of mills treating similar ores. In either case , a good overall fit indicates a model which can be used for prediction over a wide range of operating conditions. A poor overall fit, particularly if the grinding rates are lower than typical (negative inte rcepts) may indicate shortcomings in data collection. More seriously, it may also indicate more s ignificant problems such as poor liner


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design or inadequate pulp transport capacity (i.e. pulp lifters). Larger rates may indicate particularly good practice or at the coarse knots, decreasing ore competence at coarser s izes. 8.2.6.7

Variable R ates for Simulatio n & Design

This mode l is quite complex and a good appreciat ion of bot h the model a nd SAG mill operations are recommended before use for design. Comprehensive industr ial research work ov er the last decade ha s built up the database for this model and exposed some conceptual weaknesses which are being addressed with two new models. However, the variable rate s model is now a powerful tool fo r data analysis, circuit evaluation and AG/SAG mill design. The following points should be noted. Recycle Streams

Up to three recycle streams can be selected from the model menu. These should be recycles which actually go into the mill, eg. Recycle crusher product, not feed. The “Fixed Recycle” input should be set to zero for simulation to allow the c alculat ed flow of -20 +4mm to be used. (Input the measured flow for model fitting). Where the mate rial has been recycle crushe d, it is considered to h ave similar properties to new feed and is not included as -20 +4 mm recycle. NB: V5 hand les recycle loads differently from V4. See pages 106-107 for details of the differences.

Load Limits

The feed trunnion diameter indicates the maximu m volumetric load limit. If the simulated mill limits at a lower level than the actual mill, reduce this diameter. Beyond a certain load, the power model is unlikely to be reliable and the power estimates are set to zero.

Grate Flow Limits (Mass Transfer “Law”)

The flow corre lation detailed in A11.3 provi des a maximum flow estimate at the simulated mill load. The user may enter a design maximum load level for which a maximum flowrate estimate is also calculated. These es timates relate to flow through the grate. They ass ume that the pulp lifters can remove all of the gr ate discharge. This is not always true for mills operating in closed circuit with cyclone or fine screens. If the simulat ed flow exceeds the maximu m, the mill will likely fill up with fines an d go into ove rload a s the slurr y pool redu ces impact break age. This effect is not simulated by the model.

Feed Size

The F80 values fo r new feed for both simulated an d srcinal mills are entered

Considerations

by the user. For des ign, a reasonable estimate of F80 is often difficult. Power based equations typically divide by the feed size so the ass umption becomes unimportant but real mills are sensitive to feed sizing as are accurate models. The JK dat abase shows reasonably syste matic depend ence of AG/ SAG F80 (crusher P80) with all hardness measur es. The harder an ore, the coarser the resulting crusher produc t at the same crusher closed side s etting. The best correlation is with the JK abrasion parameter ta.

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For a design case, the F80 of the fee d can be estimated from the measured ta with a standard deviation of abou t 10% of the primary crusher close d side setting. F80(mm)={css-78.7-28.4ln(ta)}

(A11.7)

s.d. = 0.1 css This is not a perfect ans wer, as the size distribution slope also varies as shown below.

Typical AG/SAG mill feed sizings

The size converter model (see Appe ndix A10) can be used to adjust fro m a similar ore to the target range for simulation. (Note that it is also possi ble to condu ct a test in a pilot adit to esti mate the likely run of mine size distributio n. This distributio n can be fed to the crusher model to predict the mill feed distribution. Contact JKTech for assistance with test blast design.) The Variable Rates SAG mill model now warns if the simulated void fill fraction is >=1 and if the simulat ed load volum e is more than 0.3% different from the measured value 8.2.6.8

Known Restrictions

This model does not take acco unt of the variation in breakage energy at different mill loads. Therefore pilot and industrial operation should be measured at realistic operating loads (ie. >20%). As noted earlie r, pulp lifter capacity may limit before maximum grate capacity is reached. The single number grate characte risation (Mean relative radial position) is a useful approximation. However, it should be used with a ctual grate designs, not hypothetical variations which may not be able to be manufactured. As the database of very large mills expands, it is becoming apparent that the charge in a large coarse feed mill restr icts the maximum circulating load. Hence for Version 6.0.1 - March 2014

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mills 11m in diameter (or larger) treating coarse feed, the simulated circulating load should be restricted to 25% of new feed rate. This can be done by reducing the grate open area paramete r. This is an a rea of continuing research at JKMRC. With the large database of SAG mill test work, it is clear that maximum throughput doe s not always correspond to maximum mill power draw or maximum mill load. For hard ores, maximum thro ughput requires sufficient im pact energy at the toe of the charge. Hence thebetmaximum throug (at maximum coarseness) will often occur ween 20 and 30%hput volume mill load. discharg e Research at JKMRC is developing models which will a ccount for this effect and others such as the difficulty of removing pebbl es for crushing from very large mills. For mills of larger diameter than 10 m, a maximum recycle crusher flow of les s than 25% of new feed rate is recommended as a constraint on simulations. (Mills with very fine feed and large grates may exceed this estimate) Manipulating the SAG mill feed s ize distrib ution by pre-crushing is another way of shifting the throughput/product relationship for hard ores. A limitation has been found on the accuracy of the response of the rate equations to change s in F80, part icularly if the new feed F80 is outside the range of the data base. The recommended F80 for use in the model is calculated from the equation: F80 = 71.3 – 28.4 * ln (ta) This F80 value should be used as the Reference F80 value on the Recycles tab in the Variable Rates SAG Model equipment window. It has also been found that if the apert ure of a grate is above 3 6 mm, then the grate needs to be modelled as a series of pebble ports because modelling it as a grate can lead to optimistic throughput predictions by JKSimMet. As with model 430 there is not an explicit maximum for the mill load. However, a warning will be fla gged if the total load (ie. balls and pulp) exceeds 40 % by volume. If the total load exceeds 60% by volume an error will be flagged and the model calculations will be stopped.

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8.2.6.9

401

Variable R ates SAG Model Printout


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8.2.6.10 References

Ahlberg J H, Nilson, E N & Walsh, J L, 1967 . The Theor y of Splines a nd Their Applications. Mathematics in Science and Engineering, 38, Academic Press, New York and London Andersen J S, 1989 . Development of a Cone Crusher M odel. M.Eng.Sc Thesis, University of Queensland. Leung. K, Mo rrison R D & Whiten W J, 1987. 1987. An Ene rgy Based Ore Specific Model for Autogenous a nd Semi-autogenous Grinding Mills. Copper 87, Sa ntiago Chile. Morrell, S. 1996. Power Draw of Wet Tu mbling Mills and its Relati onship to Charge Dynamics. Part I: A Continuum Appr oach to Mathem atical Modelling of Mill Power Draw. Trans. Instn. Min.Metall, 105, C43-53 . Morrell S & Stephenson I, 1996. Slurry Discharge Capacity of Autoge nous and Semi-autogenous Mills and the Effect of Grate Design. Int. J. Miner. Process. (In press). Morrell S & Morrison R D, 1989. Ore Charge, Ball Load and Material Flow Effects on an Energy Based SAG Mil l Model. Presented SAG 1989, University of British Columbia. Editors. Mular & Agar.

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Morrell S & Morrison R D, 1996. AG and SAG Mill Circuit Selection and Design by Simulation. SAG 96, edited Mular, Barrett and Knight, Vancouver 769-790 . Mutambo. J, 1993. Further Development of an Autogenous and Semiautogenous Mill Model. M. Eng Sci. Thesis. University of Queensland (unpublished). Needham T M & Folland G.V. 1 994. Grinding Circu it Expansion at Kidsto n Gold Mine. Presented at SME Annual Meeting, Albuq uerque, New Mexico. February 14 -17.

8.2.7

High Pressure Grinding Rolls (Model 402) HPGR Model

8.2.7.1

This ch apter contains a description of the HPGR model.

Introduction

The high pre ssure grinding ro lls crusher (HPGR) - a lso known as the rolle r press or roller mill - was invented by Klaus Schönert in Germany as an outcome of his fundam ental resear ch on rock fracture (Schöner t 1 988). The device has been most widely used in cement clinker grinding in Europe, but is beginning to find application als o in mineral processing. One of the first such applicat ions was in diamond ore pro cessing in Southern Africa and latterly in Australia, where it was shown that the device offered some degree of selective liberation of the diamond from t he host rock. However the claimed advantage for most mineral processing operations is the very high reduction ratio achieved, and the favourable s pecific energy consumptio n, compared to conventional technologies. Some evidence has also been reported for downstream benefits such as reduced grinding strength and improved leachability due to microcracking (Knecht 1994). Potential applications therefore include preparation of material for fine grinding, replacement of tertiary crushing, rod milling and primary ball milling in primary grinding, and the attainment of enhanced leaching performance. The general principle is illustrated in the figure below.

Figure A12.1 - The High Pressure Grinding Rolls (Roller Mill)

Schönert’s research has shown that the most eff icient way to fractu re a rock mechanical ly is to load it between two opposing platens until it fails. One


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way to do this at a high throughput is to com press a bed of such particles between two contra-rotating driven rolls. In industrial practice these rolls can be very large, up to 2.8 m in diameter. One roll is mounted on fixed bearings, and the other can move linearly against a hydraulic ram or (in small machines) a spring. The hydraul ics a re set to deliv er a particular pre ssure to the bed of particles pass ing through the machine, com pressing it to a density gr eater than 70% by volume. This pressure, which usually exceeds 50 MPa, controls the size reduction in the machine. The material leaves as a compressed cake (flak e), which may have to be deagglomerated prior to further processin g. Particular care must be taken to do this correctly when determining a product size distribution. The preferred method is to break -up the cake using a 2 or 3 mm screen, take representative sample s and then to use an ultrasonic bath to de-agglomerate the parti cles. De-agglomeration can be completed in either water or acetone but preferably the latter. The objective is to produce a repeatable size distribution without additional comminution. 8.2.7.2

Model Structure

Underlying the structure of the size reduction model are three assumptions about the inherent breakage mechanisms that occur in HPGRs , as illustrated in the Figure below. Pre-crusher

If particles are bigger than a certain critical size they will be broken directly by the roll faces as would occur in a conventional rolls crusher. The breakage in this zone ca n be considered as a nalogous to a ‘p re-crusher’, the product s from which may subsequently pass to a region where a bed under compre ssion has formed. The boundary between the pre-crusher an d bed compression regions is defined by a critical gap (x c).

Edge Effect Crusher

Breakage at the edge of the rolls is different to that at the centre a nd conforms more to that experienced in a conventional rolls crusher. This is the so-called ‘edge effect’ which defines the proportion of relatively coarse particles usually seen in HPGR prod ucts. Its existence has been explained by the pressure gradient acro ss the width of the ro ll and the static confinement of the ore at the edges of the rolls which the cheek-plates provide.

Compressive Bed Crusher

At some point away from the edges of the rolls, an d extending upwards from the area of minimum gap (x g) to an area bounde d by the crit ical gap (x c), is a compression z one where breakage conditions are s imilar to those experienced in a compressed packed bed. From a modelling viewpoint canFeed be accommodated conceptual structure shown these in theassumptions fig ure below. firstly passes intothe the ‘pre-crusher’. Particles with diameters that exceed the critical gap (x c) are crushed below this size in a single particle breakage mode. The products from this breakage then combine with feed particles that are smaller than x c. A proportion is then diverted to another single particle crusher stage where all particles greater than the minimum gap (x g) are crushed to belo w this size. The remainder are diverted to a compression stage where a ll particles greater than x g are crushed below this size but in a compressed bed mode.

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All products then combine to produce the final HPGR product.

Figure A12.2 - Schematic Structure of the HPGR Model

8.2.7.3

Breakage Processes

HPGR Model

The model breakage one splitting process between the contains edge and three compressed bed processes zones. Forand the breakage processes the JKSimMet crusher model is used to describe the size reduction. Four model parameters are required for each breakage process: K1 , K2 and K 3 and t 10 . The first three are used to describ e the probab ility that a particle will be broken whilst the t 10 is used to describ e the product size distrib ution that results. For a detailed model description, refer to the Crusher Models section Appendix.

t10 Definition

343

of this

The t 10 is defined as the perce ntage passing one tent h of the src inal particle size in the product after breakage. Other t

n

para meters can be similarly

obtained from a product size distribution, eg. t 2 is the perce ntage passing one half of the srcinal particle size. From breakage tests the t

10

and a number of

other t n values a re determined from the breakage prod ucts. These values are stored in tabular for m in the mod el which, given a value of t

10

, uses spline

interpolation to determine the associated t n value s and hence reconst ructs the entire product size distribution. Pre-crushing

For the pre-crushing process, breakage of particles is assumed to be in single particle mode in which rocks are nipped directly by the faces of the rolls, similar to a conventional rolls crusher. The parameters used to describe crushing in this zone are determined from tests conducted in a conventional (non-HPGR) labo ratory rolls crusher and single pa rticle breakage tests, and remain constant in the m odel fitting an d s cale-up. The parameter K 2 is set as the critical gap x c, which is defined by Morrell et al (1997) by the expression


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xc

0.5 (D + x g ) ( D + x g ) 2 -

4

g

Dx g

0.5

(A12.1)

c

where xg is the working gap, D is roll diameter,

c

is bulk density of fee d and

is flake density. g

Figure A12.3 - HPG R Schema tic Showing Compress ion or Nip Angle

In the edge zones, rock breakage is also ass umed to take place in single particle mode. The parameters us ed to describe crushing in this zone are the same as those used in the pre-crushing zone, excep t for K 2 , which now take s the value of the working gap x g. Compressed Be d

In the com pressed bed cru shing zone on the other hand, size reduction is

Breakage

assumed to be sim ilar to that experienced by a bed of part icles in a piston press. The paramet ers used to describ e s ize reduct ion a re determined from tests in a laboratory or pilot scale HPGR machine combined with breakage tests in a piston pre ss. The piston press tests provide information on the relationship between s ize redu ction and energy input in a compressed bed. They also provide a descriptio n of the characte ristic s hape of the product s ize distribution. If the piston press test s are not available, then the result s from the single particle Drop Weight test may be used to determine the Compressed Bed Breakage Function (see next topic 407 ) The parameter K2 fo r the compressed bed crushing is the working gap x g, whilst K 1 is set as z ero. The parameters K 3 and t 10 are fit ted to the laborat ory scale HPGR test data. These are the only two breakage pa rameters required to be fitted to la boratory data.

Edge Crushing

The last sub-process in the model is the split to the edge and compressed bed

Bypass

zones. The edge zones are ass ociated with the drop in pressure that is experienced towards the edg e of the roll s. Their exte nt is assumed to be a function of the wor king gap. The fract ion of fee d that is crushed in the edge zones (f) can therefore be expressed as: f = g (xg/L)

(A12.2)

where g is split f actor and L is the ro ll length. Using pi lot scale HPGR test results where sizing data of both pure flake an d total product were available, the split factor g was found to be approximate ly constan t with a value of 3.4.

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In physical term s this means that the edge effect z one extended from the edge of the roll a distance equivalent to 1.7 times that of the working gap. By sizing the pure flake and total products from lab/pilot test results, f can be determined experimentally. Recent work suggests that the fraction of material being subjected to edge crushing is usually about 10%. Thus, the model may be simplified by manipu lating g (split factor) to ensure that 10% of the feed reports to the edge crushing zone. 8.2.7.4

Compressed Bed Breakage Fun ction

The product size distributions produced at different energy inputs (or reduction ratios) can be characterised by a family of “t” curves. Measurement and analysis for impact br eakage is described in the Crusher Models section 346 . This a pproach ca n be extended to predict re quired breakage power and scaled to net cru shing pow er using an efficiency factor., typically - 1.25 (see the Crusher Model topics Breakage Parameters 348 a nd Crusher Power Predictions 348 ). Single Pa rticle Impact Breakage Data

t10

t75

t50

t25

t4

t2

10.0

6.05

7.94

12.60

46.70

74.60

20.0

8.33

10.90

17.30

62.60

90.30

30.0

10.0

13.10

20.70

74.50

99.20

This approach can be exte nded to comp ressive breakage by using a piston 4

2 in a controlled manner. The press to compress closely sized fractions resulting products are sized and fitted to a spline surface. This surface can be regenerated by the model from a matrix of spline funct ion values. These values are input to the model as Compressed Be d Breakage Test

t10

t75

t50

t25

t4

t2

10.0

4.04

6.48

7.51

17.65

35.44

30.0

13.53

19.71

22.24

41.35

58.36

50.0

23.02

31.91

38.00

52.37

69.01

It can be clea rly seen that the se breakage mo dels are different. The power requirements can also be characterised with particle size dependence if required and also related to motor power (see the section on Power Draw 410 ). 8.2.7.5

Throughput

Throughput controlled principally by roll dimensions, s peed and friction profile, and materialischaracteristics such as size hardness and particle-roll (and thus nip-angle) . The profile and material of the roll surface is important in controlling both wear and machine performance, and various options are offered by the different manufacturers. The rolls throughput can be theoretically expressed a s Q = 3600 U L x gf

g

(A12.3)

where


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Q

mass throughput (tph)

U

circumferential velocity of the rolls (m/s)

L

length ofrolls (m)

xgf

working gap (m) – from the flake thickness measurements

g

flake density (t/m3 )

Note that eq uation A12.3 does not take into account the slip between feed material and the rolls surface, which can be influenced by the feed charact eristics (part icle size a nd s ize distribution, moisture, etc). The figure below shows the devi ation between measured throu ghput and throughput calculated using Equation A12.1 for primary diamondiferous ore treated through a 100 mm Polysius laboratory scale HPGR. It is obvious that Equation A12.3 over-predicts the HPGR throughput at high rolls speed, which may indicate that slip exists in the HPGR operatio n at these speeds.

Figure A12.4 - De viation of the Throughput Calculated from Eq uation A12.4 for Diamondiferous Ore Treated through a Laboratory HPGR at Various Spee ds

To correct for the slip effect it is considered t hat for a specific feed the slip is a function of the rolls speed and the relative working gap (dimensionless) which is defined as x g /D, where D is the rolls diameter. The figure below plots the corr ection factor c, (c = Q m/Qc, where Q m is the measured throughput and Qc is the throughput calculated by Equatio n A12.3) versus the product of the speed and the dimensionless gap (U * x

/D) for the

g

Diamondiferous ore using the laboratory HPGR data. A linear regression on the plot was obtained and Equation A12.3 was a ccordingly modified as: c

Comminution Models

Q = 3600 U L x g

g

(A12.4)


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409

where c is the correction factor determined from Figure A12.5 below. Recent work by Schonert (200 0) suggests that under normal operating conditions, slip does not occur in the comp ression zone. If normal operating conditions are as sured, then the correct ion factor should be set to 1.0.

Figure A12.5 - Throughput Correction Factor for Diamondiferous Ore Treated through a Laboratory Scale HPGR


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Figure A12.6 - Prediction of Throughput for Two Pilot Scale HPGRs from Equation A12.4 with Model Parameter c Calibrated Using Laboratory Scale HPGR data

Using Equation A12.4 with c determined from Figure A12.5 the throughput's for a laboratory scale HPGR (D = 0.25 m) and two pilot scale HPGRs (KHD, D = 0.8 m; Krupp Polysius, D = 0.71 m) were predicted. A comparison between the calculat ed and the measured thr oughput's is given in Figure A12. 6. The rolls speeds varied fr om 0.29 m/s to 3.1 m/s, rolls lengt h from 0.1 m to 0.21 m, rolls diameters from 0.25 m to 0.80 m, and working gaps from 3 mm to 2 3 mm. Figure A12.6 shows that good pre diction of throughput ha s been achieved by the model over the wide range of conditions tested. 8.2.7.6

Power Draw

Conventional Crusher Power

The impact size reduction model contains an energy balance equation (Andersen and Napier-Munn, 1988) which ensures that the energy for size reduction is compatible with that provided by the motor. The t10 parameter is related to the speci fic energy used by the machine and will follow a curve described by the equation: t10 = A (1 - e-bEcs )

(A12.5)

where A and b are parameter s a nd Ecs is the s pecific energy. HPGR Crusher Power

In the size reduct ion mode l the two parameters K 3 an d t10 were fitted to the laboratory scale HPGR power data. It was found that the fitted t10 's for 24 sets of Diamondiferous ore tests under various rolls speeds and feed size conditions fell o n a t10 v Ecs master curve, as shown in Figure A12.7 Equation A12.5 was hence fitted to these data to generate the A, b parameters, which are used for the scale-up as will be demonstrated in the next section. In

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JKSimMet, the points for t10 = 10, 30 and 50 are plac ed in the Compressive Breakage Specific Community Energy Matrix.

Figure A12.7 - The Fitted t10 vs Spe cific Energy Ecs for Diamondiferous Ore Treated through a Laboratory HPGR

A power coefficient kp is requ ired which relates the measure d power to that predicted by the model for size reduction. This model uses the specific energy (kWh/t) and associated t 10 v alues from the piston press breakage experiments. From these it calculate s the overall specific energy in a piston press. The difference between this value and that observed from the motor is accommodated by kp, ie. kp is the ratio of t he observed to the theoretical piston press specific energy. This coefficient has been found to be reasonably constant over a range of specific energies but increases rapidly beyond a certain limiting value. This is shown in Figure A12.8 for the 24 sets of data.


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Figure A12.8 - Relationship between Powe r Coefficient (kp) and Spec ific Energy for Diamondiferous Ore Treated Through a Laboratory Machine . (Where kp = Observed power/Piston Power)

Power Draw vs

The prediction of the working gap x g is also req uired for sim ulation. The

Working Gap

working gap depends on pressure and power draw.

Working Gap/ Specific Energy Relationship

This relationshi p is developed from the laboratory/pilot scal e test. specific motor energy is plotted against the working gap.

The

The parameters rc and rg in Equation A12.2 405 are functions of feed type, operating conditi ons (eg working pressure ) and the roll surface (eg smooth, chevroned, studded). Therefore, provided the pilot scale or the full scale machines are operat ing under s imilar conditi ons to the laboratory unit, then xg will be proportional to the diameter of the rolls. The principa l dependence of the working gap will be on the working pressure, with the gap reducing as the pre ssure increases. As working pressure is directly related to specific energy, then it will be found that as the specific energy increases the gap will decrease. An examp le of this is shown in Figure A12.9 for Diamondiferous ore treated through a laboratory machine.

Comminution Models


Model Descriptions

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Figure A12.9 - Relationship between Working Gap and Specific Energy for Diamondiferous Ore Treated Through a Laboratory Machine

8.2.7.7

HPGR Model Printout


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8.2.7.8

JKSimMet V6 Manual

Fitting the HPGR Model

SpFact K1H T10H Power Coeff. H Split Factor (g) (SpFact)

This factor determines the proportion of material that is crushed in bypass mode. This is usually 1.7 time s the effective gap at each end, the default total value being 3.4. (See Breakage Processes 405 ) Setting the split factor to zero and running a simulation generates the size distribution expected from pure compression crushing, ie. “pure flake” a nd may be compared with (or fitted to) a n actual sample taken from the centre of the roll discha rge.

Pre and Edge Crusher Model Parameters

Using the same fe ed material as for the pilot/lab HPGR test, laboratory roll crusher is operated at close to the nipping gap and the wor king gap of the HPGR.

(K1H & T10H)

The Whiten/Awachie/A nderson crusher model

343

is used to derive K 1 and

t10 where K2 is the crusher gap and K 3 is s et at 2.3. The rati o K 1 /K2 is the input to the pre crush and edge effect models along with the fitted t 10 values. It is unlikely that power can be measured with sufficient accuracy in this test to justif y using other than the defaul t power factor of 1.25. Throughput Relationship

As noted previously 407 , throughput is strongly control led by geometry at low throughput's and by slippage at high throughput's. Pilot or laboratory scale tests can be used to derive t he slope an d intercept for the slip correction factor Cp. The model defaults are for smo oth rolls. It is highly likel y that different roll surfaces will generate different correction factors.

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415

Compressed Be d Breakage

Breakage within the compressed bed is ass umed to be uniform and able to be described by a single parameter t 10 . The t 10 param eter will increase as the

(t10 HPGR)

reduction ratio increases. In compression, all particles are assumed to be able to be selected for breakage ie. K 1 = 0 and every particl e larger than the working gap will always be broken, ie. K2 = calculated Working Gap.

Power Model Fitting

The HPGR model takes a somewhat circuitous approach to power modelling. As noted pre viously, the combi nation of piston press tests and laboratory/ pilot scale HPGR produces a relationship between the compressive bed t 10 and net motor power (Figure A12.7

410

).

Developing this relationship requires some modelling using the Andersen/ Whiten model 343 . The objective is to find a t 10 for each data set with K 2 set to the working gap an d K 3 a cons tant value over all sets. To do this, enter all sets of data into one test, master slave K3 , set K2 to work ing gap and fit each of the t10 values. This prov ides a set of t

10

valu es which can be plotted against the

motor power pe r tonne (E cs) corrected for no load and the power drawn by pre-crush a nd edge crushing (as in Figure A12.7 410 ). Equation A12.5 is fitted to this data with A=1 00 and Ecs values calculated at t 10 =1 0, 30 and 50 for input into the Compressed Bed Breakage Matrix. This relationship allows compressive power draw to be calcula ted 348 for any set of K 1 , K2 , K3 an d t10 values. Figure A12.7 shows the powe r coefficient (observed motor power div ided by calculated “pis ton” power) for a range of specific energy inputs, expressed as kWh/t. If this model was ideal, the coe fficient would be constant. Between z ero and 5 kWh/t it is approxim ately constant at say 2.5 and increases rapidly at high powers (ie. the crusher becomes less energy efficient). More energy is converted into heat and does not result in further comminution. 8.2.7.9

Scaling the HPGR Model

To predict the per formance of pilot scale and full scale HPGRs the model is firstly calibrated using the results from the laboratory, conventional rolls, single particle breakage and piston bed breakage test. Figure A12.10 illustrates the scale- up procedures. Also shown in Figure A12.10 are the values of the parame ters obtained from the ca libration, which have been used to predict the two pilot scal e units and one full size machines treating a Diamondiferous ore (Morrell, Shi and Tondo, 1997).


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Figure A12.10 - Schematic of the Model Algorithm and Scale-up Procedure

The full sca le-up procedure is impleme nted in JKSimMet. When runnin g the simulations of pilot scale or of full scale machines, the paramet er K 3 for the compressed bed crushing zone is automatically adjusted until the model predicts the s ame power draw as was originally chosen for the s imulation. As a result, the calcu lated power draw is identical to that observed, and the product size distribut ion is predicted based on this power consumption. In the simulation the maximum throughput of a scale-up HPGR is calculated using the throughput model ( Equation A12.4 407 ) with the corre ction factor c

Comminution Models


Model Descriptions

417

determined in the laboratory unit with similar rolls surface on the same type of ore. The required power is then ca lculated from the maximum throug hput and the specif ic ener gy selected. The model is iterated until the bre akage power, which is the sum of the power used in the three sub-processes of precrushin g, compressed bed crushing and edge effect crushing , matches the required power. The overall product size is then predicted based on the breakage power. 8.2.7.10 Known Restrictions

Roll Surfac e

Tests using a Krupp Polysius pilot roll (ro lls diameter 0.71 m), with 4 mm profiles (on the rolls) resulted in a considerably larger working gap than was observed for the KHD pilot te sts using smooth rolls. Therefore, laboratory tests must be condu cted with a rolls surface similar to that proposed on the full scale machine.

Limited Data Base

As only limit ed produ ction scale data were available , the models need to be further tested and validated against more real data in the fut ure, and their capabilities explored in case s tudies.

Power Coefficient (kp )

Ideally, this coefficient should be constant. A better understanding and (possibly) a better representation need to be developed.

8.2.7.11 Nomenclature

Sym bol

Mea ning

nip angle (degree)

c

split factor bulk density of feed (t/m3)

c

flake density (t/m3)

g

c

correction factor for rolls throughput

D

rolls diameter (m)

Ecs

specific energy (kWh/t)

f

fraction of feed which is crushed in the edge zones

g

split factor

K 1,

K 2,

size reduction model parameters

K 3


kp

power coefficient

L

rolls length (m)

Qm

measured mass throughput (tph)

Qc

calculated mass throughput without correctio n tph)

t10

size distribution parameter

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JKSimMet V6 Manual

U

rolls circumferential speed (m/s)

xc

critical gap (m)

xgf

working gap (m).

8.2.7.12 Acknowledgeme nts

This mode l was developed with the financial s upport of the sponsors of the AMIRA P428including project (Application HigMining h Pressure Grinding Rolls in Mineral processing) the Centreoffor Technology and Equipment (CMTE). Considerable ass istance was also p rovided by the staff at K HD and Krupp Poly sius, as well as the staf f and s tudents at the JKMRC and CSIRO, Division of Mineral products. 8.2.7.13 References

Andersen J S and. Napier-M unn T J, 1988. Power prediction for cone crushers. Proc. 3rd Mill Ops Conf, Cobar, Aus. Inst. Min. Met. Andersen J S, 1988. Development of a cone crusher model. M. Eng. Sc. Thesis, University of Queensland (JKMRC). Fuerstenau D W, Shuk la A and. Kapur P C. 1991. Energy consu mption and product size distributions in choke-fed, high compression roll mills. Int. J. Miner. Process., 32: 59-79. Kapur P C, 1972. Self - preserving size spectra of comminuted particles. Chem. Engng. Science, 27: 425 -431. Knecht, J, 1994. High pressure gr inding rolls, a tool to optimise treatment of refractory and oxide gol d ores. Fifth Mill Oper ators Conf. Roxby Downs, Oct, 51-59 (AusIMM, Melbourne) Morrell, S, Shi F & Tondo, L. 1997. Modelling and scale-up of Hig h Pressure grinding rolls. IMPC Aachen. Morrell S, Lim, W, Shi F and Tondo L. 199 7. Modelling of the HPGR crusher. SME Annual Conference, Denver, Colorado. Comminution Practices Symposium, Ed Kawatra, 117-126 . Schönert K. 1988. A first surv ey of gri nding with high compression roller mills. Int J of Min Proc, 22, 401-412 . Schönert K.and San der, U., 2000. Pressure and shear on the roller surfaces of high pressur e roller mills, Pro c. XXI IMPC, Rome , Italy, Sect A4, 97 103. Tondo L, 1996. Modelling of HPGR crushers. University of Queensland (unpublished).

M. Eng Science Thesis,

Whiten W J, 1972. The simulat ion of crushing plants with mode ls developed using mu ltiple spline re gression. J. South Afr. Inst. Min. Metall. 72: 257-264.

Comminution Models


Model Descriptions

8.2.8

Size Degradation (Model 480) Size Degradation Model

8.2.8.1

419

This ch apter contains a description of the Size Degradation model.

Introduction

The concept of a degradation model has its origins in iron ore and coal operations where particles may undergo significant size reduction during mechanical as dropping on to a stock pile fr om a conveyor or perhaps a t ahandling conveyorsuch transfer point. 8.2.8.2

Model Structure

The model structure is a simple representation of a single drop which results in the particles being broken to a specified t 10 value. The bre akage distribution parameter, t10 , characterises the size distribution of the broken product. More details of this pa rameter and the concepts behind it are given under the heading Crusher Models 346 . The appearance function data discussed in this section are requ ired for the degradation model an d these a re produced as part of the standard JKMRC Drop Weight Test. Breakage Distribution Parameter (t10)

The breakage distribution parameter, t 10 , is ente red as a mode l parameter. It

Specific Comminution Energy

The Specific Comminution Energy in a drop is a function of the height of the drop and can be calculated using the following equat ion:

must be cal culated by the user and is generally based on the Ener gy v Size Reduction relatio nship for the particular ore deriv ed from the JKMRC Drop Weight test.

=Ecs

0.00272 h*

(A13.1)

where:

Energy – Size Reduction Relationship

Ecs

specific comminution energy (kWh/t)

h

height of the drop (m)

The relationship between Specific Comminution Energy a nd size reduction represented by t10 is also one of the results of the JK MRC Drop Weight test. The relationship is of the form: t10 = exp( –1A (* Ecs *b- ))

(A13.2)

where: t10

breakage distribution parameter

Ecs

specific comminution energy (kWh/t)

A & b are ore characteristic parameters Conditioning

In most cases, the damage inflicte d by a second drop is less than that in flicted by the first drop. This effect is known as conditioning. Of course, the height of each drop is important as well as the number of drops. Effectively, the particles become a little more resistant to impact after each successive drop. The amount of this effective increase in resistance depends on the ore type and on the drop heights.


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This eff ect can be include d in the simul ation by an appropriate reduction in the b value used in equation A13.2. For an ore that is only a little affe cted by conditioning, a re duction of b to 75% of its starting v alue is typical. For an ore which is significantly affected by conditioning, b is typically reduced to 40% of its starting value. Example

The A and b values fro m the JKMRC Drop Weight test for the example ore are 50 a nd 0.5 respectively. For a drop height of 20 m, from equation A13.1: Ec = 0.00272 * h s

= 0.00272 * 20 = 0.054 kWh/t and from equation A13.2 t1 = A * ( 1 – exp( - b * Ecs )) 0

= 50 * ( 1 – exp( - 0.5* 0.054)) = 1.33 this value of t10 is then entered into the model. For a second 20 m drop of an ore which is s trongly a ffected by conditioning, b is reduced to 0.2 (40% of 0.5) and from equation A13.2 t10 = A * ( 1 – exp( - b * Ecs )) = 50 * ( 1 – exp( - 0.2* 0.054 )) = 0.54 this value of t10 is then entered into the model for the second drop. Use for the Vertical Shaft Impactor

The degradation model can be used to represent a lightly loaded Vertical Shaft Impactor. In this case, the energy of an impact is calculated from the velo city of the particle imparted by the rotor. This energy must be converted to units of kWh/t before equation A13.2 can be applied. For example, for a VSI with a rotor diameter of 0.6 m spinning at 2000 rpm, the energy imparted to a particle leaving the rotor at its peripheral speed is: Ec = 0.5 * m * v2 / ( 3600 * m ) s

= 0.5 * v2/ 3600 = 0.5 * ( p * 0.6 * 2000 / 60 )2/ 3600 = 0.55 kWh/t where: m = particle mass (which cancels out)

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421

E = specific comminution energy (kWh/t) cs

v = peripheral velocity of rotor (m/s) 3600 is the conversion factor for kW h/t The E cs value is subst ituted into equat ion A13.2 to calculat e t10 for use in the model. 8.2.8.3

Degr edation Model Printout

Degrada tion Model Printout 8.2.8.4

Fitting the Degredation Model

This is a very simple model to fit, the only fittable parameter being t 10 . A typical rang e of starting estimates for degradation by drop is 0.2 to 0.8 depending on a menability to degradatio n and drop height. A typical range of starting estimates for the VSI is 5 to 20 depending on rotor diameter and speed and ore type. 8.2.8.5

Known Restrictions

It is recommended that the ore specific a ppearance function is measured by a Drop Weight test rather than using the default v alues. Although the variation of the crusher appearance function data in the JKTech data base (of ores subjected to Drop Weight testing) is not pa rticularly large, ore specific values will provide better results. If several drops actually occur, it may be better to simulate these as separate drops than as a single drop of the total a ccumulated drop height, particularly if conditioning is likely. It should also be noted that ores which are particularly susceptible to degradation are also likely to be degraded during the process of screening to determine the size distribution, thus making the size distributions somewhat doubtful.


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Index

-Fflowsheet name

-A-

-H-

adding streams 72 AG model 370

hardware key 19 hardware requirements 17 high pressure grinding rolls model

-B-

inflexion points 72 Installation procedure

361

-C-

-L-

changing circuit 99 circuit performance 99 computer requirements 17 configurable stream overview courses 19 crusher 343

loading a project

97

-Ddata collection 230 data entry conventions 81 data structure 51 direction change for streams display 58 dongle 19 drawing streams 72

-Eefficiency simplecurve 325, 326 splined 328 variable d50c 330 water & fine 326, 327 78

47

100

-Mmaintenance agreements 19 mass balance 17 mass balancing 230 infinite division problem 268 middlings problem 267

343

elemental assay labels ending a sess ion 99 equipment icons 52 equipment items 52 equipment labels 63 example project 18

403

-I-

backing up work 18 backup copy 18 ball mill perfect mixing model

crusher models cursor 57

61

72

metallurgical accounting 268 model building 56 model fitting 17 graphing results 287 printing results 287 problems 291 references 292 models 18, 343 AG 370 ball mill - perfect mixing 361 double deck screen 325 efficiency curve - variable d50c 330 high pressure grinding rolls 403 rod mill 355 SAG 370 simple efficiency - fitting 326 simple efficiency - water & fine 326 simple efficiency - water & fine - fitting simple efficiency curve 325 single deck screen 317 size converter 385 size degradation 419 splined efficiency - fitting 328

327


Index

models 18, 343 splined efficiency curve 328 variable rates SAG 386 modules 18 mouse 57

18

-T-

-N-

terminating a sess ion

naming streams nudging

streams 51 structure 18 structured example

72

-unitsU- changing -

72

-O-

updates

operatiing sys tems operating sys tems

78

19

-V-

17 17

values from simulation 56 variable rates SAG model 386 viewing stream data 94, 97

-Pparameters types 273 preferences project name

99

-W-

57 61

window size 60 windows 58

-redrawing R -flowsheet

72 restrictions 322, 330, 331, 332 Efficiency Curve Variable D50c 331 Single Deck Screen Model 322 rod mill model 355 routing of streams 72

-SSAG model 370 sample degradation model screen model double deck 325 single deck 317

419

selecting a flowsheet 100 Sieve Series 175 simulation 59 results display options 15 simulation window 87 size classes 78 size converter model 385 Standard deviation 231 start up 60 stream data 94 stream data overview 97 © 2014 JKTech Pty Ltd

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Endnotes 2... (after index)


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