c Ot 25 001_rev B_process Description Control Philosophy

Sociedad Min era Cerro Cerro Verde Verde S.A.A.

Primary ri mary Sul Sulfi fide de Project ro ject P rojec ojectt No. PS P S P 108

Proce roc ess Desc scri ript ptio ion n – Cont Control rol Philosophy Specif Speci f i c atio ati o n No. No . C-OT C-OT-2 -255-00 001 1 Rev. B 22 Apri Ap rill 2005 2005

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Clien t Name: Project Name: Name: Proj ect Numb er:

Socied ad Minera Cerro Verde S.A.A. Primary Sulfide Project PSP108 PSP108

Specif icati on C-OT-25-001 C-OT-25-001 Page 1 of 48 Rev. B

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PROCESS DESCRIPTION DESCRIPTION – CONTROL PHILOSOPHY

This This doc docu ument ent has been een rev revised ised as ind indicat icated ed below elow.. Chan Changes aft after rev revisio ision n 0 are are iden identtifie ified d by vert ertical ical bar bars at at the right side of the page, with additions being underlined. Please replace all pages of this specification and destroy the superceded copies. English is the prevailing language of this document. Rev No.

B



Originator (name/initials)

K. Wood

Rev Date

22Apr05 22Apr05

Revision Revision Descripti Descripti on

Issued Issued for Review eview

;

New Issue

APPROVAL S

Entire Specification Re-issued

ORIGINAL SIGNED BY FLUOR

DATE

CLIENT

DATE

P roject Manager: Manager: E ngineering Manager:

Brad Matthews Matthews

22Apr05

Area P roject Engineer:


22Apr05

Lead Discipline Engineer: ngineer:

Ken Wood

22Apr05 22Apr05

Process Approval:

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This This doc docu ument ent has been een rev revised ised as ind indicat icated ed below elow.. Chan Changes aft after rev revisio ision n 0 are are iden identtifie ified d by vert ertical ical bar bars at at the right side of the page, with additions being underlined. Please replace all pages of this specification and destroy the superceded copies. English is the prevailing language of this document. Rev No.

B



Originator (name/initials)

K. Wood

Rev Date

22Apr05 22Apr05

Revision Revision Descripti Descripti on

Issued Issued for Review eview

;

New Issue

APPROVAL S

Entire Specification Re-issued

ORIGINAL SIGNED BY FLUOR

DATE

CLIENT

DATE

P roject Manager: Manager: E ngineering Manager:


22Apr05

Area P roject Engineer:


22Apr05

Lead Discipline Engineer: ngineer:

Ken Wood

22Apr05 22Apr05

Process Approval:


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Table of Contents 1.

GENERAL DESCRIPTION AND SCOPE.................................................................................................. SCOPE...................................................................................................... .... 4

1.1

Summary......................................................................................................................................................4

1.2

Definitions Definitions .................................. ................. .................................. ................................. ................................. .................................. ...................................... ...................................... .......................... .........5 5

1.3

General Control Systems Design Criteria....................................................................................................6

2.

CRUSHING....................................................................... CRUSHING ......................................................................................................................... .............................................................................. ............................ 6

2.1

Process

2.2

System Interlocks.........................................................................................................................................7

2.3

Primary Crusher...........................................................................................................................................7

2.4

Conveyors onveyors and Stockpile tockpile................. .................................. ................................. ................................. .................................. .................................. ...................................... ........................9 ...9

2.5

Primary Crusher Control Station................................................................................................................10

2.6

Coarse Ore Reclaim...................................................................................................................................10

2.7

S econdary econdary Crushing and S creening creening................. ................................. ................................ ................................. ................................. .................................... ........................12 ....12

2.8

Tert Tertiary iary Crush Crushin ing. g... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... ...1 .17 7

3.

GRINDING ............................................................ ....................................................................................................................... ........................................................................................ ............................. 20

3.1

Process

3.2

Ball Mill Screen and Feeders eeders ................................. ................ ................................. ................................. ................................. ................................ ................................... ...................21 21

3.3

Ball Mills and Cyclones yclones ................................ ............... .................................. .................................. ................................. ................................. ..................................... ...........................21 .......21

3.4

System Interlocks.......................................................................................................................................23

3.5

Ball Mill Grinding Ball Addition...................................................................................................................24

4.

FLOTA TION ................................................................ ...................................................................................................................... ................................................................................. ........................... 25

4.1

Process

4.2


4.3

Rougher ougher and Scavenger cavenger Flotati lotation on................. .................................. .................................. ................................. ................................. ................................... .........................27 .......27

4.4

Rougher Concentrate Polishing.................................................................................................................29

4.5

Scavenger Concentrate Regrind and Classification..................................................................................31

4.6

Column Flotation........................................................................................................................................33

4.7

F irst Cleaner and Cleaner-S leaner-Scaven cavenger ger Flotati lotation on ................................. ................ ................................. ................................. .................................... ......................35 ...35

5.

MOLYB DENUM RECOVERY .......................................................... ................................................................................................................. ............................................................ ..... 36

5.1

Process

5.2


5.3

Rougher ougher and Scavenger cavenger Flotati lotation on................. .................................. .................................. ................................. ................................. ................................... .........................38 .......38

5.4

First Cleaner Flotation................................................................................................................................40

5.5

Cleaner leaner S cavenger cavenger Flotati lotation on ................................. ................ .................................. .................................. ................................. ................................... .................................. ...............40 40

5.6

Column Flotation........................................................................................................................................42

5.7

Molybdenum Molybdenum Concentrate Concentrate Dewate Dewatering ring and and Packag P ackaging ing .................................. ................. .................................. ................................. .......................... ..........44 44

Overview........................................................................................................................................6

Overview......................................................................................................................................20

Overview......................................................................................................................................25

Overview......................................................................................................................................36


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PROCESS DESCRIPTION DESCRIPTION – CONTROL PHILOSOPHY 6.

CONCENTRATE CONCENTRATE THICKENING, THICKENING, FILTRATION, STORAGE AND LOADOUT LOA DOUT ........... ................. ........... ........... ........... ........... ......... ... 45

6.1

Process

6.2


6.3

Concentrate Thickening.............................................................................................................................46

6.4

Concentrat oncentrate e Storage torage and Dewaterin Dewatering g ................................ ................ ................................. ................................. ................................. ..................................... .....................47 .47

6.5

Concentrate Storage and Loadout.............................................................................................................48

6.6

Concentrate Recycle Water.......................................................................................................................48

Overview......................................................................................................................................45


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PROCESS DESCRIPTION DESCRIPTION – CONTROL PHILOSOPHY 1.

GENERAL DESCRIPTION DESCRIPTION AND SCOPE 1.1

Summary A.

Scope of Specifica Specification tion The The purpos rpose e of the Proces Process s Cont Control Philo Philoso sop phy is to serv serve e as a basis asis for for the Pipin Piping g and and Instrumentation Diagrams (P&IDs) design and to provide the Control System Design Engineers with a basis for Instrumentation and Control Systems design.

B.

C.

1.

Major items of process equipment are discussed. Items that operate independently of the process (e.g., air compressors and power generation) are not included in this document.

2.

P rocess sampling that that impacts impacts the control control philosophy is included. Reference R eference specification C-SP-25-003 for specific sampling systems design information.

3.

It is not the purpose of this document to discuss the control systems and instrumentation used in this plant. Reference the Instrumentation Design Criteria (C-SP-70-001) and other related specifications listed below.

4.

Where there are multiple process lines operating in parallel, only a single line will be discussed.

Related Specifications •

C-DC C- DC-25-001 -25-001

P rocess Design Criteria

•

C-DC C- DC-65-001 -65-001

E lectrical lectrical Design Criteria riteria

•

C-DC-70-001 -DC -70-001

Instrum Instrumentation entation Design Criteria

•

C-S C- SP -25-003

P lant Sampling ampling P hilosophy

•

C-S C- SP -55-024

On-Str On-S tream eam Analyzer

•

C-SP C-S P -55-027 -55-027

P article article Size Analyzer Analyzer

•

C-S C- SP -70-002

Distribut Distributed ed Control System ystem (DCS) (DCS )

•

C-S C- SP -70-003

P rogram rogrammable Logic Control (PLC (P LC)) System ystem

Control Room Rooms s Ther There e will ill be one one main ain Conce Concen ntrator ator Cent Central ral Cont Control Room Room (CCCR) loca locatted in the grind inding ing area area,, with a number of field-hardened HMI operator control stations in outlying areas to interface to the DCS. These include: 1.

Primary Crushing Control Station (PCCS)

2.

Fine Crushing Control Station (FCCS)

3.

Copper Concentrat Concentrate e Dewatering Dewatering Station Station (CCDS (C CDS )

4.

Moly Plant Control Station (MPCS)

Control stations will operate independently of each other and will normally only control equipment within the specific control station jurisdiction. However, each station will have access to all status information throughout the system. All areas will be controllable from the concentrator concentrator central central control room.


PROCESS

Clien t Name: Project Name: Proj ect Numb er:

Socied ad Minera Cerro Verde S.A.A. Primary Sulfide Project PSP108

Specif icati on C-OT-25-001 Page 5 of 48 Rev. B

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PROCESS DESCRIPTION – CONTROL PHILOSOPHY 1.2

Definitions This process control philosophy, and control logic shown on P&IDs, will use the following definitions for control and interlocking of equipment: A.

Start:

A start signal is a pulsed signal to start a piece of equipment (pulse 0 to 1).

B.

Stop:

A stop signal is a pulsed signal to stop a piece of equipment (pulse 1 to 0).

C.

Local:

Local control is defined as control at the piece of equipment or the equipment control panel.

D.

Remote:

Remote control is defined as control distant from the piece of equipment. For example, control room operations are always remote to the equipment.

E.

Permissive:

A permissive signal is used to allow the starting of a piece of equipment. However, once the equipment is started the permissive signal will not stop it.

F.

G.

Trip:

A trip signal will stop and/or disallow the starting of a piece of equipment. The trip signal will not allow a restart of equipment until the trip condition has cleared.

Critical Safety Trip (CST): A critical safety trip is one which is required to provide personnel protection or prevent catastrophic equipment failure. These trips will be hardwired (or in the case of motors be handled via the motor protection relay). Signal wiring will be fail-safe.

H.

Non-critical Trip (NCT): A non-critical trip is one which is required from an operational standpoint and for general equipment protection. These trips will be handled via software. Signal wiring will be fail-safe. The trips of major process equipment types will be handled as follows in general: Conveyors:

Speed switch Level switch Misalignment switch Belt rip switch Belt slip Metal Detect Motors:

Motor bearing temp Overload current Ground Fault Emergency stops Motor Vibration I.

Interlock:

Pull cord

CST

NCT NCT NCT NCT NCT NCT Motor winding temp

CST

CST CS T CST CS T CST

An interlock is a trip signal which is passed between systems (or pieces of equipment) to ensure that the systems (or equipment) operate together in a safe manner (e.g., coarse ore conveyor C-3120-CV-002 not running is an interlock

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PROCESS DESCRIPTION – CONTROL PHILOSOPHY

signal for the coarse ore transfer conveyor C-3120-CV-001). Where critical interlock signals are passed between control processors they will be hardwired. No critical interlock signals will be transferred between PLCs via DH+ or DCS gateway communications to avoid spurious trips. All safety switches like pull cords and emergency stops will be hard wired. 1.3

General Control Systems Design Criteria A. The control system will be designed such that local control will always be available and that the

operator within the control room will have continuous process monitoring, control and emergency shutdown capability. Local and remote stops will always be available. Remote/local selector switches, when required, will be located in the DCS system. B. The control system will include a Distributed Control System (DCS) to provide overall process

monitoring and control. The DCS system will be overlain by a Knowledgescape high level control system for application of control strategies. Programmable Logic Controller (PLC) based control systems will be used for motor control and simple process control. Some major mechanical vendor packages (e.g. crushers, ball mills and concentrate filters) will contain their own PLC control systems, supplied by the vendors. In these cases, the equipment’s own PLC will control all items related to the piece of equipment. C.

All alarm and trip circuitry from field or local panel mounted contacts will be based on fail-safe activation. Alarm and trip contacts will open on abnormal or fault condition.

D.

Electrical shutdown systems, relays and solenoid activated devices or valves, will be deenergized for shutdown. Dual acting solenoid valves shall be energized to open and energizes the other solenoid to close. Shutdown initiation will be independent of any analog transmitter or control loop and will be from direct connected, dedicated switches wherever possible. Process equipment shutdowns will be implemented directly via the DCS or PLC controlling that part of the process. If equipment shutdown occurs due to loss of power/power failure, the equipment will return to a de-energized state and will not automatically return to a running state upon restoration of power.

E.

All slurry pump gland seal water low flow switches will alarm only and not trip the respective slurry pump unless specifically mentioned in this document or shown as such on the P&IDs.

F. The status of each piece of equipment including run/stop/local/remote is displayed on the DCS

screen. A permissive light advises the operators if the equipment is available to start. Permissive light is not indicated for any piece of equipment unless all equipment in logical sequence to operate that part of process is ready to be started. G. 2.

Refer to specification “Instrumentation Design Criteria C-DC-70-001” for further details.

CRUSHING 2.1

Process Overview A.

Ore from the mining operations is dumped, by 218 t haul trucks, into a single dump pocket with a 500 t live capacity, which feeds into the top of the primary crusher (C-3110-CR-001).

B. The Primary crusher (C-3110-CR-001) discharges the crushed ore to a 500 t discharge pocket

below the crusher. Crushed ore is withdrawn from the discharge pocket via a primary crusher discharge cute (C-3110-ST-001) by a variable speed apron feeder (C-3110-FE-001), which


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discharges to the coarse ore transfer conveyor (C-3120-CV-001). A fixed magnet (C-3110-MA001) is mounted on a monorail at the discharge of the apron feeder. The conveyor is equipped with a belt scale (C-3120-SL-001). The transfer conveyor dumps the ore onto the overland coarse ore conveyor (C-3120-CV-002). This conveyor is equipped with metal detector on detection to stop the conveyor (C-3120-MD-001) and a belt rip detection system (C-3120-ZE002) and feeds the coarse ore stockpile. C. 2.2

A sump pump (C-3110-PP-001) in the crushing area can be started and stopped from PCCS and CCCR as needed. The pump can also be operated automatically based on sump level.

System Interlocks A. The crushing and ore conveying systems are interlocked to ensure that upstream equipment

stops whenever downstream equipment trips. All conveyors, in general, will be provided with the following trips:

B.

1.

Pull-cord (CST)

2.

Belt misalignment (NCT)

3.

Low-speed (NCT)

4.

Discharge Chute Plugged (NCT)

All belt misalignment switches have two contacts. The first contact provides an alarm in PCCS and CCCR, the second contact shuts down the conveyor. The contacts will be separated such that the second contact will be installed close to the limit where the belt touches the steel.

C. The pull cord switches have two contacts as well. One is hard wired to the starter and the

second one is wired to the DCS to indicate which one of the switches has been pulled. D.

2.3

A warning horn will sound for 15 seconds prior to the starting of any conveyor or feeder and, for the coarse ore conveyor (C-3120-CV-002), will continue during the entire startup sequence. All equipment in this section is controlled remotely from the PCCS. Local control is also available.

Primary Crusher A. The primary crusher will be operated from the primary crusher control station (PCCS) located

behind the dump pocket. The dump pocket is designed for two side dumping, two trucks can be parked for dumping simultaneously. Traffic lights are provided for both dump stations and operated manually by the primary crusher operator. Red light designates a “No Dump” condition and green light indicates “Dump Allowed” condition. B. The dump station traffic lights will automatically turn red and sound siren ”Long Horn” blast on

condition which causes the crusher to stop. The lights will also turn red and sound siren on the following: 1.

Manual selection by operator (NCT)

2.

High discharge pocket level (NCT)

3.

Coarse ore conveyor tripped (C-3110-CV-002) (NCT)

4.

Coarse ore transfer conveyor (C-3120-CV-001) stopped (NCT)

5.

Apron feeder (C-3110-FE-001) stopped (NCT)


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY C. The crusher drive controls will turn the traffic lights red and sound the horn on the following: 1.

Lubrication oil filter differential pressure (to protect against dirty filters) (NCT)

2.

Hydroset oil filter differential pressure (NCT)

3.

Spider grease pump malfunction (NCT)

D. The traffic lights will not turn green before the condition is cleared. E. To alert the drivers of traffic light changes, the PCCS operator will be able to manually sound the

horn within the PCCS. F. The primary crusher will be equipped with a rock breaker, (C-3110-RB-001) which will normally

be operated remotely from its control panel in the PCCS or locally via a plug-in “waist” control unit. G. Two SPLIT system cameras monitor the truck dumping and provide an estimate about the

crusher feed particle size distribution (31AI-0113/0114). The estimate is used to provide feed back to the mining department for the control of drilling and blasting and to assist optimizing the performance of the crushing and grinding circuits. A SPLIT system camera is also installed on the coarse ore transfer conveyor (31AI-0611) to estimate the crusher discharge particle size distribution. The crusher operator manually adjusts the crusher hydroset setting to provide maximum crushing action while maintaining the required crusher throughput rate. Microwave detectors (31XE-0113/0114) are mounted at the truck dump station which detect when a truck is dumping. The signal is used by the SPLIT system to indicate when the particle size analysis can be performed. H.

An ADS system at the crusher feed chute is manually operated by the PCCS operator.

I.

Local control panels will also be available for the crusher lubrication unit.

J.

K.

The crusher drive will be provided with electrical and lubrication system protective trips including: 1.

Lubrication oil flow (NCT)

2.

Lubrication oil temperature (NCT)

3.

Lubrication oil pressure (NCT)

4.

High motor power draw (CST)

5.

High motor winding temperature (CST)

6.

High motor bearing temperature (CST)

7.

The following process trips are included

8.

High-High discharge pocket level (NCT)

9.

Emergency stop (CST)

A warning horn will sound for 15 seconds prior to the starting of the crusher. Six (6) hardwired emergency stop push-buttons will be provided for the crusher and will be located in the PCCS and in the field in locations surrounding the crusher.


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY 2.4

Conveyors and Stockpile A.

A variable speed apron feeder (C-3110-FE-001) equipped with a hydraulic drive withdraws material from the crusher discharge pocket and feeds onto the coarse ore transfer conveyor (C3120-CV-001). The feeder is equipped with a fixed magnet at the discharge end (C-3110-MA001) to remove tramp steel. The apron feeder speed is controlled by an operator specified set point either from the control room or from the local control panel (31SIC-0411). The operator can manually set the speed of the feeder to avoid discharging the crusher product onto an empty feeder and, at the same time, avoiding filling up the surge pocket under the primary crusher. The feeder speed can also be controlled automatically based on the surge pocket level or by the expert system. The apron feeder is provided with electrical and hydraulic system protective trips to stop the feeder. The feeder is also provided with the following trips: 1. 2.

Plugged apron feeder discharge chute (C-3110-ST-002) (NCT) Transfer conveyor (C-3120-CV-001) stopped (NCT)

3.

Plugged transfer conveyor (C-3120-CV-001) discharge chute (NCT)

4.

Coarse ore stockpile conveyor (C-3120-CV-002) stopped (NCT)

5.

Low-low discharge pocket level (NCT)

6.

Magnet not energized (NCT)

7.

Pull cords (CST)

8.

High-high coarse ore stockpile level (31LAHH-0748) (NCT)

B. The coarse ore transfer conveyor belt scale (C-3120-SL-001) monitors, records, and totalizes

the weight of material feeding the mill coarse ore stockpile and displays the results in both the PCCS and the CCCR (31WIC-0606). The weight scale can also be used to provide a set point to the apron feeder speed. This conveyor is also equipped with a metal detector (C-3120-MD-001) which trips the conveyor upon detection of metal on the belt. A SPLIT system camera (31AI0611) monitors the primary crusher discharge particle size distribution. C. The coarse ore transfer conveyor (C-3120-SL-001) discharges onto the fixed-speed coarse ore

(stockpile feed) conveyor (C-3120-CV-002). The stockpile will be installed with level profiling instrumentation to monitor the level in the two dead zones and one zones of the stockpile. The drive units for the coarse ore (stockpile feed) conveyor are equipped with a gearbox lubrication unit. D.

In addition to electrical and drive system protective trips, the coarse ore transfer conveyor (C3120-SL-001) is tripped on the following: 1.

High-high discharge cute level (31LAHH0619) (NCT)

2.

High-high pulley bearing temperature (31TAHH-0601/0602) (NCT)

3.

Coarse ore conveyor (C-3120-CV-002) tripped (NCT)

4.

Metal Detected (31NA-0617) (NCT)

5.

Belt tear (31XA-0618) (NCT)

6.

Belt side travel (31ZA-0608/0609)


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY E.

When the coarse ore transfer conveyor trips, the apron feeder (C-3110-FE-001) is also tripped and the traffic lights turned red.

F.

In addition to electrical and drive system protective trips, the stockpile feed conveyor (C-3120CV-002) is tripped on the following:

G.

1.

Ripped-belt (31XS-00618) (NCT)

2.

High-high pulley bearing temperature (31TAHH-0703/0702) (NCT)

3.

Belt side travel (31XA-0704/0709) (NCT)

When the stockpile feed conveyor trips, the coarse ore transfer conveyor (C-3120-SL-001) and apron feeder (C-3110-FE-001) will stop and the traffic light will be turned red.

H. The coarse ore (stockpile feed) conveyor (C-3120-CV-002) will not stop on High-high coarse ore

stock pile level. Instead, an alarm will sound in the PCCS and the apron feeder (C-3110-FE-001) will stop feeding ore to the coarse ore transfer (C-3120-CV-001). The coarse ore conveyor will then completely discharge all ore on its belt before stopping I.

2.5

In general, a bulldozer will be used for stockpile management during extended primary crusher shutdowns. When bulldozers are required on the stockpile, a mechanical lockout of the coarse ore conveyor will be used.

Primary Crusher Control Station A. The primary crusher control station (PCCS) will be located behind the crusher dump pocket,

between the two dump points, and will provide a central monitoring and control point for the entire coarse ore crushing, conveying and stockpiling system. The control station will have two graphical displays ergonomically designed for one operator. All system alarms will be annunciated on the operator console. A color printer will be provided for shift reporting and display printouts. B.

A dust suppression system will be provided in the crusher discharge pocket and at each ore transfer point. The dust suppression system will be controlled by the operators located in the PCCS. Dust suppression failure or shutdown will alarm in the PCCS. There will be a dedicated maintenance worker assigned specifically and exclusively to daily maintenance of the ADS systems in the plant, including the primary crushing area. The ADS system is interlocked to equipment in the area. ADS system C-3120-DC-005 requires booster water pump C-3100-PP002 operating to provide adequate pressure for the system on the top of the coarse ore stockpile. The operation of the pump is interlocked into the coarse ore conveyor (C-3120-CV001.

C. The following information will also be available in the concentrator central control room (CCCR):

2.6

1.

Status of crusher, feeder, sump pump and conveyors

2.

Stockpile levels

3.

Coarse ore transfer conveyor weigh scale readout

Coarse Ore Reclaim A.

Ore is reclaimed from the stockpile by four variable speed, hydraulically operated apron feeders (C-3210-FE-011/012/013/014) into coarse ore surge bins (C-3220-BN-021/022/032/024) via coarse ore reclaim conveyor (C-3210-CV-003) and coarse ore tripper conveyor (C-3210-CV-


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014). The reclaim conveyor is equipped with a belt scale (32-WI-0208) to measure and control the bin feed rate. The coarse ore is discharged from the coarse ore tripper conveyor with a coarse ore surge bin tripper (C-3210-TR-003), which distributes the ore into the bins. The coarse ore surge bins are equipped with dedicated dust controllers (C-3220-DC-061/062/063/064). B.

A self cleaning belt magnet (C-3210-MA-003) is installed above the coarse ore reclaim conveyor, which discharges the tramp metal into a tramp metal bin (C-3210-BN-011). A metal detector (32NS-0228) is installed on the conveyor after the magnet to stop the belt for detected metal.

C. The coarse ore reclaim conveyor cannot be started unless all dust control fans are running. If

any of the dust control fans is stopped during operations, the apron feeders are stopped after time delay. D.

Ordinarily the all bins are being filled with the tripper car system on continuous bases. The CCCR operator can bypass a bin manually from the DCS system. If a bin is bypassed, its dedicated dust control fan can be shut down for maintenance purposes while leaving the rest of the coarse ore reclaim system running.

E. The coarse ore surge bins are equipped with level meters. The tripper car is automatically

controlled to provide more feed into those bins which have lower than average level. Respectively the bins which are full do not receive feed until the level in the bin is decreased to a predetermined level. Proximity switches mounted at each bin indicates the tripper car position. End travel switch stops the tripper car moving if it moves pass all bins. F.

Feed blending control is assisted by the SP LIT system cameras installed on the apron feeders (31AI-0104/0114/0124/0134) assisted.

G. The apron feeders are provided with electrical and hydraulic system protective trips which stop

the feeders. The apron feeders are also equipped with the following trips:

H.

1.

Plugged apron feeder discharge 0103/0118/0128/0138) (NCT)

2.

Coarse ore reclaim conveyor (C-3210-CV-003) stopped (NCT)

3.

Coarse ore tripper conveyor (C-3210-CV-014) stopped (NCT)

4.

Low stockpile discharge 0101/0111/0121/0131) (NCT)

5.

High-high coarse ore surge bin level (C-3230-BN-021/022/023/024) (all bins at the same time) (32LAH-0427/0527/0627/0727) (NCT)

6.

ADS system trip (C-3210-DC-011/012/013/014) (NCT)

7.

Pull cords (CST)

8.

Dust control fans tripped (C-3220-FA-061/062/062/0640) (after time delay) (NCT)

chute

chute

level

(C-3110-ST-019/020/021/022) (32LAHH-

(C-3210-ST-011/012/013/014)

(32LAL-

In addition to electrical and drive system protective trips, the coarse ore reclaim conveyor (C3210-CV-003) is provided with the following protective trips: 1. 2.

Magnet not energized or stopped (NCT) Tripper car discharge chute plugged (32LAH-0331) (NCT)


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Mining & Minerals


I.

3.


4.


5.

Coarse ore reclaim conveyor discharge cute plugged (32LAHH-0211) (NCT)

6.

High-high pulley temperature (32TAHH-0201/0202)

7.

Pull cords (CST)

8.

Belt side travel (32XA-0203/0204) (NCT)

In addition to electrical and drive system protective trips, the coarse ore tripper conveyor (C3210-CV-014) is provided with the following protective trips: 1.

Tripper car discharge chute plugged (32LAH-0331) (NCT)

2.

Coarse ore tripper (C-3210-TR-023) stopped (NCT)

3.


4.

High-high pulley temperature (32TAHH-0301/0302) (NCT)

5.

Coarse ore reclaim conveyor discharge cute plugged (32LAHH-0211) (NCT)

6.

Pull cords (CST)

J.

The high-high coarse ore bin level (all at one time) does not trip the conveyors but trips the apron feeders instead. The conveyor is then allowed to empty itself into the bins. The tripper car is programmed to bypass an individual surge bin, if it is full, while still providing feed to the empty bins.

K.

ADS dust suppression system is provided at each apron feeder feed and discharge chute as well as in the secondary crusher product transfer conveyor transfer chute (C-3220-ST-050). The dust suppression system control is interlocked with the respective equipment and can also be controlled by the operators in the CCCR. Dust suppression failure or shutdown will alarm in the CCCS and will trip equipment after a time delay.

L.

A “start” command available from DCS will start the total equipment train from the dust collectors to the apron feeders with a single command on a logical sequence. Likewise, the “shut-down” command can be initiated from DCS. Alternatively the operator can start and stop all equipment separately following the logical sequence. The CCCR operator selects which apron feeders he wants to operate.

M. The shut down sequence does not stop the dust collectors; they are operated continuously and

are only shut down by the CCCR operator. N. The following information will be available in the CCCR:

2.7

1.

Status of ADS systems, dust collector fans, feeders, sump pump, conveyor and tripper

2.

Surge bin levels

3.

Coarse ore reclaim conveyor weigh scale readout

Secondary Crushing and Screening A. The secondary crushing circuit consists of four lines each including a coarse ore surge bin (C-

3220-BN-021/022/023/024), a belt feeder (C-3220-FE-3220-021/022/023/024), double deck


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Mining & Minerals


screen (C-3220-SC-021/022/023/024) and a 750 kW cone crusher (C-3220-CR041/042/043/044) operating in parallel. The screens separate the +50 mm material for crushing; screen undersize is directed into a tertiary crushing circuit. Metal detectors are installed on the belt feeders to prevent crusher liner damage. The feeder is stopped for the removal of the steel detected. B. The Feed into the crushers through screens is estimated by measuring the feeder speed

(32SI_0407/0507/0607/0707) and the height of the ore on the feeder (32LI0407/0507/0607/0707), which are used to control the variable speed feeders through the DCS system to provide steady feed to the crushers (32WIC-0407/0407/0607/0707). The secondary crusher feed chute level is measured and controlled to ensure choke feed into the crusher (32LIC-0429/0429/0629/0729). The feed chute level controller provides the set point to the feed rate control. C. The crusher power draw is measured and the feed rate into the crusher is reduced if the power

draw reaches a preset high limit (32J I-0416/0516/0616/0716). The high power draw control overrides the feed chute level controls. The crusher setting is kept as fine as possible; a vibration monitor is used to detect tramp metal relief system activation. D.

All four crusher products are discharged onto a common secondary crusher discharge conveyor (C-3220-CV-004). The discharge conveyor directs the product onto a secondary crusher product transfer conveyor (C-3220-CV-005), which discharges onto the coarse ore tripper conveyor thus returning the product back into the coarse ore surge bins.

E. The screen undersize is directed onto a coarse ore screen undersize conveyor (C-3200-CV-

006), which discharges onto a coarse ore screen undersize transfer conveyor (C-3220-CV-007). The screen undersize transfer conveyor feeds the HPGR surge bin feed conveyor (C-322-CV008), which feeds the HPGR feed surge bins (C-3230-BN-031/032/033/034) through two HPGR shuttle conveyors (C-3220-CV-012/013). The shuttle conveyors are mounted on rails and moved to feed the bin requesting the feed with four motorized wheels. A gate on a shuttle conveyor splitter box (C-3220-ST-095) is used to direct the feed into one of the two shuttle conveyors. During normal operations only one of the shuttle conveyor needs to be operating. F. The HPGR surge bin feed conveyor cannot be started before at least one of the shuttle

conveyors is operating and the gate in the HPGR surge bin feed conveyor is in the right position to feed the operating shuttle conveyor. G. The shuttle conveyors are operated from the DCS to provide feed into the four HPGR surge bins

depending on the surge bin level. A gate in the HPGR surge bin feed conveyor head chute and the shuttle conveyors are automatically operated to provide ore into the bin requesting feed. The gate can be moved to provide feed into both shuttle conveyors simultaneously, if requested by the operator. H.

I.

Since the crushers are difficult start when they are loaded with ore, the crusher motors are only stopped by internal drive system interlocks or on the following: 1.

High-high vibration monitor reading (32VAHH-0436/0536/0636/0736) (NCT)

2.

High-high discharge chute level (32LAHH-0418/0518/0618/0718) (NCT)

3.


If any condition on the downstream equipment requires shutting down the crushing circuit, the feeder only is shut down and the crusher and the screen are left running on “stand by” mode.


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FLUOR

Mining & Minerals

PROCESS DESCRIPTION – CONTROL PHILOSOPHY J.

The secondary crushing plant production is monitored by a coarse ore screen u/size belt scale (C-3220-SL-006) (32WI-1301) and the plant circulating load by the secondary crusher product scale (C-3220-SL-004) (32WI-1201). The particle size distribution is monitored by a SPLIT system camera (32AIT-1207).

K.

All transfer chutes in the secondary crushing system are equipped with ADS dust control sprays, which are turned on and off automatically when the equipment are started or stopped. The HPGR surge bins have dry dust collectors (C-3230-DC-071/072/073/074), which must be running before the secondary crushing system can be started.

L.

The equipment in the secondary crushing system will be started in the logical order starting from the shuttle conveyors on the screen underflow conveyor system and the secondary crusher product transfer conveyor on the crusher product conveyor system. Before the any of the crushing lines can be started, the coarse ore reclaim conveyor and the dry dust collectors (C3230-DC-071/072/073/074) need to be started. If a dust collector fan (C-3230-FA071/072/073/074) is tripped during operations an alarm is provided in the CCCR, but the conveyors are not automatically tripped (permissive controls).

M. The secondary crushing system can be started automatically with a “start” command from the

DCS system. A permissive light will indicate when the system interlocks allow all the required equipment to start. A “stop” command will stop the line and empty all conveyors and chutes before stopping the equipment. The operator needs to select which crushers he would like to start or stop before initiating the start up and shut down sequences. The operator can also start the equipment in logical order manually from DCS. N.

A sump pump (C-3220-PP-021) in the secondary crushing area can be operated remotely from the CCCR or can be run automatically based on sump level.

O.

In addition to electrical and drive system protective trips, the coarse ore screen feeders are tripped for:

P.

1.

Low-low coarse ore surge bin level (NCT)

2.

Belt tear (32XA-0414/0514/0614/0714) (NCT)

3.

High-high pulley bearing temperature (21TAHH-0432/0433 & 0532/0533 & 0632/0634 & 0732/0733) (NCT)

4.

Belt side travel (32ZA-0402/0409 & 0506/0509 & 0602/0609 & 0702/0709) (NCT)

5.

Coarse ore screen stopped (C-3220-SC-021/022/023/024) (NCT)

6.

High-high secondary crusher feed chute level (C-3220-ST-41/42/43/44) (NCT)

7.

High-high screen undersize chute level (C-3220-ST-051) (NCT)

8.


9.

Coarse ore screen undersize conveyor stopped (C-3220-CV-006) (NCT)

10.

Secondary crusher discharge conveyor stopped (C-3220-CV-004)

11.

Pull cords (CST)

In addition to electrical and drive system protective trips, the coarse ore screens (C-3220-SC021/022/023/024) are tripped on following: 1.

Secondary crusher stopped (C-3220-CR-021/022/023/024) (NCT)


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Mining & Minerals

PROCESS DESCRIPTION – CONTROL PHILOSOPHY 2.


3.

Vibration monitor trip (32VAHH-0419/0519/0619/0719) The coarse ore screen also trips the coarse ore feeders (C-3220-FE021/022/023/024)

NOTE!!!

Q. The secondary crusher discharge (C-3220-CV-004) conveyor trips on: 1.

Electrical and drive system protective trips (CST)

2.

High-high secondary crusher discharge conveyor head transfer chute level (C-322-ST049) (NCT)

3.

Secondary crusher product transfer conveyor trips (C-3220-CV-005) (NCT)

4.


5.

Pull cords (CST)

6.


7.

Belt side travel (32ZA-1206/1217) (NCT)

8.

High-high pulley bearing temperatures (32TAHH-1203/1204) (NCT) The secondary crusher discharge conveyor also trips the coarse ore feeders (C3220-FE-021/022/023/024)

NOTE!!!

R. The secondary crusher product transfer conveyor (C-3220-CV-005) trips on: 1.


2.

High-high secondary crusher product transfer conveyor head transfer chute level (C-322ST-050) (NCT)

3.

Coarse ore tripprer conveyor (C-3210-CV-014) stopped (NCT)

4.


5.


6.

Pull cords (CST)

7.

High-high pulley bearing temperatures (32TAHH-1231/1232) (NCT) The secondary crusher discharge conveyor also trips the coarse ore feeders (C3220-FE-021/022/023/024) and the secondary crusher discharge conveyor (C3220-CV-004)

NOTE!!!

S. The coarse ore screen undersize conveyor (C-3220-CV-006) trips on: 1.


2.

High-high coarse ore screen undersize conveyor head transfer chute level (C-322-ST-055) (NCT)

3.

Coarse ore screen undersize transfer conveyor trips (C-3220-CV-007) (NCT)

4.


5.


6.

Pull cords (CST)


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FLUOR

Mining & Minerals


High-high pulley bearing temperatures (32TAHH-1331/1332) (NCT) The coarse ore screen undersize conveyor also trips the coarse ore feeders (C3220-FE-021/022/023/024)

NOTE!!!

T. The coarse ore screen undersize transfer conveyor (C-3220-CV-007) trips on: 1.


2.

High-high coarse ore screen undersize transfer conveyor head transfer chute level (C-322ST-057) (NCT)

3.

HPGR surge bin feed conveyor trips (C-3220-CV-008) (NCT)

4.


5.

Belt side travel (32-ZA-1351/1352)

6.

Pull cords (CST)

7.

High-high pulley bearing temperatures (32TAHH-1333/1334) (NCT) The coarse ore screen undersize transfer conveyor also trips the coarse ore feeders (C-3220-FE-021/022/023/024) and the coarse ore screen undersize conveyor (C-3220-CV-006)

NOTE!!!

U. The coarse ore screen undersize conveyor is equipped with self cleaning belt magnet C-3220-

MA-006), which needs to be running before the coarse ore screen undersize conveyor can be started. However, the belt magnet trip only provides an alarm on DCS, but does not trip the screen undersize conveyor or related equipment during normal operations (permissive). V. The HPGR surge bin feed conveyor (C-322-CV-008) trips on: 1.


2.

High-high HPGR surge bin feed conveyor head transfer chute level (32LAHH-1406) (C322-ST-095) (NCT)

3.

Both HPGR surge bin feed shuttle conveyors trip at the same time (C-3220-CV-012/013) (NCT)

4.

Gate in HPGR surge bin feed conveyor head chute is jammed (32XA-1422) (NCT)

5.

Belt tear (32XA-1421)

6.


7.

Pull cords (CST)

8.

High-high pulley bearing temperatures (32TAHH-1401/1402) (NCT) NOTE!!!

HPGR surge bin feed conveyor (C-322-CV-008) also trips the coarse ore feeders (C-3220-FE-021/022/023/024), the coarse ore screen undersize conveyor (C3220-CV-006), coarse ore screen undersize transfer conveyor (C-3220-CV-007), ball mill screen oversize conveyor (C-3310-CV-011) and ball mill screen feeders (C-3310-FE-101,102/201,202/301,302/401,402)

W. If both of the shuttle conveyors are operating and one of them is tripped, the gate directing feed

into the respective conveyor will be closed. If the gate does not close after a set time period, the HPGR surge bin feed conveyor will be tripped.


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FLUOR

Mining & Minerals


X. The HPGR shuttle conveyor No. 1 (C-3220-CV-012) trips on the following: 1.


2.

High-high HPGR surge bin levels (C-3230-BN-031/032) (at the same time) (NCT)

3.

Pulley bearing temperature (32TAHH-1501/1502) (NCT)

4.


5.


6.

Pull cords (CST) The HPGR surge bin feed shuttle conveyor No. 1 (C-3220-CV-012) also trips HPGR surge bin feed conveyor (C-322-CV-008) the coarse ore feeders (C-3220FE-021/022/023/024), the coarse ore screen undersize conveyor (C-3220-CV006), coarse ore screen undersize transfer conveyor (C-3220-CV-007), ball mill screen oversize conveyor (C-3310-CV-011) and ball mill screen feeders (C3310-FE-101,102/201,202/301,302/401,402) if the HPGR surge bin feed shuttle conveyor No. 2 (C-3220-CV-013) is not running

NOTE!!!

Y. The HPGR surge bin feed shuttle conveyor No. 2 (C-3220-CV-013) trips on the following: 1.


2.

High-high HPGR surge bin levels (C-3230-BN-033/034) (at the same time) (NCT)

3.

Pulley bearing temperature (32TAHH-1503/1504) (NCT)

4.


5.


6.

Pull cords (CST) The HPGR surge bin feed shuttle conveyor No. 2 (C-3220-CV-013) also trips HPGR surge bin feed conveyor (C-322-CV-008) the coarse ore feeders (C-3220FE-021/022/023/024), the coarse ore screen undersize conveyor (C-3220-CV006), coarse ore screen undersize transfer conveyor (C-3220-CV-007), ball mill screen oversize conveyor (C-3310-CV-011) and ball mill screen feeders (C3310-FE-101,102/201,202/301,302/401,402) if the HPGR surge bin feed shuttle conveyor No. 1 (C-3220-CV-012) is not running

NOTE!!!

Z. The following information will be available in the CCCR: 1.

Status of ADS systems, dust collector fans, feeders, sump pump, conveyor and tripper

2.

Surge bin levels

3.

Coarse ore reclaim conveyor, secondary crusher product and screen undersize weigh scale readout

4.

Gate position

5. 2.8

Tripper car position

Tertiary Crushing


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Mining & Minerals

PROCESS DESCRIPTION – CONTROL PHILOSOPHY A.

Four HPGR crushers (C-3230-CR-031/032/033/034), operating in parallel, are used in the tertiary crushing circuit. The crushers are fed with variable speed belt feeders (C-3230-FE031/032/033/034) from individual surge bins (C-3230-BN-031/032/033/034). The belt feeders are equipped with metal detectors (C-3230-MD-031/032/033/034). Gates in the feeder bypass chutes (C-3230-ST-076/077/078/079) are opened to direct the metal onto the HPGR discharge conveyor (C-3230-CV-009) continuing onto the HPGR product conveyor (C-3230-CV-010) and then into the ball mill feed surge bins (C-3310-BN-101/201/301/401).

B.

As the HPGR crushers operate most efficiently with choke feed, level measurement and control in the HPGR feed chute (31LIC-2121/2221/2321/2421) is used to maintain choke feed by controlling the feeder speed through a feed controller (32WIC-2107/2207/2307/2407) in DCS system. The tertiary crushing plant production is measured by a weight scale (C-323-SL-009) on the HPGR discharge conveyor (C-3230-CV-009).

C. The HPGR crushers are equipped with variable speed drives (32SIC-2125/2210/2325/2420).

The speed is used to control the respective HPGR feed surge bin level (32LIC2119/2203/2323/2423), the level controller provides the set point to the feeder speed. At high bin levels the speed is set at maximum, at low-low signal the feeder is stopped to prevent dumping ore onto an empty feeder. The CCCR operator provides the set point to the bin level. Ordinarily the HPGR is not stopped automatically if the HPGR feed chute is empty, CCCR operator will decide if the shutdown of the feed is long enough to justify shutting down the crusher. Normally the crusher is shut down manually. D.

HPGR feed size is also monitored with cameras (32AI-2116/2227/2238/2436)

E.

Each crushing line is equipped with an individual dust scrubber (C-3230-031/032/033/034). A crushing line cannot be started before the respective scrubber is running. If the scrubber fan (C3230-FA-031/032/033/034) will trip during operations, the feeder will trip and cannot be started before the dust scrubber is operating. Effluent from the scrubbers is piped into scrubber effluent sumps and pumped with scrubber effluent return pump (C-3230-PP-030) into primary cyclone feed sumps. The operator can select remotely between two pump sumps in the grinding circuit (C-3310-BX-101 or 201) with remotely controlled valves (33XS-2111/2611/3111/3611) into which pump and sump and how much he selects to discharge the effluent. Pinch valves are used in control, the valve position determines the amount of effluent discharged into the pump box.

F.

Water addition into scrubbers is remotely controlled with on-off knife gate valves. The effluent pump gland water is equipped with a local flow meter and low flow switch, which prevents the pump starting with low gland seal water flow. Low water flow during operations will alarm in the CCCR, but does not stop the pump.

G. The HPGR product conveyor discharges into the ball mill surge bins by a tripper car (C-3230-

TR-010), which is automatically controlled by the DCS system to maintain proper bin levels. The tripper car is equipped with proximity switches to provide the tripper car position and over travel switch to shut down the tripper car if it goes over the end limit. H. The HPGR plant production is monitored by a belt scale mounted on the HPGR discharge

conveyor (C-3230-SL-009) (32WI-3106). The HPGR product particle size distribution is estimated with a SPLIT camera system (32AI-3129) I.

Each ball mill surge bin is equipped with two dry dust collectors (C-3310-DC101,102/201,202/301,302/401,402), which must be running before the HPGR product conveyor can be started.


PROCESS




FLUOR

Mining & Minerals

PROCESS DESCRIPTION – CONTROL PHILOSOPHY J.

The tertiary crushing system can be started automatically with a “start” command from the DCS system. A ready light will indicate when the system interlocks allow all the required equipment to start. A “stop” command will stop the line and empty all conveyors and chutes before stopping the equipment. The operator needs to select which crushers he would like to start or stop before initiating the start up and shut down sequences. The operator can also start the equipment in logical order manually from DCS. Before using automatic start the operator needs to select which crushers will be started.

K.

A sump pump (C-3230-PP-031) in the HPGR area can be operated remotely from CCCR or automatically on the sump level.

L.

In addition to electrical and drive system protective trips, the HPGR feeders (C-3230-FE031/032/033/034) are tripped for:

M.

1.

Low-low HPGR surge bin level (C-3230-BN-031/032/033/034) (NCT)

2.

Metal bypass chute jammed (C-3230-ST-076/077/078/079) (NCT)

3.

HPGR stopped (C-3230-CR-031/032/033/034) (NCT)

4.

High-high feeder discharge chute level (C-3230-ST-066/067/068/069) (NCT)

5.

High-high bearing temperature (32TAHH-2131/2132 & 2231/2232 & 2331/2332 & 2431/2432) (NCT)

6.

Belt tear (32XA-2133/2236/2334/2433)

7.

Belt side travel (32ZA-2137/2102 & 2211/2204 & 2309/2302 & 2409/2402)

8.

HPGR discharge conveyor stopped (C-3230-CV-009) (NCT)

9.

Pull cords (CST)

Since the crushers are difficult start if they are loaded with ore, the crusher motors are only stopped by internal drive system interlocks or on the following: 1.

High-high vibration monitor reading (NCT)

2.

High-high discharge chute level (NCT)

3.


N. The HPGR discharge conveyor (C-3230-CV-009) trips on: 1.


2.

High-high discharge conveyor (C-3230-CV-009) head transfer chute level (C-322-ST-086) (NCT)

3.

HPGR product conveyor trips (C-3230-CV-010) (NCT)

4.

High-high pulley bearing temperatures (32TAHH-3101/3102) (NCT)

5.

Belt tear (32ZA-3108) (NCT)

6.


7.

Pull cords (CST) NOTE!!!

HPGR discharge conveyor (C-3230-CV-009) also trips HPGR crusher feeders (C-3230-FE-031/032/033/034)


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FLUOR

Mining & Minerals


O. The HPGR product conveyor (C-3230-CV-010) trips on: 1.


2.

High-high ball mill feed surge bin levels (C-3310-BN-101/201/301/401) (all at same time) (NCT)

3.

High-high tripper car discharge chute level (C-3230-ST-087) (NCT)

4.


5.

Belt tear (32XA-3208)

6.


7.

Pull cords (CST) The HPGR product conveyor (C-3230-CV-010) also trips HPGR discharge conveyor (C-3230-CV-009, and HPGR crusher feeders (C-3230-FE031/032/033/034)

NOTE!!!

P. The following information will be available in the CCCR: 1.

Status of ADS systems, dust collector fans, feeders, sump pump, conveyors and tripper

2.

Surge bin levels

3.

Weigh scale readout

4. 3.

Tripper car position

GRINDING 3.1

Process Overview A.

Four ball mills (C-3320-MI-101/201/301/401), operating in parallel mode are used to grind the HPGR product down to about 110 micron P80. Each ball mill receives feed from a surge bin with two parallel, variable speed belt feeders (C-3310-FE-101, 102/201, 202/301, 302/401, 402) each feeding a double-deck, vibrating screen. Feeders are equipped with feed rate controls (22WIC1107, 1127/1207, 1227/1307, 1327/1407, 1427) and the set point for the throughput comes from CCCR by the DCS system. Originally the throughput rate is set by the operator, later the throughput will be controlled by an Expert System.

B. The feeders discharge into ball mill screen feed chutes, where water is added to dilute the

screen underflow density to about 36%. The slurried feed is directed onto double deck screens (C-3310-ST-105,106/205,206/305,306/405,406), where +6 mm material is transported back into the tertiary crushing circuit and -6 mm material flows through the screen into a primary cyclone feed sump. The +6 mm material is directed onto a ball mill screen oversize conveyor (C-3310CV-011), which discharges onto the HPGR surge bin feed conveyor (C-3230-CV009). C. The

screens are mounted above the primary cyclone feed sumps (C-3310-BX101/201/301/401), where the slurry from the screen underflow and ball mill discharge are combined to produce the cyclone feed. The combined screen underflow and ball mill discharge is pumped with primary cyclone feed pumps (C-3310-PP-101/201/301/401) into primary cyclone clusters (C-3330-CS-101/201/301/401). The primary cyclone underflow flows by gravity to the


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Mining & Minerals


ball mills (C-3320-MI-101/201/301/401) via cyclone underflow launders (C-3230-LA102/202/302/402). The discharge from the ball mill flows through a launder (C-3320-LA101/201/301/401) back into the primary cyclone feed sump. D. The cyclone overflow is sampled with overflow samplers (C-3330-SA-101/201/301/401) and

assayed with in stream analyzers (C-3330-SA-102/103). Only two analyzers are used as a multiplexer is used between two cyclone overflow samples. The samples are also analyzed for particle size (C-3330-AZ-101/301). From the sampler the cyclone overflow is directed into the flotation circuit. E. 3.2

All equipment in the grinding circuit, except local manually controlled on-off valves, are controlled from CCCR.

Ball Mill Screen and Feeders A. The mass flow onto the screens is estimated based on the feeder speed measurements (32SI-

1103/1123 & 1203/1223 & 1303/1323 & 1403/1423) and the ore bed height measurement. The mass flow set point is initially provided by the CCCR operators, later the mass flow will be controlled by the expert system. B.

Ratio control (32FFIC-1101/1102 & 1201/1202 & 1301/1302 & 1401/1402) is provided between the feeder tonnage and the water addition into the screen feed chutes (32FIC-1101/1102 & 1201/1202 & 1301/1302 & 1401/1402) to maintain constant screen underflow density. Water sprays are also mounted on the top of the screen decks and the spray water addition is monitored (32FIC-1130/1230/1330/1430). The quantity of spray water is controlled from DCS. The spray water is automatically turned on when the screen is started and off when the screen is shut down. The ratio controller between the feed tonnage and screen feed chute water addition is automatically turned on to a predetermined set point and the water flow controller on remote set point mode when the feeder is started

C.

Water addition into the screen feed box is critical to prevent cyclone feed pump damage and plugging up the cyclone feed pipe. Therefore a deviation alarm between the screen feed water flow set point and measurement will be programmed to warn the CCCR operator for possible density problems (32FAHL-1101/1102 & 1201/1202 & 1301/1302 & 1401/1402).

D. The screen feeder feed chute is equipped with a low chute level detector for feeder belt

protection (32LAL-1101/1121 & 1201/1221 & 1301/1321 & 1401/1421). To avoid disturbing the grinding process the low level detector only provides an alarm for the CCCR operator, who has to decide if an action is required or not. E. The screen oversize conveyor is equipped with belt scales between every second screen

oversize chute to allow estimating the actual feed into each ball mill by deducting the amount of screen oversize material from the screen feed 32WI-1536/1537/1538/1539). 3.3

Ball Mills and Cyclones A.

Cyclone feed density (33DI-2116/2616/3116/3616) and flow (33FI-2117/2617/3117/3617) is measured and the mass flow calculated (33FI-2118/2618/3118/3618). The cyclone feed density is controlled with water addition into the ball mill discharge launder (33FIC2204/2704/3204/3704) through the Expert System. Water is metered with magnetic flowmeters and controlled with pneumatically operated butterfly valves at every addition point in the circuit. The pump box is equipped with local manual water addition point, which severs as a back up and commissioning water source.


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FLUOR

Mining & Minerals

PROCESS DESCRIPTION – CONTROL PHILOSOPHY B. The primary cyclone feed sump level is measured and controlled with the primary cyclone feed

pump (C-3310-PP-101/201/301/401) speed. The pump intake is equipped with automatic water flush and isolation valve. Both the pump sump and the pump intake pipe have automatic drain valves. When the cyclone feed pump is tripped, the isolation valve closes and the sump and pump drain valves open automatically to drain the cyclone feed pipe and sump. C.

Before the cyclone feed pump can be started, the pump sump drain valve, the pump inlet drain valve and the pump flush water valve need to be closed and the isolation valve opened.

D. The valves are detailed in the table as follows: Pump

C-3310-PP-101 C-3310-PP-102 C-3310-PP-103 C-3310-PP-104 E.

Pumpbox Drain Valve

33XS-2101 33XS-2601 33XS-3101 33XS-3601

Pump Drain Valve

Pump Inlet Valve

Flush Water Valve

33XS-2102 33XS-2602 33XS-3102 33XS-3602

33XS-2104 33XS-2604 33XS-3104 33XS-3604

33XS-2103 33XS-2603 33XS-3103 33XS-3603

Gland seal water to the primary cyclone feed pump is measured with a local flow meter equipped with a low flow switch. The gland seal water line has a manual shut off valve. Interlock in DCS prevents starting up the pump with low gland seal water flow and provides an alarm, but does not trip the pump, during normal operations. The gland water system is also equipped with low gland water pressure alarm

F. The cyclone cluster consists of 14 660 mm cyclones with automatic shut off valves. The cyclone

feed pressure (33PIC-2222/2722/3222/3722) is measured and controlled by automatically opening and closing cyclones. Water is added into cyclone overflow (33FIC2202/2702/3202/3702) and underflow (33FIC-2203/2703/3203/3703) launders through magnetic flow meters and control valves. A density measurement on the cyclone overflow line is used to control the feed density into the flotation circuit, a density controller in DCS automatically adjusts the water addition into the cyclone overflow launder. G.

A sump pump (C-3310-PP-103/203/303/403) in the ball mill area can be operated remotely from the CCCR or automatically based on the sump level.

H.

For a normal shut down for maintenance purposes the following sequence is to be used: 1.

Shut down belt feeders

2.

After the screens have run empty, shut down screens and close screen water valves

3.

I.

Turn the ball mill discharge launder water controller on manual mode

4.

In the CCCR, place pump flow controller in automatic and ramp down flow set point after one minute to a minimum recommended flow set point

5.

Leave pump running and monitor cyclone feed density until density is below 1.1 t/m3

6.

Stop pump

7.

Close ball mill discharge launder water valve and open suction and side drain valve

In order to restart the system after a shut down the following procedure is to be used: 1.

Close suction side drain valve.


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Open ball mill discharge launder water valve

3.

Start pump on water in manual at low speed

4.

Start double deck screens, turn spray water on

5. 6.

Turn screen feed box water addition controller on automatic mode Start ball mill screen feeders

J.

The drive unit for the cyclone feed pumps will be equipped with a forced oil gearbox lubrication unit.

K.

Each ball mill has a wrap around variable speed motor and caliper brake. The caliper brake is designed to be fail closed, that is, it uses hydraulic fluid to open and a spring to close. Normal starting operation of the mill will release the caliper brake and starts ramping the ball mill speed up to the operating speed. Normal stopping operation will ramp the speed of the mill to zero and then apply the caliper brakes. A ball mill fault condition (e.g., lubrication system failure, motor failure, loss of power) will cause the motor to stop and the caliper brakes to instantly close. Refer to the ball mill operation manual for a complete description of mill operation.

L.

The vendor-supplied control system for the ball mill and wrap around motor will provide all electrical system, lubrication system and other required protective trips for the mill and mill motor. Ball mill and motor alarm and trip monitoring will be performed from the CCCR with a diagnostic display also available in the ball mill motor cycloconverter drive electrical room. In addition to electrical, drive system and mill/motor lubrication system protective trips, the ball mill is provided with the following personnel and protective trips: 1.

Emergency stop local push buttons (CST)

2.

Feed chute attached to trunnion liner (kirk key interlock)

M. The ball mill and wrap around, variable speed drive motor will be controlled by a vendor supplied

control system (PLC) which interfaces with the plant control system (DCS). The speed of the ball mill will be controlled by an operator-specified set point. The ball mill will normally be operated from the Concentrator central control room (CCCR). A local motor control panel will be provided on the mill operation platform adjacent to the ball mill. Ball mill inching operations will be performed from this local panel only. N.

3.4

Primary collector, secondary collector (if required), moly collector and milk of lime are also added to the ball mill at the cyclone underflow launder. The collector addition rates will be controlled by operator specified set points or by ratio control cascaded from the ball mill feed weight controller. (Collectors are added proportionally to new feed weight, with adjustments to the rate for variations in feed grade). Lime addition is controlled to an operator specified pH set point, with pH measurement downstream in the cyclone overflow (33AIC-2401/2402/3401/3402).

System Interlocks A.

In addition to electrical and drive system protective trips, the ball mill screen feeders (C-3310FE-101,102/201,202/301,302/401,402) are tripped for the following: 1.

Ball mill tripped (C-3320-MI-101/201/301/401) (NCT)

2.

Cyclone feed pump tripped (C-3310-PP-101/201/301/401) (NCT)

3.

High-high feeder discharge chute level (C-3310-ST-103,104/203,204/303,304/403,404) (NCT)


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High-high screen oversize chute level (C-3230-ST-105,106/205,206/305,306/405/406) (NCT)

5.

High-high screen undersize chute level (C-3310-ST-107,108/207,208/307,308/407,408) (NCT)

6.

Screen oversize conveyor tripped (C-3310-CV-011) (NCT)

7.

Ball mill feed screen tripped (C-3310-ST-105,106/205,206/305,306/405,406) (NCT)

8.

HPGR surge bin feed conveyor tripped (C-3220-CV-008) (NCT)

9.

Both HPGR shuttle conveyors tripped (C-3229-CV012/013) (NCT)

10.

High-high pulley bearing temperatures (33TAHH-1116/1117 & 1125/1126, 1216/1217 & 1225/1226, 1316/1317 & 1325/1326, 1416/1417 & 1425/1426) (NCT)

11.

Belt tear (33XA-1108/1128 & 1208/1228 & 1308/1328 & 1408/1428) (NCT)

12.

Belt side travel (33ZA-1102/1109 & 1122/1129, 1202/1209 & 1222/1229, 1302/1309 & 1322/1329, 1402/1409 & 1422/1429)

13.

Pull cords (CST)

B. The screen oversize conveyor (C-3310-CV-01) trips on: 1.


2.

High-high head chute level (C-3310-ST-091) (NCT)

3.

HPGR surge bin feed conveyor trip (C-3220-CV-008)

4.

Both HPGR shuttle conveyors tripped (C-3229-CV012/013)

5.


6.


7.


8.

Pull cords (CST) NOTE!!!

3.5

Screen oversize conveyor (C-3310-CV-01) trips the ball mill screen feeders (C3310-FE-101,102/201,202/301,302/401,402)

Ball Mill Grinding Ball Addition A.

Ball mill grinding balls are stored in a ball storage bin (C-3320-BN-051) located on the north west corner of the grinding building. The ball mill ball storage bin (C-3320-BN-051) is located below a dump pocket and is fed directly by ball transport trucks. Balls are discharged from the ball storage bin onto a high lift conveyor (C-3320-CV-021) by means of a fixed speed rotary drum feeder (C-3320-ZM-040) and discharge chute (C-3320-ST-114). The ball charge rotary drum feeder is interlocked with the high lift conveyor (C-3320-CV-021). The ball feed rate is measured by means of a belt scale (C-3320-SL-022) on the ball mill ball transfer conveyor (C-3320-CV022). The belt scale reading and the diverter gate positions are used to summarize the ball addition to individual mills (33WIQ-4126/4121/4122/4123).

B.

In addition to electrical protective trips, the ball charge high lift conveyor (C-3320-CV-021) is provided with the following protective trips: 1.

Plugged discharge chute (C-3320-ST-115) (33LAHH-4101) (NCT)


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY 2. C.

Balls are transferred from the high lift conveyor (C-3320-CV-021) to the ball mill ball transfer conveyor (C-3320-CV-022) via transfer chute (C-3320-ST-115). Automatic diverter gates (C3320-ZM-101/201/301/401) located on the ball mill transfer conveyor (C-3320-CV-022) will be used to direct balls to each individual mill. The diverter gates will be used to direct the balls to the desired mill as and when required. The balls will fall via gravity to each mill circuit via a feed chute (C-3320-ST-113/213/313/413) and the individual ball mill cyclone underflow chute. Excess balls on the conveying system not diverted to any mill will be conveyed to the Ball Mill Ball Overflow Bin (C-3320-BN-052) via the ball mill ball overflow chute (C-3320-ST-116).

D.

In addition to electrical protective trips, the ball transfer conveyor (C-3320-CV-022) is provided with the following protective trips:

E.

4.

Ball mill ball transfer conveyor (C-3320-CV-022) stopped (NCT)

1.

All diverter gates are open (C-3320-ZM-101/201/301/401) (NCT)

2.

More than one diverter gate is open (C-3320-ZM-101/201/301/401)\

3.


4.


Grinding balls can be added using a ball bucket and an overhead crane if the automatic system is down. A hook mounted scale (C-3320-SL-020) can then be used to estimate the ball addition to mills.

FLOTATION 4.1

Process Overview A. The rougher-scavenger flotation circuit is set up as four (4) rows of ten (10) flotation cells. Each

flotation cell is 160 m3 and the ten cells in each row of cells are set up in pairs of two cells each with level control between each pair of cells. The first two cells in each row of cells have individual level controls. Each row of rougher-scavenger cells is gravity fed by the overflow from each of the four primary grinding cyclones. B. The first cell in each row of cells is used as a rougher flotation cell. Concentrate from each of

these cells is collected via gravity and sent to the polishing mill circuit. The second cell in each row of cells will normally be used as a scavenger cell but can also be used as a rougher cell, as required. The remaining eight (8) cells per row are to be used exclusively as scavenger flotation cells. Cells are numbered as follows:

C.

•

Row one

Rougher cells Scavenger cells

3410-CF-101/102 3410-CF-103 to -110

•

Row two


3410-CF-201/202 3410-CF-203 to -210

•

Row three


3410-CF-301/302 3410-CF -303 to -310

•

Row four


3410-CF-401/402 3410-CF -403 to -410

Frother is added to the first, third, fifth, and seventh rougher flotation cell (4 in total). Primary collector, secondary collector and molybdenum collector are added to the third, fifth and seventh scavenger flotation cells. Refer to section 5.0 Reagents for more detail.


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY D.

Rougher concentrate from each row of cells flows via gravity to the rougher concentrate samplers (3410-SA-103/104 & 3410-SA-303/304) for on stream analysis (3410-AZ-103/104 & 3410-AZ-303/304) and collection of shift samples. All of the four rougher concentrate streams are collected in one launder (3410-LA-105) after analysis and fed via gravity to the polishing mill feed pumpbox (3420-BX-501) from where it is pumped via one of two transfer pumps (3420-P P501/502) to the polishing mill feed distributor (3420-DI-502) and fed by gravity to the rougher concentrate polishing mills (3420-ML-501/502). The rougher concentrate is milled to a target value of 80% passing 50 microns in the polishing mills (3420-ML-501/502). The discharge from the rougher concentrate polishing mills flows by gravity to a sampler (3420-SA-501) for on stream analysis (3420-AZ-501) and particle size analysis (3420-AZ-502). The main process stream from the sampling system falls via gravity into the column cell feed pumpbox (3420-BX502) from where it is pumped via one of two column cell feed pumps (3420-PP-503/504) to the column cell feed distributor (3430-DI-501).

E.

Scavenger concentrate, from each row of cells flows via gravity to the scavenger concentrate samplers (3410-SA-203/204 & 3410-SA-403/404) for on stream analysis (3410-AZ-203/204 & 3410-AZ-403/404) and collection of shift samples. All of the scavenger concentrate streams are collected in one launder (3410-LA-106) after analysis and fed via gravity to the scavenger concentrate collection pumpbox (3420-BX-503). This pumpbox is sized at fifty (50) m3 to accommodate reasonable fluctuations in concentrate production rates and minimize surge in downstream processes.

F.

Scavenger flotation tailing from each row of cells pass through individual sample stations (3410SA-102/202/302/402) where on stream analysis (3410-AZ-103/203/303/403) is carried out and shift samples collected. The tailing stream from each tailing sampler falls into a tailing collection launder (3710-LA-001) and are transported via gravity to a bulk plant tailing sampler (3710-SA001) and analyzer (3710-AZ-001) before being split into two streams and fed to the tailing thickeners.

G.

Recycle streams from the regrind mills (3420-ML-503/504/505) and the cleaner scavenger concentrate stream are combined in the scavenger concentrate pumpbox (3420-BX-503). The regrind cyclone feed pumps (3420-P P-505/506) are used to feed the combined concentrates from the scavenger concentrate pumpbox to the regrind cyclone cluster (3420-CS-501). Dilution water is added to the scavenger concentrate pump box to allow for cyclone feed density control. The cyclone underflow passes through the cyclone underflow launder (3420-LA-501) to the regrind mill feed pumpbox (3420-BX-504), in which the slurry density is controlled through addition of process water and the flow is split to feed each regrind mill (3420-ML-503/504/505). The underflow from the cyclone underflow launder flows via gravity to the regrind mill feed pumpbox (3420-BX-504) and feed pumps (3420-PP-507/508/509). The regrind mill feed stream is fed into the bottom of the regrind mills and flows up through the mills and via gravity from the mill discharge to the scavenger concentrate collection sump (3420-BX-503).

H. The regrind cyclone overflow stream is split and one stream is fed through a gravity sampler

(3420-SA-504) for particle size analysis (3420-AZ-502), and then flows via gravity to the scavenger concentrate collection pumpbox (3420-BX-503). The second stream split from the regrind cyclone overflow flows via gravity to the feedbox of the first cleaner flotation cells (3430BX-505). The first cleaner and cleaner scavenger cells are one row of ten (10) one hundred and sixty cubic meter cells (160m3). The first six cells are the first cleaner cells and the last four cells the cleaner scavenger cells. Concentrate from the first cleaner cells (3440-CF-501 to -506) flows via gravity to the column cell feed sampler (3420-SA-502) and analyzer (3420-AZ-501) before falling via gravity into the column cell feed pumpbox (3420-BX-502). Concentrate from the cleaner scavenger cells (3440-CF-507 to -510) flows via gravity to the column cell feed sampler


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(3420-SA-503) and analyzer (3420-AZ-501). This concentrate material then flows to the regrind circuit via the scavenger concentrate pumpbox (3420-BX-503). I.

The tailing stream from the cleaner scavenger cells flow via gravity through a tailing sampler (3440-SA-513) and analyzer (3440-AZ-505) before flowing via gravity into the combined scavenger tailing collection launder (3710-LA-001).

J.

Concentrate from the column cell feed pump box (3420-BX-502) is fed via the column cell feed pumps (3420-PP-503/504) to the column cell feed distributor (3430-DI-501). The distributor splits the stream into four (4) streams, which are then fed into the four column cells (3430-CM501/502/503/504). The column cells are each 5.0 m diameter and 12.0 m high.

K. Tailing material from each column flows via gravity through a column tailing sampler (3430-SA-

509 to -512) and a shared analyzer (3420-AZ-504) before falling via gravity into the column cell tailing pump box (3430-BX-505). The tailing is then pumped via the column tailing transfer pumps (3430-PP-512/513) to the first cleaner cells.

4.2

L.

Concentrate from each column flows via gravity through a column concentrate sampler (3430SA-505 to -508) and a shared analyzer (3420-AZ-503) before falling via gravity into the column concentrate pump box (3430-BX-506). The concentrate is then pumped via the column concentrate transfer pumps (3430-P P-504/515) to the bulk concentrate thickener feed box (3510-BX-003).

M.

Each cell or pair of cells is equipped with froth vision cameras for future froth rate controls.

N.

All equipment in the flotation and regrind areas will be controlled from the concentrator central control room (CCCR). Ability to control locally from the field will also be provided.

O.

Floor sump pumps in the cleaner flotation and regrind areas can be started and stopped remotely from CCCR or operated automatically based on sump level. The status of the pump and the sump level are displayed in the CCCR.

P.

In general, launder spray water addition is performed manually. Process water will be piped to process sumps for commissioning, startup and spray water requirements. Process water is added to the combined scavenger concentrate collection pumpbox (3430-BX-506) and regrind mill feed pumpbox (3420-BX-504) and is measured and controlled to achieve the desired pulp densities in the flows to the first cleaner cells and the regrind mills.

System Interlocks. In general, there are no flotation system interlocks between pieces of equipment, with the exception of the regrind feed pumps which cannot be started unless the respective vertimill is running. More detailed trip information is provided in the individual section descriptions.

4.3

Rougher and Scavenger Flotation A.

Cyclone overflow from the grinding circuit flows by gravity to the rougher flotation feed distributor (3310-DI-003) and then to each row of flotation cells.

B.

A total of forty (40) rougher and scavenger flotation cells are provided in four (4) rows of ten (10) cells each. The first cell in each row of cells is to be used as a rougher flotation cell, the second cell in each row as either a rougher or scavenger cell and the remaining eight (8) cells in each row as scavenger cells. The cells except the first two on each row are all installed as pairs of cells, with five (5) pairs of cells per row. The first cell has a feedbox and separate level controls.


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Frother is added to the first, third, fifth, and seventh flotation cells in each row. Primary collector, secondary collector and moly collector are added to the third, fifth and seventh cells. Refer to section 5.0 Reagents for more details. C.

Level control of the rougher and scavenger flotation cells will be performed by dual level controllers. Two external dart valves are used to control the flow of slurry from the first cell to the second cell and then to subsequent cell pairs. The first dart valve is used in the range of zero to fifty percent (0-50%) of controller output and the second valve is used for fifty to one hundred percent (50-100%). The last cell on each bank has only one level control valve installed. Ultrasonic sensors will be used to detect both the pulp and froth levels. The froth bed depth will be controlled to allow for optimization of recovery and grade as a function of varying feed conditions. The following remote (DCS) controller configuration will be used for the level controls of the cells: Cell

Row #1

Row #2

Row #3

Row #4

Rougher 1 Rougher/Scavenger 2 Scavenger 3/4 Scavenger 5/6 Scavenger 7/8 Scavenger 9/10

34LIC-0101 34LIC-0108 34LIC-0203 34LIC-0207 34LIC-0303 34LIC-0307

34LIC-0113 34LIC-0121 34LIC-0212 34LIC-0217 34LIC0312 34LIC-0317



D.

Concentrate from each row of rougher and scavenger cells are collected in a separate rougher and scavenger concentrate launders (3410-LA-103/203/303/403 & 3410-LA-104/204/304/404). Concentrate from the second cell in each row of cells can be diverted to the scavenger concentrate collection launder. This is to be done manually via the use of a movable, remote controlled dart valve in the overflow launder. This action is dependant on mineralogical characteristics of ore and plant performance.

E.

Rougher concentrate from each row of cells is laundered to one sampler (3410-SA103/104/303/304) and analyzed (3410-AZ-103/104/303/304) prior to being combined and fed to the rougher concentrate collection pumpbox (3420-BX-501) and polishing vertimill feed distributor (3420-DI-502) via a combined rougher collection launder (3410-LA-105).

F.

Scavenger concentrate from each row of cells is laundered to one sampler (3410-SA203/403/404) and analyzed (3410-AZ-203/204/403/404) prior to being combined and fed to the scavenger concentrate collection pumpbox (3420-BX-503) via a combined collection launder (3410-LA-106). The scavenger concentrate collection pumpbox (3420-BX-503) is monitored in the CCCR.

G.

Scavenger flotation cell tailings flow by gravity from each row of flotation cells through individual samplers (3410-SA-102/202/302/402) and analyzers (3410-AZ-103/203/303/403) to a tailing collection launder (3710-LA-001) and then to a bulk tailing sampler (3710-SA-001) and analyzer (3710-AZ-001) before being fed to the individual tailing thickeners.

H.

Each of the concentrate and tailing samplers will be fitted with automated shift sample collection systems.


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Froth vision cameras have been installed on all cells of pair of cells in the rougher/scavenger circuit as detailed in the following tables:

I.

Row #1: Cell # CF-101 Tag # 34AIC-0103

CF-102 34AIC-0107

CF-103/104 34AIC-0201

CF-105/106 34AIC-0206

CF-107/108 34AIC-0301

CF-109/110 34AIC-0

CF-201 34AIC-0116

CF-202 34AIC-0119

CF-203/204 34AIC-0211

CF-205/206 34AIC-0216

CF-207/208 34AIC-0311

CF-209/210 34AIC-033

Row #3: Cell # CF-301 Tag # 34AIC-1102

CF-302 34AIC-1101

CF-303/304 34AIC-1201

CF-305/306 34AIC-1206

CF-307/308 34AIC-1301

CF-309/310 34AIC-13

Row #4 Cell # CF-401 Tag # 34AIC-2102

CF-402 34AIC-2101

CF-403/404 34AIC-1211

CF-405/406 34AIC-1216

CF-407/408 34AIC-1311

CF-409/410 34AIC-1316

Row #2: Cell # Tag #

4.4

J.

The Expert System will be programmed to control the level in the cells to maintain set froth discharge velocity into the launders. The froth bed thickness and bubble size is maintained with froth addition rate. The windows on the top of the bubbles are also analyzed by the froth vision and used to control the collector addition rate.

K.

Air accumulators are installed at the end of each cell to keep the tailings valve closed if the instrument air pressure is lost.

L.

Two local control stations are installed in the copper flotation area providing an access to all flotation area process control information to the flotation area operators.

Rougher Concentrate Polishing A. The rougher concentrate is polished prior to feeding the material to the final column cleaner

cells. The main design parameter for the polishing mills (3420-ML-501/502) is to achieve as constant mill residence time as possible to minimize over grind thus optimizing flotation recovery and grade. This is achieved through pump flow control and flow smoothing via the surge facility within the rougher concentrate collection sump. (In addition the use of variable grinding material loads within the mill itself could be used to modify the extent of polishing as required). The polishing mill is specified to produce a product with a target particle size of 80% passing 50 microns. Mill control will be performed by the plant DCS. B. The polishing mill feed pump box (3420-BX-501) level is monitored in the CCCR. Polishing mill

feed pumps (3420-P P-501/502) are equipped with variable speed drives to maintain a constant volume flow rate to the polishing mill. The level controller (34LIC-2021) for the pumpbox (3420BX-501) is used to provide a set point to the pump speed. The operator provides the set point to the level control, the pumpbox volume is utilized to control the frothy rougher concentrate and assist to provide steady operating conditions to the polishing mills. C. The solids flow rate to the polishing mills (34FI-2106) is estimated by using on line volumetric

flow rate (34FI-2013) and pulp density (34DIC-2014). Water is added into the sump through water flow control loop (34FIC-2001). The set point to the water flow controller is provided by a polishing mill feed density controller.


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY D. The feed pumps (3420-PP-501/502) will be DCS controlled. P ump can only be started when

gland seal water is present and flow to the polishing mills exists. Low gland seal water flow during normal operations will initiate an alarm in CCCR, but does not stop the pump. The pumps are equipped with remotely controlled dump valves on the pumpbox and pump inlet lines as well as isolation valves on the pump inlet and discharge as described in the following table. Pump

C-3420-PP-501 C-3420-PP-502

Pumpbox Drain Valve

34XS-2003

Pump Drain Valve

34XS-2006 34XS-2008

Inlet Valve

34XS-2004 34XS-2007

Discharg e Valve

34XS-2009 34XS-2011

E. The polishing mill power is controlled by grinding media addition; sand is initially used as

grinding media. The sand is stored in a polishing mill sand bin (C-3420-BN-516) above the polishing mills. From the bin the sand enters the mill through a pipe with two on-off valves (34XV-2106/2107/2108/2109) mounted at predetermined distance from each other. The power control is a batch process by varying the sand addition to the mills. In the beginning of the control cycle the sand pipe feeding the mill is full of sand down to the bottom valve. F.

When the stirred mill is operating at set power draw, both valves on the sand line are kept closed. When the mill power draw decreases below a set value, the bottom valve (34XV2107/2109) opens emptying the sand in the pipe into the mill. After the pipe is empty the bottom valve closes and the top valve (34XV-2106/2108) opens filling the pipe with sand again. After the pipe is full the top valve closes and the system is ready to add sand into the mill again.

G. The polishing mill feed pumps cannot be started unless one of the polishing mill feed valves on

the distributor (C-3420-DI-502) is open and the respective mill is running. In addition to electrical protective trips, each polishing mill feed pump is provided with the following protective trips: 1.

Suction valve not open (NCT)

2.

All stirred mill distributor feed valves closed (NCT)

3.

Stirred mill motor tripped (NCT)

H. The polishing mill is only tripped for internal drive interlocks, otherwise the mill is shut down and

started up manually from the CCCR. I.

During maintenance periods a bypass line from the polishing mill distributor (3420-DI-502) may be used to transfer concentrates directly to the column cell feed pump box (3420-BX-502). For use of the overflow line the interlock between the polishing mills (3420-ML-501/502) and the feed pumps (3420-PP-501/502) can be over-ridden by the area supervisor.

J.

The product from the polishing mills (3420-ML-501/502) flows by gravity to a polishing mill product sampler (3420-SA-501) where a combined concentrate product stream is analyzed (3420-AZ-501) and a sample withdrawn for particle size analysis (3420-AZ-503). The discharge from the product sampler falls via gravity into the column cell feed pumpbox (3420-BX-502).

K.

A pH meter is installed on the polishing mill product sampler and controls the lime addition into the rougher and scavenger concentrate launders (34AIC-2201).

L.

The first cleaner concentrate stream is also fed to the column cell feed pumpbox (3420-BX-502) via a sampler (3420-SA-502) and analyzer (3420-AZ-501). The cleaner-scavenger concentrate can be fed to the column cell feed pumpbox (3420-BX-502) via a sampler (3420-SA-503) and


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analyzer (3420-AZ-501), but normally passes through the sampler and flows via gravity to the scavenger concentrate collection pumpbox (3420-BX-503). M. The column cell feed pumps (3420-PP-503/504) transfer the combined polished rougher

concentrate and first cleaner concentrate to the column cell feed distributor (3430-DI-501). These pumps are variable speed and alarm on loss of seal water. N. The column feed pumps cannot be started unless one of the column feed valves on the

distributor is open. In addition to electrical protective trips, each column cell feed pump is provided with the following protective trips: 1.


2.

All feed distributor valves closed (NCT)

O. The column cell feed pump box level (34LIC-2204) is monitored and controlled in the CCCR.

Column cell feed pumps (3420-P P-503/504) are equipped with variable speed drives to maintain a constant volume flow rate to the column cells. This is required to ensure steady state operation of the columns and achieve the desired final grade requirements. As this level leaves the required range (either too high or too low) the level controller will increase or decrease the pump speed. This procedure is used to keep the column cell feed flow rate as constant as possible. Additionally the solids fow rate (34FI-2216) to the column cell feed distributor (3430-DI-501) is calculated by using on-line volumetric flow rate (34FI-2216) and pulp density (34DI-2214). An automated water makeup valve has been included that may be used to add dilution water to control column cell feed pulp density through a density controller (34DIC-2214). P. The column cell feed pumps (3420-PP-503/504) will be DCS controlled. P ump can only be

started when gland seal water flow is present and flow to the polishing mills exists. Low gland seal water flow during normal operations will initiate an alarm in CCCR, but does not stop the pump. The pumps are equipped with remotely controlled dump valves on the pumpbox and pump inlet lines as well as isolation valves on the pump inlet and discharge as described in the following table. Pump

C-3420-PP-503 C-3420-PP-504 4.5

Pumpbox Drain Valve

34XS-2203

Pump Drain Valve

34XS-2208 34XS-2217

Inlet Valve

34XS-2204 34XS-2207

Discharg e Valve

34XS-2209 34XS-2211

Scavenger Concentrate Regrind and Classification A. The scavenger concentrate regrind and classification circuit consists of a scavenger concentrate

collection pumpbox (3420-BX-503), regrind cyclone feed pumps (3420-PP-505/506), regrind cyclone cluster (3420-CS-501), regrind mill feed pumpbox and pumps (3420-BX-504 & 3420PP-507/508/509) and three regrind mills (3420-ML-003/004/005). B. The scavenger concentrate from the main rougher-scavenger flotation circuit is the main feed

stream to the scavenger concentrate collection pumpbox (3420-BX-503). In addition, cleanerscavenger concentrate and regrind mill product streams are fed to this pump box. From there the slurry is pumped to the feed distributor of a fourteen (14) way regrind cyclone feed distributor that feed a set of fifteen inch (15”) diameter regrind cyclones (3420-CS-501A to P). The overflow stream from the regrind cyclone passes through a cyclone overflow sampler (3420-SA-504) to generate a sample stream for particle size analysis (3420-AZ-502), before flowing via gravity to the scavenger concentrate collection pumpbox.


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY C. The underflow from the regrind cyclone flows via gravity to the cyclone underflow launder (3420-

LA-501) and then to the regrind mill feed pumpbox (3420-BX-504) where it is split into three (3) streams, each of which is pumped to a regrind mill (3420-ML-003 /004/005). D. The scavenger concentrate collection pump box level (34LIC-2302) is monitored in the CCCR.

Regrind cyclone feed pumps (3420-PP-505/506) are equipped with variable speed drives, which are used to control the level in the scavenger concentrate collection pumpbox (34LIC-2302). E. The solids flow rate to the regrind cyclone feed (34FI-2307) is to be calculated by using on-line

volumetric flow rate (34FI-2306) and pulp density (34DI-2308). An automated water makeup valve with flow meter has been included to allow for make up water addition (34FIC-2301) to adjust pulp density as required. Initially the flow rate is set by the operator, later the set point for the water flow controller will be provided by the Expert System. F. The regrind cyclone feed pumps (3420-PP-505/506) will be DCS controlled. Pump can only be

started when gland seal water is present and flow to the polishing mills exists. Low gland seal water flow during normal operations will initiate an alarm in CCCR, but does not stop the pump. The pumps are equipped with remotely controlled dump valves on the pumpbox and pump inlet lines as well as isolation valves on the pump inlet and discharge as described in the following table. Pump

C-3420-PP-505 C-3420-PP-506 G.

Pumpbox Drain Valve

34XS-2323

Pump Drain Valve

34XS-2324 34XS-2326

Inlet Valve

34XS-2313 34XS-2314

Discharg e Valve

34XS-2303 34XS-2321

Water can also be added remotely from CCCR to the cyclone underflow launder (3420-LA-501) if required. The set point to the water flow controller (34FIC-2318) is provided by the CCCR operator.

H. The vertimill feed pumps (3420-PP-507/598/509) are equipped with variable speed drives to

control the vertimill feed. On each mill system, the vertimill feed box level is used to cascade a setpoint to each of the vertimill feed pump flow controller to maintain constant feed sump level. Flowrate and density are measured on each vertimill feed line, mass flow rates are calculated and data is used by the expert system to control the pulp density to regrind mills through addition of process water. I.

The regrind mill feed pumps (3420-PP-507/508/509) will be DCS controlled. Pump can only be started when gland seal water is present and flow to the polishing mills exists. Low gland seal water flow during normal operations will initiate an alarm in CCCR, but does not stop the pump. The pumps are equipped with remotely controlled dump valves on the pumpbox as well as mill inlet. The pumps have as isolation valves on the pump inlet and discharge lines, the valves are further described in the following table. Pump

C-3420-PP-507 C-3420-PP-508 C-3420-PP-509 J.

Pumpbox Drain Valve

34XS-2411

Pump Drain Valve

Mill Drain Valve

Inlet Valve

Discharg e Valve

34XS-2413 34XS-2502 34XS-2512

34XS-2412 34XS-2521 34XS-2522

34XS-2403 34XS-2501 34XS-2511

34XS-2408 34XS-2507 34XS-2517

The three regrind vertimills (3420-ML-503/504/505) and regrind feed pumps (3420-507/508/509) are controlled by the plant DCS. The feed control into the vertimills is performed as follows:


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY •

•

•

•

•

•

•

Total flow into the vertimills is calculated with the magnetic flow meters (34FIC2407/2506/2516) The result from the calculation is the measurement for the total flow controller, which on long term will be in the expert system, but initially a temporary controller will be programmed (34FFIC-2402) The set point to the feed controller is provided by the pump box level controller (334LIC2402) The total flow controller provides set points to individual vertimill flow controllers (34FIC2407/2506/2516) The vertimill flow controllers provide the set point to the pump speed controllers (34SIC2405/2505/2525) The feed density to each vertimill is measured (34DIC-2406/2504/2514), averaged and used as a set point to the pumpbox water controller (34FIC-2401). Later the set point is provided from the Expert System. The solids flow into each vertimill is calculated based on the flow and density measurements (34FI-2404/2503/2513).

K. The feed pumps will be interlocked with the respective vertimill such that the mill must be

running for the pump to run. The pump suction, and discharge lines have remote controlled isolation valves installed. Two remotely controlled drain lines, one on the pump suction and one at the vertimill are used drain the pipeline and the mill when the pump is tripped. The pump discharge valve will automatically close when the pump stops. The mill inlet valves are fitted with fail closed actuators. In addition to electrical protective trips, each vertimill feed pump is provided with the following protective trips:

L. M.

1.

Vertimill not running (NCT)

2.

Pump suction valve closed (NCT)

3.

Pump discharge valve closed (NCT)

The vertimill power is monitored and controlled by manually adding grinding media as required. Vertimill is started and shut down remotely from CCCR. The mill drive is protected by internal electrical protective trips, but is not interlocked with other process equipment in the area.

N. The product from the three regrind vertimills flows via gravity to the scavenger concentrate

collection pump box (3420-BX-503) and then is pumped to the cyclone cluster (C-3420-CS-501). 4.6

Column Flotation A. The column flotation cleaning circuit is set up as four (4) five meter diameter by twelve meter

high circular column cells (3430-CM-501 to -504). Each column cell will be fitted with froth vision, froth wash water control, air control, level control, and pressure indicators. The columns will be fed from the polishing mill circuit via the column cell feed pumps (3420-P P-503/504) and the column cell feed distributor (3430-DI-501). The column cell feed distributor is equipped with automated gate valves, one for each of the four columns. B.

Each column cell is fed via an internal distributor. Aeration is provided at the base of the columns via sparging nozzles, with the concentrate reporting to the concentrate collection


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launder at the top of the cells. Wash water is added to the top of each column to assist in gangue and pyrite removal from the final concentrate (34FIC-3101/3102/3201/3202). C. The tailing stream from each column is withdrawn from the base of the column. The tailing flow

is measured with magnetic flow meters to provide indication about the feed distributor (C-3430DI-501) performance. A control valve on the tailings line and a float to measure pulp level are used to control the pulp level in the column itself (34LIC-3106/3111/3206/3211). The flotation air controllers (34FIC-3112/3152/3212/3252) as well as other controllers in the system will be controlled in the future by the expert system based on on-line assays and froth vision measurements (34AI-3117/3118/3217/3218). D. The concentrate from each column flows via gravity to a sampling system (3430-SA-

505/507/508/508) and on stream analysis (3430-AZ-503) before reporting via gravity to the column concentrate collection pumpbox (3430-BX-506). From there the concentrate is pumped by variable speed transfer pumps (3430-P P-514/515) to the copper-molybdenum thickener feed box (3510-BX-003). E. The column cell concentrate and tailing pump box level (3420-BX-505) will be monitored in the

CCCR. Column cell tailing and concentrate pumps (3420-PP-512/513 & 3420-PP-514/515) are equipped with variable speed drives to maintain a constant level in their associated feed sumps. The operator in the CCCR will enter the desired sump level set-point in the sump level controller (34LIC-3403 & 34LIC-3303). The main level control is performed by changing the pump speed. If the column concentrate pump is running on minimum speed with low pumpbox level, water is added into the pump boxes by the level controller (34LIC-3303 through a water control valve (34XS-3301). The solids flow rate (34FI-3317) in the concentrate stream is estimated by using on-line volumetric flow rate (34FI-3317) and pulp density (34DI-3318) measurements. F.

A water makeup valve for the column tailing sump (34DV-3418) has been included that is used to control the column tailings pulp density (34DIC-3418). The tailings flow is also measured (34FI-3417) and the solids flow rate calculated (34FI-3419).

G. The column start up and shut down are performed through a programmed sequence explained

in the vendor flotation column operating instructions. To perform the sequence the column are equipped with remote controlled water flush and drain valves as follows: Equipment No.

C-3430-CM-501 C-3430-CM-502 C-3430-CM-503 C-3430-CM-504 H.

Bottom of Column

Column Discharge

Discharge Pipe

Drain Valve

34XS-3121/3122/3123/3124 34XS-3161/3162/3163/3164 34XS-3221/3222/3223/3224 34XS-3261/3262/3263/3264

34XS-3126 34XS-3166 34XS-3226 34XS-3266

34XS-3127 34XS-3167 34XS-3227 34XS-3267

34XS-3129 34XS-3169 34XS-3229 34XS-3269

A bypass line is installed for the column cell level control valve with a manual pinch valve to enable servicing the pinch valve without shutting down the column. Therefore the level control valve has remote controlled isolation valves installed on the intake and discharge line of the valve as described in the following table: Equipm ent No.

C-3430-CM-501 C-3430-CM-502 C-3430-CM-503 C-3430-CM-504

Contro l Valve Inlet

34XS-3128 34XS-3168 34XS-3228 34XS-3268


Contro l Valve Outlet

34XS-3116 34XS-3156 34XS-3216 34XS-3256

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PROCESS DESCRIPTION – CONTROL PHILOSOPHY I.

J.

4.7

The column cell concentrate and tailings pumps (3420-PP-514/515 & 512/513) will be DCS controlled. Pump can only be started when gland seal water is present and flow to the polishing mills exists. Low gland seal water flow during normal operations will initiate an alarm in CCCR, but does not stop the pump. The pumps are equipped with remotely controlled dump valves on the pumpbox. The pumps have as isolation valves on the pump inlet and discharge lines, the valves are further described in the following table. Pumpbox

Pump

C-3430-BX-506 C-3430-BX-506 C-3430-BX-505 C-3430-BX-505

C-3420-PP-514 C-3420-PP-515 C-3420-PP-512 C-3420-PP-513

Pumpbox Drain Valve

34XS-3302 34XS-3402

Pump Drain Valve

Inlet Valve

Discharg e Valve

34XS-3307 34XS-3316 34XS-3407 34XS-3416

34XS-3304 34XS-3306 34XS-3404 34XS-3406

34XS-3312 34XS-3313 34XS-3412 34XS-3413

In addition to electrical protective trips, each column cell product pumps (tailing and concentrate) are provided with the following protective trips: 1.


2.

Discharge valve not open (NCT)

First Cleaner and Cleaner-Scavenger Flotation A. The first cleaner and cleaner scavenger flotation cells are set up as one bank of ten (10) agitated

flotation cells. Each flotation cell is 160 m3 and the ten cells are set up in pairs of cells with level control between each pair of cells. The first six (6) cells have been set up as the first cleaner cells (3440-CF-501 to -506) and the last four (4) as the cleaner scavenger cells (3440-CF-507 to -510). B. The regrind cyclone overflow and tailings from the four column flotation cells flow via gravity to

the column tailing collection pumpbox (3430-BX-505). This slurry is then pumped by the column tailing transfer pumps (3430-PP-512/513) to the first cleaner cells (3440-CF-501 to -506). Concentrate from the first cleaner flotation cells flows via gravity to the column cell feed sampler (3420-SA-502) and analyzer (3420-AZ-501) before feeding into the column cell feed pumpbox (3420-BX-502). Concentrate from the cleaner-scavenger flotation cells flows via gravity to the column cell feed sampler (3420-SA-503) and analyzer (3420-AZ-501) before feeding into the scavenger concentrate collection pumpbox (3420-BX-503). The facility also exists to bleed cleaner scavenger concentrate to the column cell circuit on conditions of high circulating loads. C. The first cleaner cells tailing flows directly into the cleaner scavenger flotation cells (3420-CF-

507 to -010). Tailing from the cleaner scavenger flotation cells flows via gravity through the cleaner scavenger tailing sampler (3440-SA-513) and analyzer (3440-AZ-505), before being combined in the tailing collection launder (3710-LA-001) with the tailing stream from the main rougher scavenger flotation circuit. The cleaner scavenger concentrate flows by gravity through the column cell feed analyzer (C-4320-AZ-505) to the combined scavenger concentrate launder (C-3410-LA-106). D.

Level control of the cleaner and cleaner scavenger flotation cells will be performed by dual level controllers. Two external dart valves are used to control the flow of slurry to subsequent cell pairs. The first dart valve is used in the range of zero to fifty percent (0-50%) of controller output and the second valve is used for fifty to one hundred percent (50-100%). Ultrasonic sensors will be used to detect both the pulp and froth levels. The froth bed depth will be controlled to allow


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for optimization of recovery and grade as a function of varying feed conditions. The following remote (DCS) controller configuration will be used for control of the cells:

E.

1.

Controller #1 (34LIC-3501): First Cleaner 1 & 2 Cells (3440-CF-501/502) Level

2.


3.


4.

Controller #4 (34LIC-3601): Cleaner-Scavenger 1 & 2 Cells (3440-CF-507/508) Level

5.

Controller #5 (34LIC-3603): Cleaner-Scavenger 3 & 4 Cells (3440-CF-509/510) Level

Each pair of cells is equipped with froth vision cameras and froth rate controls: Cell # Tag #

CF-501/502 34AIC-3508

CF-503/504 34AIC-3509

CF-505/506 34AIC-3511

CF-507/508 34AIC-3606

CF-509/510 34AIC-3607

F. The froth vision camera information will be used by the Expert System to control the cell level to

achieve frother addition and the cell level to achieve set froth production rate. G. The Expert System will be programmed to control the level in the first cleaner cells to maintain

set froth discharge velocity into the launders. The froth bed thickness and bubble size is maintained with froth addition rate. The windows on the top of the bubbles are also analyzed by the froth vision and used to control the collector addition rate. 5.

MOLYBDENUM RECOVERY 5.1

Process Overview A.

B.

Introduction 1.

Mo is recovered from bulk concentrate by depressing Cu minerals with NaHS. The bulk concentrate from the rougher circuit is first treated in a mechanical Mo rougher/scavenger flotation circuit after a thickening stage, the rougher/scavenger tailing is the final copper concentrate and is directed into Cu dewatering circuit. Rougher concentrate is pumped into a mechanical first cleaner flotation circuit. The first cleaner concentrate is thickened and directed into the column cleaner flotation circuit. The first cleaner tailing is pumped back into the Cu-Mo Thickener.

2.

The column flotation circuit includes five additional cleaning stages. Concentrate from each stage is pumped into the next stage and tailing returned into the previous stage. The second cleaner tailing (tailing from the first column) is directed into a cleaner/scavenger circuit, where the concentrate is pumped into the first cleaner concentrate thickener. Cleaner scavenger tailing is pumped into the first cleaner flotation.

Process Description 1.

Bulk Concentrate from the final cleaner column cells is pumped to the Cu-Mo Concentrate Thickener (C-3610-TK-001). The thickener overflow flows by gravity to the Cu thickener overflow tank (C-3610-TK-002). The thickener underflow is fed to the Mo conditioning tank (C-3520-TK-001), which feeds the molybdenum rougher/scavenger flotation circuit (cells C-3520-CF-603/604/605/606) through a Mo Rougher Feed Sampler (C-3520SA-601).

2.

All pumping stages in the Mo-circuit have an operating and a stand by pump installed. One of the pumps is equipped with a variable speed drive and the other one is fixed speed. The


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level in the pumpbox feeding the pumps is controlled by varying the pump speed. Water can be added into the pumpbox with local, manually operated valves. 3.

Rougher concentrate flows by gravity into a rougher concentrate pumpbox (C-3520-BX601) from one side of the rougher concentrate bank. After rougher flotation stage, pump (C-3520-PP-601/602) transfers the rougher concentrate to the first cleaner flotation cells (C-3520-CF-607/608/609/610/611/612/619) through a Mo rougher concentrate sampler (C3520-SA-602) and Mo first cleaner conditioner (C-3520-TK-603). As the rougher flotation cells discharge from both sides, pump C-3520-PP-607 is used to pump concentrate from one side of the bank into the rougher concentrate pumpbox (C-3520-BX-601) feeding the rougher concentrate pumps (C-3520-PP-601/602). Rougher concentrate pumpbox (C3520-BX-615) feeds the rougher concentrate pump (C-3520-PP-607) on the other side of the bank.

4.

Mo rougher flotation tailing is the final copper concentrate. The rougher tailing flows by gravity through a Mo rougher tailing sampler (C-3520-SA-603) into a Mo rougher tailing pumpbox (C-3520-BX-602). One of the rougher tailing pumps (C-3520-PP-603/604) is used to pump the tailing into the copper concentrate thickener feed box (C-3610-BX-001).

5.

Scavenger concentrate returns to the Cu-Mo concentrate thickener via one of two pumps (C-3520-PP-605/606). Final tailing of the rougher/scavenger circuit is transferred by a pump (C-3520-PP-603/604) to the Cu concentrate thickener feed box (C-3610-BX-001).

6.

First cleaner concentrate flows by gravity to the cleaner/scavenger concentrate pumpbox (C-3520-BX-606) and is pumped with one of the cleaner scavenger concentrate pumps (C3520-PP-617/618) into the Mo 1st Cleaner Concentrate Thickener (C-3520-TK-602). First cleaner tailing flows by gravity into first cleaner tailing pumpbox (C-3520-BX-604) and is transported by a pump (C-350-PP-609/610) to the Cu-Mo Thickener. Thickener underflow is transferred by a pump (C-3520-PP-611/612) to a second cleaner feed pumpbox (C3520-BX-608).

7.

Thickener underflow is pumped from the second cleaner feed pump box by one of the second cleaner feed pumps (C-3520-PP-622/623) into the first stage of five stages of column flotation to produce a final molybdenum concentrate. Concentrate from the second cleaner column (C-3520-CM-601) flows by gravity to the third cleaner feed pumpbox (C3520-BX-610) from where it is pumped by one of two pumps (C-3520-PP-626/627) to the third cleaner column cell (C-3520-CM-602). Concentrate from the third column cleaner (C3520-CM-602) flows by gravity to the fourth cleaner feed pumpbox (C-3520-BX-611) from where it is pumped by one of two pumps (C-3520-PP-628/629) to the fourth cleaner column cell (C-3520-CM-603). Concentrate from the fourth column cleaner (C-3520-CM603) flows by gravity to the fifth cleaner feed pumpbox (C-3520-BX-612) from where it is pumped by one of two pumps (C-3520-PP-630/631) to the fifth cleaner column cell (C3520-CM-604).

8.

Concentrate from the fifth column cleaner cell (C-3520-CM-604) flows by gravity to the sixth cleaner feed pumpbox (C-3520-BX-613) from where it is pumped by one of two pumps (C-3520-PP-632/633) to the sixth cleaner column cell (C-3520-CM-605). Concentrate from the sixth column cleaner (C-3520-CM-605) flows by gravity to the final Mo concentrate pumpbox (C-3520-BX-614) through the final Mo concentrate sampler (C3520-SA-604), from where it is pumped by one of two pumps (C-3520-PP-634/635) to the Mo concentrate filter (C-3530-FL-601). The final Mo concentrate pumpbox is an agitated tank and therefore serves as the Mo concentrate storage tank as the Mo concentrate filtering is a batch process.


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Tailing from the second cleaner column cell flows by gravity to the second cleaner tailing pumpbox (C-3520-BX-609) and is then pumped into the feed box of the cleaner-scavenger flotation cells (C-3520-CF-613 to 620). Cleaner-scavenger concentrate flows by gravity to the cleaner scavenger pumpbox (C-3520-BX-606), where it is combined with first cleaner concentrate. Cleaner-scavenger tailing flows by gravity to the cleaner scavenger tailing pumpbox (C-3520-BX-605) and is then transferred to the Mo rougher concentrate pumpbox by one of the cleaner scavenger tailing pumps (C03520-PP-615/616).

10. Tailing from the third column cell flows by gravity to the second cleaner column feed

pumpbox (C-3520-BX-608). Tailing from the fourth column cell flows by gravity to the third cleaner column feed pumpbox (C-3520-BX-610). Tailing from the fifth column cell flows by gravity to the fourth cleaner column feed pumpbox (C-3520-BX-611) and the tailing from the sixth cleaner column flows by gravity to the fifth cleaner column feed pumpbox (C3520-BX-612). 5.2

System Interlocks In general there are no system interlocks between pieces of equipment in the Mo flotation circuit. Pumps in the Mo circuit cannot be started without adequate gland water flow. During operation low gland water flow will provide an alarm, but does not stop the pump.

5.3

Rougher and Scavenger Flotation A.

Cu-Mo thickener underflow is pumped by a variable speed pump (C-3510-PP-055/056) to an agitated conditioning tank (C-3510-TK-001). The underflow flow is measured (35FIC-0123) as well as the density (35DIC-0119). From the measurements the mass flow is calculated (35FQI0129). The underflow density is controlled by the density controller providing the set point to the flow controller which controls the pump speed. Alternatively the tank pressure controller (35P IC0118) or the rake torque controller (35OIC-0313) can be used to provide the set point to the flow controller. Testwork during operation will determine which control will be preferred. The sludge level in the thickener is measured (35LI-0111) and displayed in the DCS system. The conditioned concentrate slurry overflows the tank and feeds the rougher flotation cells.

B. The thickener is provided with remote controlled flush water connection (35XS-0112). The

underflow pumps are equipped with remote controlled flush water, drain and shut off valves as indicated in the following table: Pump

PP-055 PP-056 C.

Flush Valve

35XS-0113 35XS-0114

Dump Valve

35XS-0111 35XS-0109

Inlet Valve

35XS-0117 35XS-0116

Discharg e Valve

35XS-0126 35XS-0127

Cu-Mo thickener underflow can be recycled by closing a valve on the Mo conditioner tank feed line (35XS-0128) and opening the recycle valve (35XS-0108). The thickener underflow can also be sent to copper concentrate safety screen by closing the recycle valve and opening a valve on the safety screen feed line (35XS-0107).

D. Thickener overflow flows by gravity to the Cu-concentrate thickener overflow tank (C-3610-TK-

005). E.

A total of six rougher and scavenger cells are provided in a single row. The first four cells are to be used as rougher flotation cells and the remaining two cells as scavenger. The cells are all installed in pairs. Each pair of cells has a feedbox, two flotation chambers and a discharge box. The discharge box is fitted with a set of dart valves that are used to control the level in the


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flotation chambers via the controlled outlet to the next flotation pair or final tailing. Frother is added to the feed box of the first flotation cell. F.

pH is measured from the rougher feed sampler (35AI-0202) and third rougher cell (35AI-1111). ORP is measured from the second rougher cell (35AI-1108), fourth rougher cell (35AIC-1112) and sixth rougher scavenger flotation cell (35AI-1206). The fourth rougher cell ORP measurement is used to control the NaHS addition to the Mo rougher conditioner tank.

G.

Level control of the rougher and scavenger flotation will be performed by single loop controllers. The following controller configuration will be used for control of the cells: 1.

Controller #1 (35LIC-1102): Rougher 1/2 Cells (C-3520-CF-601/602) Level

2.

Controller #2 (35LIC-1106): Rougher 3/4 Cells (C-3520-CF-603/604) Level

3.

Controller #3 (35LIC-1219): Scavenger 5/6 Cells (C-3520-CF-605/606) Level

H.

Rougher concentrate is collected in launders and separate pump boxes on both sides of the bank of cells. The rougher concentrate from both sideS is combined into one single pumpbox for sampling purposes before entering the next process stage. The rougher concentrate pump #1 (C-3520-PP-607) pumps into rougher concentrate pumpbox #2 (C-3520-BX601), which feeds the rougher concentrate pump #2 (C-3520-PP-601/602) directing the concentrate through rougher concentrate sampler (C-3520-SA-602) into Mo first cleaner conditioner tank (C-3520 TK-603).

I.

The rougher concentrate flow (35FI-1514) and density (35DI-1513) are measured and the mass flow calculated (35FI-1512).

J.

Rougher scavenger concentrate is collected in launders on each side of the bank and discharged into a scavenger concentrate pumpbox (C-3520-BX-603). The rougher scavenger concentrate is transferred by a pump (C-3520-PP-605/606) to the Cu-Mo concentrate thickener. The rougher scavenger concentrate flow (35FI-1214) and density (35DI-1213) are measured and the mass flow calculated (35FI-1211).

K.

Rougher scavenger flotation tailing flows by gravity into a pumpbox (C-3520-BX-602) and is then pumped to the Cu concentrate thickener (C-3610-BX-001) feed box through a Mo rougher tailing sampler (C-3520-SA-603). The Mo rougher scavenger tailing flow (35FI-2814) and density (35DI-2813) are measured and the mass flow calculated (35FI-2812).

L.

Those pumping stages in the Mo flotation circuits, which have an operating and stand by pumps installed, are equipped with isolation valves. The list of rougher flotation circuit valves follows: Pump

Mo Rougher Concentrate #2 PP-601 Mo Rougher Concentrate #3 PP-602 Mo Scavenger Concentrate PP-605 Mo Scavenger Concentrate PP-606 Mo Rougher Tailing PP-603 Mo Rougher Tailing PP-604

Inlet Valve

35XS-2902 35XS-2903 35XS-1202 35XS1219 35XS-2802 35XS-2803

Discharg e Valve

35XS-2916 35XS-2917 35XS-1216 35XS-1217 35XS-2816 35XS-2817

M. The pump boxes are equipped with ultrasonic level measurements enabling controlling of the

pumpbox level. The pumpbox level is controlled by the pump speed as follows: Pump Box

Level Controller


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Mo Rougher Concentrate Mo Scavenger Concentrate Mo Rougher Tailing

5.4

35LIC-2901 35LIC-1218 35LIC-2801

First Cleaner Flotation A.

Rougher concentrate is pumped via one of two rougher concentrate pumps (C-3520-PP601/602) to the first cleaner conditioning tank (C-3520-TK-603). Cleaner scavenger tailing is also introduced into the first cleaner conditioning tank by one of the two cleaner scavenger tailing pumps (C-3520-PP-615/615). Mo collector and NaHS are also added into the first cleaner conditioning tank.

B.

Concentrate from the first cleaner flotation cells is collected in a launder and flows by gravity to the Mo first cleaner scavenger concentrate pumpbox (C-3520-BX-606). Tailing from the first cleaner flotation cells flow by gravity to the first cleaner tailing pumpbox (C-3520-BX-604). One of the two first cleaner tailing pumps (C-3520-PP-609/610) direct the tailing into Cu-Mo thickener feed box (C-3510-BX-003).

C.

A total of seven cleaner cells are provided in a single row. The first four cells are all installed in pairs and the last three are installed as a single unit. Each pair or unit of cells has a feedbox, two to three flotation chambers and a discharge box. The discharge box is fitted with a set of dart valves that are used to control the level in the flotation chambers via the controlled outlet to the next flotation pair or tailing.

D.

Level control of the cleaner flotation will be performed by a single loop controller. The following local controller configuration will be used for control of the cells: 1.

Controller #1(35LIC-1303): Cleaner 1/2 Cells (C-3520-CF-603/608) Level

2.

Controller #2 (35LIC-1307): Cleaner 3/4 Cells (C-3520-CF-609/610) Level

3.

Controller #3 (35LIC-1402): Cleaner 5/6 Cells (C-3520-CF-611/612/619) Level

E. The Mo first cleaner tailing pump isolation valves are also remote controlled as follows: Pump

Mo First Cleaner Tailing PP-609 Mo First Cleaner Tailings PP-610

5.5

Inlet Valve

35XS-1407 35XS-1408

Discharg e Valve

35XS-1409 35XS-1411

F.

Mo first cleaner tailing flow (35FI-1414) and density (35DI-1413) are measured and the mass flow calculated (35FI-1412). The tailing pumpbox level is measured and controlled (35LIC-1406) by the tailing pump speed.

G.

pH is measured from the first cell of the first cleaner flotation bank (35AI-1302). ORP is measured from the second (35AI-1309), fourth (35AIC1306) and seventh (35AI-1423) cell. The ORP measurement from the fourth cell is used to control the NaHS addition into the Mo first cleaner conditioner tank.

H.

All instruments and controls will be connected on a communication highway to the plant control system. This will allow remote monitoring from the CCCR or the Mo plant control room MPCS.

Cleaner Scavenger Flotation


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY A. Thickened first cleaner/cleaner scavenger concentrate is pumped by a thickener underflow

variable speed pump (C-3520-PP-611/612) to the second cleaner feed pumpbox (C-3520-BX608). The pumping is controlled by flow (35FIC-1723) and density (35DIC-1719) measurements and controls on the pump discharge, the pumps are equipped with variable speed drives. The flow controller changes the pump speed. The set point to the flow controller is provided by the density controller; alternatively the thickener pressure (35PIC-1718) or rake torque (35OIC1703) can be used to provide a set point to the flow controller. B. The thickener rake drive has a vendor supplied PLC control system that will interface to the plant

control system for remote monitoring and control. The thickener is provided with an interface level transmitter (35LI-1704) C. The thickener is provided with remote controlled flush water connection (35XS-1712). The

underflow pumps are equipped with remote controlled flush water, drain and shut off valves as indicated in the following table: Pump

PP-611 PP-612

Flush Valve

35XS-1713 35XS-1714

Dump Valve

35XS-1711 35XS-1709

Inlet Valve

35XS-1717 35XS-1716

Discharg e Valve

35XS-1726 35XS-1727

D. Thickener underflow can be recycled back into the thickener by closing a valve on the Mo

second cleaner feed line (35XS-1707) and opening a recycle valve (35XS-1708). Thickener overflow is pumped into first cleaner tailing pumpbox by Mo cleaner area sump pump (C-3520PP-614). E.

Second cleaner flotation tailing is pumped via one of two pumps (C-3520-PP-624/625) to the first cell of the cleaner scavenger flotation cells (C-3520-CF-613/614/615/616/617/618/620).

F.

A total of seven cleaner-scavenger cells are provided in a single row. The cells are all installed in pairs except the last three which are interconnected as a single bank. Each pair and the last three cells have a feedbox, two or three flotation chambers and a discharge box. The discharge box is fitted with a set of dart valves that are used to control the level in the flotation chambers via the controlled outlet to the next flotation pair or tailing.

G.

Level control of the cleaner-scavenger flotation will be performed by single-loop controllers. The following controller configuration is used for control of the cells: 1.

Controller #1 (35LIC1503): Cleaner-scavenger 1/2 Cells (C-3520-CF-613/614) Level

2.

Controller #2 (35LIC-1507): Cleaner-scavenger 3/4 Cells (C-3520-CF-615/616) Level

3.

Controller #3 (35LIC-1502): Cleaner-scavenger 5/6 Cells (C-3520-CF-617/618/620) Level

H.

All local controllers will be connected on a communication highway to the plant control system. This will allow remote monitoring and control of the flotation cell level controllers from the CCCR or MPCR.

I.

Cleaner-scavenger flotation tailing discharges to a cleaner scavenger tailing pumpbox (C-3520BX-605) and is then transferred by one of two pumps (C-3520-PP-615/616) to the Mo first cleaner conditioning tank (C-3520-TK-603). The tailing flow (35FI-1514) and density (35DI-1513) are measured at pump discharge providing an estimate of mass flow (35FI-1512).

J.

Cleaner-scavenger concentrate discharges to Mo cleaner scavenger concentrate pumpbox (C3520-BX-606). First cleaner concentrate is also fed to the pumpbox. The slurry is pumped to the


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Mo first cleaner concentrate thickener. The combined first cleaner concentrate and cleaner scavenger concentrate flow (35FI-1542) and density (35DI-1543) are measured at pump discharge allowing estimating the mass flow (35FI-1541) K.

Mo cleaner scavenger concentrate and tailings pumps are equipped by remotely controlled inlet and discharge valves as follows: Pump

Inlet Valve

Mo Cleaner Scavenger Concentrate PP-617 Mo Cleaner Scavenger Concentrate PP-618 Mo Cleaner Scavenger Tailing PP-615 Mo Cleaner Scavenger Tailing PP-616

5.6

Discharg e Valve

35XS-1532 35XS-1533 35XS-1507 35XS-1508

35XS-1536 35XS-1537 35XS-1509 35XS-1511

L.

The concentrate pumpbox level is measured and controlled (35LIC-1531) by varying the pump speed. The tailings pumpbox level is controlled (35LIC-1506) respectively.

M.

ORP is measured from the second (35AI-1531), fourth (35AI-1532) and the seventh (35AI-1501) cleaner scavenger cell.

Column Flotation A.

B.

From the second cleaner feed pumpbox (C-3520-BX-608) the thickener underflow is pumped to the second cleaner column (C-3520-CM-601) by one of the two pumps (C-3520-PP-622/623). The flow (35FI-2114) and the density (35DI-2113) are measured and the mass flow is calculated (35FI-2117). The column circuit consists of five separate columns operating in series. Each column is equipped with level, air flow and froth wash water controls as indicated in the following table. Additionally, the pressure of the slurry inside the column is measured and monitored in the control rooms providing a second estimate of the pulp level and the pulp density inside the column. The table below details the controls and measurements around the column cells: Stage

Equipm ent No.

2nd Cleaner 3rd Cleaner 4th Cleaner 5th Cleaner 6th Cleaner

C-3520-CM-601 C-3520-CM-602 C-3520-CM-603 C-3520-CM-604 C-3520-CM-605

Level Control

Ai r Cont ro l

35LIC-2123 35LIC-2223 35LIC-2323 35LIC-2423 35LIC-2523

35FIC-2121 35FIC-2221 35FIC-2321 35FIC-2421 35FIC-2521

Water Control

35FIC-2122 35FIC-2222 35FIC-2322 35FIC-2422 35FIC-2522

Column Pressure

35PI-2136 35PI-2236 35PI-2336 35PI-2436 35PI-2536

Each column is fed by two pumps, one operating and one stand by. One of the pumps is equipped with an AFD drive, which is used to control the level in the pumpbox. The concentrate from the column flows by gravity into a pumpbox feeding the next column in series, the tailing from the column is directed by gravity into a pumpbox feeding the previous column. The following table includes all pump boxes in the column flotation circuit and where the feed into the pump box is originated from (excluding pumps): Stage

Pumbox No.

2nd Cleaner Feed

C-3520-CM-608

3rd Cleaner Feed

C-3520-CM-610

4th Cleaner Feed

C-3520-CM-611

5th Cleaner Feed

C-3520-CM-612

Feed to Pumpbo x

Thickener U/F 3rd Cleaner Tailing 2nd Cleaner Concentrate 4th Cleaner Tailing 3rd Cleaner Concentrate 5th Cleaner Tailing 4th Cleaner Concentrate


Equipm ent No.

C-3520-TM-601 C-3520-CM-602 C-3520-TM-601 C-3520-CM-603 C-3520-TM-602 C-3520-CM-604 C-3520-TM-603

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6th Cleaner Feed 2nd Cleaner Tailing Final Concentrate

C-3520-CM-613 C-3520-CM-609 C-3520-CM-614

6th Cleaner Tailing 5th Cleaner Concentrate 2nd Cleaner Tailing 6th Cleaner Concentrate Mo Filter Recycle

C-3520-CM-605 C-3520-TM-604 C-3520-TM-601 C-3520-CM-605 C-3520-FL-601

C. The final concentrate flows by gravity from the sixth cleaner column cell into a final concentrate

sampler (C-3520-SA-604) feeding the final concentrate pumpbox by gravity. The final concentrate pumpbox is an agitated tank and has a double duty as a Mo concentrate stock tank for the Mo pressure filter. D.

All pumps can be remotely started and stopped from CCCR and MP CR. The pumps are equipped with remote controlled isolation valves on pump inlet and discharge. There is one variable speed drive available to control the pumpbox level at each stage. The following table includes the controls associated with each pumpbox in the circuit:

Stage

Pumbox No.

Discharg e Pump No

Inlet Valve

Discharg e Valve

2nd Cleaner Feed

C-3520-CM-608

3rd Cleaner Feed

C-3520-CM-610

4th Cleaner Feed

C-3520-CM-611

5th Cleaner Feed

C-3520-CM-612

6th Cleaner Feed

C-3520-CM-613

2nd Cleaner Tailing

C-3520-CM-609

Final Concentrate

C-3520-CM-614

C-3520-PP-622 C-3520-PP-623 C-3520-PP-626 C-3520-PP-627 C-3520-PP-628 C-3520-PP-629 C-3520-PP-630 C-3520-PP-631 C-3520-PP-632 C-3520-PP-633 C-3520-PP-624 C-3520-PP-625 C-3520-PP-634 C-3520-PP-635

35XS-2102 35XS-2103 35XS-2202 35XS-2203 35XS-2302 35XS-2303 35XS-2402 35XS-2403 35XS-2502 35XS-2503 35XS-2601 35XS-2602 35XS-2701 35XS-2702

35XS-2111 35XS-2116 35XS-2211 35XS-2216 35XS-2311 35XS-2316 35XS-2411 35XS-2416 35XS-2511 35XS-2516 35XS-2607 35XS-2608 35XS-2707 35XS-2708

Level Control

35LIC2101 35LIC2201 35LIC2301 35LIC2401 35LIC2501 35LIC2603 35LIC2703

E. The bottom of the column and discharge pipe is equipped with remote controlled water flush

connections to fluidize the slurry inside the column and the pipe during start up and shut down, if that is required. The following table includes the controls of the water flush valves on all column cells: Stage


Equipment No.


Bottom of Column

35XS-2126 A-D 35XS-2226 A-D 35XS-2326 A-B 35XS-2426 A-B 35XS-2526 A-B

Column Discharge

35XS-2131 35XS-2231 35XS-2331 35XS-2431 35XS-2531

Discharge Pipe

35XS-2133 35XS-2233 35XS-2333 35XS-2433 35XS-2533

F. The column discharge pipes are equipped with remote controlled dump valves, which allow

emptying the column remotely. A bypass line is constructed around the control valves to enable servicing the valve without shutting down the column. A manual valve on the bypass line can be used to control the column level while the control valve is being serviced. The control valve can be isolated from the process with remotely controlled knife gate valves.


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G. The following table includes all the isolation and dump valves installed around all columns: Stage


Equipm ent No.


Contro l Valve Inlet Isolation Valve

35XS-2132 35XS-2232 35XS-2332 35XS-2432 35XS-2532

Control Valve Discharge Isolation Valve

35XS-2124 35XS-2224 35XS-2324 35XS-2414 35XS-2513

Dump Valve

35XS-2134 35XS-2234 35XS-2334 35XS-2434 35XS-2534

H. There are six H2S gas analyzers installed in the Mo flotation area, which are located as follows:

I.

5.7

1.

35AI-0201

Mo Rougher Flotation Conditioning Tank

2.

35AI-1301

Mo First Cleaner Conditioning Tank

3.

35AI-1424

Mo First Cleaner Tailing Pump Area

4.

35AI-2106

Mo Second Cleaner Feed Pump Area

5.

35AI-2206

Mo Third Cleaner Feed Pump Area

The alarm units display the H2S gas content of the ambient air in DCS and provide an alarm for high level. An audible high H2S alarm is hard wired from the analyzer sounding a horn to inform the personnel to clear the area if allowable limits have been exceeded.

Molybdenum Concentrate Dewatering and Packaging A.

Mo concentrate slurry is pumped from the Mo concentrate pumpbox (C-3520-TK-614) by one of two Mo concentrate pumps (C-3520-PP-634/635) to the Mo concentrate filter (C-3520-FL-601). The Mo concentrate is usually recirculated back into the tank on continuous bases to prevent the filter feed line sanding. The Mo concentrate pumpbox can be used as a dewatering tank by stopping the agitator and discharge pump for a short time and let the solids settle on the bottom. The tank is equipped with dewatering nozzles with manual valves at different elevations on the side of the tank. Filtering is a batch process controlled by vendor’s PLC and monitored through the DCS system.

B. The filter operates through filter feed, manifold wash, diaphragm press, air dry, cake discharge

and cloth was cycles. The operation of the filter is further explained in the Larox filter operators manual. C. The de-watered concentrate discharges into a Mo concentrate dryer (C-3530-DR-601) through a

screw feeder (C-3530-CV-601) for further reducing the moisture content. The filtrate discharges to a filtrate manifold wash water return tank (C-3530-TK-612) through an air release tank (C3530-TK-607) and is pumped filtrate water return manifold pump (C-3530-PP-661) to the Mo first cleaner concentrate thickener. An area spillage pump transfers spills to the Mo first cleaner concentrate thickener as well.


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY D.

Mo concentrate filter manifold tank (C-3530-TK-650) and pump (C-3530-PP-658) are used to wash the manifold between filter fill and diaphragm press cycles. Pressure water tank (C-3530ZM-602) and pump (C-3530-PP-622) are used to pressurize the rubber diaphragms during the water press cycle. Cloth wash water tank (C-3530-TK-611) and pump (C-3530-TK-659) are used to wash the filter cloth after the cake discharge cycle.

E.

An indirect heat screw dryer dries the Mo concentrate to its final moisture. The dried Mo concentrate is discharged to and stored in a concentrate storage bin (C-3530-BN-601). A wet scrubber (C-3530-DC-601) will process the dryer off gas and discharge to the dewatering area sump pump to be transferred to the Mo first cleaner concentrate thickener.

F.

Heat from hot oil recirulated through the dryer is used to dry the Mo concentrate. A medium heating system (C-3530-ZM-601) electrically heats the oil in a hot oil heater. The operation of the dryer and the oil heater is controlled by the vendor supplied P LC control system that will interface to the plant control system for remote monitoring and control.

G. The Mo concentrate packaging system (C-3530-ZM-607) is manually operated to fill the Mo

concentrate drums. A rotary valve (C-3530-FE-601) installed on the bottom of the dried Mo concentrate storage bin is manually operated to fill the drums. A forklift (C-5850-ME-011) is used to transfer the Mo concentrate from the packaging system into the Mo concentrate storage area and to load the barrels onto transport trucks. 6.

CONCENTRATE THICKENING, FILTRATION, STORAGE AND LOA DOUT 6.1

Process Overview A. The following process description applies to the normal operation of the copper concentrate

thickener, concentrate storage tanks and filters. B.

Copper concentrate from the molybdenum rougher scavenger tailing stream is pumped to the copper concentrate thickener feed box (C-3610-BX-001). Spillage from the filter area and filtrate from Cu pressure filters are also returned into the feed box. The concentrate flows by gravity from this feed box to the feed well of the concentrate thickener (C-3610-TK-001). Dilute flocculant is added to the thickener at a controlled rate to assist in solids settling. The overflow from the copper concentrate thickener flows via gravity to the concentrate thickener overflow tank (C-3610-TK-005) and from there is pumped by the concentrate thickener overflow pumps (C-3610-PP-047/048) to the copper concentrate water supply tank (C-3620-TK-043), Cu thickener spray water header (C-3610-TK-005) and Cu-Mo thickener (C-3510-TK-002) spray water header. Excess water is directed into the tailing collection launder #1 (C-3710-LA-001).

C. The underflow stream from the thickener is pumped to the copper concentrate storage tank feed

distributor (3620-DI-001) through a copper concentrate safety screen (C-3620-SC-041). From the feed distributor, the concentrate can be directed to either of the concentrate storage tanks (3620-TK-003/004) by locally or remotely controlled pneumatic dart valves. The concentrate storage tanks are agitated (3620-AG-001/002) and can be either locally or remotely operated. The tanks are provided with level measurements. The plant can be controlled from CCCR or from Molybdenum Plant Control Station MPCS or from the filter plant control station FPCS. D.

Concentrate slurry is pumped by the variable speed filter feed pumps (3620-P P-049/050) from the concentrate storage tanks to the pressure filters (3620-FL-001/002). The filter feed cycle and operation is to be controlled by the vendor PLC. One filter feed pump operates at a time and feeds both filters in a sequence as required. A filter feed loop returning to the concentrate safety screen will be used as on “as required” basis. Alternatively the concentrate return can be


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directed into the copper concentrate thickener feed box (C-3610-BX-001) if the concentrate density requires upgrading. The recycle loop is not used during normal operations, rather the filter feed pumps are stopped when the filters are not accepting feed. Double acting pinch valves in this line will serve as isolation valves. The return line is kept closed whenever a filter is in a feed mode or standby mode. The recycle valves are operated manually. E.

Each filter is controlled by its own control panel through a programmed sequence of feed, diaphragm press, header wash, air drying,, cake discharge and cloth wash. Each filter discharges concentrate directly to a concentrate storage area located beneath the filters. The filters are equipped with integral load cells, which will be used to monitor the loading of the filter and the weight of each batch of filter cake produced. A comparison of weight before and after drying will provide an indication of water removal efficiency during drying.

F. The vendor supplied filter package consists of two (2) pressure filters, one pressing air

compressor, one pressing air receiver, two (2) drying air compressors, one drying air receivers, two (2) cloth spray water booster pumps, copper concentrate water supply tank, two (2) copper concentrate wash water pumps, two filter feed pumps, a gland water booster pump and two PLC control packages. G.

Filtrate, cloth and manifold flush water from the pressure filters flows via gravity to the filtrate/manifold wash water return box (C-3620-BX-002) and is pumped (C-3620-PP-051/052) to the copper concentrate thickener (3610-TK-001) via the thickener feed box (3610-BX-001). General filter area spillage and concentrate thickener spillage are also pumped back to the concentrate thickener (3620-PP-054 & 3610-PP-053) through the filtrate/manifold wash water return box.

H. The manifold flush water is pumped from the copper concentrate water supply tank (C-3620-TK-

043) with copper concentrate wash water pumps (C-3620-PP-043/044) into the slurry manifold after each pump cycle. From the header the water is directed into the filtrate/core wash water return pumpbox (C-3620-BX-002). I.

The equipment supplied by the vendor will be controlled by the supplier’s PLC. Information about all equipment is displayed in CCCR and in the Filter Plant Control Station (FPCS) located in the filter building. Other equipment than what is supplied by the vendor is controlled from CCCR or FPCS.

J.

Sump pumps in the concentrate storage, filtration, and filtrate thickener areas will be controlled remotely from CCCR or automatically based on sump level.

K. The filter feed pumps have its own gland seal water system. Fresh water is directed into a gland

seal water tank (C-3620-TK-060) through a local level controller. A gland seal booster pump (3620-PP-060) receives water from the tank and pumps it into the filter area gland seal water header. A cloth spray booster pump (C-3600-PP-096/099) receives water from the same tank and directs water into the cloth wash sprays during the filter cloth wash cycle. 6.2

System Interlocks In general, there are no system interlocks between pieces of equipment with the exception of the filter feed pumps and filter operation. More detailed information is provided in the individual section descriptions.

6.3

Concentrate Thickening


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY A.

Filtrate from the concentrate filters, cloth wash water and water from core washing flow via gravity to the wash water return pumpbox (3620-BX-002) and then transferred back to the concentrate thickener feed box (3610-BX-001) by the wash water return pumps (3620-PP051/052). Other spillage area process streams are also fed back to the concentrate thickener feed box. Overflow from the concentrate thickener flows via gravity to the concentrate recycle thickener overflow tank (3610-TK-005) where it is combined with overflow from the Cu-Mo thickener (3510-TK-002). The concentrate thickener underflow is pumped (3610-PP-045/046) to a safety screen (3620-SC-041) before it flows into the concentrate storage tank distributor (3620-DI-001). The Cu concentrate underflow pumps (3610-PP-045/046) are to be operated continuously in either a recycle or transfer mode as dictated by the thickener underflow density. Filter performance is directly affected by feed pulp density and the objective of the final concentrate thickener is to achieve as high as possible a pulp density without generating too viscous a material for pumping. A remote controlled recycle valve (36XS-0108) will allow for the recycling of thickener underflow back to the thickener feed tank when opened and to transfer to the copper storage tank distributor (3620-DI-001) when closed.

B. The thickener underflow pumps (3610-PP-045/046) will be variable speed drive centrifugal

pumps. Control will be via flow measurement and control (36FIC-0123) and density measurement (36DI-0119) on the pump discharge to achieve the required underflow density. The flow controller provides the set point to the pump speed. All suction and discharge side pump isolation valves (36ZS-0126/0127/0108) can be actuated from the DCS, MP CS, FPCS or locally. Flush water addition with remote controlled valves is provided for the thickener underflow cone (36ZS-0112) and thickener underflow pumps (36ZS-0113/0114). A pressure transmitter (36PIT-0118) is installed on the bottom of the thickener providing the possibility of controlling the S.G. of pulp inside the thickener with pump speed. Testwork after startup will determine if the controlling of the thickener tank pressure or thickener torque will provide better stock tank feed density control than controlling the pump speed according to the thickener underflow density. C. The thickener is also provided with an interface level transmitter (36LI-0111). The interface level

is used to manually control the flocculant addition into the thickener. D.

Only one underflow pump will be running under normal operating conditions, the other pump is isolated from the process by remotely controlled knife gate valves. Pump C-3610-PP-045 has the suction side isolation valve (36XS-0117) and discharge side isolation valve (36XS-0126). The pump intake has a remotely controlled dump valve (36XS-0111) to drain the line when the pump is stopped. Respectively pump C-3610-PP-046 has the isolation valves (36XS-0116) and (36XS-0127) and the dump valve (36XS-0109). All valves can also be operated locally.

E. The thickener rake drive has a vendor supplied PLC control system that will interface to the plant

control system for remote monitoring and control of the rake from the MPCS. The vendor package includes the torque (36OI-0103), rake lift position (36ZI-0101) and sludge interface level (36LI-0111) in addition to the drive status information. 6.4

Concentrate Storage and Dewatering A.

Concentrate is fed from the concentrate thickener underflow pumps (C-3610-PP-045/046), through a safety screen (3620-SC-041) and into the concentrate storage tank feed distributor box (C-3620-DI-001). Scrap from the safety screen is discarded into a drum. The distributor box is equipped with two pneumatically operated dart valves (36XS-0301/0302), which can feed concentrate slurry into either copper concentrate storage tank (C-3620-TK-003/004). These valves can be opened and closed either locally, from CCCR or from the filter plant control station (FPCS).


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PROCESS DESCRIPTION – CONTROL PHILOSOPHY B.

Each concentrate storage tank is equipped with an agitator (C-3620-AG-001/002). The slurry discharged from the storage tanks by variable-speed filter feed pumps (C-3620-PP-049/050), one operating and one stand by. The agitators and pumps can be operated (start/stop) either locally or remotely. The filter feed pump speed is controlled by a filter feed algorithm in the vendor’s PLC. Both discharge holding tanks have level transmitters that report to the FPCS which displays the tank levels to CCCR and FP CR operators. The discharge holding tank lowlow alarms are interlocked to the tanks agitators and the filter feed pumps.

C. The filter feed pumps (C-3620-PP -049/050) discharge into a filter feed loop that feeds both

automatic pressure filters (C-3620-FL-001/002). The concentrate can be directed back to the concentrate storage tank feed distributor (C-3620-DI-001), or alternately, to the concentrate thickener feed box (C-3610-BX-001), but the return loop is not used under normal operations. Vendor supplied double acting pinch valves located on the slurry distribution header on each filter and controlled by the filter PLC direct the feed into the filters. The slurry recycle can also be directed into the concentrate thickener feed box by closing the recycle valve on the filter feed loop (26XS-2102) and opening the thickener feed valve (36XS-2101). Both valves can be remotely controlled from CCCR, FPCR or locally. When either of the filters is not accepting feed, the filter feed pumps are shut down. D. The pressure filters are automatically controlled through their own vendor-supplied PLC control

systems that will interface with the plant control system. The vendor control system will automatically control all filter operations, all vendor supplied equipment can also be individually controlled through the vendor PLC. The vendor filter package includes two (2) pressure filters, one pressing air compressor, one pressing air receiver, two (2) drying air compressors, one drying air receiver, two (2) cloth spray water booster pumps, two (2) slurry distributor wash pumps (C-3620-PP-043/044), two (2) filter feed pumps (C-3620-PP-049/050), gland seal booster pump (3620-PP-060), PLC control and associated valves and sensors. Fresh water will be used as cloth wash water from the gland seal water tank. Filtrate and wash water will be collected in the filter wash water tank (3620-TK-043) and pumped back into the copper thickener by the filter/manifold wash water return pump (C-3620-PP-051/052) and the vendor supplied cloth spray water booster pump (C-3610-PP-096/099). 6.5

Concentrate Storage and Loadout Concentrate from the individual filters will fall by gravity to a storage area directly below the filters. A total storage capacity of 3600 t is provided. This represents a total of about 24 h storage capacity. Concentrate will be removed from this storage area and loaded onto trucks using front end loaders. An additional separate storage facility of 5,000 t is also provided, which requires loader rehandling of the filtered concentrate.

6.6

Concentrate Recycle Water A.

Overflow from the concentrate thickener (3610-TK-001) flows via gravity to the concentrate thickener overflow tank (3610-TK-005). As fresh water is used in the final column cells of the main plant and also the molybdenum plant, the quality of this water is expected to be as good or better than process water (tailing thickener overflow) and is to be used as the filter manifold wash water for the Cu concentrate filter presses (3620-FL-001/002), thickener spray water in Cu concentrate thickener (C-3610-TK-001) and in the Cu-Mo concentrate thickener (3510-TK-002). The remainder of this water will flow into the tailing collection launder #1 (C-3710-LA-001).

B.

All water used by the filters is returned into the copper concentrate thickener feed box (C-3610BX-001) with filtrate/core was water return pumps (C-3620-PP-051/052). The water will report


PROCESS

c Ot 25 001_rev B_process Description Control Philosophy

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