Recent studies on the application of fluidised-bed flotation for treating sulphide ores at a coarser grind Massimiliano Zanin1, Bellson Awatey1 and Jaisen Kohmuench2 1
Ian Wark Research Institute, University of South Australia , Australia Australia
2
ERIEZ Flotation Division, USA
Ian Wark Research Institute Australian Research Council Special Research Centre For Particle and Material Interfaces
Coarse Particles Flotation 100 •
Probability of detachment is high for coarse particles.
•
Recovery of base metals diminishes outside 20150µm range
•
Impeller mechanisms generate turbulence, but necessary to maintain particles in suspension.
•
The froth phase also reduces coarse particles recovery.
80
) % ( 60 y r e v o c 40 e R
Copper Lead-Zinc Coal
20
Phosphate
0 1
10
100
Particle Diameter (Microns) Gontijo et al, 2007. Can J Chem Eng, 85, 739-747 Jameson et al, 2008. Centenary of Flotation Commemorative Volume, (SME), USA, pp. 339 –372.
1000
Fluidised-bed Flotation Technology Flotation in quiescent conditions enhances the recovery of coarse particles - Concept originally devised in early 1990’s - First industrial installation in 2004 (ERIEZ) for the recovery of coarse potash (+3.5x0.8-mm). - Demonstrated advantages in the flotation of low s.g. minerlas (potash, phosphate, spodumene, diamonds) - Only recently tested for base metals
In this work, flotation of sulphide ores has been tested with HydroFloat, at very coarse grind
Hydrodynamic Advantages 1.
Reduced settling velocity, increased probability of collision and attachment
2.
Plug flow conditions, increased retention time
3.
Absence of turbulence, decreased probability of detachment
The hydrodynamic environment favours coarse particles flotation
Mechanical vs Fluidised-bed Flotation Fluidisedbed Cell Mechanical Cell
No froth layer Froth layer limits recovery Reduced turbulence
Water + AIr
High turbulence causes particles detachment Grano, S., 2006, Minerals Engineering, 19, 1307-1318 Kohmuench et al, 2001. Miner & Metall Process, 18, 61-67
Fluidised-bed flotation requires separate treatment of the fines (max. top/bottom size ratio 1:6)
Laboratory Setup HydroFloat HF-150 140x600 mm DxL 300 kg/h max
Laboratory scale HydroFloat separator at UniSA, supplied by ERIEZ
Ores Tested 1. Highly liberated Zn ore (P 80 = 750 um) 100
50 mass
80
40
% , g 60 n i s s a p s s 40 a M
% , n30 o i t u b i r t s20 i D
20
10
0
0 100
1000 Particle size, um
Zn
-250
425 - 250 850 - 425 Particle size range, um
1180 850
Mineral
Mass %
+250 um floated in HydroFloat (80% of the mass, 78% of the Zn)
Sphalerite
12
Dolomite
71
-250 um floated in Denver cell (20% of the mass, 22% of the Zn)
Quartz
10
Ores Tested 2. Poorly liberated Cu ore (P 80 = 400 um) 100
70 mass
60
80
Cu
50 % , n o i 40 t u b i r30 t s i D 20
% , g 60 n i s s a p s s 40 a M 20
10 0
0 100
1000 Particle size, um
-150
250 - 150
425 250
600 - 425 850 - 600
Particle size range, um
Mineral
Mass %
+150 um floated in HydroFloat (62% of the mass, 40% of the Cu)
Chalcopyrite
6
Pyrite
6
-150 um floated in Denver cell (38% of the mass, 60% of the Cu)
Dolomite
25
Quartz
45
Ore 2 Liberation by QEM-Scan LIBERATION IS A LIMITING FACTOR
2. Poorly liberated chalcopyrite •
30
•
25
•
20 15 m u , -250/150 e z i s -425/250 e l c -600/425 i t r a -850/600 P
10 5 0 <= 10%
10%-40%
40%-90%
>= 90%
Liberation
Distribution of Cp in the coarse flotation feed (+150 um) by size and liberation class
15% of Cp is <10% liberated 33% of Cp is <40% liberated Cp in the size fractions +425 um is mainly unliberated
Mineral
Mass %
Chalcopyrite
6
Pyrite
6
Dolomite
25
Quartz
45
Flotation Tests and Conditions Two series of tests: 1.
Comparison between mechanical cell and fluidised-bed flotation cell on the coarse flotation feeds (recovery by size)
2.
Split flotation of coarse and fine feed fractions for improved overall flotation performance ORE
Ore 1 (Zn)
Ore 2 (Cu)
pH
10
10.5
Activator
CuSO4
-
Prim. collect.
SIPX
PAX
Sec. collect.
-
Diesel Oil
Frother
PPG425*
PPG425*
(*) 30 g/t PPG425 in mechanical cell 1 g/t PPG425 in Hydrofloat
Flotation Results
Ore 1 (Zn ore): Mechanical vs Fluidised-bed (b)
(a) DENVER CELL
Increasing collector
FLUIDISED-BED FLOTATION
5-80 g/t SIPX
Increasing collector 5-80 g/t SIPX
• •
Fluidises-bed flotation outperformed mechanical cell for particles > 250 um Zn recovery up to 88% for 1 mm particles (@ 250 g/t CuSO4 and 80 g/t SIPX)
Ore 2 (Cu ore): Fluidised-bed Flotation RESULTS IN DENVER CELL NOT AVAILABLE
•
•
FLUIDISED-BED FLOTATION
Recovery of the coarse particles is lower compared to the Zn ore (<60% above 250 um) Liberation is a limiting factor (significant fully locked particles in tailings)
Split Flotation (Lab Scale) d80= 750 um d80= 400 um
DENVER CELL FINES
Aim: •
•
•
Early rejection of gangue and low-grade composites Reduction of energy and reagents consumption Increased throughput to the plant
COARSE
FLUIDISED-BED FLOTATION
DENVER CELL
Results: Ore 1 (Zn ore) Denver cell 9.37
100
d80-750 µm
9.71
1.3
21.2
Tails -250 µm
Screen
+250 µm 9.26
Con
78.8
FLUIDISED-BED HydroFloat FLOTATIONcell 95% Zn Recovery
63.2
20.1
Con 56.3
3.1
75.1
Regrind circuit
Con
Final Tails 3.7
Legend Zn grade, %
66.4
72.1
Final tails
2.4
4.1
Rghr Con (combined) 65.7
Zn Distribution, %
3.0
Tails
d80-250 µm
0.52
1.1
92.2
Rghr Con (Combo) 92% Zn Recovery
Results: Ore 2 (Cu ore) Denver cell 2.11
100
d80-400 µm
3.74
0.07
60.1
Tails -150 µm
Screen
+150 µm 1.56
Con
39.9
FLUIDISED-BED HydroFloat FLOTATION cell 60% Cu Recovery
10.06
59.3
Con 3.19
0.11
23.5
Regrind circuit
Con
Final Tails 16.4
Legend Cu grade, %
6.81
23.1
Final tails
0.08
1.2
Rghr Con (combined) 8.93
Cu Distribution, %
0.4
Tails
d80-150 µm
0.9
0.8
82.4
Rghr Con (Combo) 82% Cu Recovery
Conclusions •
•
•
•
•
Coarse sulphide particles up to 1 mm can be efficiently recovered in fluidised-bed flotation, in spite of the high s.g. In general, fluidised-bed flotation outperforms mechanical cells as particle size increases > 250 um There is potential for using fluidised-bed flotation as a scalper before conventional rougher flotation to produce a low-grade throw away tailing stream Energy for grinding and reagents consumption can be significantly reduced The only limitation is the feed mineralogy. Selectivity drops for finely disseminated ores (e.g. porphyry copper) at very coarse grind, due to liberation issues
Acknowledgements
The authors kindly acknowledge the Australian Research Council (ARC) (LP100200533) and the AMIRA International P260F project for the financial support.
P260 - Flotation
