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Council for Mineral Technology
An overview of HPGR testwork
program at Mintek5th June 2009
Johnny T. Kalala
Head of Comminution, Minerals Processing Division, Mintek
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• Introduction• HPGR’s on site at Mintek
• Key questions on HPGR
• HPGR testwork program – Development/ Improvement of test procedures
– HPGR operation
– Flowsheets development
– Modelling and simulations
– Downstream benefits
– HPGR control• Conclusion
Presentation overview
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HPGR is maturing to become a
competitive technology in designing
comminution circuits
Introduction
Motivation to implement a HPGRØ Improve Energy efficiency
Ø Cost reduction by not using grinding media
Ø Debottlenecking
Ø Metallurgical performance
Ø Differential comminution
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HPGR’s on site at Mintek
1. Polysius HPGRStudded rolls
Diameter=0.250 m
Width=0.100 mTop size: 12 mm
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Crushing in a HPGR
Feed
Product
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Ø Amenability of different ore type to HPGR?
Key questions
Throughput (t/h)
Ore competency
cost Morley (2006)
Ø Testing
ØQuantification of HPGR benefits
Does an open circuit HPGR do a better job than a modern closed circuit
cone crusher for tertiary crushing duties?
Does HPGR technology provide lower energy and steel consumption?
Does HPGR technology lead to better concentrate circuit grades and recoveries?
Ø Limitations of the technology
Does HPGR technology lead to better kinetic of flotation or leaching?
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1. Improved method for testing
ü Amount of sample to be used
ü Data recording
ü Sampling
2. Development of a flake competency index to
characterise the competency of HPGR flakes
3. Piston die compression test to predict HPGR
performance
4. Wear tests
HPGR testwork program
1. Testing: ore amenability
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HPGR testwork program
1. Influence of operating variables
0
20
40
60
80
100
120
140
160
180
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00
Time[Seconds]
POWERFixedRoller [kW] POWERFloat. Roller [kW] PressureDE[bar] PressureNDE[bar] GapDE[mm] GapNDE[mm]
Typical HPGR test output
Hydraulic pressure
Power
Operating gap
I. Ore amenability
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HPGR testwork program
2. Piston die compression test263g UG2 -12mm, compression at different forces
0
200
400
600
800
1000
1200
1400
1600
1800
0 1 2 3 4 5 6 7
Displacement, mm
A p p l i e d F
o r c e ,
k N
Max. Force 100kN2 500kN2 1700kN3
Input Energy, Nm 85.28 574.15 2519.16
Energy returned, % 7.2 23.7 48.4
RR50 1.4 2.8 5.3
Solid fraction 0.72 - 0.88
I. Ore amenability
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HPGR testwork program
1
10
100
0.01 0.1 1 10 100
Particle mesh size [mm]
M a s s p e r c e n t a g e l e s s
t h a n s i z e
Feed
0.18 kW/t
0.33 kWh/t
0.69kW/t
0.89 kWh/t
1.26 kWh/t
1.54 kWh/t
1.98 kWh/t
Feed fit
0.18 kW/t fit
0.33 kWh/t fit
0.69kW/t fit
0.89 kWh/t fit
1.26 kWh/t fit
1.54 kWh/t fit
1.98 kWh/t fit
2. Piston die compression test
Merensky ore: top size 12 mm
I. Ore amenability
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HPGR testwork program
3. Development of a “ Mintek” flake competency testHPGR flake deagglomeration using a scrubber: Kimberlite oreMerensky ore flake
Kimberlite flake after deagglomeration in a scrubber
Circuit used at Jwaneng
I. Ore amenability
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HPGR testwork program
3. Development of a “ Mintek” flake competency test
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
0.0 2.0 4.0 6.0 8.0 10.0
Screening time (min)
% P a s s i n g
m e s h s i z
Merensky
Gold ore
Kimberlite
Influence of ore type on screening kinetic
30.0
40.0
50.0
60.0
70.0
80.0
90.0
0.0 2.0 4.0 6.0 8.0 10.0
Screening time (min)
% P a s i n g
m e s h s i z
HP90 %-3.35 mm
HP120 %-3.35 mm
HP60 %-3.35 mm
Influence of hydraulic pressure on
screening kinetic for a Merensky ore
I. Ore amenability
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0
5
10
15
20
25
30
35
40
45
50
0 1 2 3 4 5 6
Moisture (%)
W
e a r r a t e ( g / t )
UG2 (4 N/m m2) Merensky (4 N/m m2) UG2 (2 N/m m2) UG2 (6N/m m2)
HPGR testwork program
I. Ore amenability
4. Wear test
UG2 and Merensky results on Polysius studded rolls
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HPGR testwork program
II. Influence of operating conditions
Merensky, 1.85% Moisture, product size distribution
10
20
30
40
50
60
70
1 2 3 4 5 6 7 8
Specific press force, N/mm2
% l
e s s t h a n s i z e
% passing 75 microns % passing 300 microns % passing 600 microns
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HPGR testwork program
III. Flowsheet development
Comminution circuit without using steel as grinding media
1 - HPGR feed
2 - HPGR discharge
3 - Repulper dilution
4 - Flash float feed
5 - Flash f loat concentrate
6 - Flash f loat tails
7 - Primary mill discharge8 - Primary float dilution
9 - Primary float feed
10 - Primary float concentrate
11 - Primary float tails
HPGR
0.6 mm
mesh
(-70+25) mm
pebbles
AG mill
Pebble mill
Primary
float
ROM
feed
Water
Secondary
float
Dewatering
hydrocyclone
(-70+0.6) mm
Pebbles + sand
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HPGR testwork program
Ø Assessing HPGR benefits as a tertiary crusher in comparison to modern
cone crusher choke fed
III. Flowsheet development
Action in a cone crusher Action in a HPGR
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HPGR testwork program
III. Flowsheet development
Ø Assessing HPGR benefits as a tertiary crusher in comparison to modern
cone crusher choke fed
HPGR
Repulper Flash float Primary ball mill
1
2
3
4
10
5
6 7
8
9
1 - HPGR feed
2 - HPGR discharge
3 - Repulper dilution
4 - Flash float feed
5 - Flash float concentrate
6 - Flash f loat tails
7 - Primary mill discharge
8 - Primary float dilution9 - Primary float feed
10 - Primary float concentrate
11 - Primary float tails
11
Basic Northam circuit
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HPGR testwork program
IV. Modelling, simulation and scale up
Objectives:
- Development of steady state and dynamic model for HPGR
- Scale-up from HPGR laboratory test and compression tests
- Plant surveys
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HPGR testwork program
V. Downstream benefits
Objectives: Quantification of HPGR downstream benefits
Ø Milling
- Reduction of spec. energy consumption
- Reduction of BBWI
Ø Flotation and leaching- Faster kinetic
- Better recovery
Ø Mineralogy
- Liberation
- Quantification of microcracks
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HPGR testwork program
Objectives: Improve HPGR performance by providing better control
Ø Maintain throughput by changing roll speed
Ø Maintain or avoid cake formation
Ø Control the quality of HPGR product by changing on line the split between
edge and centre productØ Maintain an autogenous layer on HPGR to minimize wear
VI. HPGR control
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The future of the HPGR depends on
progress made to improve the current
understanding of the technology and on
our ability to exploit all benefits provided.
Conclusion
Current limitations of the technology:Ø Feed top size ( ~ 80 mm)
Ø Feed moisture
Ø Product size distribution
Ø Classification of HPGR product
ØCapacity
ØWear rate
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• Mintek
• Polysius
• IMS
• Comminution group, Minerals ProcessingDivision
Acknowledgements
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www.mintek.co.za
Thank you