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Council for Mineral Technology
An overview of HPGR testwork program at Mintek
5th June 2009
Johnny T. KalalaHead of Comminution, Minerals Processing Division, Mintek
• 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
HPGR is maturing to become a competitive technology in designing comminution circuits
Introduction
Motivation to implement a HPGRØ Improve Energy efficiencyØ Cost reduction by not using grinding mediaØ DebottleneckingØ Metallurgical performanceØ Differential comminution
Ø Amenability of different ore type to HPGR?
Key questions
Throughput (t/h)
Ore competency
cost Morley (2006)
Ø TestingØQuantification 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 technologyDoes HPGR technology lead to better kinetic of flotation or leaching?
1. Improved method for testingü Amount of sample to be usedü Data recordingü 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
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]
POWER Fixed Roller [kW] POWER Float. Roller [kW] Pressure DE [bar] Pressure NDE [bar] Gap DE [mm] Gap NDE [mm]
Typical HPGR test output
Hydraulic pressure
Power
Operating gap
I. Ore amenability
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
App
lied
Forc
e, k
N
Max. Force 100kN2 500kN2 1700kN3Input Energy, Nm 85.28 574.15 2519.16Energy returned, % 7.2 23.7 48.4RR50 1.4 2.8 5.3Solid fraction 0.72 - 0.88
I. Ore amenability
HPGR testwork program
1
10
100
0.01 0.1 1 10 100Particle mesh size [mm]
Mas
s pe
rcen
tage
less
than
siz
eFeed0.18 kW/t0.33 kWh/t0.69kW/t0.89 kWh/t1.26 kWh/t1.54 kWh/t1.98 kWh/tFeed fit0.18 kW/t fit0.33 kWh/t fit0.69kW/t fit0.89 kWh/t fit1.26 kWh/t fit1.54 kWh/t fit1.98 kWh/t fit
2. Piston die compression test
Merensky ore: top size 12 mm
I. Ore amenability
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 scrubberCircuit used at Jwaneng
I. Ore amenability
HPGR testwork program
3. Development of a “ Mintek” flake competency test
0.010.020.030.040.050.060.070.080.090.0
0.0 2.0 4.0 6.0 8.0 10.0
Screening time (min)
% P
assi
ng m
esh
size
MerenskyGold oreKimberlite
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
asin
g m
esh
size
HP90 %-3.35 mmHP120 %-3.35 mmHP60 %-3.35 mm
Influence of hydraulic pressure on screening kinetic for a Merensky ore
I. Ore amenability
0
5
10
15
20
25
30
35
40
45
50
0 1 2 3 4 5 6
Moisture (%)
Wea
r rat
e (g
/t)
UG2 (4 N/mm2) Merensky (4 N/mm2) UG2 (2 N/mm2) UG2 (6N/mm2)
HPGR testwork programI. Ore amenability
4. Wear test
UG2 and Merensky results on Polysius studded rolls
HPGR testwork programII. 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 8Specific press force, N/mm2
% le
ss th
an s
ize
% passing 75 microns % passing 300 microns % passing 600 microns
HPGR testwork programIII. Flowsheet development
Comminution circuit without using steel as grinding media
1 - HPGR feed2 - HPGR discharge3 - Repulper dilution4 - Flash float feed5 - Flash float concentrate6 - Flash float tails7 - Primary mill discharge8 - Primary float dilution9 - Primary float feed10 - Primary float concentrate11 - Primary float tails
HPGR
0.6 mmmesh
(-70+25) mm pebbles
AG mill Pebble mill
Primaryfloat
ROM feed
Water
Secondary float
Dewatering hydrocyclone
(-70+0.6) mmPebbles + sand
HPGR testwork program
Ø Assessing HPGR benefits as a tertiary crusher in comparison to moderncone crusher choke fed
III. Flowsheet development
Action in a cone crusher Action in a HPGR
HPGR testwork programIII. Flowsheet development
Ø Assessing HPGR benefits as a tertiary crusher in comparison to moderncone crusher choke fed
HPGR
RepulperFlash float Primary ball mill
1
23
4
105
6 7
8
9
1 - HPGR feed2 - HPGR discharge3 - Repulper dilution4 - Flash float feed5 - Flash float concentrate6 - Flash float tails7 - Primary mill discharge8 - Primary float dilution9 - Primary float feed10 - Primary float concentrate11 - Primary float tails
11
Basic Northam circuit
HPGR testwork programIV. 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
HPGR testwork programV. 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
HPGR testwork program
Objectives: Improve HPGR performance by providing better control
Ø Maintain throughput by changing roll speedØ Maintain or avoid cake formationØ 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
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 moistureØ Product size distributionØ Classification of HPGR productØCapacityØWear rate