vertimill® performance updates in secondary and … vertimill® performance updates in secondary...
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VertiMill® Performance Updates in Secondary and Regrind Duties at Cannington Mine, BHP-B
Sam Palaniandy, Malcolm Powell and Marko Hilden (JKMRC)Jonathan Allen and Kamran Kermanshahi (Metso Minerals)Bill Oats and Mark Lollback (BHP-Billiton Cannington Mine)
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• Low grade finely disseminated ore bodies
• Typically base metal concentrator – adopted ABC/SABC circuit
• Current issues– High circuit throughput– Not enough grinding power– Difficult to achieve the targeted grind size
• Solutions– Install more grinding power – extra ball mill in secondary circuit– Alternately – install low speed gravity induced stirred mill for
extra grinding power and fine grinding
Introduction
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• Metso Minerals has engaged JKMRC to conduct research into stirred milling technology
• Research in stirred milling technology – Focusing on VertiMill®– Performance evaluation – Process modelling– Refining scale up procedure
• Scope of the research includes– Site surveys– Laboratory testwork– Fundamental research – PEPT, DEM
‘Collaborative Research in Stirred Milling Technology’
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VertiMill® Components
Motor
Reducer
Screw with liner
Separating tank
Feed port
Media port
Magnetic liner
Mill discharge launder
Disc launder
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• Close Circuit– Top feed– Bottom feed– With or without separating tank
• Open circuit– With or without separating tank
VertiMill® Circuit Configuration
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Sites Commodity Duty Configuration
Cadia Valley Operation (Australia) Au‐Cu SecondaryTertiaryRegrind
CC, TF
Cannington Mine (Australia) Ag‐Pb‐Zn SecondaryRegrind
CC, TF
Minera Candelaria (Chile) Cu Regrind CC, TF and BF with ST
Foskor (South Africa) P Secondary OC
Barrick Cowal (Australia) Au Regrind CC, TF
Northland Resources (Sweden) Fe Secondary CC, TF, BF
Samarco (Brazil) Fe Regrind CC, BF
Circuit Surveys
Completed six sites with 57 comprehensive data set
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• Development of site specific survey methodology
• Independent evaluation of the circuit performance
• Training for junior metallurgist in conducting survey and circuit performance evaluation
• Recommendations for performance improvement
• Operational and maintenance recommendations
Values through Collaborative Survey Exercise
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• Ag-Pb-Zn mine in northwest Queensland• Early adaptor of VertiMill technology
– Secondary – two VTM-1500-WB (2002 & 2008)– Regrind – three VTM-800-WB (1996)
• Survey exercise– Secondary and all regrind circuits– Extensive data collection – various levels of circuit feed rate and mill
power draw
BHP-B Cannington Mine
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Secondary circuit layout
Splitter box
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Cannington Pb and Zn regrind circuit layout
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Survey Feed rate (t/h)
Power Draw A (kW)
Power Draw B (kW)
Cyclone Pressure(kPa)
Sump level (%)
Water add to sump (m3/h)
Water add mill A (m3/h)
Water add mill B (m3/h)
Cyclone feed % solids(%)
Cyclone feed
flowrate(m3/h)
1 345 1004 ‐ 146 63.2 ‐ 50.0 ‐ 71.1 2035
2 386 991 ‐ 131 60.1 38.9 50.1 ‐ 72.1 2062
3 386 1003 712 129 60.0 ‐ 50.0 40.1 71.0 2062
4 427 986 1006 129 65.0 ‐ 50.0 45.0 71.1 2032
Circuit operational condition – Secondary circuit
All circuits – good agreement between measured and balance data
Good sampling practice
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CircuitFeed rate (t/h)
Cyclone feed flow rate (m3/h)
Cyclone feed % solids
Cyclone feed pulp density
Power draw (kW)
Sump level (%)
Water addition (m3/h)
Cyclone Pressure (kPa)
Pb Regrind A
60.0 126 55 1785 560 65.0 39.0 180
Pb Regrind B
63.0 115 50 1672 516 60.0 18.0 170
Zn Regrind 39.9 259 36.8 1372 580 60.4 41.4 175
Circuit operational condition – Pb and Zn circuit
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Distinct Features of VertiMill® PSD - Secondary
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10
20
30
40
50
60
70
80
90
100
1 10 100 1000
cumm. %
passing
size (µm)
Circuit feedCyclone OF
F98 – 470 µm P98 – 237 µm
F80 – 188 µm P80 – 101 µm
% ‐10 µm
Feed – 12 %
Product – 14 %
Survey Tph Power (kW) F80 (µm) P80 (µm)
1 345 1004 148 99.3
2 386 991 153 128
3 386 1715 188 101
4 427 1991 208 118
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Distinct Features of VertiMill® PSD - Regrind
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10
20
30
40
50
60
70
80
90
100
1 10 100 1000
cumm. %
passing
size (µm)
Circuit Feed
Cyclone OF
F98 – 87 µm P98 – 24 µm
F80 – 45 µm P80 – 21 µm
% ‐10 µm
Feed – 24 %
Product – 41 %
Survey Tph Power (kW) F80 (µm) P80 (µm)Pb Circuit 1 60.0 560 47.6 19.5Pb Circuit 2 63.0 516 44.6 22.2Zn Regrind 39.9 580 35.8 21.2
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OR /
Performance Evaluation Methodology
• Particle size
• Power draw
• Throughput
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Secondary Circuit Performance Evaluation
2.91 2.57 4.45 4.66
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34.1
16.820.6
28.6
64.9
27.4
36.6
0
10
20
30
40
50
60
70
1 2 3 4
SE/O
Wi/SSE@
75 (k
Wh/t)
Survey
SE
OWi
SSE@75um
Tph = 345P= 1004 kW
Tph = 386P= 991 kW
Tph = 386P= 1715 kW
Tph = 427P= 1991 kW
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Regrind Circuit Performance Evaluation
9.33 8.1914.5
29.936.5
69
0
10
20
30
40
50
60
70
80
Pb Regrind A Pb Regrind B Zn Regrind
SE/SSE@25
um (k
Wh/t)
Circuit
SE
SSE@25um
Tph = 60P= 560 kW
Tph = 63P= 516 kW
Tph = 40P= 580 kW
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Reduction Ratio Plot
1.0
1.2
1.4
1.6
1.8
2.0
2.2
100 96 92 88 84 80 76 72 68 64 60 56 52 48 44 40 36 32 28 24 20 16 12 8
redu
ction ratio
% passing
Survey 1 Survey 2 Survey 3 Survey 4
Survey Tph Power (kW)
1 345 10042 386 9913 386 17154 427 1991
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Recommendation• Split at cyclone UF launder• Same number of cyclones for both sides• Operate same number of cyclone• One spare cyclone• Maintain the cyclone performance
Common issues in the circuits – Poor mill feed split
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20
40
60
80
100
1 10 100 1000
cumm. %
passing
size (µm)
Cyclone UF
Mill A
Mill B
Cyc UF P80 = 270 µmMill A feed P80 = 239 µmMill B feed P80 = 272 µm
Cyclone Cluster – Top view
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• Inconsistent water addition– Cyclone feed sump (50 %)– Bottom of the mill (13 %)
Common issues in the circuits
0
10
20
30
40
50
60
70
80
90
0 20 40 60
water add
ition
(m3/h)
time (min)
Sump Bottom of mill
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Effect of mill feed density on power draw
Especially for high SG ores% solidsAmount of finesRelative density – ore vs media
y = ‐8.3255x2 + 1328.1x ‐ 51936R² = 0.9213
70075080085090095010001050110011501200
76 78 80 82 84 86
Power draw (k
W)
mill feed % sol (%)
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• Removing the coarse tail
• Do not produce fine particles
– That may enhance floatation performance and recovery
• Operating at lower specific energy
• Regulating the feed to rougher - buffer
– Absorbing the disturbance from the primary circuit
• Requires small floor space
• Retrofitting in existing grinding circuit
– Without interrupting the existing process
What these circuits do and Why??
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• Supporting deficiency grinding power in primary circuit
• Achieving finer grind size
• Example– VTM-3000-WB at Newcrest Cadia Valley Operation– Feed rate ~ 750 tph– F80 = 150 µm and P80 = 90 µm– SE = 2.75 kWh/t
• Cannington circuit– Two VTM-1500-WB offers operational flexibility– Other options
• Convert one mill to tertiary grind• One mill open circuit and another mill closed with cyclone
VertiMill® in tertiary grinding duty
Palaniandy et. al., 2013 – MetPlant 2013
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• Increase grinding capacity in the circuit and able to grind finer
• Good sampling prac ce → reliable performance evalua on
• The mills are operating within their expected grinding duties
• Identified opportunities for performance enhancement and better utilisation of the technology
• Successful collaborative effort between research institution, equipment supplier and sites → Best Prac ce and u lisa on of technology → profitable operation
Conclusion
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Stirred Milling-The Enabling Technology-
“An opportunity to reduce circuit SE and improve mineral recovery
for your operation”
A chance for collaborative work to achieve Best Practice
Collaborative Research in Stirred Milling Technology
For more Information
JKMRC
Malcolm [email protected]
Metso Minerals
Adam [email protected]
Kamran [email protected]