VertiMill Performance Updates in Secondary and Regrind Duties at Cannington Mine, BHP-B

Transcription

1 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) 1

2 Introduction 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 2

3 Collaborative Research in Stirred Milling Technology 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 3

4 VertiMill Components Motor Screw with liner Feed port Reducer Disc launder Media port Magnetic liner Mill discharge launder Separating tank 4

5 VertiMill Circuit Configuration Close Circuit Top feed Bottom feed With or without separating tank Open circuit With or without separating tank 5

6 Circuit Surveys Sites Commodity Duty Configuration Cadia Valley Operation (Australia) Au Cu Secondary Tertiary Regrind CC, TF Cannington Mine (Australia) Ag Pb Zn Secondary CC, TF Regrind 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 Completed six sites with 57 comprehensive data set 6

7 Values through Collaborative Survey Exercise 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 7

8 BHP-B Cannington Mine 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 8

9 Secondary circuit layout Splitter box 9

10 Cannington Pb and Zn regrind circuit layout 10

11 Circuit operational condition Secondary circuit Survey Feed rate (t/h) Power Draw A (kw) Power Draw B (kw) Cyclone Pressure (kpa) Sump level (%) Water add to sump (m 3 /h) Water add mill A (m 3 /h) Water add mill B (m 3 /h) Cyclone feed % solids (%) Cyclone feed flowrate (m 3 /h) All circuits good agreement between measured and balance data Good sampling practice 11

12 Circuit operational condition Pb and Zn circuit Circuit Feed rate (t/h) Cyclone feed flow rate (m 3 /h) Cyclone feed % solids Cyclone feed pulp density Power draw (kw) Sump level (%) Water addition (m 3 /h) Cyclone Pressure (kpa) Pb Regrind A Pb Regrind B Zn Regrind

13 Distinct Features of VertiMill PSD - Secondary cumm. % passing F µm P µm 80 F µm P µm 70 Survey Tph Power (kw) F80 (µm) P80 (µm) % 10 µm Feed 12% Product 14% Circuit feed Cyclone 118OF size (µm) 13

14 Distinct Features of VertiMill PSD - Regrind cumm. % passing F98 87 µm P98 24 µm 80 F80 45 µm P80 21 µm 70 Survey 60 % 10 µm Tph Power (kw) F80 (µm) P80 (µm) Pb Circuit Pb Circuit Feed 2 24 % Zn Regrind Product 41% Circuit Feed Cyclone OF size (µm) 14

15 Performance Evaluation Methodology Particle size Power draw Throughput / OR / 15

16 Secondary Circuit Performance Evaluation (kwh/t) Tph = 345 P= 1004 kw Tph = 386 P= 991 kw Tph = 386 P= 1715 kw Survey 3 4 Tph = 427 P= 1991 kw 36.6 SE OWi SSE@75um 16

17 Regrind Circuit Performance Evaluation (kwh/t) SE Tph = 60 P= 560 kw 29.9 Tph = 63 P= 516 kw 36.5 Tph = 40 P= 580 kw Pb Regrind A Pb Regrind B Zn Regrind Circuit 17

18 Reduction Ratio Plot 2.2 Survey 1 Survey 2 Survey 3 Survey 4 reduction ratio Survey Tph Power (kw) % passing 18

19 Common issues in the circuits Poor mill feed split cumm. % passing Cyc UF P80 = 270 µm Mill A feed P80 = 239 µm Mill B feed P80 = 272 µm Cyclone UF Mill A Mill B 1 10 size (µm) 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 Cyclone Cluster Top view 19

20 Common issues in the circuits Inconsistent water addition Cyclone feed sump (50 %) Bottom of the mill (13 %) water addition (m3/h) Sump Bottom of mill 0 20 time (min)

21 Effect of mill feed density on power draw Power draw (kw) Especially for high SG ores % solids Amount of fines Relative density ore vs media y = x x R² = mill feed % sol (%) 21

22 What these circuits do and Why?? 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 22

23 VertiMill in tertiary grinding duty 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 Palaniandy et. al., 2013 MetPlant 2013 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 23

24 Conclusion 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 24

25 Collaborative Research in Stirred Milling Technology Stirred Milling -The Enabling Technology- An opportunity to reduce circuit SE and improve mineral recovery for your operation For more Information JKMRC Sam Palaniandy Malcolm Powell Metso Minerals A chance for collaborative work to achieve Best Practice Adam Moore adam.moore@metso.com Kamran Kermanshahi kamran.kermanshahi@metso.com 25