Metallurgium TM. Lessons Learned from the Copper Industry Applied to Gold Extraction. John O. Marsden

Transcription

1 Metallurgium TM Lessons Learned from the Copper Industry Applied to Gold Extraction John O. Marsden Keynote Presentation at World Gold 2009 Conference, Johannesburg, South Africa, October 30 th, 2009

2 Overview Introduction Managing the innovation process Cost control & business improvement Material Characterization Comminution Biological heap leaching Pressure leaching of copper-gold concentrates (& ores) Flowsheet innovation Conclusions Metallurgium TM

3 Introduction The Copper Industry Large volume 17 million tons per year copper production Typical ore value between $20 and $40/ton ($2.00/lb) Supply-demand balance, cyclical by nature Cycle periodicity is 6-9 years Cycles drive major business trends Exploration, new mine development, mine closures, process improvements, R & D, technology innovation Metallurgium TM

4 Copper Price for

5 Introduction The Gold Industry Small volume 2,600 tons per year gold production Typical ore value between $50 and $200/ton ($750/oz) Supply-demand balance plays lesser role Global/regional financial conditions, political stability, future global economic outlook are major drivers Near term pricing and changes tend to play a dominant role in industry developments but should they? Metallurgium TM

6 Gold Price for

7 Drivers for improvement & innovation Changing value of metal in today s currency? Metallurgium TM

8 Drivers for improvement & innovation Changing value of metal in today s currency? Depends on point in the cycle Do sustained high prices or sustained low prices drive innovation? Metallurgium TM

9 Drivers for improvement & innovation Changing value of metal in today s currency? Depends on point in the cycle Do sustained high prices or sustained low prices drive innovation? Declining ore grades Between 1988 and 2006, average copper head grade declined from 1.08% to 0.84% 22% decrease in grade; 45% decrease in margin Metallurgium TM

10 Drivers for improvement & innovation Changing value of metal in today s currency? Depends on point in the cycle Do sustained high prices or sustained low prices drive innovation? Declining ore grades Between 1988 and 2006, average copper head grade declined from 1.08% to 0.84% 22% decrease in grade; 45% decrease in margin Increasing complexity of ores Increased capital and operating costs Decreased metallurgical recoveries Metallurgium TM

11 Drivers for improvement & innovation Changing value of metal in today s currency? Depends on point in the cycle Do sustained high prices or sustained low prices drive innovation? Declining ore grades Between 1988 and 2006, average copper head grade declined from 1.08% to 0.84% 22% decrease in grade; 45% decrease in margin Increasing complexity of ores Increased capital and operating costs Decreased metallurgical recoveries Quality of people Limited availability of graduates Losing expertise through retirements Metallurgium TM

12 Drivers for improvement & innovation Burning platform syndrome Necessity is the mother of invention Gold industry challenges Difficult to replace ore reserves Limited ore resource opportunities Severe competition amongst gold producers for resources and reserves Declining ore grades, fixed tails grade effects Increasing ore complexity Availability of expertise and skills Increasing energy cost Environmental and social pressures Metallurgium TM

13 Managing the Innovation Process Experienced, dedicated and self-motivated staff to lead Centralized, applied technology development group Operations do not have the time, resources nor imperative Develop & maintain strategic plan for innovation Well-coordinated, operationally-focused approach Operators involved at every step Strong focus on effective commercial application/ technology transfer Communicate process clearly and often Make timely go-no go decisions Every innovation needs a champion

14 Risk-Benefit Profiling Value Creation Potential High Value, Low Risk Easy Positive Decisions Low Value, Low Risk Lower Impact Decisions H i g h V a l u e, H i g h R i s k Highest Impact Decisions Low Value, High Risk Easy Negative Decisions Relative Risk Profile Metallurgium TM

15 Cost Control & Business Improvement Several initiatives implemented in copper industry Continuous Improvement Six Sigma Lean Production Establish leadership and accountability Determine what process to be used Define how the initiative will be executed Establish metrics to measure progress Set a timeline for execution Measure and communicate results regularly Metallurgium TM

16 Improvement in Operating Efficiency Reduction in operating cost of existing process Improvement in metal(s) recovery Increase in throughput Debottlenecking or expansion Improvement in ore quality (grade) to process Implementation of a new technology Other improvements Safety, health & environmental Sustainable development Social responsibility aspects Metallurgium TM

17 Business Improvement Initiatives Team-based approach Rank and prioritize opportunities Cross-functional; cross-operations Cost-center focus Best practices identification/implementation Benchmarking Metallurgium TM

18 Material Characterization A core competency in our business Improved process design capability Improved ore routing within the mine Improved diagnostic capability (trouble-shooting and problem solving) Improved process optimization Metallurgium TM

19 Material Characterization

20 Material Characterization Alteration Codes Visual Logging Data QemSCAN Alteration Codes QemSCAN Data Qz TickMarks Triangle lines Qz TickMarks Triangle lines COR AC2 COR QSAC1 COR AC3 MET AC3 MET AC4 MET AC5 NWX AC2 MET QSAC1 MET QSAC2 MET QSAC3 NWX QSAC1 NWX QSAC2 NWX AC3 NWX AC4 NWX AC5 Ksp Se Ksp Se Precision and accuracy of data greatly improved QemSCAN Alteration Codes XRD Data Qz TickMarks Triangle lines COR QSAC1 MET QSAC1 MET QSAC2 MET QSAC3 NWX QSAC1 NWX QSAC2 Benefits to: Ore control & ore type routing Process control Mine design & sequencing Plant design Ksp Se

21 Comminution Scales of economy Optimal grind size for NPV versus cash flow Stirred milling High pressure grinding rolls (HPGR) HPGR and stirred milling Metallurgium TM

22 Candelaria, Copiapo, Chile

23 Candelaria 80,000 mtpd

24 Grind Size versus Recovery Do you know the optimal grind size? What metal price are you using? How well is your process controlled? Metallurgium TM

25 Chino, New Mexico

26 Chino Grinding Optimization Optimal grind size was 80% -150 microns Actual grind size through the 1980 s and into the 1990 s was 80% -300 microns Approximately 8-9% copper recovery difference Added four VTM-1250 Vertimills as a tertiary grinding stage 20-25% energy improvement vs. ball milling Design modifications were critical for success Height:diameter ratio reduced Shaft strengthened Door access modified Slurry entry point changed VTM-3000 (and larger) in design Metallurgium TM

27 Chino, New Mexico

28 High Pressure Grinding Rolls Cerro Verde milling circuit incorporates high pressure grinding rolls (HPGR) instead of SAG mills 108,000 mtpd Four 2.4 x 1.6 m HPGR s Advantages vs. SAG mills Improved energy efficiency 2.4 kwh/t vs kwh/t Greater flexibility Lower unit cost Disadvantages vs. SAG mills Additional capital cost Significant financial benefit

29 Cerro Verde, Arequipa, Peru

30 HPGR at Cerro Verde

31 HPGR at Cerro Verde

32 Biological Heap & Stockpile Leaching Ore stacking systems Air injection distribution Solution application rate & distribution Solution chemistry control Temperature control Bacteria developments Heap modelling & simulation Metallurgium TM

33 Morenci Biological Heap Leach 85,000 tpd

34 Morenci Biological Heap Leach 85,000 tpd

35 Cerro Verde Biological Heap Leaching

36 Pressure Leaching of Cu-Au Concentrates Potential application to treat sulphide copper-gold ores High temperature and medium temperature applications C versus C Elemental sulphur formation and effect Metallurgium TM

37 Elemental Sulphur Formation Proportion of sulfide sulfur in feed converted to elemental sulfur (%)

38 Concentrate Leaching at Bagdad, Arizona 55,000 tpy copper sulphide concentrate High temperature pressure leaching at 225 C Integrated with copper heap leaching, SX and EW circuit

39 Concentrate Leaching at Morenci, Arizona 200,000 tpy copper sulphide concentrate Medium temperature pressure leaching at 160 C Super-fine grinding to 98% <15 µm; 80% <7 µm

40 Concentrate Leaching High Temperature Concentrate 1,000 mtpd Water Cooling Water Slurry Formation Pressure Leaching Feed Heap/Stockpile/Tank* Leaching Lime Flash Let Down Solid/Liquid Separation Solids (optional) Precious Metals Leaching/Recovery Neutralization Solution Extraction Electrowinning LEGEND: Flow (m3/hr) Cu (g/l) H2SO4 (g/l) Fe (gpl) Gold/Silver Bullion Tailings Disposal Cathode Copper *Tank includes vat or agitated or stirred leaching vessel

41 Concentrate Leaching Medium Temperature Concentrate 1,000 mtpd Water From Tailings Slurry Formation Super Fine Grinding Acid Water Pressure Leaching Raffinate to Cooling Solution LEGEND: Flow (m3/hr) Cu (g/l) H2SO4 (g/l) Fe (gpl) *Tank includes vat or agitated or stirred leaching vessel Lime Flash Let Down Solid/Liquid Separation Solids Solids Limestone and/or Lime Partial Solution Neutralization Solid/Liquid Separation Solids Solution Extraction Precious Metals Leaching/Recovery (optional) Neutralization Electrowinning Gold/Silver Bullion Tailings Disposal Raffinate to Neutralization Cathode Copper

42 Options for Gold & Silver Recovery After high temperature pressure leaching Neutralization and cyanide leaching Hot lime boil to enhance silver extraction CIP/CIL After medium temperature pressure leaching Neutralization and cyanide leaching Accept high cyanide consumption (2-4 kg/t) Sulfur removal followed by cyanidation Molten sulfur filtration Other methods Thiosulfate leaching Utilize copper in system Metallurgium TM

43 Innovation in Flowsheet Design Integration of milling & cyanide leaching with heap leaching in gold Integration of milling, flotation & concentrate leaching with heap leaching in copper Copper-gold ore pressure leaching options Treatment of rougher concentrates Lower grade, higher recovery Selective flotation Pyrite/chalcopyrite/chalcocite separations Co-extraction of uranium, other metals Metallurgium TM

44 Chimney Creek Flowsheet (Nevada)

45 Conclusions Significant opportunities exist to apply lessons learned from the copper industry (and others) to gold Managing the innovation process Cost control & business improvement Technological advances Material characterization Comminution Biological heap leaching Concentrate leaching Innovation in flowsheet design Critical for complex, lower grade ores Metallurgium TM