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Processing Considerations for the Cobalt Recovery from Congolese Copperbelt Ores

Processing Considerations for the Cobalt Recovery from Congolese Copperbelt Ores. B. Swartz, S. Donegan, S. Amos Presented M. Reolon 24 – 26 February 2009. Introduction. Increased global demand for Cu and Co Increased political stability in DRC Renewed interest Cu & Co deposits

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Processing Considerations for the Cobalt Recovery from Congolese Copperbelt Ores

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  1. Processing Considerations for the Cobalt Recovery from Congolese Copperbelt Ores B. Swartz, S. Donegan, S. Amos Presented M. Reolon 24 – 26 February 2009

  2. Introduction • Increased global demand for Cu and Co • Increased political stability in DRC • Renewed interest Cu & Co deposits • Studies and projects

  3. Introduction Cu and Co • Agitated oxide leach of Cu & Co • Recovered from Cu SX raffinate bleed • Produce Co intermediate • Metal production if viable Aim • Introduces Co production options • Presents NPV comparison of the selected options

  4. Cobalt Processing Options Three levels of Co recovery • Concentrate by gravity separation • not considered further • Intermediate cobalt salt • Cobalt metal Factors to be considered • Operation (safe, simple, robust) • Technical (proven, robust) • Environmental • Commercial

  5. Cobalt Intermediates Introduction Cobalt Processing Options • Concentrates • Intermediates • Metals • NPV Comparisons

  6. Cobalt Intermediates

  7. Cobalt Intermediates • Impurity removal prior to intermediate production

  8. Cobalt Intermediate Fe / Mn / (Al) removal Cu removal Al removal

  9. Cobalt Intermediate Fe / Mn / (Al) removal Cu removal Al removal Co Precipitation

  10. Cobalt Intermediate Single stage • Lower purity Co Two stage • Higher purity Co saltproduct from 1st stage • Recycle 2nd stage slurry to Fe / Mn precipitation

  11. Cobalt Intermediate Four main options • Cobalt hydroxide precipitation • Cobalt carbonate precipitation • Cobalt sulphide precipitation • Cobalt sulphate crystallization

  12. Cobalt Hydroxide Intermediate Cobalt hydroxide precipitation • pH 7.5 (1st stage) • pH 8 - 8.5 (2nd stage) - lime Slaked lime • Forms gypsum impurity in Co salt • Availability Milk of magnesia • No gypsum produced Caustic soda • No gypsum produced • Na2SO4 disposal considerations

  13. Cobalt Hydroxide Intermediate Advantages • Low operating costs • Little effluent disposal issues (except with NaOH) • No toxic emissions • Relatively simple plant to operate and maintain Disadvantages • Lower product quality

  14. Cobalt Carbonate Intermediate Cobalt Carbonate Precipitation • 1st stage precipitation using Na2CO3 Advantages • Relatively simple plant to operate and maintain • Good recoveries • Compatible to future metal production Disadvantages • Na2SO4 disposal issues

  15. Cobalt Sulphide Intermediate Cobalt Sulphide Precipitation H2S - Not considered for further discussion NaHS Advantages • Low capital cost • Product purity Disadvantages • HSE issues • Low recoveries • Less desirable product

  16. Cobalt Sulphate Intermediate Cobalt Sulphate Crystallization • Falling film evaporator • Crystallizer • Dry, bag and ship Advantage • Marketable product • Compatible to future metals plant Disadvantage • Expensive to build and operate • Co-crystallization of all impurities

  17. Cobalt Intermediate Conclusions • CoS and CoSO4 rejected • Environmental issues to determine between Co(OH)2 and CoCO3 • Current projects preference for Co(OH)2 • 2 stage precipitation preferred

  18. Cobalt Metal Introduction Cobalt Processing Options • Concentrates • Intermediates • Metals • NPV Comparisons

  19. Cobalt Metal Two Processes • Cathode by electrowinning • Powder / briquettes by hydrogen reduction • Not considered further

  20. Cobalt Metal by Electrowinning Co cathode – two processes considered • Co(OH)2 redissolution • Impurity removal by filtration and IX • Co Cathode in EW • Co solution SX • Impurity removal by SX and IX • Co Cathode in EW

  21. Cobalt Metal Conclusions • SX equal or superior to redissolution • Capital and environmental factors predominate • Recommend Co precipitation and redissolution

  22. Cobalt Metal Introduction Cobalt Processing Options • Concentrates • Intermediates • Metals • NPV Comparisons

  23. Comparative NPV between Co(OH)2 and Metal High level NPV on three scenarios • Co(OH)2 intermediate product • Phase 1 Co(OH)2 intermediate product, Phase 2 Cathode metal product • Co(OH)2 intermediate to cathode metal product (no intermediate product) • Basis in Paper • Capital and operating cost - comparison only

  24. Comparative NPV between Co(OH)2 and Metal • Significant benefits for metal product over intermediate product • No significant difference between intermediate product to cathode, or direct resolution to cathode

  25. Conclusions • Often environmental consideration and operational complexity determine optimum route • Follow less complex route in early years (Co(OH)2 production) • Do not underestimate Co metal plant complexity • With experience and cash flow, consider upgrade to metal producing facility

  26. Thank You

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