1. B. Swartz, S. Donegan, S. Amos
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. Introduction Cobalt Processing Options Concentrates Intermediates
Metals
NPV Comparisons

5. 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

6. Cobalt Concentrates Introduction Cobalt Processing Options
Intermediates
Metals
NPV Comparisons

7. Cobalt Concentrates Lowest cost method
Inconsistent and poor performance
Early cash flow generator
Not considered further

8. Cobalt Intermediates Introduction Cobalt Processing Options
Concentrates
Intermediates
Metals
NPV Comparisons

9. Cobalt Intermediates

10. Cobalt Intermediates
Impurity removal prior to intermediate production

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

12. Cobalt Intermediate Cu removal by Precipitation pH 5.5 - lime
Precipitate to leach
Secondary SX

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

14. Cobalt Intermediate Single stage Lower purity Co Two stage
Higher purity Co salt product from 1st stage
Recycle 2nd stage slurry to Fe / Mn precipitation

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

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

17. 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

18. 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

19. 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

20. 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

21. CoCO3 > Co(OH)2 > CoSO4 > CoS
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
Effluent Discharge
Rated Best to Worst
Available
CoCO3 > Co(OH)2 > CoSO4 > CoS
not available
Co(OH)2 > CoCO3 > CoSO4 > CoS

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

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

24. Cobalt Metal by H2 Reduction
Produce metal powder or briquettes
Require natural gas source
Require H2 plant
Capital and operating costs higher
More complex plant
Lower recoveries
H2 reduction not considered further

25. 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

26. Cobalt Metal by EW using Co(OH)2 intermediate
Co precipitation
Co redissolution
Fe/Mn scavenge
Zn / Cu IX
Ni IX
Co EW
Product Preparation

27. Cobalt Metal by EW using Co SX
Cu SX
Co SX extract
Ca, Ni, Mg rejected
Co SX strip
Zn SX
Zn, Fe removed
Cu IX
Co EW
Disadvantages
Solvent contamination
Na2SO4 disposal

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

29. Cobalt Metal Introduction Cobalt Processing Options Concentrates
Intermediates
Metals
NPV Comparisons

30. 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

31. Comparative NPV between Co(OH)2 and Metal
NPV Input Data
Capital
High level, comparative purposes only
Includes earthworks, civils, structural, mechanical, piping, instruments
Excludes indirect cost
From raffinate pond to products, including reagents
Operating Cost
Incremental (additional to Cu production costs)

32. 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

33. 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

34. Thank You