Process for the treatment of molybdenum concentrate

1. A process for the extraction of molybdenum and copper, comprising the steps of:

subjecting a molybdenumcopper concentrate to a first pressure oxidation in the presence of oxygen and a first feed solution containing copper and halide to produce a first copper containing solution and a solid residue containing molybdenum;

subjecting a copper concentrate to a second pressure oxidation in the presence of oxygen and a second feed solution containing copper and halide to produce a second copper containing solution and a solid residue;

subjecting the second copper containing solution to solvent extraction to produce a pregnant copper solution and a raffinate;

recycling a first portion of said raffinate as said second feed solution to the second pressure oxidation along with said first copper containing solution; and

recycling a second portion of said raffinate as said first feed solution to the first pressure oxidation.

2. The process according to claim 1 , further comprising the step of subjecting said second portion to neutralization prior to recycling the second portion to the first pressure oxidation.

3. The process according to claim 1 , wherein said molybdenumcopper concentrate and said copper concentrate are obtained by subjecting a coppermolybdenum concentrate to a flotation process to produce a float comprising said molybdenum-copper concentrate and a tail comprising said copper concentrate.

4. The process according to claim 1 , wherein the first and second pressure oxidations are carried out at a temperature of from about 115° C. to about 175° C.

5. The process according to claim 4 , wherein the pressure oxidations are carried out at a temperature of about 150° C.

6. The process according to claim 1 , wherein said second feed solution contains from about 0 g/L to about 50 g/L free acid.

7. The process according to claim 6 , wherein the copper in the first and second feed solutions has a concentration of about 10 to 20 g/L.

8. The process according to claim 7 , wherein the concentration of copper in the feed solutions is about 15 g/L.

9. The process according to claim 1 , wherein the halide is chloride and the chloride in the first and second feed solutions is maintained at a value of about 8 to 15 g/L.

10. A process according to claim 9 , wherein the chloride in the feed solutions is maintained at a value of about 12 g/L.

11. The process according to claim 1 , wherein the first pressure oxidation is carried out with a solids density of up to about 1000 g/L.

12. The process according to claim 11 , wherein the solids density is about 500 g/L.

13. The process according to claim 1 , wherein the first pressure oxidation is carried out with a solids density of about 250 to 800 g/L.

14. The process according to claim 1 , wherein the second pressure oxidation is carried out with a solids density of about 120–300 g/L.

15. The process according to claim 1 , wherein the copper is present as copper sulphate in the first and second feed solutions.

16. The process according to claim 1 , wherein the halide is present as copper chloride in the first and second feed solutions.

17. A method for purification of a molybdenum concentrate contaminated with copper, comprising the step of subjecting the molybdenum concentrate to pressure oxidation in the presence of oxygen and a feed solution containing copper and chloride to produce a pressure oxidation solution containing copper and a solid residue containing molybdenum, the amount of chloride in the feed solution being about 8 to 15 g/L.

18. The method according to claim 17 , wherein the pressure oxidation is carried out at a temperature of from about 115° C. to about 175° C.

19. The method according to claim 18 , wherein the pressure oxidation is carried out at a temperature of about 150° C.

20. The method according to claim 17 , wherein the pressure oxidation is carried out under an oxygen pressure of about 350 to about 1800 kPa.

21. The method according to claim 17 , wherein the copper in the feed solution has a concentration of about 10 to 20 g/L.

22. The method according to claim 21 , wherein the concentration of copper in the feed solution is about 15 g/L.

23. The method according to claim 17 , wherein the chloride in the feed solution is maintained at a value of about 10 to 15 g/L.

24. A method according to claim 23 , wherein the chloride in the feed solution is maintained at a value of about 12 g/L.

25. The method according to claim 17 , wherein the feed solution is provided by recycling at least part of the pressure oxidation solution to the pressure oxidation.

26. The method according to claim 25 , wherein the pressure oxidation solution is subjected to copper solvent extraction to produce a pregnant copper solution and a raffinate and wherein at least part of the raffinate is recycled to the pressure oxidation.

27. The method according to claim 18 , wherein the pressure oxidation is carried out with a solids density of about 1000 g/L.

28. The method according to claim 18 , wherein the pressure oxidation is carried out with a solids density of about 500 g/L.

29. The method according to claim 17 , wherein the copper is present as copper sulphate in the feed solution.

30. The method according to claim 17 , wherein the chloride is present as copper chloride in the feed solution.

31. The method according to claim 17 , wherein the pressure oxidation is carried out with a solids density of about 250 to 800 g/L.