Solvent extraction of impurity metals from a valuable metal sulphate solution

• US 20030064013A1
• Filed: 10/15/2002
• Published: 04/03/2003
• Est. Priority Date: 12/24/1999
• Status: Active Grant

• Current Assignee: BHP Billiton Nickel West Pty Limited (BHP Group Ltd.)
• Original Assignee: BHP Billiton SSM Indonesia Holdings Pty., Ltd. (BHP Group Ltd.)
• Inventors: Chamberlain, Tony, OʼCallaghan, John
• Granted Patent: US 7,727,496 B2
• Time in Patent Office: Days
• US Class Current: 423/139
• CPC Class Codes: C22B 23/043 Sulfurated acids or salts thereof
• CPC Class Codes: C22B 23/0453 Treatment or purification of solutions, e.g. obtained by leaching C22B23/0407 takes precedence
• CPC Class Codes: C22B 23/0484 in acidic type solutions
• CPC Class Codes: C22B 3/3842 Phosphinic acid, e.g. H2P(O)(OH)
• CPC Class Codes: Y02P 10/20 Recycling

Abstract

The present invention relates generally to a method of extracting cobalt and other impurity metals from a concentrated nickel sulphate solution by a solvent extraction process whereby a cationic solvent extractant is separately pre-equilibrated with a portion of a purified nickel sulphate solution in such a manner that it is loaded with nickel without precipitating insoluble nickel double salts. The nickel loaded extracted is then transferred to an impure cobalt nickel solution where the cobalt and certain other impurity metals exchange with nickel leaving a purified concentrated nickel sulphate solution suitable for hydrogen reduction or electrowinning. The cobalt loaded extractant is stripped with dilute sulphuric acid before being recycled whilst an aqueous cobalt stripped solution is further processed to recover cobalt.

Claims

1. A method of pre-equilibrating a cationic solvent extractant, said method involving contacting the cationic extractant with a portion of a purified valuable metal stream wherein valuable metal ions of said portion of the purified stream are loaded on the cationic extractant to form a pre-equilibrated cationic extractant.

2. A method of pre-equilibrating a cationic solvent extractant as defined in claim 1 wherein the purified valuable metal stream is a purified nickel sulphate stream.

3. A method of pre-equilibrating a cationic solvent extractant as defined in claim 2 wherein the purified nickel sulphate stream is a raffinate of a solvent extraction circuit.

4. A method of pre-equilibrating a cationic solvent extractant as defined in any one of the preceding claims wherein pre-equilibration of the cationic extractant with the valuable metal ions is effected with the direct addition of an ammonia solution.

5. A method of pre-equilibrating a cationic solvent extractant as defined in claim 4 wherein said portion of the purified valuable metal stream is preconditioned by dilution with a diluent to achieve a predetermined concentration of the valuable metal sufficient to avoid formation of insoluble ammonium/metal sulphate double salts.

6. A method of pre-equilibrating a cationic solvent extractant as defined in claim 5 wherein the diluent is water.

7. A method of pre-equilibrating a cationic solvent extractant as defined in any one of claims 1 to 3 wherein pre-equilibration of the cationic extractant is effected with the direct addition of magnesia or magnesium hydroxide.

8. A method of pre-equilibrating a cationic solvent extractant as defined in any one of the preceding claims wherein the cationic solvent extractant comprises a phosphinic acid.

9. A method of pre-equilibrating a cationic solvent extractant as defined in claim 8 wherein the phosphinic acid is bis (2,4,4 trimethylpentyl) phosphinic acid, or a derivative thereof.

10. A method of pre-equilibrating a cationic solvent extractant as defined in any one of the preceding claims wherein the cationic extractant is diluted with another diluent.

11. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit, said method comprising the steps of:

i) contacting a cationic solvent extractant with a portion of a purified valuable metal sulphate stream wherein valuable metal ions of said portion of the purified stream are loaded on the cationic extractant to form a pre-equilibrated cationic extractant; and

ii) contacting the pre-equilibrated cationic extractant with the impure valuable metal sulphate stream in said solvent extraction circuit wherein the impurity metal ions exchange with the valuable metal ions whereby the pre-equilibrated cationic extractant is loaded with the impure metal ions and a raffinate of said extraction circuit is enriched in the valuable metal ions.

12. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in claim 11 wherein the purified valuable metal stream is a purified nickel sulphate stream.

13. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in claim 11 or 12 wherein the impurity metal ions include cobalt, copper, zinc and/or manganese.

14. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in claim 12 wherein the purified nickel sulphate stream is the raffinate of the solvent extraction circuit.

15. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in any one of claims 11 to 14 wherein the impure valuable metal sulphate stream is a concentrated nickel sulphate liquor obtained by acid pressure leaching of a nickel-cobalt sulphide mineral.

16. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in any one of claims 11 to 15 wherein pre-equilibration of the cationic extractant with the valuable metal ions is effected with the direct addition of an ammonia solution.

17. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in claim 16 wherein said portion of the purified valuable metal stream is preconditioned by dilution with a diluent to achieve a predetermined concentration of the valuable metal sufficient to avoid formation of insoluble ammonium/metal sulphate double salts.

18. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in claim 17 wherein the diluent is water.

19. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in any one of claims 11 to 15 wherein pre-equilibration of the cationic extractant is effected with the direct addition of magnesia or magnesium hydroxide.

20. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in any one of claims 11 to 19 further comprising the step of stripping of an impurity loaded cationic extractant from the solvent extraction circuit with sulphuric acid to yield the cationic extractant for recycle to pre-equilibration.

21. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in claim 20 wherein said step of stripping of said impurity loaded extractant produces an aqueous impurity metal strip solution which is processed to recover one or more of said impurity metal ions.

22. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in any one of claims 11 to 21 also comprising the step of electrowinning a high purity electrolyte of the nickel enriched raffinate to recover high purity nickel.

23. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in any one of claims 11 to 21 wherein the nickel enriched raffinate or a derivative thereof is subjected to hydrogen reduction.

24. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in any one of claims 11 to 23 wherein the cationic solvent extractant comprises a phosphinic acid.

25. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in claim 24 wherein the phosphinic acid is bis (2,4,4 trimethylpentyl) phosphinic acid, or a derivative thereof.

26. A method of extracting impurity metal ions from an impure valuable metal sulphate stream in a solvent extraction circuit as defined in any one of claims 11 to 25 wherein the cationic extractant is diluted with another diluent.

27. A method of pre-equilibrating a cationic solvent extractant, said method involving contacting the cationic extractant with an aqueous metal ion solution with the direct addition of an ammonia solution to effect loading of the metal ion on the cationic extractant to form a pre-equilibrated cationic extractant, the metal ion solution being selected or preconditioned to a predetermined concentration of the metal ions sufficient to avoid formation of insoluble ammonium/metal sulphate double salts.

28. A method of pre-equilibrating a cationic solvent extractant as defined in claim 27 wherein the metal ion solution is preconditioned by dilution with a diluent to achieve the predetermined concentration of metal ions.

29. A method of pre-equilibrating a cationic solvent extractant as defined in claim 28 wherein the diluent is water.

30. A method of pre-equilibrating a cationic solvent extractant as defined in any one of claims 27 to 29 wherein the metal ion solution is a portion of a purified valuable metal sulphate stream that being a raffinate of an impurity solvent extraction circuit.