Method of recovering copper and precious metals

Patent metadata

Field	Value
Publication number	US-10023936-B2
Application number	US-201414895740-A
Country	US
Kind code	B2
Filing date	Jun 6, 2014
Priority date	Jun 7, 2013
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

Provided is a method of recovering copper and one or more precious metals comprising leaching copper-bearing ore and/or concentrate under atmospheric or slightly pressurized conditions at a temperature below the boiling point of the leach solution in a sulfuric acidic solution in the presence of one or more alkali metal or alkali earth metal halides, whereby the total halide concentration is from 30 to 115 g/L, to dissolve copper and to obtain a leaching liquor comprising copper, sulfur species, and halides in solution. The leaching liquor is then subjected to a solid-liquid separation after which a first aqueous pregnant leach solution and a copper depleted leaching residue are obtained. Copper is purified by solvent extraction from the first aqueous pregnant leach solution to obtain a first copper-containing loaded organic solution and a first aqueous raffinate. The copper containing loaded organic solution is stripped and copper is recovered.

First claim

The invention claimed is:

1. A method of recovering copper from copper-bearing sulfide ore and/or concentrate comprising the steps of:
(a) leaching copper-bearing ore and/or concentrate under atmospheric or elevated pressure up to 300 kPa at a temperature below the boiling point of the leach solution in a sulfuric acid solution in the presence of one or more alkali metal or alkali earth metal halides, whereby the total halide concentration is from 30 to 115 g/L, to dissolve copper and to obtain a leaching liquor comprising copper, sulfur species, and halides in solution;
(b) solid-liquid separating the leaching liquor to obtain a first aqueous pregnant leach solution and a copper depleted leaching residue;
(c) extracting copper by solvent extraction from the first aqueous pregnant leach solution to obtain a first copper-containing loaded organic solution and a first aqueous raffinate; subjecting a bleed stream of the first aqueous raffinate to a copper hydroxychloride precipitation step; and after solid-liquid separation precipitating impurities from the copper-depleted solution;
(d) stripping copper from the first copper containing loaded organic solution with an electrolyte solution to obtain a copper-depleted organic solution and a copper-containing electrolyte solution; and
(e) recovering copper from the copper containing electrolyte solution.

2. The method as claimed in claim 1 , wherein copper is recovered from the copper-containing electrolyte solution by electrowinning to obtain to obtain metallic copper and a copper-depleted electrolyte solution.

3. The method as claimed in claim 1 , wherein the method comprises recycling a majority of the first aqueous raffinate to the copper leaching step (a).

4. The method as claimed in claim 1 , wherein the method further comprises the steps of:
(f) extracting silver by solvent extraction from the first aqueous raffinate to obtain a silver-containing loaded organic solution and a second aqueous raffinate;
(g) stripping the silver-containing loaded organic solution to obtain a silver-containing aqueous solution; and
(h) recovering silver from the silver-containing aqueous solution.

5. The method as claimed in claim 4 , wherein silver is recovered from silver-containing aqueous solution by precipitation, cementation, or electrowinning.

6. The method as claimed in claim 4 , wherein the method comprises recycling a majority of the second aqueous raffinate to the copper leaching step (a).

7. The method as claimed in claim 4 , wherein silver is extracted from the first aqueous raffinate with an organic solution of a tertiary phosphine sulfide diluted in a hydrocarbon diluent optionally comprising organophosphoric acid, organophosphonic acid, organophosphinic acid, and/or carboxylic acid modifier.

8. The method as claimed in claim 7 , wherein the tertiary phosphine sulfide is triisobutylphosphine sulfide.

9. The method as claimed in claim 7 , wherein the modifier is di-(2-ethylhexyl)phosphoric acid (D2EHPA) or tertiary carboxylic acid.

10. The method as claimed in claim 4 , wherein the silver-containing loaded organic solution is scrubbed with a diluted acid solution to remove impurities, prior to stripping step (g).

11. The method as claimed in claim 4 , wherein the method comprises subjecting a bleed stream of the second aqueous raffinate to a copper hydroxychloride precipitation; and after solid-liquid separation precipitating impurities from the copper-depleted solution.

12. The method as claimed in claim 4 , wherein in the precipitation of copper hydroxychloride from the first aqueous raffinate and/or the second aqueous raffinate the pH is 2.6 to 7.

13. The method as claimed in claim 1 , wherein copper is extracted from the first aqueous pregnant leach solution by solvent extraction utilizing an organic solution comprising hydroxyoxime based copper extractant diluted in a hydrocarbon solvent as the copper extractant.

14. The method as claimed in claim 13 , wherein the hydroxyoxime based copper extractant is selected from aldoximes, ketoximes, and any mixtures thereof.

15. The method as claimed in claim 13 , wherein the volume ratio of the first aqueous pregnant leach solution and the organic solution is between 1:6 and 6:1.

16. The method as claimed in claim 1 , wherein the first copper-containing loaded organic solution is scrubbed with a diluted acid solution to remove impurities, prior to stripping step (d).

17. The method as claimed in claim 1 , wherein leaching of metals in step (a) is conducted in oxidation-reduction potential of 400 to 600 mV Ag/AgCl vs. Pt; and pH from 1.7 to 3.

18. The method as claimed in claim 1 , wherein oxygen, oxygen enriched air, or air is used in leaching of metals in step (a); and it is conducted under total pressure of from 87 to 300 kPa.

19. The method as claimed in claim 1 , wherein the first aqueous pregnant leach solution contains from 1 to 100 g/L copper.

Assignees

• Outotec Finland Oy

Inventors

• Valkama Kari
• Sinisalo Pia
• Karonen Janne
• Hietala Kari

Classifications

• C01G3/05

  Chlorides · CPC title

• C22B3/22

  by physical processes, e.g. by filtration, by magnetic means {, or by thermal decomposition} (treatment or purification of solutions by liquid-liquid extraction C22B3/26) · CPC title

• C22B15/0091

  by cementation · CPC title

• C25C1/12

  of copper · CPC title

• C22B11/04

  by wet processes (extraction of metal compounds by leaching in organic solutions C22B3/16; treatment or purification of solutions by liquid-liquid extraction C22B3/26) · CPC title