Recovery of gold from solution

Patent metadata

Field	Value
Publication number	US-10144989-B2
Application number	US-201615557885-A
Country	US
Kind code	B2
Filing date	Mar 17, 2016
Priority date	Mar 18, 2015
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A method is disclosed for recovering gold from a gold-containing organic solution containing soluble gold. The method comprises contacting the gold-containing organic solution with an aqueous stripping solution in order to extract gold from the gold-containing organic solution into the aqueous stripping solution. The aqueous stripping solution containing gold is separated from the organic solution. The separated aqueous stripping solution containing gold is contacted with a reducing agent containing sodium metabisulphite, in order to reduce gold from the aqueous stripping solution.

First claim

The invention claimed is:

1. A method for recovering gold from a gold-containing organic solution containing soluble gold, wherein the method comprises
contacting a pregnant leach solution containing gold with a gold extraction reagent containing organic diester and organic alcohol to obtain the gold-containing organic solution;
contacting the gold-containing organic solution with an aqueous stripping solution to extract gold from the gold-containing organic solution into the aqueous stripping solution;
separating the aqueous stripping solution containing gold from the organic solution;
contacting the separated aqueous stripping solution containing gold with a reducing agent containing sodium metabisulphite to reduce gold from the aqueous stripping solution;
wherein the aqueous stripping solution contains sodium chloride, and wherein the aqueous stripping solution is weakly acidic so that the gold remains soluble in the aqueous stripping solution.

2. A method according to claim 1 , wherein the method comprises recovering reduced solid gold from the aqueous stripping solution by filtering the aqueous stripping solution.

3. A method as claimed in claim 1 , wherein the method comprises reducing gold from the aqueous stripping solution containing gold without scrubbing the gold-containing organic solution.

4. A method as claimed in claim 1 , wherein the method comprises stripping the gold-containing organic solution without scrubbing the gold-containing organic solution.

5. A method as claimed in claim 1 , wherein
the organic diester comprises a diester of 2,2,4-trialkyl-1,3-pentanediol, and/or the organic alcohol comprises 2-ethylhexanol.

6. A method as claimed claim 1 , wherein the pregnant leach solution is an acidic chloride solution where gold is a gold chloride complex H + AuCl 4 − .

7. A method as claimed in claim 1 , wherein the method comprises
using a molar ratio of sodium metabisulphite to gold for reducing part of the gold in a first reducing step;
using in a second reducing step fresh reducing agent containing sodium metabisulphite, in order to reduce gold remaining in the aqueous stripping solution after the first reducing step.

8. A method as claimed in claim 1 , wherein the method comprises using a ratio of sodium metabisulphite to gold, for reducing all of the gold.

9. A method as claimed in claim 1 , wherein the method comprises performing stripping of the gold-containing organic solution in a continuous stirred tank reactor.

10. A method as claimed in claim 1 , wherein the aqueous stripping solution contains 100 g/l or less of sodium chloride.

11. A method as claimed in claim 1 , wherein the aqueous stripping solution contains 10 g/l of sodium chloride.

Assignees

• Outotec Finland Oy

Inventors

• Haapalainen Mika

Classifications

• C22B11/04 Primary

  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

• C22B11/042 Primary

  Recovery of noble metals from waste materials · CPC title

• C22B11/00 Primary

  Obtaining noble metals · CPC title

• C01G7/003

  Preparation involving a liquid-liquid extraction, an adsorption or an ion-exchange · CPC title

• C22B3/44

  by chemical processes (treatment or purification of solutions by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42) · CPC title