Method for recovering gold

Patent metadata

Field	Value
Publication number	US-10907237-B2
Application number	US-201615770534-A
Country	US
Kind code	B2
Filing date	Oct 27, 2016
Priority date	Oct 29, 2015
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

Provided is a method of recovering gold, and optionally silver, from gold-bearing, and optionally silver-bearing, double refractory raw material, comprising the steps of (a) leaching the gold-bearing, and optionally silver-bearing, double refractory raw material in a chloride containing leaching solution to dissolve gold and to obtain a leach solution comprising gold, and optionally silver, in solution, whereby the redox of leaching solution in the chloride leaching step is above 550 mV vs. Ag/AgCl; and simultaneously contacting the leach solution comprising gold, and optionally silver, in solution with a re-sorptive material to obtain a gold-containing, and optionally silver-containing, re-sorptive material; and (b) recovering gold and optionally silver from the gold-containing, and optionally silver-containing, re-sorptive material.

First claim

The invention claimed is:

1. A method of recovering gold, and optionally silver, from a gold-bearing, and optionally silver-bearing, double refractory raw material, comprising the steps of
(a) leaching the gold-bearing, and optionally silver-bearing, double refractory raw material in a chloride containing leaching solution to dissolve gold, and optionally silver, and to obtain a leach solution comprising gold, and optionally silver, in solution, wherein a redox potential of the leaching solution in the leaching step is above 550 mV to 720 mV vs. Ag/AgCl, achieved by a presence of cupric and/or ferric ions, and a feed of an oxygen containing gas; and
simultaneously contacting the leach solution comprising gold, and optionally silver, in solution with a re-sorptive material to obtain a gold-containing, and optionally silver-containing, re-sorptive material; and
(b) recovering gold, and optionally silver, from the gold-containing, and optionally silver-containing, re-sorptive material.

2. The method as claimed in claim 1 , wherein the gold-bearing, and optionally silver-bearing, double refractory raw material comprises at least 0.01% w/w preg-robbing matter.

3. The method as claimed in claim 1 , wherein the gold-bearing, and optionally silver-bearing, double refractory raw material comprises less than 80%-native gold of the total gold in the said raw material.

4. The method as claimed in claim 1 , wherein the re-sorptive material is selected from the group consisting of activated carbon, resin, organic solvents, organic substances, inorganic carbon, rubber, plastics, biopolymers, and combinations thereof.

5. The method as claimed in claim 1 , wherein the re-sorptive material is activated carbon.

6. The method as claimed in claim 1 , wherein the concentration of the re-sorptive material is at least 5 g/L in the leaching solution.

7. The method as claimed in claim 1 , wherein the total chloride concentration of the leaching solution is from 100 to 450 g/L.

8. The method as claimed in claim 1 , wherein the chloride containing leaching solution contains dissolved copper and/or iron ions in a concentration that is from above 20 to 120 g/L.

9. The method as claimed in claim 1 , wherein the leaching step (a) is performed in the absence hydrogen peroxide and nitric acid.

10. The method as claimed in claim 1 , wherein pH in the leaching step (a) is below a precipitation limit for cupric and/or ferric.

11. The method as claimed in claim 1 , wherein the leaching step (a) is conducted in an oxidation-reduction potential above 580.

12. The method as claimed in claim 1 , wherein gold is recovered from the gold-bearing re-sorptive material pyrometallurgically, by eluation, by stripping, or by leaching gold from a pyrometallurgically received ash.

13. The method as claimed in claim 1 , wherein a reactor is used in the leaching step (a), where over pressure at the top of the reactor is less than 0.5 bar.

14. The method as claimed in claim 1 , wherein the temperature of the leaching step (a) is at or below the boiling point of the leaching solution.

15. The method as claimed in claim 1 , wherein the leaching step (a) is performed in the absence added of bromide ions.

16. The method as claimed in claim 1 , wherein the chloride containing leaching solution contains bromide ions in a concentration that is from 0 to 100 g/L.

Assignees

• Outotec Finland Oy

Inventors

• Lundström Mari
• Ahtiainen Riina
• O'Callaghan John

Classifications

• Y02P10/20

  Recycling · CPC title

• C22B3/24

  by adsorption on solid substances, e.g. by extraction with solid resins · CPC title

• C22B3/04

  by leaching (C22B3/18 takes precedence) · CPC title

• 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

• C22B11/02

  by dry processes · CPC title