Hydrometallurgical treatment of anode sludge

Patent metadata

Field	Value
Publication number	US-2017198370-A1
Application number	US-201515313748-A
Country	US
Kind code	A1
Filing date	May 27, 2015
Priority date	May 28, 2014
Publication date	Jul 13, 2017
Grant date	—

Abstract

The present invention provides a method of separating precious metals from anode sludge obtained from copper electrolysis, comprising (a) leaching the anode sludge in an aqueous sulfuric acid solution to remove leachable chlorides and to obtain a first leaching residue depleted of chlorides; (b) pressure leaching the first leaching residue to dissolve Ag and Se and to obtain a first filtrate comprising Ag and Se and a second leaching residue depleted of Ag and Se; and (c) leaching the second leaching residue with an aqueous hydrochloric acid solution to dissolve Au and PGMs to obtain a second filtrate comprising Au and PGMs and a final leaching residue.

First claim

1 . A method of separating precious metals from anode sludge obtained from copper electrolysis, comprising
(a) leaching the anode sludge in an aqueous sulfuric acid solution to remove leachable chlorides and to obtain a first leaching residue depleted of chlorides; (b) pressure leaching the first leaching residue to dissolve Ag and Se and to obtain a first filtrate comprising Ag and Se and a second leaching residue depleted of Ag and Se (c) leaching the second leaching residue with an aqueous hydrochloric acid solution to dissolve Au and PGMs to obtain a second filtrate comprising Au and PGMs and a final leaching residue.

2 . The method as claimed in claim 1 , wherein, prior to step (c), the method comprises
(d) leaching the second leaching residue obtained from step (b) in an aqueous sulfuric acid solution to dissolve bismuth and optionally remaining silver, selenium and/or tellurium to obtain a third filtrate comprising Bi and optionally Ag, Se and/or Te and a further treated second leaching residue further depleted of at least Bi; and/or (e) leaching the second leaching obtained from step (b) or (d) in an aqueous hydrochloric acid solution to dissolve lead and optionally remaining selenium and/or tellurium to obtain a fourth filtrate comprising Pb, and optionally Se and/or Te and a still further treated second reaching residue further depleted of at least lead.

3 . The method as claimed in claim 1 , wherein leaching in step (a) is performed under oxidizing conditions for oxidizing copper present in the anode sludge.

4 . The method as claimed in claim 1 , further comprising recovering Ag and Se from the first filtrate.

5 . The method as claimed in claim 4 , wherein the recovery of Ag and Se is accomplished by sulfur dioxide cementation.

6 . The method as claimed in claim 4 , wherein the recovery of Ag is accomplished by silver chloride precipitation.

7 . The method as claimed in claim 1 , further comprising recovering of Au and PGMs from the second filtrate.

8 . The method as claimed in claim 7 , wherein the recovery of Au is accomplished by reduction of gold.

9 . The method as claimed in claim 7 , wherein the recovery of PGMs is accomplished by cementing of PGM.

10 . The method as claimed in claim 1 , wherein leaching step (a) is accomplished under an elevated temperature, typically from 60 to 95° C., preferably from 80 to 90° C. and under atmospheric pressure.

11 . The method as claimed in claim 1 , wherein leaching step (b) is accomplished under an elevated temperature, typically more than 140° C., preferably from 160 to 170° C. and under an elevated pressure from 5 to 9 bar.

12 . The method as claimed in claim 1 , wherein leaching step (c) is accomplished under an elevated temperature, typically form 70 to 90° C., preferably from 75 to 85° C. and under atmospheric pressure.

13 . The method as claimed in claim 1 , wherein an oxidizing agent, preferably oxygen or hydrogen peroxide, more preferably oxygen, is used in the pressure leaching step (b).

14 . The method as claimed in claim 1 , wherein leaching in step (b) is accomplished in an aqueous sulfuric acid solution, preferably containing from 200 to 500 g/L H 2 SO 4 .

15 . The method as claimed in claim 1 , wherein an oxidizing agent, preferably hydrogen peroxide or chlorine, more preferably hydrogen peroxide, is used in the leaching step (c).

Assignees

• Outotec Finland Oy

Inventors

• Virtanen Henri
• Schmachtel Sönke

Classifications

• C22B11/042 Primary

  Recovery of noble metals from waste materials · CPC title

• C22B61/00

  Obtaining metals not elsewhere provided for in this subclass (iron C21) · CPC title

• C22B3/06

  in inorganic acid solutions {, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions} · CPC title

• C22B3/10

  Hydrochloric acid {, other halogenated acids or salts thereof} · CPC title

• C22B7/007

  by acid leaching · CPC title