US 12,264,380 B2
Method for recovering precious metal
Marco Stemmler, Santa Fe Springs, CA (US)
Assigned to HERAEUS DEUTSCHLAND GMBH & CO. KG, Hanau (DE)
Appl. No. 17/756,015
Filed by Heraeus Deutschland GmbH & Co. KG, Hanau (DE)
PCT Filed Sep. 30, 2020, PCT No. PCT/EP2020/077319
§ 371(c)(1), (2) Date May 13, 2022,
PCT Pub. No. WO2021/099021, PCT Pub. Date May 27, 2021.
Claims priority of application No. 19209661 (EP), filed on Nov. 18, 2019.
Prior Publication US 2022/0389537 A1, Dec. 8, 2022
Int. Cl. C22B 11/00 (2006.01); C22B 3/42 (2006.01)
CPC C22B 11/042 (2013.01) [C22B 3/42 (2013.01)] 17 Claims
 
1. A method for recovering precious metal from an acidic aqueous solution containing dissolved precious metal and free chlorine, the method comprising the following successive steps:
(1) providing an acidic aqueous solution containing precious metal and free chlorine;
(2) combining a salt of a non-precious metal present in a low oxidation state as a solid or as an aqueous solution with the acidic aqueous solution to completely or substantially completely consume the free chlorine and form an acidic aqueous mixture, and
(3) adding non-precious metal to the acidic aqueous mixture formed in step (2) to precipitate elementary precious metal, wherein
the acidic aqueous solution is characterized by (i) a fraction of dissolved precious metal in the range of 100 to 500 mg/l, (ii) a pH in the range of −0.8 to +1 and (iii) a content of the free chlorine in the range of 0.1 to 1 g/l, and
the dissolved precious metal comprises at least one precious metal selected from the group consisting of gold, platinum, palladium, rhodium, iridium, osmium and ruthenium.