Method for cleanly extracting metallic silver

Patent metadata

Field	Value
Publication number	US-2022112616-A1
Application number	US-201816647530-A
Country	US
Kind code	A1
Filing date	Jul 13, 2018
Priority date	Sep 21, 2017
Publication date	Apr 14, 2022
Grant date	—

Abstract

A method for cleanly extracting metallic silver includes: mixing an acidic solution containing Ce 4+ and NO 3 − with a silver-containing material for leaching; after the leaching is completed, carrying out a solid-liquid separation to obtain a leaching solution containing Ce 3+ and Ag + ; and electrolyzing the leaching solution, wherein an oxidation reaction of Ce′ occurs at an anode to realize a regeneration of Ce 4+ and an electrolytic reduction occurs at a cathode to reduce Ag + to obtain the metallic silver. Ce 4+ is used as a leaching agent and an intermediate oxidant to implement a cyclic operation of solution leaching and electrolytic regeneration on the silver-containing material. Almost no NO x and waste liquid are caused by the extraction process, and the invention is clean and environmentally friendly.

First claim

What is claimed is:

1 . A method for cleanly extracting metallic silver, comprising the following steps:
(1) mixing an acidic solution containing Ce 4+ and NO 3 − with a silver-containing material to obtain a mixture for a leaching; after the leaching is completed, carrying out a solid-liquid separation on the mixture to obtain a leaching solution; and (2) electrolyzing the leaching solution obtained in step (1), wherein an oxidation reaction of Ce 3+ occurs at an anode to obtain a solution containing Ce 4+ to achieve a regeneration of Ce 4+ , and a reduction reaction of Ag + occurs at a cathode to obtain the metallic silver.

2 . The method according to claim 1 , wherein in step (1), a concentration of Ce 4+ in the acidic solution containing Ce 4+ and NO 3 − is at least 0.1 mol/L.

3 . The method according to claim 1 , wherein in step (1), a concentration of H + in the acidic solution containing Ce 4+ and NO 3 − is at most 1 mol/L.

4 . The method according to claim 1 , wherein an indication of completion of the leaching in step (1) includes a ratio of Ce 4+ to a total amount of Ce in the leaching solution is at most 5% and a concentration of Ag + is at least 0.1 mol/L.

5 . The method according to claim 1 , wherein in step (1), the leaching solution is subjected to a purification treatment before the electrolyzing.

6 . The method according to claim 1 , wherein in step (2), the leaching solution is electrolyzed by an electrolytic cell with a diaphragm, the electrolytic cell is separated into a cathode zone and an anode zone by the diaphragm, and the leaching solution enters the electrolytic cell from the cathode zone.

7 . The method according to claim 1 , wherein in step (2), during the electrolyzing, a current density of the anode ranges from 100 A/m 2 to 4000 A/m 2 , and a current density of the cathode ranges from 50 A/m 2 to 700 A/m 2 .

8 . The method according to claim 1 , wherein the solution containing Ce 4+ obtained after the electrolysis in step (2) is returned to step (1) for recycling.

Assignees

• Inst Process Eng Cas

Inventors

• Zhang Hui
• Dong Xulong
• Qi Tao

Classifications

• C22B3/065 Primary

  Nitric acids or salts thereof · CPC title

• C22B3/045

  Leaching using electrochemical processes · CPC title

• C22B11/048 Primary

  from spent catalysts · CPC title

• C25C1/20 Primary

  of noble metals · CPC title

• C25C7/00

  Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells (for the production of aluminium C25C3/06 - C25C3/22) · CPC title