# US 4,394,356 A · Recuperation of cyanides from rinsing solutions of cyanidric processes for eletrodeposition of metals

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- Number: US 4,394,356 A
- Document ID: US4394356A
- Status: Granted
- Kind: A
- Application number: 06/285,222
- Filed: 1980-09-25
- Granted: 1983-07-19
- Earliest claimed: 1980-09-25
- Inventors: Michael F. Peuser; Jose B. Bartolo
- Web page: https://patentgrep.com/patent/US4394356A

## CPC

- C01C 3/08: Simple or complex cyanides of metals {(C01C3/001, C01C3/002 take precedence)}
- Y10S 210/904: -CN containing
- Y10S 210/912: Heavy metal
- C01C: AMMONIA; CYANOGEN; COMPOUNDS THEREOF ({metal hydrides, monoborane, diborane or addition complexes thereof C01B6/00}; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; azides C01B21/08; {compounds other than ammonia or cyanogen, containing nitrogen, non-metals and optionally metals C01B21/082}; metal imides or amides C01B21/092; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; compounds containing silicon C01B33/00; compounds containing boron C01B35/00)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

Process for the recuperation of an insoluble salt of a metal from the rinsing solution of an electrodeposition of the metal.

## Claims

### Claim 1

A process for recuperation of a cyanide from a rinsing solution of a cyanidric process for electrodeposition of copper, the solution containing a soluble complex cyanide of an alkali metal and copper, comprising adding to the solution a soluble simple salt of bivalent copper reacting with said complex cyanide and any free cyanide ions in said solution to form and precipitate an insoluble cyanide of copper, and separating said precipitant for reuse, said precipitation, being conducted without using hydrochloric acid by adding sodium bisulfite to the solution to reduce the pH of the solution to between 1.5 and 4.0 and the copper ion of the simple salt to a cuprous state for precipitating insoluble cuprous cyanide.

### Claim 2 (depends on 1)

A process according to claim 1, wherein the added salt is a salt of copper and a strong acid.

### Claim 3

A process for recuperation of a cyanide from a rinsing solution of a cyanidric process for electrodeposition of cadmium, the solution containing a soluble complex cyanide of an alkali metal and cadmium, comprising conducting the process in two stages, in a first whereof the solution is diluted to a cadmium content below 17 g/l, a soluble salt of zinc and a strong acid is added to the diluted solution to precipitate insoluble zinc cyanide, and the precipitate is separated from the solution, and in the second stage adding to the solution from the first stage an alkali compound reacting with cadmium ions in the solution to form and precipitate an insoluble cadmium salt, and separating the precipitate.