The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
Jul. 16, 1996

Filed:

Apr. 27, 1995
Applicant:
Inventors:

Michael R Hill, Wantage, GB;

Mark D Neville, Stanford-in-the-Vale, GB;

Andrew D Turner, Abingdon, GB;

Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C02F / ;
U.S. Cl.
CPC ...
205494 ; 205747 ; 205750 ; 205751 ; 205770 ; 204264 ;
Abstract

Effluent streams from photographic processes contain both silver and thiosulphate ions, and because of the formation of complex anions it is difficult to remove the silver. The silver may be removed using a cell (12) with a cathode (24) exposed to the effluent liquid, and an anode (25) separated from the liquid by a barrier (22) permeable at least to anions. Some silver sulphide is formed electrochemically at the cathode (24); at the anode (25) water is electrolysed and becomes acidic, so the complex anions migrating through the barrier (22) generate silver sulphide chemically. The resulting silver sulphide precipitate is separated from the liquid by a filter (14).


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