Method for the recovery of silver from waste photographic fixer solutions

Patent ·

OSTI ID:5364206

Posey, F A; Palko, A A

The method of the present invention is directed to the recovery of silver from spent photographic fixer solutions and for providing an effluent essentially silver-free that is suitable for discharge into commercial sewage systems. The present method involves the steps of introducing the spent photographic fixer solution into an alkaline hypochlorite solution. The oxidizing conditions of the alkaline hypochlorite solution are maintained during the addition of the fixer solution so that the silver ion complexing agents of thiosulfate and sulfite ions are effectively destroyed. Hydrazine monohydrate is then added to the oxidizing solution to form a reducing solution to effect the formation of a precipitate of silver which can be readily removed by filtration of decanting. Experimental tests indicate that greater than 99.99% of the original silver in the spent photographic fixer can be efficiently removed by practicing the present method. Also, the chemical and biological oxygen demand of the remaining effluent is significantly reduced so as to permit the discharge thereof into sewage systems at levels in compliance with federal and state environmental standards.

• DOE Contract Number: W-7405-ENG-26
• Assignee: EDB-84-029663
• Patent Number(s): None
• Application Number: ON: DE84005906
• OSTI ID: 5364206
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320302* -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Materials
320305 -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Industrial Waste Management
ELEMENTS
METALS
PHOTOGRAPHY
REAGENTS
RECOVERY
RECYCLING
SILVER
TRANSITION ELEMENTS