Method for the recovery of silver from waste photographic fixer solutions
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 or 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.
- Assignee:
- Dept. of Energy
- Patent Number(s):
- US 4445935
- OSTI ID:
- 6450039
- Resource Relation:
- Patent File Date: Filed date 13 Dec 1982; Other Information: PAT-APPL-449312
- Country of Publication:
- United States
- Language:
- English
Similar Records
Method for the recovery of silver from waste photographic fixer solutions
Removal of silver in photographic processing waste by TiO{sub 2}-based photocatalysis
Related Subjects
CHEMICAL EFFLUENTS
DEMETALLIZATION
MATERIALS RECOVERY
PHOTOGRAPHY
SILVER
RECOVERY
CHLORITE MINERALS
DECANTATION
FILTRATION
HYDRATES
HYDRAZINE
OXIDATION
POLLUTION ABATEMENT
PROCESS SOLUTIONS
REMOVAL
CHEMICAL REACTIONS
DISPERSIONS
ELEMENTS
MANAGEMENT
METALS
MINERALS
MIXTURES
NITROGEN COMPOUNDS
PROCESSING
SEPARATION PROCESSES
SILICATE MINERALS
SOLUTIONS
TRANSITION ELEMENTS
WASTE MANAGEMENT
WASTE PROCESSING
320305* - Energy Conservation
Consumption
& Utilization- Industrial & Agricultural Processes- Industrial Waste Management