Development and Application of Ion Exchange Silver Recovery System.

A study was conducted on the feasibility and extent of application of the ion exchange process as a method for silver recovery from spent photographic fixer solutions. The study demonstrates the technical feasibility of using ion exchange systems to recover silver from photographic fixer solutions for silver concentrations between 0.05 and 0.5 gml. However, ion exchange system operation at or above silver concentrations of 0.5 gml appears to negate any cost advantages over the electrolytic recovery systems. In addition, operation at concentrations under 0.05 gml requires about 10 times the resin needed at concentrations of 1.0 mgl. A previously postulated resin-fouling mechanism was supported by experimental exchange data from a series of synthetic spent fixer solutions. Fouling during silver stripping may be caused by the formation of colloidal sulfur and silver sulfide particles with electrostatic charges neutralized by anionic exchange sites of the resin. A re-examination proved that an aqueous sodium acetate prewash of an anionic exchange column is a satisfactory method of preventing resin fouling by inorganic colloids.