Method of recovering silver and paper from silver-coated paper film

Abstract

A process for recovery of silver from silver-containing photographic emulsion-coated films, particularly films with paper or polymeric substrates. The process includes immersing photographic silver emulsion coated substrates, particularly paper, in a water-based solution of sodium hydroxide and sodium borohydride, with sufficient presence of an alkali metal hydroxide to maintain the solution at a pH of 11.0 to 12.0. Silver-containing emulsion layers are stripped from the substrate, while gelatin and other adhesive layers are dissolved. Silver present in a silver halide form is reduced to form metallic silver. The silver-laden emulsion is then treated using a polyamine coagulant and flocculant to induce precipitation of solids, particularly metallic silver, out of the solution. The exposure time of the paper to the wash bath is carefully controlled to permit recovery of the paper substrate.

Dependencies are inferred from the claim text.