Method for recovering silver from waste solutions containing thiosulfate compounds

摘要

In a process for recovering silver from spent photographic treatment solution comprises mixing nitric acid with a quantity of the treatment solution to precipitate from the solution silver sulfide. The silver sulfide may be then converted to pure silver. The improvement comprises mixing less than two parts of concentrated nitric acid solution with more than ten parts of the treatment solution to precipitate out of solution silver sulfide. The solution is filtered to remove the silver sulfide precipitate from the solution to yield a solid residue which includes silver sulfide.