METHOD OF RECOVERING SILVER, GOLD, PLATINUM, AND PALLADIUM FROM SECONDARY MATERIAL CONTAINING PRECIOUS METALS Russian patent published in 1997 - IPC

FIELD: precious metals production. SUBSTANCE: secondary precious metal waste, prior to be dissolved in hot aqua regia, is melted in melting pot and granulated, and slurry obtained after dissolution in aqua regia is neutralized with sodium carbonate and filtered under vacuum. Resultant silver chloride precipitate is washed with weak hydrochloric acid solution and hot water followed by melting to form metal silver, whereas solution containing gold, platinum, and palladium is poured into precipitating reactor to precipitate gold. To this solution, ferric sulfate is added under stirring and heating, solution is filtered, and gold-containing precipitate is washed with hot water, dehydrated, and melted. Platinoids remaining in solution are further precipitated as metals or sulfides, filtered off, washed with hot water, dried, and melted. EFFECT: separate isolation of silver, gold, and platinoid concentrate provided. 7 cl