METHOD OF METALLIC SILVER PRODUCING Russian patent published in 1997 - IPC

FIELD: noble metals. SUBSTANCE: method involves mixing silver salt with potassium or sodium hydroxide taken at amount 120-150% of stoichiometry, mixture tabletting under pressure 15-25 MPa, caking at 400-500 C for 0.3-1 h, cake cooling in the process of its an aqueous treatment and separation of silver deposit. Caking stage can be carried out for two stages at similar technological parameters of each stage. After the first stage cake is cooled in air to the room temperature, ground and tabletted again. Method ensures to increase silver reduction degree to 99.9-100% and its purity to 99.99%. Method can be used for producing metallic silver from the secondary silver-containing raw (silver chloride, bromide, iodide, sulfite, sulfate or their mixtures). EFFECT: improved method, enhanced purity, decreased alkaline reagent consumption. 4 cl, 1 tbl