CONCENTRATING METHOD FOR SILVER FROM COPPER ELECTROLYSIS SLIME

摘要

PURPOSE:To separate and concentrate silver from lead in an early time with good separability in high yields by acting alkali hydroxide upon the intermediate of copper electrolysis slime contg. lead as sulfate and silver as chloride and treating the resultant residues with a nitric acid soln. CONSTITUTION:An intermediate of copper electrolysis slime contg. lead as sulfate and silver as chloride is allowed to react with an aq. soln. of alkali hydroxide or alkali carbonate to convert the lead to lead hydroxide and lead carbonate which are soluble in nitric acid. The treated intermediate is prepd. into an aq. slurry of usually about 100-160g/l, to which an alkali is added at about 1.2 times the content of lead. The reaction is allowed to take place in about one hour at <=40 deg.C reaction time. This is subjected to solid-liquid sepn., and nitric acid soln. at about a stoichiometric amt. is added to the resultant residues to allow the same to react and to separate silver in the residue and lead in the filtrate. The reaction is completed in about 1hr. About >=90% lead elutes in the soln. and silver is concd. in the form of silver chloride in the residues.