METHOD FOR REPROCESSING BISMUTHIFEROUS SULFIDE CONCENTRATES Russian patent published in 1996 - IPC

FIELD: hydraulic metallurgy. SUBSTANCE: method involves leaching raw material out with solution containing 25-50 g/l of sulfuric acid and 50-100 g/l of sodium chloride; extracting bismuth from leaching solution joined with washing operation cake solution containing 10-20 g/l of sulfuric acid and 40-80 g/l of sodium chloride, by solution containing 10% of tertiary aliphatic amine and 7-8%- octyl alcohol in white spirit or kerosene; washing extract with solution containing 20-60 g/l of sulfuric acid. Extraction is conducted at organic-aqueous phase ratio of 1:6 and washing is conducted at organic-aqueous phase ratio of 1:1. Commercial fraction of C₇-C₉ of nitrate tertiary aliphatic amine is used as tertiary aliphatic amine. Re-extraction is carried out by means of solution containing 100 g/l of nitric acid and 500 g/l of ammonium nitrate with organic-aqueous phase ratio of 5:1. Base product is separated from re-extract by neutralization with ammonia till pH reaches 2.5-2.6. EFFECT: increased purity of end product and simplified process. 4 cl, 3 tbl