METHOD FOR PRODUCING METALLIC BISMUTH WITH THE PRODUCTION OF BASIC BISMUTH NITRATE Russian patent published in 2022 - IPC C22B30/06 C01G29/00 

FIELD: hydrometallurgy.

SUBSTANCE: invention relates to the hydrometallurgy of rare metals, namely to the processing of bismuth-containing materials to obtain bismuth basic nitrate. Metallic bismuth is dissolved in nitric acid with a concentration of 7-8 mol/l at a temperature of 60-70°C in the presence of ammonium nitrate with a molar ratio of ammonium nitrate to bismuth of 1.5-3.5. Hydrolytic purification of bismuth from impurity metals is carried out by adding a solution of bismuth nitrate to water at 50-80°C with a volume ratio of water and bismuth-containing solution 7-9:1. Basic bismuth nitrate is obtained as a result of sequential hydrolysis, first with water, and then with a solution of ammonium carbonate. The precipitate is washed with water at 15-40°C and dried at 80-120°C. The mother and washing solutions after filtration are combined and ammonium carbonate is added at a temperature of 50-60°C and pH of the mixture 1.0. The resulting bismuth-containing solution is filtered. The mother and washing solutions are combined and additional precipitation of bismuth is carried out by adding ammonium carbonate to the above-mentioned combined solution to pH 3.0 at a temperature of 50-60°C. The basic nitrate bismuth precipitate is filtered and sent to the stage of dissolution of metallic bismuth. The solution obtained after filtration is purified from impurity metals with a solution of ammonium carbonate to a pH of 8.0.

EFFECT: method provides basic bismuth nitrate with a content of basic impurity metals: lead, copper, silver, no more than 1∙10^-5% with full use of bismuth and ammonium nitrate solution, while eliminating the release of toxic nitrogen oxides into the gas phase.

1 cl, 1 tbl, 2 ex