METHOD OF PROCESSING BISMUTH METAL TO OBTAIN BASIC BISMUTH CARBONATE Russian patent published in 2024 - IPC C01G29/00 C22B30/06 C22B3/44 

FIELD: chemistry; various technological processes.

SUBSTANCE: invention relates to processing bismuth-containing materials to obtain bismuth compounds. Metal bismuth is dissolved in nitric acid with concentration of 7 mol/l at temperature of 75 °C in the presence of ammonium nitrate with a molar ratio of ammonium nitrate to bismuth equal to 2.9. Hydrolytic purification of bismuth from impurity metals is carried out by adding ammonium carbonate solution to the obtained solution to pH 0.9 at temperature of 60 °C. Basic bismuth nitrate precipitate is washed with nitric acid solution with concentration of 0.1 mol/l at temperature 60 °C, treating the precipitate with ammonium carbonate solution at pH 8, temperature 22 °C. Basic bismuth carbonate is washed with water at temperature of 60 °C and dried at temperature of 70–75 °C. Bismuth is precipitated from mother and washing solutions obtained at the stage of precipitation of basic bismuth nitrate, at pH 3 and temperature 60 °C the addition of ammonium carbonate solution. Precipitate is directed to a step for dissolving bismuth metal. Impurity metals lead, silver and copper are deposited from the solution at pH 8 by adding ammonium carbonate solution. Precipitate is filtered and the obtained ammonium nitrate solution is sent to a step for dissolving bismuth metal.

EFFECT: method simplifies the process, increases the degree of extraction of bismuth into product from 93,6% to 98,9%, and also fully uses bismuth and ammonium nitrate solution in producing basic bismuth carbonate.

1 cl, 2 ex