METHOD FOR PROCESSING LEAD-BISMUTH ALLOY TO OBTAIN LEAD AND BISMUTH COMPOUNDS Russian patent published in 2024 - IPC C01G21/18 C01G29/00 C22B13/00 C22B30/06 C22B3/06 

FIELD: metallurgy of non-ferrous metals.

SUBSTANCE: method for processing lead and bismuth-containing materials to produce lead and bismuth compounds. Lead is leached from a lead-bismuth alloy with a solution of nitric acid with a concentration of 4.1-4.3 mol/l, containing 0.5-5.0 wt.% urea at a temperature of 70-90°C and a liquid to solid weight ratio of 4.53-4.55. Lead carbonate is added to the resulting solution, as well as a solution of ammonium carbonate with a concentration of 2.5 mol/l until the pH of the solution is 2.0-3.0, and the bismuth-containing precipitate is separated by filtration. The lead-containing solution is evaporated to obtain lead nitrate composition Pb(NO₃)₂, which is separated by filtration and dried. Lead is precipitated from the mother liquor by adding ammonium carbonate salt. The resulting lead carbonate is sent to adjust the lead-containing solution. Bismuth-containing precipitate, which is the main nitrate of the composition [Bi₆O₅(OH)₃](NO₃)₅⋅3H₂O, processed at a temperature of 60-70°C with a solution of nitric acid with a concentration of 6.0 mol/l. Bismuth is precipitated from the resulting solution at 45-55°C with the addition of ammonium carbonate solution until the pH of the solution is 0.9. The precipitate is washed with a solution of nitric acid with a concentration of 0.1 mol/l, distilled water at a temperature of 50-60°C and dry the basic nitrate of the composition [Bi₆O₅(OH)₃](NO₃)₅⋅3H₂O reagent grade at a temperature of 90-100°C.

EFFECT: method allows to increase the degree of extraction of lead into nitrate, increase the purity of the bismuth-containing product from technical purity to the “reagent grade” qualification, and also eliminate the need to operate with lead-containing solutions concentrated in nitric acid when producing lead nitrate.

1 cl, 1 tbl, 2 ex