Patent ID: 8568670

Claim:
A process for producing basic lead carbonate from redundant slag obtained from refining crude bismuth and neutralizing slag, the process comprising the following steps of: (1) immersing the neutralizing slag in water to obtain sodium hydroxide solution as a supernatant liquor; (2) leaching the redundant slag in an aqueous solution of sodium chloride having a concentration of 300-400 Kg/m 3 , a pH of 1-4, at 85-95° C. with stirring for 1-1.5 h, and adding a sulfide salt to the solution of sodium chloride and redundant slag in an amount sufficient to precipitate copper ions therefrom and thereby forming a leached lead chloride solution, and controlling a final pH of the leached lead chloride solution to 3.5-5.5; and then filtering the lead chloride solution to obtain a final lead chloride; (3) alkali neutralizing, filtering and washing the final lead chloride by washing, 3-6 times, with the supernatant liquor to form a filter slag; and (4) carbonate converting the filter slag by charging into clean water containing an amount of ammonium bicarbonate 2-3 times of a theoretical amount of ammonium bicarbonate required by the filter slag, and using sufficient supernatant liquor to adjust pH to 8-11 and stirring for 1-2 h to obtain a basic lead carbonate, and then crystallizing and precipitating, filtering, and washing the basic lead carbonate.