Recovery of lead in form of high purity lead carbonates from spent lead batteries incl. electrode paste

A process for recovering the lead content of an impure starting material in the form of electrode paste or slime from discarded lead batteries and/or of a lead mineral in the form of high purity lead carbonate and/or lead oxycarbonate, comprising dissolving lead oxide and other soluble substance in an acid leaching solution, characterized in that the leaching acid is selected from the group consisting of acetic acid, nitric acid, fluoboric acid and fluosilicic acid and the process comprises the following steps:

• a) adding sulphuric acid to an acid leaching suspension of an impure starting material to convert dissolved lead compounds to insoluble lead sulphate;
• b) separating a solid phase comprising lead sulphate and undissolved substances from the acid leaching solution;
• c) selectively dissolving lead sulphate contained in said separated solid phase in an aqueous solution of at least a solubilizing compound selected from the group consisting of sodium acetate, ammonium acetate, potassium acetate, urea acetate, mono-, di- or tri-ethanolamine acetate, dimethyl, ethyl or propyl amine, water soluble amides and sodium thiosulphate;
• d) separating a solution containing dissolved lead sulphate from a solid phase residue including undissolved impurities;
• e) adding to the separated solution of lead sulphate a sodium or potassium or ammonium carbonate to form insoluble lead carbonate and/or lead oxycarbonate and a soluble sulphate of the same cation of the added carbonate salt;
• f) separating precipitated carbonate and/or oxycarbonate of lead from the dissolving solution containing sulphate of the cation of said solubilizing compound.