Reclaiming of lead in form of high purity lead compound from recovered electrode paste slime of dismissed lead batteries and/or of lead minerals

1. A process for reclaiming the lead content of impure electrode paste or slime from discarded batteries and/or lead minerals, in form of high purity lead compound comprising:

a) suspending an impure lead containing material in an aqueous bath containing at least a lead oxide dissolving acid;

b) reducing any insoluble lead dioxide to lead oxide by introducing into the suspension hydrogen peroxide, a sulphite or sulphurous anhydride;

c) converting all dissolved lead oxide to lead sulphate in the aqueous bath;

d) dissolving lead sulphate in an aqueous solution of an acetate salt;

e) precipitating and separating purified lead compound by adding to said acetate salt solution a hydroxide of the same cation of said acetate salt.

2. A process for reclaiming the lead content of impure electrode paste or slime from discarded batteries and/or lead minerals, in form of high purity lead compound comprising:

a) suspending impure starting material in an acid leach solution of an acid selected from the group consisting of acetic, nitric fluoboric and fluorosilicic acid;

b) gradually introducing into the acid leach suspension a compound selected from the group consisting of hydrogen peroxide, sulphites and sulphurous hydroxide to reduce insoluble lead dioxide to soluble lead oxide;

c) adding to the acid leach suspension sulphuric acid for converting dissolved lead oxide to insoluble lead sulphate;

d) separating a solid phase constituted by lead sulphate and undissolved impurities from the acid leach suspension;

e) 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, potassium acetate and ammonium acetate;

f) separating the solution containing dissolved lead sulphate from a solid phase residue including undissolved impurities;

g) adding to the separated solution of lead sulphate a hydroxide of the same cation of said solubilizing compound for forming insoluble lead oxide or hydroxide, and a soluble sulphate of the same cation of the added hydroxide;

h) separating an insoluble purified lead compound from the solution containing also sulphate of the cation of said solubilizing compound.

3. The process of claim 2 , comprising gradually cooling or gradually heating a separated dissolving solution of an impure solid phase of precipitated lead sulphate and of insoluble impurities for selectively precipitating the sulphate of the cation of the solubilizing compound, and of separating it from a limpid dissolving solution that is recycled to step e), in order to maintain the sulphate concentration below saturation.

4. The process of claim 2 , wherein sulphatation of the dissolved lead oxide is carried out by adding to an acid leach suspension sulphuric acid in a stoichiometric amount or slightly above based on an estimated content of dissolved lead oxide.

5. A process, for reclaiming the lead content of impure electrode paste or slime from discarded batteries and/or lead minerals, in form of high purity lead compound comprising:

a) suspending an impure lead containing starting material in a lead sulphate dissolving aqueous solution of a salt belonging to the group composed of the acetates of sodium, potassium and ammonium;

b) adding to the suspension sulphuric acid in an amount sufficient to convert all lead oxides to lead sulphate soluble in the acetate salt solution and slowly adding to the suspension either hydrogen peroxide or a sulphite or bubbling sulphurous anhydride in an amount, adapted to reduce any lead dioxide to lead oxide that is then converted to soluble lead sulphate by the sulphuric acid;

c) separating a limpid acetate salt solution containing dissolved lead sulphate from a solid phase residue including all undissolved compounds and impurities;

d) adding to the separated solution of lead sulphate either carbonate or hydroxide of the same cation of the acetate salt of the lead sulphate dissolving solution for precipitating highly pure lead carbonate, lead oxycarbonate or both or lead oxide or hydroxide, respectively, while forming sulphate of the cation, soluble in the acetate salt solution;

e) separating a precipitated high purity lead compound from the acetate salt solution now containing sulphate of the same cation of the acetate salt.

6. The process of claim 5 , wherein said acetate salt solution containing sulphate of the same cation of the acetate salt separated from the precipitated compound of lead is recycled to step a) and the increasing content of sulphate of the same cation in the solution is maintained below saturation limit by continuously or periodically cooling at least a portion of the solution separated from the precipitated lead compound to cause selective crystallization of sulphate salt of the same cation of the acetate salt and removing said sulphate salt as a by-product.

7. The process of claim 5 , wherein prior to cooling for selectively precipitating sulphate salt of the same cation of the acetate salt, the solution is contacted with a chelating resin adapted to sequester any residual lead ions from the solution for selectively precipitating substantially lead-free sulphate salt of the same cation of the acetate salt, upon cooling.

8. The process of claim 5 , wherein the selective dissolution of the lead sulphate is carried out by suspending an impure material in an aqueous solution of sodium acetate having a concentration comprised between 10 g and 120 g of salt in 100 g of water at a temperature comprised between 20° C. and boiling point, for a stirring time of between 5 and 180 minutes.

9. The process of claim 5 , wherein selective dissolution of the lead sulphate is carried out by suspending an impure material in an aqueous solution of ammonium acetate having a concentration comprised between 20 g and 120 g of salt in 100 g of water at a temperature comprised between 20° C. and boiling point, for a stirring time of between 5 and 180 minutes.

10. The process of claim 5 , wherein selective dissolution of the lead sulphate is carried out by suspending an impure material in an aqueous solution of potassium acetate having a concentration comprised between 20 g and 120 g of salt in 100 g of water at a temperature comprised between 20° C. and boiling point, for a stirring time of between 5 and 180 minutes.

11. The process of claim 5 , further comprising suspending a separated solid phase residue including all undissolved compounds and impurities in hot concentrated hydroxide of the same cation of the selected acetate salt for converting and dissolve compounds of lead or concretions thereof that could not be dissolved in the acetate salt solution in form of plumbite salt of the hydroxide cation, separating a lead plumbite containing alkaline liquor from a solid phase of impurities contained in the starting material and adding the separated lead plumbite containing liquor to the separated acetate solution for precipitating all reclaimable lead as highly pure lead compound.