Method of recovering lead values from battery sludge

Abstract

A process for recovery of substantially all lead values in battery sludge as metallic lead is disclosed. By means of the process, lead is substantially completely and efficiently recovered as metallic lead in an environmentally acceptable manner. The process comprises (a) subjecting the sludge to low temperature reducing conditions; (b) converting lead sulfates to insoluble nonsulfur containing compounds while solubilizing all sulfur materials and thereafter separating the solid residue by solid-liquid separation techniques; (c) dissolving the solid products resulting from steps (a) and (b) in an acid selected from the group consisting of fluoboric and fluosilicic acid; (d) collecting the supernatant from step (c) by means of solid-liquid separation techniques; and (e) electrowinning the lead from the collected supernatant. The lead peroxide reduction of step (a) may be effected by low temperature reducing roasts or by contacting the lead peroxide with sulfur dioxide gas or sulfites.

Dependencies are inferred from the claim text.