Chemical-Free Method for Recovery of Lead from Spent Lead Paste by Reductive Sulfation Technique from By-product Utilization

Abstract

Poisonous wastes, including lead slag, mattes, acidic sludge, particulates, and emissions of airborne gases, are primary industrial wastes related to the lead-acid battery industry. Herein, the phase conversion technique for PbO₂/PbSO₄ components and impurity contents of spent lead paste were studied. The reductive sulfur fixation technique was employed for the extraction of pure lead product from spent lead paste and immobilizing sulfur, which was relatively improved as compared to the release of sulfur oxides and lead particulates when traditional recycling techniques were used. Furthermore, a bench-scale experiment was carried out for the revival of chemical reagents and removal of impurities from the spent lead paste to understand the reliability and efficiency of this novel method from the perspective of a chemical-free process. The results reveal that the products were achieved in three distinct layers, i.e., impurities-free P-paste, sulfated residue (PbSO₄), desulfurized residue (PbCO₃) and the final product (α-PbO). In this work, the recovery efficiency of spent lead-acid batteries is higher than 99.9%. Moreover, the metal impurities such as Fe, Sb, Zn, Cu, and Mg were efficiently removed, and 99.89/99.999/99.94% of the reduction/sulfation/carbonization efficiency were achieved. This chemical-free research paves novel and appropriate extraction of lead for engineering and industrial sectors.