Preparation of High-Purity Lead Chloride and Lead Oxide from Spent Lead Paste by Crystallization

Compared with conventional pyrometallurgical recycling, hydrometallurgical recycling offers distinct advantages by mitigating emissions of waste gas and lead-containing dust; however, it also encounters challenges in effectively eliminating metal impurities from spent lead paste. This study presents a novel hydrometallurgical process for the recovery of spent lead paste, which entails the production of high-purity lead chloride through crystallization, coupled with the recovery of lead oxide via dechlorination, thereby realizing the preparation of high-purity recovered products. First, sulfated lead paste was leached using a sodium chloride solution. Lead could be completely leached when the solid–liquid ratio was 40 g·L −1 , the concentration of sodium chloride solution was 250 g·L −1 , the reaction temperature was 80 °C, and the leaching time was 20 min. Subsequently, the leachate was filtered and further treated through dilution with distilled water (at 1.6 times) at 0 °C, thereby yielding high-purity lead chloride through the crystallization process, wherein metal impurities were effectively prevented from precipitating out. Finally, the lead chloride product was dechlorinated using sodium hydroxide solution. The dechlorination conditions were as follows: the solid–liquid ratio was 136.09 g·L −1 , the crystallization temperature was 0 °C, and the concentration of sodium hydroxide solution was 11.51 mol·L −1 . α-PbO was obtained under these conditions. In this study, spent lead paste was recycled with the advantages of low energy consumption and no harmful gas emissions, thereby providing a new idea for recycling lead-containing waste. Graphical Abstract