Sustainable extraction of lead and re-use of valuable metals from lead-rich secondary materials

Traditional lead metallurgy, a highly complicated lead extraction process for valuable metal recovery, has exhausted resources and produced a variety of hazardous wastes that are extremely harmful to the environment and unfavorable to the sustainable development of the lead industry. Vacuum metallurgy has become a promising emerging technology contributing to refining primary metals and the recovery of secondary nonferrous metal wastes. The technology is therefore relevant in the context of a transition to a more environmentally friendly circular economy. There is a growing interest in using vacuum distillation for extraction of Pb and valuable metals recovery from lead-rich secondary materials including crude lead, waste Pb-Sn alloy (WPSA) and lead anode slime (LAS). Results indicated that vacuum extracted lead (99.5% Pb) was obtained from crude lead (92.88%) using the two stage high-low temperature vacuum distillation process. Removals of 99.99% for Cu, 99.50% for Sn, and 98.00% for Ag, were achieved respectively. The valuable metals of Ag, Cu and Sn were recovered and concentrated in the final residue. Vacuum separation results of WPSA demonstrated that the purity of Pb reached 99.4% and recovery of Sn was above 86.0%. A novel integrated smelting-vacuum method is proposed here to reuse LAS. Copper and Ag were successfully enriched in the residues whilst Pb was collected in volatiles. The appropriate vacuum process effectively extracted Pb whilst recycling valuable metals, in a sustainable and environmentally friendly manner.