Deeply removing lead from Pb-Sn alloy with vacuum distillation
(1. General Research Institute for Nonferrous Metals, Beijing 100088, China;2. National Engineering Laboratory for Vacuum Metallurgy, Kunming University of Science and Technology,Kunming 650093, China)
Abstract: Activity coefficients of Pb-Sn alloy with different Pb contents at 777 °C were calculated with molecular interaction volume model, which agree well with the available experimental values. Activity coefficients at 800-1300 °C were predicted to supply valuable data for thermodynamic calculation of vacuum distillation. Small-scale and continuous industrialized experiments of vacuum distillation for two different components of Pb-Sn alloys were performed and the lead content in refined tin was decreased to less than 0.01% successfully. Vacuum distillation treatment of Pb-Sn alloy in which lead content fluctuated from 10% to 90% was put forward. The final product is crude lead with purity above 99.5% and refined tin with lead content less than 0.01%.
Key words: Pb-Sn alloy; molecular interaction volume model; vacuum distillation; activity coefficient