Vapor–liquid phase diagrams of Pb–Sn and Pb–Ag alloys in vacuum distillation

• The VLE phase diagrams of Pb–Sn and Pb–Ag alloy systems in vacuum distillation were calculated.
• The distillation conditions of Pb–Sn and Pb–Ag alloy systems were discussed.
• It is important to estimate the separation degree and the products composition quantitatively.

A procedure has been proposed to calculate the vapor–liquid equilibrium (VLE) phase diagrams of Pb–Sn and Pb–Ag alloys in vacuum distillation based on VLE calculations and molecular interaction volume model (MIVM). The results show good agreement with experimental data which indicate that VLE phase diagram under vacuum obtained by this method is available and reliable. The VLE phase diagram provides an intuitive and convenient way to analyze the product component dependence of temperature or pressure during the process of vacuum distillation. It has a significant advantage to guide for the experiment and industrial production in vacuum metallurgy.