Modeling and measurement of vapor-liquid equilibrium of In-Pb and In-Pb-Sn alloy systems in vacuum distillation

This study reports the measurement and modeling of vapor-liquid equilibrium (VLE) in In-Pb and In-Pb-Sn alloys subjected to vacuum distillation at a system pressure of 5-10 Pa in the temperature range of 1100-1280 K. Pb and In was satisfactorily separated by a single-stage distillation at 1180 K. Pb was thoroughly removed from In-Pb-Sn alloy by a single-stage distillation at 1220 K. Molecular interaction volume model (MIVM) was used to calculate the activities of components of In-Pb alloy. The deviations were small. The activities of components of In-Pb-Sn alloy were also predicted by MIVM. The VLE of In-Pb and In-Pb-Sn alloy systems were predicted by MIVM and VLE theory. The calculated results agree well with VLE data determined from experiments, which indicates that the calculated VLE is reliable. The VLE can be used to guide the separation of indium-based alloys by vacuum distillation. In this study, the model prediction was combined with vacuum distillation experiments, which not only verified the reliability of MIVM for indium-based alloys, but also optimized the process pa-rameters of vacuum distillation of indium-based alloys, providing theoretical guidance for the separation and purification of indium-based alloys by vacuum distillation or the treatment of indium-containing complex materials.