Application of molecular interaction volume model in separation of Pb-Sn-Sb ternary alloy by vacuum distillation

Based on the molecular interaction volume model (MIVM), the activities of components of Pb-Sn-Sb ternary alloy were predicted. The vapor-liquid phase equilibrium of Pb-Sn-Sb alloy system was calculated using the activity coefficients of Pb-Sn-Sb alloy system in the process of vacuum distillation. The calculated results show that the content of Sn in vapor phase increases with the increasing distillation temperature and content of Sn in liquid phase. However, the content of Sn in vapor phase is only 0.45% (mass fraction) while 97% in liquid phase at 1100 degrees C, which shows that the separating effect is very well. Experimental investigations on the separation of Pb-Sn-Sb ternary alloy were carried out in the distillation temperature range of 1100-1300 degrees C under vacuum condition. It is found that the Sn content in vapor phase is 0.54% while 97% in liquid phase at 1100 degrees C. Finally, the predicted data were compared with the experimental results showing good agreement with each other.