Simulation and Measurement of Vapor-Liquid Equilibrium of Cu-Bi and Cu-Bi-Ag Alloys in Vacuum Distillation
摘要
In this study, vacuum distillation of copper-bismuth and copper-bismuth-silver alloys was conducted under the conditions of temperature of 1073–1273 K and system pressure of 3–5 Pa. bismuth was thoroughly separated from copper by a single-stage distillation of copper-bismuth alloy at 1273 K and 3–5 Pa. The content of copper in the residue is 98.94 wt pct, while the content of bismuth in the volatile is 96.30 wt pct. In the temperature range of 1098–1198 K, the content of bismuth in the volatiles was remained above 95 wt pct, and the contents of silver and copper in the volatiles were less than 0.1 wt pct when vacuum distillation was conducted on copper-bismuth-silver alloy. This indicates that bismuth was effectively separated from copper and silver by a single distillation. The activity of components of copper-bismuth alloy was calculated using Molecular Interaction Volume Model and Modified-Molecular Interaction Volume Model. The prediction deviation of Modified-Molecular Interaction Volume Model is smaller than that of Molecular Interaction Volume Model. Based on the Modified-Molecular Interaction Volume Model and vapor-liquid equilibrium theory, the vapor-liquid equilibrium value of copper-bismuth and copper-bismuth-silver alloys was predicted and the corresponding vapor-liquid equilibrium phase diagram was drawn. The predicted vapor-liquid equilibrium value are in good agreement with the experimental data determined in this study. This study provides a new method and reliable model for efficient separation of copper-bismuth and copper-bismuth-silver alloys by vacuum distillation.