Theoretical research on vacuum separation of Au-Ag alloy

金银合金真空分离的理论研究

To provide an accurate prediction of the product component dependence of temperature and pressure in vacuum distillation and give convenient and efficient guidance for the designing of the process parameters of industrial production, according to the molecular interaction volume model(MIVM), the separation coefficient(β) and vapor-liquid equilibrium composition of Au-Ag alloy at different temperatures are calculated. Combined with the vapor-liquid equilibrium(VLE) theory, the VLE phase diagrams, including the temperature-composition(T-x) and pressure-composition(p-x) diagrams of Au-Ag alloy in vacuum distillation are plotted. The triple points and condensation temperatures of gold and silver vapors are calculated as well. The results show that the β decreases and the contents of gold in vapor phase increase with the distillation temperature increasing. Low pressures have positive effect on the separation of Ag and Au. The difference between the condensation temperatures of gold and silver is about 450 K in the pressure range of 1-10 Pa.

为准确预测金银合金真空蒸馏过程中产品成分与温度和压力的关系,并为工业生产参数的设计提供便捷和有效的指导,根据分子相互作用体积模型(MIVM),计算不同温度下金银合金的分离系数(β)和气−液平衡成分。结合气液相平衡(VLE)理论,绘制金银合金真空蒸馏的温度−成分、压力−成分相图。同时,对金、银三相点和金、银蒸气冷凝温度进行计算。理论研究结果表明:随着蒸馏温度的升高,分离系数减小,金在气相中的含量增加;低温对分离金银具有积极效果;在压强1~10 Pa范围内,金、银冷凝温度相差约450 K。