Experimental investigation and modelling of separation behavior for the Bi–Cu–Pb system in vacuum distillation containing one binary azeotrope

The VLE (vapor-liquid equilibrium) experiments for the Bi–Cu–Pb system containing a sub-binary azeotrope at 1 and 10 Pa were carried out. The VLE data for the sub-binary and ternary systems were correlated using the Wilson equation. Based on the Euler-Newton homotopy method, the azeotropic points of the Bi–Cu–Pb system at different temperatures were predicted. The results showed good agreement with experimental data. The thermodynamic consistency of the experimental values was verified by Van Ness test. This work provides a theoretical basis for vacuum distillation of ternary alloy containing a sub-binary azeotrope. It is helpful to determine suitable experimental conditions for the separation and purification of crude metals in vacuum distillation.