Experimental investigation and modelling of phase equilibria for the Ag–Cu–Pb system in vacuum distillation

• VLE (vapor–liquid equilibria) measurements under vacuum condition are reported for the Ag–Cu–Pb system.
• The experimental results of VLE for the Ag–Cu–Pb system were correlated using Wilson equation.
• Calculated partial Gibbs free energies were compared with the experimental values.

In this work, vapor–liquid equilibria (VLE) of the Ag–Cu–Pb system were experimentally investigated in vacuum distillation. The experimental results show that the content of Pb in liquid phase is 0.005 (mole fraction) under the experimental condition of 1173 K, 90 min and 10 Pa. The amount of Pb in volatiles increased to 0.9911 (mole fraction). It indicates that Pb can be satisfactorily removed from Ag–Cu alloy. With the Wilson equation, the partial Gibbs free energies of Pb in liquid Ag–Cu–Pb alloys were calculated, and the predicted values agree well with the experimental data, which shown that the interaction parameters are reliable. Using binary data only, the VLE for the Ag–Pb and Ag–Cu–Pb systems under vacuum condition were obtained. The calculation results demonstrate that this approach can lead to accurate VLE data predictions for the binary and ternary systems based on the Wilson equation.