Isobaric (vapour + liquid) equilibria of binary Pb-Sn and Sb-Sn system AT2Pa

Abstract

A new experimental method for determining vapor-liquid equilibrium (VLE) of binary alloys was designed in this study. The VLE data of Pb-Sn and Sb-Sn alloys were determined by using this new method. The experimental data passed the thermodynamic consistency test (Van Ness test), and the y (MAD) was 0.4066 and 0.6667, respectively, indicating that the experimental method is correct and reliable. The activity coefficient of Pb-Sn and Sb-Sn alloys was calculated by using the molecular interaction volume model (MIVM). The maximum average relative deviation Si and maximum average standard deviation Si* are ±1.34% and ±0.009, respectively, which indicates that the calculation of the activity coefficient of the Pb-Sn and Sb-Sn alloys by MIVM is reliable. The VLE data of Pb-Sn and Sb-Sn alloys were calculated based on the VLE theory and MIVM, and the calculated results agreed well with the experimental VLE data. The VLE phase diagrams of Pb-Sn and Sb-Sn alloys were also established in this study. The VLE phase diagrams offer a valid and intuitive way to analyze the product compositions' dependence of temperature and pressure during the process of vacuum distillation. This will have immense significance in guiding the actual production of vacuum metallurgy.

Isobaric vapor-liquid equilibria of ternary lead-tin-antimony alloy system at 2 Pa

“…The VLE data of the Pb-Sn-Sb alloy were determined using a steel chamber, as described in our previous work [5].…”

“…The chamber, in which a capillary had been previously inserted, was welded and evacuated to 2 Pa. The chamber was then placed in a resistance furnace [5]. The experiments were conducted at 1023, 1073, 1123, 1173, and 1223 K, respectively, until the system reached equilibrium.…”

“…The Sb and Pb content in the vapor phase (volatiles) and liquid phase (residues) were determined by titration analysis, and the detailed determination procedure is available in Ref. [5]. The Sn content in the volatiles and residues were obtained by solving the equation of mass balance accounting for the VLE.…”

“…Using the method in Ref. [5], the combined standard uncertainty at the experimental conditions in this study was estimated to be ± 0.003 in mole fraction.…”

“…Reliable vapor-liquid equilibrium (VLE) data are crucial for the optimization of the original process and the design of the new process in vacuum distillation. In our previous work [5], VLE data of the binary Pb-Sn and Sb-Sn alloy systems were obtained using the new experimental method proposed in the Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology (KUST), China. Investigating the VLE data of ternary alloy systems has a more practical significance because most of the alloys produced and rec0overed from smelters and resource recovery industries are ternary or multicomponent alloys.…”