Modeling and measurement of vapor-liquid equilibrium of In–Pb and In–Pb–Sn alloy systems in vacuum distillation

Self Cite

Huge amounts of Au and Ag are recovered from the hazardous waste lead anode slime. The conventional extraction of precious metals from lead anode slime is based on pyrometallurgical and electrolytic processes, which are seriously conditioned by the separation of harmful elements As and Sb. In this paper, an innovative and efficient oxidation–vacuum volatilization–carbon reduction process was proposed to separate and enrich Ag and Au from lead anode slime. Before vacuum volatilization, selective oxidation of the lead anode slime was performed. Then, vacuum volatilization and vacuum carbon reduction were used to obtain a gold- and silver-rich alloy. The feasibility of the process was verified experimentally and theoretically. The effects of temperature and time on vacuum volatilization separation and reduction enrichment were investigated. The experimental results showed that the Ag content in the resulting gold- and silver-rich alloy was as high as 67.58%, Au was as high as 4287 g/t, and the efficiencies for the recovery of Ag and Au from the lead anode slime were 99.25% and 99.91%, respectively. The gold- and silver-rich alloy can be directly used to produce Ag ingots. Moreover, no gas or wastewater was discharged in this process, so Ag and Au were recovered in a sustainable and cleaner manner.

Section: Determination Of Saturated Vapor Pressurementioning

confidence: 99%

Separation and Enrichment of Au and Ag from Lead Anode Slime by a Selective Oxidation–Vacuum Volatilization–Carbon Reduction Process

Yi,

Gao,

et al. 2024

Self Cite

“…The study of the thermodynamic properties of solutions is essential for metallurgical preparation or the development of new materials. Among them, binary liquid alloys are characterized by simple structure and easy processing, which are widely used in aerospace, automotive, marine, and other fields [1]. Due to the complexity and accuracy limitations of actual high temperature experiments, in many cases, the experimental measurement process is difficult and the thermodynamic data results obtained are not accurate [2,3].…”

Section: Introductionmentioning

confidence: 99%

Estimation of Activity and Molar Excess Gibbs Energy of Binary Liquid Alloys Pb-Sn, Al-Sn and In-Zn from the Partial Radial Distribution Function Simulated by Ab Initio Molecular Dynamics

Zhang,

Chen,

et al. 2024

For the present, it is difficult to obtain thermodynamic data for binary liquid alloys by experimental measurements. In this study, the molecular dynamics processes of the binary liquid alloys Pb50-Sn50, Al50-Sn50, and In50-Zn50 were simulated by using the ab initio molecular dynamics (AIMD) principle, and their partial radial distribution functions (PRDF) were obtained at different simulation steps. Combined with the relevant binary parameters of the Molecular Interaction Volume Model (MIVM), Regular Solution Model (RSM), Wilson Model, and Non-Random Two-Liquid (NRTL) models. The integral terms containing the PRDF were computed using the graphical integration method to obtain the parameters of these models, thus estimating their activity and molar excess Gibbs energy. The total average relative deviations (ARD) of the activity and molar excess Gibbs energy estimates of the four models for the binary liquid alloys Pb50-Sn50, Al50-Sn50, and In50-Zn50 at full concentration when the PRDF is obtained by the symmetry method are MIVM: 21.59% and 59.35%; RSM: 21.63% and 60.27%; Wilson: 24.27% and 86.7%; NRTL: 23.9% and 83.24%. When the PRDF is obtained by the asymmetric method: MIVM: 22.86% and 68.08%; RSM: 32.84% and 68.66%; Wilson: 25.14% and 82.75%; NRTL: 24.49% and 85.74%. This indicates that the estimation performance of the MIVM model is superior to the other three models, and the symmetric method performs better than the asymmetric method. The present study also derives and verifies the feasibility of Sommer’s equation for estimating the molar excess Gibbs energy and activity of binary liquid alloy systems in the Miedema model by using different equations of enthalpy of mixing versus excess entropy given by Tanaka, Ding, and Sommer. The total ARD of Tanaka, Ding, and Sommer’s relational equations in the Miedema model for estimating the activities and molar excess Gibbs energies of the binary liquid alloys Pb-Sn, Al-Sn, and In-Zn are 3.07% and 8.92%, 6.09% and 17.1%, and 4.1% and 14.77%. The results indicate that the estimation performance of the Miedema model is superior to the other four models.

“…The excess Gibbs energy and activity thermodynamics models are widely used in gasliquid phase equilibrium reactions [1][2][3][4]. Engineers usually obtain the model parameters by using experimentally-determined excess Gibbs energy and activity to fit a regression equation [5][6][7][8][9][10]. Therefore, it is challenging to use the thermodynamic models to estimate gas-liquid equilibrium without relying on experimental thermodynamic values [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Estimation of Component Activities and Molar Excess Gibbs Energy of 19 Binary Liquid Alloys from Partial Pair Distribution Functions in Literature

Wang

Chen

Tao

2023

This work proposes a new method for estimating the molar excess Gibbs energy and activity of liquid alloy based on recent research. The local composition theory provides a connection between the structures of liquid alloys and the thermodynamic models. The partial pair distribution function (PPDF) was utilized to calculate the parameters of the MIVM, RSM, Wilson, and NRTL. The statistics of the number of molecular pairs of MIVM and RSM were rewritten, which resulted in new forms of the two models. To enhance the NRTL’s estimation performance, the coordination number was incorporated into it (M-NRTL). The aforementioned model and Quasi-chemical model (QCM) were utilized to estimate the excess Gibbs energy and activity of 19 alloys. The alloys contained multiple sets of PPDFs, which enabled the calculation of multiple sets of model parameters. The work examined the impact of expressing the model parameters as first-order linear functions of the components or as constants on the accuracy of the estimation. The parameters were treated as constants. MIVM, RSM, and M-NRTL provided an average relative deviation (ARD) of activity of less than ±20% for 15, 10, and 9 alloys by estimation. When model parameters were expressed as a function of components, QCM showed the best estimation performance, having nine alloys with an ARD of less than ±20%. The number of alloys with an ARD of less than ±20% corresponding to MIVM, RSM, Wilson, NRTL, and M-NRTL was six, five, three, five, and two, respectively. This new method offers simplicity, numerical calculation stability, and excellent reproducibility.