Thermodynamic Modeling of the Pb-S and Cu-Pb-S Systems with Focus on Lead Refining Conditions
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Thermodynamic Modeling of the Pb-S and Cu-Pb-S Systems with Focus on Lead Refining Conditions Denis Shishin1
•
Jiang Chen2 • Evgueni Jak1
Submitted: 31 March 2020 / Accepted: 20 April 2020 Ó ASM International 2020
Abstract Thermodynamic modeling of the Pb-S and CuPb-S systems is presented. All available experimental data in these systems are collected, assessed and used to optimize the model parameters. For the liquid phase, a solution (CuI, PbII, SII) is developed using the modified quasichemical model in pair approximation. Liquid copper, liquid lead metal, as well as matte phases are described using single solution with miscibility gaps. Earlier thermodynamic assessments available in the literature did not include all the data on the solubility of Cu and S in liquid Pb at low temperatures, \ 750 °C (1023 K), which is important for lead fire refining. In the present study, these additional data points are used in the optimization. For the composition of lead in equilibrium with matte at temperatures [ 900 °C (1123 K), a significant discrepancy among different sets of literature data and existing thermodynamic assessments is revealed. Preliminary experiments are performed with the goal to understand the nature of the problem and to develop the methodology based on high-temperature equilibration, rapid quenching and electron probe x-ray microanalysis. The results of this study help to select accurate literature results in the optimization of model parameters. The resulting database is applicable to calculate slag/matte/metal distribution of lead in copper smelting and converting, as well as for predictions in the lead smelting and fire refining.
& Denis Shishin [email protected] 1
PYROSEARCH, School of Chemical Engineering, University of Queensland, Queensland, QLD 4012, Australia
2
Centre for Advanced Microscopy, Australian National University, Canberra, ACT 2601, Australia
Keywords drossing FactSage lead refining matte thermodynamic modeling
1 Introduction The thermodynamics of the Cu-Pb-S system determines the distribution of these elements among slag, matte, metal and gas phases in the pyrometallurgical extraction of copper and lead. Thermodynamic assessments are available in literature. Dessureault[1] modeled phase equilibria and thermodynamics of the Pb-S and Cu-Pb-S system. Only activity data have been used to optimize the model parameters in the Cu-Pb-S system. Decterov and Pelton[2] included phase equilibria data for the Cu2S-PbS pseudo-binary section and the distribution data of Pb between matte and copper metal. In the above studies,[1,2] liquid lead phase was modeled using a separate solution model from matte, which does not provide an accurate description of the Pb-S side in the Cu-Pb-S system. No liquid immiscibility is observed in the Pb-S system above the liquidus. Only metastable immiscibility is possible below the liquidus in the Pb-S system. In the Cu-Pb system, the liquid immiscibility is observed in a narrow temperature range. A more recent study by Johto and Taskinen[3] use
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