Thermodynamic optimization of the PbO–FeO–Fe2O3–SiO2 system

Liquidus phase equilibrium data of the present authors for the PbO–FeO–Fe2O3 system at various oxygen potentials, PbO–“Fe2O3”–SiO2 system in air, and PbO–“FeO”–SiO2 in equilibrium with metallic Pb, combined with phase equilibrium and thermodynamic data from the literature, have been used to obtain a self-consistent set of parameters of the thermodynamic models for all phases in the PbO–FeO–Fe2O3–SiO2 system. The modified quasichemical model is used for the liquid slag phase. For the liquid phase, the PbO–FeO, PbO–Fe2O3, PbO–FeO–Fe2O3, PbO–FeO–SiO2 and PbO–Fe2O3–SiO2 parameters are optimized in the present study. From these model parameters, the optimized ternary phase diagram is back calculated. Present set of parameters describe previous and new experimental data well, and can be used for predictions of the PbO–FeO–Fe2O3–SiO2 phase equilibria over wide ranges of oxygen partial pressured, compositions and temperatures, as well as multicomponent systems.