Thermodynamic optimization of the binary PbO-“Cu2O”, “Cu2O”-SiO2 and ternary PbO-“Cu2O”-SiO2 systems

Liquidus phase equilibrium data obtained in the recent study by the authors for the binary PbO–“CuO”, “CuO”–SiO and the ternary PbO–“CuO”–SiO systems in equilibrium with metallic Cu or Pb–Cu alloy (as a part of research program on the characterization of the multicomponent PbO–ZnO–FeO–FeO–“CuO”–CaO–SiO system), 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. The modified quasichemical model is used for the liquid slag phase. From these model parameters, the optimized ternary phase diagram is back calculated. Liquidus surface with cristobalite, tridymite and quartz (SiO), two immiscible liquids, cuprite (CuO), lead silicates (PbSiO, PbSiO, PbSiO, PbSiO), massicot (PbO) and copper plumbite CuPbO primary phase fields has been constructed. Available experimental data are described within uncertainties. Oxygen partial pressures and distribution of lead between slag and metal have been calculated.