The Integrated Experimental Phase Equilibria and Thermodynamic Modelling Study of the PbO-ZnO-FeO-FeO_1.5-MgO-SiO₂ System, and Demonstration of Its Industrial Application

The process chemistries of pyrometallurgical processes are becoming increasingly complex; computational tools capable of predicting the phase equilibria and the mass and energy balance of the multicomponent slag/metal/matte/speiss/gas system are required for optimizing the operation of existing and the development of novel processes. In the present study, the phase equilibria of the PbO-ZnO-FeO-FeO_1.5-MgO-SiO₂ system in equilibrium with metal or air were studied using the equilibration and quenching technique, followed by the use of an electron probe X-ray microanalysis (EPMA) to measure the phase assemblages and compositions of equilibrated samples. The newly obtained experimental phase equilibria data addressed gaps and inconsistencies in the available literature data and were used for the optimization of thermodynamic model parameters describing the complex multi-component system. The present work was a part of the integrated experimental and thermodynamic modeling research program on the phase equilibria of the Cu-Pb-Fe-Zn-Ca-Si-O-S-Al-Mg-Cr-As-Sn-Sb-Bi-Ag-Au-Ni-Co slag/metal/matte/speiss system. The applicability of the research program results to modern industrial needs was demonstrated by the development of the mass and energy balance of a zinc slag fuming process in Kazzinc. The potential for reducing coal consumption per unit of cleaned slag was demonstrated.