Integrated Experimental and Thermodynamic Modeling Study of the Pb-Fe-O-S-Si System: Effect of Temperature and p(SO2) on Slag-Matte-Metal-Tridymite Equilibria

Abstract

An integrated experimental and thermodynamic modeling study has been used to characterize phase equilibria in the Pb-Fe-O-S-Si system. The experimental approach developed for investigation of this system, which involves the use of high-temperature equilibration, quenching, and electron probe X-ray microanalysis, has enabled to overcome difficulties associated with high corrosive tendency of the condensed phases and high vaporization rates of Pb species specific to this system. The study shows that systematic, accurate direct experimental measurements of the Pb, Fe, Si, and S concentrations in the coexisting phases in this system are now possible. The results obtained for the slag-matte-metal-tridymite phase equilibria at 1100 °C and 1200 °C appear to be the first systematic quantitative experimental data on phase compositions in equilibrium in the Pb-Fe-O-S-Si system. First systematic experimental measurements have also been undertaken for the gas-slag-matte-tridymite equilibria at p(SO2) = 0.6 atm at 1200 °C. Thermodynamic calculations have been performed using the FactSage thermodynamic package. The experimental data have been used, along with other relevant measurements, to develop a self-consistent thermodynamic database that can be used for optimization of industrial processes.