Re-optimization of the FeO–Fe2O3–SiO2 system integrated with experimental phase equilibria studies

Abstract

The Fe–Si–O system is important in understanding the slag chemistry of copper production which involves fayalite slags. It is also an important part of a 20-component Cu-Pb-Zn-Fe-Ca-Si-O-S-Al-Mg-Cr-Na-As-Sn-Sb-Bi-Ag-Au-Ni-Co thermodynamic database being developed for multiple processes and applications of ferrous and nonferrous metallurgy. The present work presents experimental data on high-temperature silica liquidus/miscibility gap in the Fe-Si-O system measured by equilibration/quenching/electron probe X-ray microanalysis (EPMA) method as well as a thermodynamic reassessment of the Fe–Si–O system within the 20-component database. The slag phase has been modeled within the modified quasichemical formalism to account for short-range ordering phenomena. The heat capacities of liquid endmembers have been updated in a way consistent with the physical principles of liquid slag cooling and glass transition, potentially opening a way for lower-temperature applications of the database regarding the leaching of minor elements from partially crystallized slags. Recent developments in thermodynamic modeling and optimization allowed us to perform the assessment of the system in a consistent way as a part of a multicomponent experimental dataset, leading to a superior prediction quality of the resulting thermodynamic database for industrial applications.