Thermodynamic Activities of “FeO” in some Ternary “FeO”‐Containing Slags

Thermodynamic data concerning “FeO”‐containing slags is of importance in ladle refining of steel. With a view to generate a set of reliable and self‐consistent thermodynamic data for these slags, experimental determination of the activities of iron oxide in the Al2O3‐“FeO”‐SiO2, CaO‐“FeO”‐SiO2 and “FeO”‐MgO‐SiO2 systems was carried out using the gas equilibration method involving CO‐CO2‐Ar gas mixtures in the temperature range 1823‐1923 K. The slag samples kept in Pt crucibles were quenched after the equilibration and subjected to chemical analysis. The thermodynamic activities of “FeO” in the slags were calculated from the experimental data. The results are incorporated into a thermodynamic description of silicate melts developed in the present laboratory. The model is based on a Temkin‐Lumsden approach and is able to compute the thermodynamics of higher order systems from the lower order ones. The model was updated with the present results and iso‐activity contours of “FeO” in the three component systems are presented at 1873. The capacity of the model to predict the thermodynamic activites in four‐, five‐, and six‐component slags is demonstrated in the case of steelmaking slags.