Chemical potentials of oxygen in four-phase assemblages of the system CaO-P2O5-CaF2-FexO

In steelmaking processes, because of environmental requirements and health considerations, there is a strong incentive to reduce slag volume. The key to meet this requirement is the better understanding of phosphorus removal, which relies on the knowledge of the thermodynamic properties of slags and fluxes used for dephosphorization. In this study, the liquidus compositions of the four-phase assemblages in the quaternary system CaO-P2O5-CaF2-FexO were determined at 1573K by employing electron probe microanalysis. Measurements were also made on the FexO activities at temperatures between 1523K and 1673K by employing an electrochemical technique involving stabilized zirconia electrolyte.