Effect of Iron Oxide Dissolution on Thermochemical Property of Solid Solution between Ca2SiO4 and Ca3P2O8 at 1573 K

The key to a better understanding of phosphorus removal from hot metal is to know the thermochemical properties of solid solution between Ca₂SiO₄ and Ca₃P₂O₈. Although the solid solutions would inevitably incorporate iron oxide in steelmaking slags, there is a still lack of knowledge about the solid solutions containing iron oxide. The present study focused on the effect of FeO dissolution on the activities of components in the Ca₂SiO₄-Ca₃P₂O₈ solid solution. The P₂O₅ activities were measured in the solid solution containing FeO at 1573 K. Subsequently, the activities of Ca₂SiO₄, Ca₃P₂O₈, and Fe₂SiO₄ were derived from the Gibbs-Duhem equation with the measured P₂O₅ activities and reported FeO activities. When iron oxide dissolved into the Ca₂SiO₄-Ca₃P₂O₈ solid solution, the Ca₃P₂O₈ activity decreased, while the Ca₂SiO₄ activity was insensitive. As a result, the dissolution of iron oxide into the solid solution caused a drastic decrease in the P₂O₅ activity.