Activities of FeO and P₂O₅ in dephosphorization slags Co existing with solid solutions between di-calcium silicate and tri-calcium phosphate

Towards better understanding of the phosphorus removal from hot metal with low-basicity slags, electrochemical technique incorporating MgO-stabilized zirconia was conducted to measure simultaneously the activities of FeO and P₂O₅ within heterogeneous CaO–SiO₂–P₂O₅–FeO slags. The FeO activity was fairly insensitive to the variation of Ca₃P₂O₈ content in solid solutions between Ca₂SiO₄–Ca₃P₂O₈, while the P₂O₅ activity increased with an increase in Ca₃P₂O₈ content. By using the present values for activities, phosphorus distribution ratios were estimated between molten slag and carbon-saturated iron. The relationship between phosphorus distribution ratio and FeO content in molten slag was consistent with the phase diagram of the pseudo-ternary CaO–(SiO₂–P₂O₅)–FeO system