Activities of P₂O₅ in Solid Solutions between Di-calcium Silicate and Tri-calcium Phosphate at 1573 K

Abstract

The knowledge of P₂O₅ activities in solid solutions between Ca₂SiO₄ and Ca₃P₂O₈ is required for more effective dephosphorization. In the present study, firstly, the P₂O₅ activities in these solid solutions coexisting with CaO or CaSiO₃ at 1573 K were measured by equilibrating molten copper with oxide phases under a stream of Ar + H₂ + H₂O gas mixtures. Subsequently, the sub-regular solution model was applied to Ca₂SiO₄–Ca₃P₂O₈ solid solutions. The P₂O₅ activities calculated with the solution model agreed well with the present experimental results and the literature data. It was found that the P₂O₅ activity in Ca₂SiO₄–Ca₃P₂O₈ solid solution coexisting with CaO was about 7 digits lower than that coexisting with CaSiO₃.