Activity of P<sub>2</sub>O<sub>5</sub> in Solid Solution between Di-calcium Silicate and Tri-calcium Phosphate at 1823 and 1873 K

Abstract

By applying the chemical equilibrium method, the equilibrium between liquid iron and 2CaO∙SiO2-3CaO∙P2O5 solid solution has been measured with oxygen partial pressure of 5.22×10−12 atm at 1823 K and 1.41×10−11 atm or 4.25×10−10 atm at 1873 K. The phosphorus partition ratio between 2CaO∙SiO2-3CaO∙P2O5 solid solution and liquid iron was observed. The activity of P2O5 relative to hypothetical pure liquid P2O5 was determined from the phosphorus content in liquid iron and the reported thermodynamic data. The activity of P2O5 in 2CaO∙SiO2-3CaO∙P2O5 solid solution increased with the increase of 3CaO∙P2O5 content in solid solution. The activity coefficient of P2O5 in 2CaO∙SiO2-3CaO∙P2O5 solid solution also increased with the increase of 3CaO∙P2O5 content in solid solution.