The addition of silica to steelmaking slags to decrease the binary basicity can promote phosphate enrichment in quenched slag samples. In this study, we experimentally investigated phosphate enrichment behavior in CaO-SiO2-FeO-Fe203-P205 slags with a P205 content of 5.00% and the binary basicity B ranging from 1.0 to 2.0, where the （%Fe/O）/（%CaO） mass percentage ratio was maintained at 0.955. The experimental results are explained by the defined enrichment degree c, of solid solution 2CaO·SiO2-3CaO·P205 （C2S-C3P）, where R_C2S-C3P is a component of the developed ion and molecule coexistence theory （IMCT）-Ni model for calculating the mass action concentrations Ni of structural units in the slags on the basis of the IMCT. The asymmetrically inverse V-shaped relation be- tween phosphate enrichment and binary basicity B was observed to be correlated in the slags under applied two-stage cooling conditions. The maximum content of PROs in the C2S-C3P solid solution reached approximately 30.0% when the binary basicity B was controlled at 1.3.
In order to further verify the accuracy and feasibility of the calculated mass action concentrations Ni of Al and Fe by the developed atom and molecule coexistence theory(AMCT)model,i.e.,AMCT-N,model,for representing activities aR,i of Al and Fe in Fe-Al binary melts reported in the first part of the serial studies,the molar mixing thermodynamic functions of Fe-Al binary melts over a temperature range from 1823 to 1973 K have been calculated based on Ni of Al and Fe as well as the effect of temperature on activity coefficients 7,of Al and Fe as■lnγj/■T=■ln(Ni/xi)/dT by the developed AMCTN-Ni model,where T is absolute temperature and.v,is the mole fraction of element i or compound i in metallic melts.The reported molar mixing thermodynamic functions of Fe-Al binary melts as well as the reported excess molar mixing thermodynamic functions of Fe-Al binary melts relative to ideal solution as a basis from the available literatures have been critically assessed and applied as criteria to verify the developed AMCT-Al,model.The effect of changing temperature onγi of Al and Fe,i.e.,activity coefficient gradients■lnγAl/■T and■lnγFe/■T,which are two indispensable parameters to calculate the molar mixing thermodynamic functions of Fe-Al binary melts,can be accurately obtained by the developed AMCT-Ni,model and expressed by the cubic polynomial functions.Not only the partial molar mixing thermodynamic functions of Al and Fe in Fe-Al binary melts but also the integral molar mixing thermodynamic functions of Fe-Al binary melts can be accurately calculated by the developed AMCT-Al,model.Furthermore,the excess partial and integral molar mixing thermodynamic functions of Fe-Al binary melts relative to ideal solution as a basis can also be precisely calculated by the developed AMCT-Ni,model.
