A phosphorus distribution prediction model for CaO–SiO 2 –MgO–FeO–Fe 2 O 3 –Al 2 O 3 –P 2 O 5 slags based on the IMCT

Abstract

A thermodynamic model for predicting the phosphorus distribution ratio L _P of CaO–SiO₂–MgO–FeO–Fe₂O₃–Al₂O₃–P₂O₅ slags was developed by considering the mass action concentration of ion couples or structural units in slags based on the ion-molecule coexistence theory (IMCT) and is referred to as the IMCT-L _P model. Compared with the equilibrium mole number or mass percentage of the slag components, the mass action concentration for structural units of CaO–SiO₂–MgO–FeO–Fe₂O₃–Al₂O₃–P₂O₅ slags used in HIsmelt smelting reduction ironmaking can characterize the reaction ability of the components. The mass action concentration of the iron oxides may characterize the oxidizing ability of the slag. The dephosphorization reactions in the HIsmelt smelting reduction vessel are jointly controlled by basic oxides and the oxidizing ability of the slag. The IMCT model can not only accurately predict the total phosphorus distribution ratio of metallurgical slags but also forecast the respective phosphorus distribution ratio of basic oxides in the slag, i.e. the dephosphorization contribution rates of 3CaO·P₂O₅, 4CaO·P₂O₅ and 2CaO·P₂O₅ were 99.7%, 0.227% and 0.033%, respectively. Moreover, to more conveniently predict the phosphorus distribution ratio, the empirical formulas of the phosphorus distribution ratio considering slag composition and temperature were determined by mathematical regression.