Thermodynamic Modelling of Phosphorus in

This study reviews and assesses published phase diagrams of key P2O5-containing systems relevant to steelmaking slag and experimental data on phosphorus partitioning between liquid iron and slags composed of SiO2-Al2O3-Fe2O3-FeO-MnO-MgO-CaO-Na2O. A dataset obtained under carefully controlled experimental conditions was selected to optimize parameters of the generalized central atom (GCA) model for phosphorus-containing slag systems. The developed model database accurately represents the liquidus temperature of key P2O5-containing systems and the phosphorus distribution ratio between steelmaking slags and liquid iron. The GCA model was used to simulate the dephosphorization reaction in the steelmaking process across various operating conditions, including slag chemistry and temperature. Results indicate that the phosphorus distribution ratio between slags and liquid iron reaches a peak with varying FeOx content in the slag and that phosphorus deportment to the slag is enhanced by lowering temperature and MgO content while increasing the CaO/SiO2 ratio. A comparison with phosphorus distribution data from a commercial basic oxygen steelmaking furnace demonstrates that current operating conditions do not achieve phosphorus equilibrium levels, with the degree of phosphorus dis-equilibrium increasing with slag viscosity.