Evaluation of Phosphorus Enrichment Capacity of CaO–SiO2–FeO–MgO–MnO–P2O5–Al2O3 Dephosphorization Slag Based on Ion‐Molecule Coexistence Theory

Abstract

Herein, the phosphorus enrichment capacity of CaO–SiO2–FeO–MgO–MnO–P2O5–Al2O3 dephosphorization slag is studied based on ion‐molecule coexistence theory (IMCT) and industrial experiment. The equilibrium mass percentages of structural units in dephosphorization slag have different degrees of linear relationship with the corresponding mass action concentrations N i . The calcium phosphate in dephosphorization slag has the greatest contribution to phosphorus distribution ratio and phosphate capacity, up to 99.99%, in which 3CaO·P2O5 has about 94.97%. Compared with the other 23 phosphorus distribution ratio and 7 phosphate capacity empirical models, IMCT model can accurately predict the phosphorus distribution ratio with the lowest average relative error of 3.70% and the second lowest standard deviation of 2.34%, and phosphate capacity with the lowest average relative error of 0.80% and the lowest standard deviation of 0.52%. At 1620–1640 °C, with increasing phosphorus enrichment contribution ratio of 2CaO·SiO2 in slag, the dephosphorization capacity of slag is greatly improved. The change trends of phosphorus enrichment capacity evaluation indexes of slag calculated based on IMCT are well consistent with the change trend of dephosphorization ratio of molten steel, indicating the IMCT calculation results can correctly predict the phosphorus enrichment capacity of dephosphorization slag in converter dephosphorization process.