Phosphorus Distribution between MgO-saturated CaO-Fe_tO-SiO₂-P₂O₅-MnO Slags and Liquid Iron

Abstract

The phosphorus distribution ratios between CaO-MgO_sat.-Fe_tO-SiO₂-P₂O₅(≤3 wt%)-MnO (25 wt%) or CaO-MgO_sat.-Fe_tO-SiO₂-P₂O₅ (45 wt%) slags and liquid iron have been obtained in the temperature range from 1 550 to 1 650°C, The dephosphorization quotients can be expressed by the following three different equations.
i) log (P₂O₅)/([P]²(Fe_tO)⁵)=0.145[(%CaO)+0.3(%MgO)-0.5(%P₂O₅)+0.6(%MnO)]+22 810/T-20.506
ii) log (P₂O₅)/([P]²(Fe_tO)⁵)=7.87 log [(%CaO)+0.3 (%MgO)-0.05(%Fe_tO)-0.5(%P₂O₅)+0.6(%MnO)]+22 240/T-27.124
iii) log (P)/([P](T.Fe)^5/2)=0.0720[(%CaO)+0.3(%MgO)+0.6(%P₂O₅)+0.6(%MnO)]+11 570/T-10.520
The activity coefficient of P₂O₅ by TURKDOGAN and PEARSON'S treatment can be expressed as follows :
logγ_P2O5=-1.02(23N_CaO+17N_MgO+8N_FetO-26N_P2O5+13N_MnO)-22 990/T+9.490
In the plot of logarithms of activity coefficient of Fe_tO against mole fraction of SiO₂, the values for log γ_FetO tend to increase with increasing the P₂O₅ content.