Effects of Na₂O and BaO Additions on Phosphorus Distribution between MgO-saturated CaO-Fe_tO-SiO₂-P₂O₅ Slags and Liquid Iron

Abstract

Experiments have been made to study the effect of Na₂O(7-13 wt%) and BaO (4 wt%) additions on the phosphorus distribution between liquid iron and MgO-saturated CaO-Fe_tO-SiO₂-P₂O₅ (≤1 wt%) slags at 1550°C. The effect of Na₂O or BaO on the logarithms of the equilibrium quotient, k_p=(%P₂O₅)/ ([%P]² ·(%Fe_tO)⁵), was found to be 1.2 and 0.9 times as large as that of CaO on weight percent basis, respectively. The values for log k_p can be expressed as log ^k_p= 0.145[ (%CaO) +0.3 (%MgO)-0.5 (%P₂O₅)+1.2 (%Na₂O)+0.9 (%BaO) ] +22810/T-20.506
The effect of Na₂0 or BaO on the activity coefficients of P₂O₅ was also studied by the TURKDOGAN and PEARSON'S treatment. The following expression for the log_γP2O5is obtained for the Na₂O- or BaO-containing slags.
log_γP2O5=-1.02(23N_CaO+17N_MgO+8N_FetO-26N_P2O5+33N_Na2O+42N_BaO)-22990/T+9.490