1987 Volume 27 Issue 5 Pages 332-339
From the study of the dephosphorization of liquid iron by the Na2O-SiO2-Fe2O3 fluxes containing CaO, MnO2, or Al2O3 at 1600°C, the contributions of CaO, MnO, and Al2O3 on the phosphorus distribution between liquid iron and Na2O-MgO-FetO-SiO2 slaps were derived.
The phosphorus distribution ratio and the equilibrium quotient were expressed by the following equations including the terms of (%CaO), (%MnO), and (%Al2O3). (i) log {(%P)/[%P]}=0.092{(%Na2O)+0.8(%CaO) +0.6(%MnO)-0.9(%Al2O3)}+2.5log(%T.Fe) -3.54 (1600°C) (ii) log[(%P2O5)/{[%P]2•(%FetO)5}]=8.87log{(%Na2O) +0.1(%MgO)+0.7(%CaO)+0.6(%MnO) -0.9(%Al2O3)}-14.94 (1600°C)
The activity coefficients of P2O5 and FetO were expressed in terms of the mole fraction of the slag components, and the effects of CaO, MnO, and Al2O3 on these activity coefficients were investigated.
The relationship between phosphate capacity and theoretical optical basicity for the Na2O-based slags containing CaO, MnO, or Al2O3 was examined and compared with that for the CaO-based slag. The phosphate capacities of these slags could not be represented uniquely by the theoretical optical basicity. Furthermore, the manganese distribution observed in this experiment was analyzed and compared with that reported for the CaO-based slag.