THERMODYNAMICS OF O, N, AND S IN LIQUID FE EQUILIBRATED WITH CAO-AL2O3-MGO SLAGS

Nitrogen and S distribution ratios between CaO-Al2O3-MgO slags and liquid Fe were measured at 1873 K as a function of Al (or Mg, Ca) content in metal, using CaO, MgO, and Al2O3 crucibles. Based on the results for the solubility product of MgO, the equilibrium constant, K(Mg), for the reaction MgO = Mg underbar + O underbar and the first-order interaction parameter, e(O)Mg (e(Mg)O, were estimated to be log K(Mg) = 7.8 +/- 0.2 and e(O)Mg = -190 +/- 60 (e(Mg)O = -290 +/- 90), respectively. The activities of Al2O3 at the slag compositions double-saturated with CaO/MgO, MgO/MgO.Al2O3, and MgO.Al2O3/CaO.2Al2O3 components were obtained from the S distribution ratios between slag and metal, coupled with the reported values of sulfide capacities. Nitride capacities were also estimated from the N distribution ratios and the activities of Al2O3.