Activities in CaO-MgO-Al₂O₃ Slags and Deoxidation Equilibria of Al, Mg, and Ca

Abstract

The equilibrium experiments between CaO-Al₂O₃-MgO-0.06 to 0.85%MnO-0.5 to 2.1%Fe_tO-0.07 to 0.3%S (mass content in %) slag and liquid iron were carried out at 1823 and 1873 K in order to assess the activities of Al₂O₃ and MgO along the spinel (MgO·Al₂O₃) saturation line. The activities of CaO in an entire liquid region were first determined at 1823 and 1873 K from the reported values for sulfide capacity, coupled with the activity coefficients of CaS which were estimated from those in the CaO-Al₂O₃ slags. On the basis of these iso-activity lines for CaO, the activities of Al₂O₃ and MgO were calculated by using he method of Schuhmann, in which the assessed activities of Al₂O₃ and MgO on the spinel saturation line were taken as the starting points. The activity coefficients of Fe_tO and MnO along the spinel saturation line were determined and the deoxidation equilibria of Al, Mg, and Ca were discussed.