Equilibrium between Molten Iron Alloys and CaO-Al₂O₃-CaS Slags Saturated with CaS

Abstract

Experimental study was conducted on the equilibrium between molten Fe-Al-S alloys and CaO-Al₂O₃-CaS slags in a CaS crucible at 1 873 K. The equilibrium relation could be represented by the following reaction :
3CaO(s)+2Al+3S=3CaS(s)+Al₂O₃(s)
By application of the Gibbs-Duhem equation, integration techniques were developed which allowed us to calculate the activities of CaO and Al₂O₃ from the slag composition and the activities of aluminum and sulfur in the alloy. The free energy of the above reaction was also determined as well as the free energies of formation of calcium aluminate compounds, CaO·Al₂O₃(CA), CaO·2Al₂O₃(CA₂), and CaO·6Al₂O₃(CA₆)from their constituent oxides.