Calculation of CaS and MnS activities and their application to calcium treatment of steel

For the CaS-MnS system, a regular solution model for the solid solution and an ideal solution model for the liquid phase were adopted to calculate the activities of CaS and MnS at steelmaking temperatures. The independently calculated activities for the solids and liquids agreed well at the liquids compositions. The calculated results have been used to study the interactions between oxide and sulphide inclusions with the melt, during and after calcium injection, and to interpret the kinetic paths towards thermodynamic equilibrium.