Some aspects on MgO solubility in complex slags

A magnesia capacity is defined, C_Mg²⁺ = (%Mg²⁺)/a_MgO and its relation to optical basicity is examined and discussed. The solubility of MgO in complex slags, in equilibrium with magnesiowustite, is derived from the activity of MgO in the magnesiowustite and from the magnesia capacity as given by the slag's optical basicity. It is found that the activity of MgO in the magnesiowustite can be derived from %O] assuming ideality in the FeO–MgO system at 1600°C. It is also found that the MgO saturation contents in complex slags are accurately derived from the equation: In addition, the relation between the magnesia capacity and the capacities of vanadium and phosphorus is examined and the relative basicity of the oxides is discussed.