Sulfide Capacity and Phase Equilibria of MnO–TiO₂–MnS System at 1723 K

Abstract

The sulfide capacity and the activity of MnO in the MnO–TiO₂ system were measured at 1 723 K. Also, the phase equilibria of the MnO–TiO₂–MnS system were estimated by measuring the solubility of MnS in the melts. The thermodynamic behavior of MnO and TiO₂ in the MnO–TiO₂ system exhibits a negative deviation from ideality at 1723 K. The sulfide capacity increases and the activity coefficient of MnS decreases with increasing MnO content in the MnO–TiO₂ system. The solubility of MnS in the MnO–TiO₂ system increases with increasing MnO content up to about 50 mol%, followed by nearly constant value of about 80 mass% MnS. The solubility of MnS equilibrated with MnO is in good correspondence with the value obtained from the phase diagram of the MnO–MnS binary system. Compared with the phase diagram of the MnO–SiO₂–MnS system, a homogeneous liquid region in the MnO–TiO₂–MnS system is found to be wider at the same temperature. The activity of MnS increases with increasing MnS content at a fixed MnO/TiO₂ ratio in the MnO–TiO₂–MnS system. Also, the activity slightly decreases with increasing TiO₂ content at a fixed MnS/MnO ratio, whilst MnS activity rapidly decreases by increasing the content of MnO at a constant TiO₂/MnS ratio.