Sulfide capacity and phase equilibria of MnO-TiO₂-MnS system at 1723 K

The sulfide capacity and the activity of MnO in the MnO-TiO₂ system were measured at 1723 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.