Dissolution Thermodynamics Of MgO,Al₂O₃,TiO₂and CaO In CaCl₂and CaCl₂-NaCl Molten Salts

In the temperature range of923-1173K, MgO, Al2O3and TiO2saturated molten salt CaCl2and CaCl2-NaCl were prepared and chemical analysis methods was used to study the solubility of the oxides in molten CaCl2and CaCl2-NaCl. The activity coefficient of the oxides was calculated through phase equilibrium between the oxides in the molten salts and in its pure state. With increasing temperature, the solubility of the oxides in the molten salts was increased and the activity coefficient was decreased. In the mixed molten salt the solubility of the oxides is lower than the solubility in the CaCl2, the addition of NaCl reduce the solubility of the oxides in molten CaCl2. The activity coefficient in molten CaCl2-NaCl is higher than that in in CaCl2, showing that the oxides suffered strong attraction from CaCl2than from CaCl2-NaCl. This work provides the basic data for the molten salt extraction and refining of metals.By electromotive force method was used to determine the activity of5%wt CaO in equimolar molten CaCl2-NaCl in the temperature range of923-1173K. According to the standard electromotive force reported in reference and the Nernst equation the activity and activity coefficient of CaO in molten CaCl2-NaCl was calculted.With increasing temperature, the activity coefficient of CaO decreased. This conclusion is consistent with the variation trend of CaO activity with temperature in saturation state.