Phase composition and liquidus temperatures of the CaO–SiO2–MgO-13 wt%Al2O3–TiO2 system in reduction conditions

Effects of TiO₂, binary basicity and MgO content on the liquidus temperatures of TiO₂–CaO–SiO₂–MgO–Al₂O₃ slags were experimentally studied in equilibrium with carbon. The experimental techniques include high temperature equilibration, quenching and Electron Probe X-ray Microanalysis (EPMA). It was found that the major primary phase in the composition range investigated is M₃O₅ (M = Ti, Mg, Al). The liquidus temperatures increase with increasing TiO₂ and MgO contents, whereas decrease with increasing CaO/SiO₂ mass ratio. The experimentally determined liquidus temperatures are much higher than the predicted ones by FactSage and the primary phases between the experiment results and predictions are also different. The mole fractions of Al₂TiO₅ and Ti₃O₅ in the M₃O₅ phase decrease, but MgTi₂O₅ increases with increasing MgO content and CaO/SiO₂ in the samples. Moreover, the proportions of Al₂TiO₅ and MgTi₂O₅ in the M₃O₅ phase decrease, while Ti₃O₅ proportion in the M₃O₅ phase increases with increasing the reaction time. The mole ratio of Ti³⁺/Ti⁴⁺ in the M₃O₅ phase decreases with MgO content and CaO/SiO₂ mass ratio in the samples but increases with increasing reaction time.