Phase equilibria of the CaO–SiO2–TiO2–Al2O3–MgO system in air at 1250–1400 °C

The equilibrium phase relations of the CaO–SiO2–TiO2–Al2O3–MgO system were investigated experimentally in air at 1250–1400 °C using a high-temperature equilibration/quenching technique, followed by direct phase analysis by scanning electron microscopy equipped with X-ray energy dispersive spectroscopy. The equilibrium solid phases of silica, rutile, and pseudobrookite solid solution were found to coexist with the liquid phase. The 1300–1400 °C isothermal sections were constructed based on the experimentally measured liquid compositions. The experimental results were compared with simulations using MTDATA and FactSage thermodynamic software and their databases. This study provides guidelines for the selective crystallization of pseudobrookite from titania-bearing slag.