Isothermal phase diagram of CaO–SiO2–Nb2O5-5wt% Fe2O3–TiO2 system at 1200 °C

Abstract

The lack of thermodynamic data such as the phase diagram of CaO–SiO2–Nb2O5–Fe2O3–TiO2 system has seriously hampered the comprehensive utilization of niobium, titanium and other resources in the Bayan Obo tailing. In this study, phase equilibria of the CaO–SiO2–Nb2O5–Fe2O3–TiO2 system at 1200 °C were investigated using high temperature equilibrium experiment for the first time, and the CaTiO3–Ca10Nb2Si6O27–Ca2SiO4–Ca2Nb2O7 solid phase coexistence region was determined. Afterwards, based on the high temperature equilibrium experiments, the liquidus surfaces of the liquid + CaTiO3 and liquid + SiO2 equilibrium coexistence regions in CaO–SiO2–Nb2O5-5wt% Fe2O3–TiO2 system at 1200 °C were calculated using mathematical methods of interpolation and fitting. Finally, the 1200 °C isothermal phase diagrams of CaO–SiO2–Nb2O5-5wt%Fe2O3–TiO2 system were plotted. The results of the study can provide theoretical guidance for the enrichment and extraction processes of niobium and titanium resources in the Bayan Obo tailing.