Phase Equilibria of CaO-SiO2-La2O3-Nb2O5 System in Reducing Atmosphere

Abstract

In the current work, the phase equilibria of CaO-SiO2-La2O3-Nb2O5 system at 1200 °C in reducing atmosphere (PO2 = 10−15 atm) was investigated according to the melting separation process for extracting lanthanum and niobium resources from Bayan Obo tailing. High temperature equilibrium experiment, scanning electron microscope, and energy dispersive spectrometer (SEM-EDS) were used to determine the compositions of equilibrium phases. According to the experiment results, the phase equilibria of the CaO-SiO2-La2O3-Nb2O5 system in reducing atmosphere were ascertained and the 1200 °C isothermal phase diagram of CaO-SiO2-La2O3-Nb2O5 system in reducing atmosphere was constructed. The research results not only play an important role in guiding the development of the lanthanum and niobium extraction process, but also enrich the thermodynamic data of relevant silicate slag systems.