Subsolidus Phase Relations in the CaO–SiO₂–Nb₂O₅–La₂O₃ Quarternary System at 1273 K

摘要

The lack of phase diagrams and other related thermodynamic information for the silicate slag system with additions Nb and REE seriously restrict the comprehensive utilization of REE-Nb-Fe ore deposit resources in China. In this study, the equilibrium phase relations in the CaO–SiO_(2)–Nb_(2)O_(5)–La_(2)O_(3) quarternary system at 1273 K and 1473 K were investigated experimentally using the high-temperature equilibrium experiment followed by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). Subsolidus phase relations in the CaO–SiO_(2)–Nb_(2)O_(5)–La_(2)O_(3) quarternary system and La_(2)O_(3)–SiO_(2)–Nb_(2)O_(5) ternary system were determined and presented in the form of independent tetrahedron regions and triangle regions, respectively, according to the Gibbs Phase Rule, the isothermal section for 5 wt %La_(2)O_(3) and 10 wt %La_(2)O_(3) at 1273 K were also constructed respectively.