Subsolidus Phase Relations in the CaO-SiO_2-Nb_2O_5-La_2O_3 Quarternary System at 1 273 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_2O_5-La_2O_3 quarternary system at 1 273 K and 1 473 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_2O_5-La_2O_3 quarternary system and La_2O_3-SiO_2-Nb2O_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_2O_3 and 10 wt%La_2O_3 at 1 273 K were also constructed respectively.