Phase equilibria of CaO-SiO 2 -Gd 2 O 3 system and the feasibility of rare-earth recovery

Abstract Phase equilibria of the CaO-Gd 2 O 3 -SiO 2 slag system at 1773 K and 1873 K were investigated by characterizing equilibrated samples with electron probe microanalysis (EPMA). Four three-phase equilibria and five two-phase equilibria are formed in the CaO-Gd 2 O 3 -SiO 2 ternary system at 1773 K in argon atmosphere. While three three-phase equilibria, six two-phase equilibria and one liquid phase are presented in the system at 1873 K. The isothermal section of the phase diagram is thereafter constructed based on the experimental results. The feasibility of the rare earth recovery is also discussed based on the phase relations.