Thermal treatment for the separation of phosphate and recovery of rare earth metals (REMs) from Korean monazite

•Effective process for separation and recovery of rare earth metals.•Alkaline thermal treatment under optimized condition is used to dephosphorize monazite.•99% phosphate was separated and recovered as value added product of sodium tri-phosphate.•The oxide of rare earth concentrate was leached in chloride medium to recover high percentage of rare earth metals.

Systematic study for thermal decomposition of monazite to remove phosphate as a valuable product using Na2CO3 and NaOH roasting processes to validate the TG/DTA studies is reported here. Monazite in 1:1 wt. ratio with Na2CO3 and NaOH requires a temperature of 900 °C and 400 °C, respectively, for 120 min in order to achieve complete conversion of rare earth phosphate into its oxides. The roasted mass was washed, dried and leached in 6 M HCl for 2 h, pulp density 30 g/L at 80 °C which results in >90% REMs recovery. Leach liquor generated will be further processed by solvent extraction and precipitation processes.