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.