Processing of Korean monazite concentrate for the recovery of rare earth metals (REMs)

Abstract

Rare earths metals (REMs) have gained immense awareness due to their inimitable properties and wide range of applications. REMs are naturally present in minerals like monazite, bastnasite, apatite, etc. The present work is focused on comparative study for the recovery of REMs from original Korean monazite and dephosphorized monazite by acid treatment. Direct leaching of original sample using dilute HCl at elevated temperature for 2 hrs maintaining pulp density < 100 g/L results in ~25% REMs dissolution, which increases to 45% by two-step leaching due to the presence of phosphate in the mineral which hinders the REMs leaching due to the formation of RE complex. However, > 93% REMs is leached in single stage from dephosphorized monazite under same conditions. Systematic dephosphorization studies were made using pyro/ hydrometallurgical methods. Further precipitation, solvent extraction or ion exchange method are used for the selective separation of REMs from the generated leach liquor.