Recovery of High Purity Y2O3by Solvent Extraction Route Using Organo-Phosphorus Extractants

Abstract

A rare earth concentrate assaying about 60% Y₂O₃, is generally obtained directly from Y rich minerals like xenotime or from monazite after preliminary fractionation of rare earths chloride as is practised currently at Indian Rare Earths Ltd.. Alwaye. Using this intermediate concentrate. SX process has been developed in our laboratory to purify Y (>99.9%) in presence of NH₄SCN. The process parameters for DEHPA and PC 88A systems have been optimised using a computer program in BASIC. The DEHPA flowsheet has been tested at bench-scale to produce several kilograms of 93% Y₂O₃. During these trials certain problems were faced due to high acidities. With PC 88A there were no problems and the flowsheet based on the solvent was confirmed at pilot-plant level. The solution containing 93% pure Y₂O₃, is purified further by another cycle of SX with 50% TBP in kerosene in presence of 1.0 M NH₄ SCN. The impurities are extracted leaving >99.9% pure Y₂O₃ in the aqueous phase. The process parameters optimised for obtaining >90% recovery of Y₂O₃ are described.