Hydrometallurgical Studies for the Recovery of Rare Earths from Micro-Granite Ore Deposit of Bhatikhera, Rajasthan, India

Abstract

This paper presents results on the characterization and hydrometallurgical studies for the recovery of Rare Earth Elements (REE) from micro-granite type hard rock REE deposit of Bhatikheda, Siwana Ring Complex, Rajasthan, India. The total REE (TREE) content of the ore is 0.36%. Heavy REE (HREE) constitutes about 40% of the TREE by weight. Allanite, zircon and gittinsite were identified as the major REE bearing phases. The nature of occurrence of REE phases in the ore is widely varying with the presence of fully liberated grains to those which occur very finely disseminated in lighter gangue minerals. Physical beneficiation using gravity-based separation techniques gave suboptimal performance. Agitation leaching of ground ore with different mineral acids gave good solubilisation of light REE (LREE), about 75%, but the leach recovery of HREE was only 40%. However, sulfation roasting followed by aqueous leaching (SRAL) yielded leach recovery of 85% of total REE under optimised conditions. The lean tenor of TREE in the leachate coupled with its complex solution chemistry necessitated use of ion exchange (IX) process with strong cationic resin in lieu of conventional solvent extraction based separation and purification. The dissolved REE values from the purified liquor were quantitatively precipitated in the form of TREE fluoride using HF as the precipitant. The final product was about 90% pure on dry weight basis. An integrated process scheme for the recovery of TREE values from the Bhatikhera hard rock deposit is designed-