Evaluation of Chelating Resins Efficiency in Recovering Rare Earth Elements from Sulphate-Rich Acid Solutions

Abstract

This work investigates the use of chelating resins for recovering rare earth elements (REE) from a laboratory solution with pH and sulphate concentrations similar to those of an acid mine drainage (AMD). The loading experiments were performed in ion exchange columns, fed with a solution at pH 3.5 containing 0.49 g L^-1 of REE, 0.06 g L^-1 of impurities and 1.11 g L^-1 of sulphate ions. The highest loading was obtained for the PUROLITE^® MTS 9500 resin activated with Na⁺, and it was 101.8 mg g^-1, which corresponds to a sorption efficiency of 73%. The loading results showed that the resins have greater selectivity for REE over impurities. Regarding elution, greater efficiency (i.e., 96%) was obtained with the resin PUROLITE^® MTS 9300; however, this resin presented lower loadings. A final liquor with a maximum REE concentration of 1.72 g L^-1 and maximum impurities concentration of 0.02 g L^-1 was obtained for PUROLITE^® MTS 9500 resin activated with H⁺, which presents an elution efficiency of 80%.