Selective dissolution of rare-earth element carbonates in deep eutectic solvents

Dissolution in choline-chloride based deep eutectic solvents (DES) of rare earth elements (REE) from high-purity single carbonate salts of Y, La, Ce, Nd and Sm and from their multicomponent mixtures and also bastnäsite mineral was assessed with a prospect to gain an understanding on the leaching behavior of bastnäsite ores as REE source from DES suspensions. Urea, malonic acid and citric acid were used in different proportions with choline chloride in order to form deep eutectic solvents with desired viscosity and functionality. The results obtained prove promising for use insolvato-metallurgical processes in terms of selective dissolution of the higher-atomic-number (Z) rare earth elements at the expense of the lower-ZREEs and the gangue-originating metal impurities, thus initiating separation among the different REE members from the early hydrometallurgical steps.