Separation of rare-earth ions in strong magnetic fields

The rare earths are a group of metals that are of high technological importance, because of their use in permanent magnets fluorescent lamps, batteries and catalysts. The rare earths occur as mixtures of elements in nature and these mixtures have to be separated before the rare earths can be used in applications. Two major challenges in the field of separation of rare earths by solvent extraction are: (1) the development of a highly selective extraction agent that is able to remove one rare-earth element from a mixture without co-extraction of the other elements; (2) the development of a process that allows extraction of rare earths from a chloride solution to an organic phase by an extractant belonging to the class of the solvating extractants. The rare-earth industry prefers chloride solution extractions because hydrochloric acid is cheaper than nitric acid, and because waste water treatment is simpler for chlorides compared to nitrates. Solvating extractants that extract metals salts rather metal ions are the preferred type of extractants, because they allow loading a high amount of rare earths in the organic phase, which can then be easily back extracted by water instead of strong acids. This project is about the science behind a new separation process called “split anion extraction”, which makes the rare earths extraction from a chloride solution possible through the use of thiocyanate or nitrate ionic liquids via a solvating mechanism.