Crystallization is a family of techniques that allows rare earth elements (REEs) to be separated from other elements and obtained as a concentrate, or as a pure compound. However, the similar properties of the REEs usually makes crystallization unsuitable as a method to separate them from each other. An exception is the separation of Ce(IV) and Eu(II) from trivalent REEs.<br/>Currently, reaction crystallization is the dominant technique for separation of REEs by crystallization. Antisolvent crystallization is a promising alternative for selective separation of REEs as a concentrate or purer phases if coupled with other techniques such as solvent extraction. By antisolvent crystallization, it is possible to obtain REE salts that have moderate to high solubilities in aqueous solution, which could be advantageous in further processing, e.g., for individual REE separation. <br/>In this talk, fundamental aspects common to all methods of crystallization of ionic compounds are covered, and the underlying chemistry is highlighted, to explain the behavior of the different REEs and to give a deeper understanding of the phenomena at hand. The development of novel flowsheets for antisolvent crystallization are highlighted. Furthermore, the effect of process conditions such as supersaturation, agitation mechanism, antisolvent type and concentration, the importance of the feeding point with respect to local supersaturation and seeding are assessed, with emphasis on the final crystal product quality.

Separation of rare earth elements by crystallization techniques

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.