Progress in the extraction and separation of rare earths and related metals with novel extractants: A review

Rare earths (REs) play a key role in high-tech fields and the associated thorium is a vital element for nuclear energy. However, to be used in high-tech industry or nuclear energy, these elements must first be recovered from the deposits and purified. As solvent extraction is the main technology for the recovery and purification of the metals, the review mainly presents our recent works on the extraction and separation of tetravalent cerium cation by neutral -aminophosphonates, the individual rare earth separation by -aminophosphonic acids, and the continuous preparation of high-purity thorium. The extraction and separation of some other metals are also discussed.