Challenges for the production of heavy rare earth elements from hard rocks

Heavy rare earth elements (HREE) have been produced from ion-adsorption type deposits in southern China. Despite extremely low REE grades (0.2-0.05wt.%) of the deposits, exploitation of REE from this deposit type is very competitive because REE are easily extracted from the ores by ammonium sulfate solution. For the purpose of producing HREE outside China, a variety of sources are examined. They are 1) ion adsorption deposits outside China, 2) HREE-rich carbonatites, 3) alkaline rock complexes, 4) sedimenthosted phosphates associated with uranium mineralization, 5) xenotime associated with tin granites, and 6) iron-oxide apatite deposits. The major challenges for the production of HREE from these hard rock deposits are mineral beneficiation, REE extraction and treatment of radioactivity. © 2014 Soc. Mater. Eng. Resour. Japan.