STRUCTURAL STATE OF REE IN ION ADSORPTION DEPOSITS: A XANES/EXAFS STUDY OF LATERITES FROM MADAGASCAR AND CHINA

摘要

Lateritic ion adsorption deposits (IADs) are the world’s dominant source for heavy rare earthelements (HREE: Gd-Lu), which are critically important for the production of high strengthmagnets for the renewable energy and low carbon transport industries. Despite their highimportance they are currently only mined in S.E. China. Despite low REE concentrations(0.05 - 0.2 wt% RE_2O_3), exploitation of IADs is economically viable through REE liberation byacid leaching. Similar but higher grade IADs, currently explored in Brazil, Madagascar andSE Asia, may provide alternative supply of HREE, but it is unclear whether these lateritic clays aredirect structural analogues to the easily leachable Chinese clays.