MINERALOGICAL ANALYSIS AND RECOVERY OF RARE EARTH ELEMENTS FROM U.S. DOMESTIC COAL RESOURCES

Rare earth elements and yttrium (REY) are essential for the development of low-carbon, renewable energy technologies. Increasing demand from energy and high-end technology manufacturing sectors is currently bounded by a limited domestic supply of REY. To support the development of emerging renewable energy technologies, it is necessary to identify domestic sources of REY that are both reliable and economical. United States’ domestic coal and coal utilization byproducts are promising sources of recoverable REY. This study focuses on the characterization of REY-bearing minerals and the development of a selective, aqueous solution-based process to recover REY and other critical elements from coal and coal bearing strata. Multi-modal characterization techniques, including quantitative SEM-based microanalysis, are used to determine the elemental and mineralogical properties of field and laboratory reacted samples. This work demonstrates the effect of different leaching solutions on the physical and mineralogical properties of clay and other clay-rich sedimentary source rocks. We also examine the efficacy of various organic acid-based solutions for the extraction and recovery of REY. Our results provide greater insight into the mineral distribution and binding environment of REY and other critical elements in underclay and other sedimentary geologic materials associated with coal bearing strata. Furthermore, we demonstrate the use of various low molecular weight organic acid-based solutions for selective leaching and recovery of REY and critical metals from clay.