Rare-Earth Element Phase Associations in Four West Virginia Coal Samples

Abstract

Rare-earth elements are critical components of technologies used in renewable energy, communication, transportation, and national defense. Securing supply chains by developing domestic rare-earth resources, including coal and coal byproducts, has become a national priority. With some of the largest coal reserves in the country, states within the Appalachian Basin can play a key role in supplying these elements. Understanding rare-earth element phase associations and the processes that lead to enrichment in these coals will inform resource prospecting and recovery techniques. This study used sequential leaching in addition to scanning electron microscopy and energy-dispersive X-ray spectroscopy to identify rare-earth element modes of occurrence in WV coals. The results indicate that heavier elements have a stronger association with organic matter and that phosphate minerals are primary sources of both heavy and light rare-earth elements. However, these phases are shielded by a resistant aluminosilicate matrix that can impede the recovery of rare-earth elements using traditional methods.