ENHANCING RECOVERY OF RARE EARTH ELEMENTS FROM APPALACHIAN COALS AND UNDERCLAY

Rare earth elements (REE) are critical for essential technologies used in renewable energy, communication, transportation, and national defense. Although these elements are vital to economic and national security, the U.S. is currently >95% import reliant on rare earth metals and compounds, leading to significant supply chain insecurities. Securing a domestic supply of REE has become a national priority. Coal is a promising domestic resource for these elements because it is abundant, mining infrastructure is already in place, and enrichment of REE can rival that of conventional ores in select coal seams. Additionally, coal byproducts such as fly ash and refuse can be used as sources of REE, providing an opportunity to increase REE production while simultaneously addressing environmental issues related to coal waste disposal. With some of the largest coal reserves in the country, states within the Appalachian Basin, including West Virginia, can play a key role in maintaining the nation’s supply of REE. Previous studies have indicated that REE in Appalachian Basin coals and coal byproducts are often shielded by a resistant aluminosilicate matrix that impedes recovery of REE through traditional methods. This study explores the use of calcination and alkaline roasting with sodium carbonate as methods to decompose the silicate matrix and enhance recovery of REE in West Virginia bituminous coals and underclay. The work also compares the performance of citric acid and hydrochloric acid as leaching agents to extract REE. Results suggest that alkaline roasting prior to acid leaching significantly improves recovery of REE from Appalachian coals and underclay. Additionally, citric acid outperformed hydrochloric acid in terms of total REE recovery when used as leaching agents after alkaline roasting.