ASSESSING COAL ASH RESOURCES AND POTENTIAL FOR RARE EARTH ELEMENT DEVELOPMENT IN THE UNITED STATES

Heavy reliance on imported rare earth elements, particularly from China, underscores the need to develop these resources within the United States. The objective of this study was to quantify coal ash resources and the potential rare earth elements (REE) extraction within the US. We compiled data on spatiotemporal variability in coal ash resources and disposition from the US Energy Information Agency, US Geological Survey, and American Coal Ash Association and data on levels of REE from the literature. Results show that a total of ~2.6 billion tons of accessible coal ash resources accumulated in the US from 1950 to 2020. Power plants represent the major source of coal ash, accounting for ~80% of total coal ash. Coal ash represents an average of ~10% of coal combustion, ranging from 11% for bituminous to 14% for lignite. About 60% of coal ash is considered accessible in landfills and ponds with the remaining ~40% used or sold. Information on REE levels in coal ash is limited. Literature data show moderate concentrations of REE in ash from the Powder River Basin in Wyoming which are fairly readily extractable. Although REE levels are higher in Appalachian coal ashes relative to those in the Powder River Basin, these are more difficult to extract. Rising concerns about surface water or groundwater contamination in the vicinity of coal ash deposits underscores the value of using ash for REE extraction to partially offset remediation costs. Continued research on these ash deposits should enhance our understanding of the potential of ash as a REE resource and value in reducing environmental contamination.