Sampling and Characterization of Coal Basins as an Alternative Rare-Earth Element Resource

J. Kay, B. Folkedahl, C. Nyberg, I. Feole
University of North Dakota,
United States

Keywords: REE alternative sources, REE resource characterization, Coal


The University of North Dakota (UND) through the Energy & Environmental Research Center (EERC) and the Institute for Energy Studies teamed with the University of Kentucky Center for Applied Energy Research, Microbeam Technologies Inc., the Kentucky Geological Survey (KGS), the North Dakota Geological Survey (NDGS), and the mining industry to execute a contract with the U.S. Department of Energy National Energy Technology Laboratory (NETL) to obtain and characterize samples of U.S. domestic precombustion coal and coal-related materials with a minimum concentration of 300 parts per million (ppm) total rare-earth elements (TREEs) as the material is removed from the ground, with no processing other than drying. The project team obtained and analyzed a total of 609 samples of coal or coal-related materials from western and eastern regions of the United States that have potentially high levels of TREEs in regions that are not well characterized. In the western United States, the team conducted most of the sampling and characterization in the Fort Union Group within the Lignite/Williston Basin (herein referred to as the Williston Basin) and within the Powder River Basin (PRB). Previous work conducted by UND and NDGS has revealed high levels of TREEs in lignite coal seams from the Williston Basin that are associated with volcanic ash (tuffaceous) deposition during Paleocene formation of these sediments. Through this effort, UND collected and analyzed a total of 522 samples of coal and coal-related materials from the Williston Basin, PRB, and Gulf Coast sampling locations. Of the 522 materials, 23 had TREEs greater than 300 ppm on a whole-dry-sample basis as pulled from mines, outcrops, or power plant ash bunkers. Although the total number of samples with TREEs measuring >300 ppm was relatively small, another 21 samples had levels >250 ppm and another 35 had levels >200 ppm. Samples showing >300-ppm TREEs on a mass basis were from the western resources (23) and the eastern Appalachian region (six). The highest TREE content measured in any of the coal samples was 1024 ppm from the H bed lignite of western North Dakota. The highest TREE concentration in any of the ash samples was 1089 ppm, which was collected from pilot-scale combustion of Harmon lignite coal from western North Dakota. None of the samples with TREEs ≥300 ppm had heavy REEs/light REEs ≥1, which is consistent with other studies. On an ash basis, more than 250 coal samples had a TREE concentration higher than 300 ppm. Data gained and lessons learned from this work are contributing to the UND EERC-led Williston Basin CORE-CM project. Sponsored by NETL, this program is one of 13 programs awarded across the nation to examine the supply chain for domestic production of high-value, nonfuel products from carbon ore, REEs, and critical minerals (CORE-CM).