FROM WASTE TO WEALTH: ANALYZING RARE EARTH ELEMENTS IN COAL REFUSE PILES

Western Pennsylvanian coal refuse piles have emerged as a potential source of rare earth elements (REEs) and critical minerals offering opportunities for resource recovery that could benefit both economic growth and environmental sustainability. Eureka Mine 40 is an inactive coal mine from the early 1900s, located in Scalp Level, Pennsylvania. During mining, waste byproducts were accumulated into a coal refuse pile that borders Little Paint Creek and has been contaminating the creek with acid mine drainage since its development. Analysis of LiDAR images and GIS data has revealed that the Eureka Mine 40 refuse pile to be approximately 11,000 cubic meters in volume. REEs are an essential resource for advancing technologies and recoverable concentrations have been found in coal refuse piles leading to an interest in evaluating these sites of long-term environmental contamination for reclamation. REEs are a scarce resource, especially in the United States where coal refuse piles could be a much-desired domestic source. Nine samples were tested for their major, minor, and trace elements concentrations from bulk whole rock samples collected at the Eureka Mine 40 refuse pile. These samples had a range of different lithologies from leeched clays, soil, oxidized shales, slag, the coarse and fines (<60 microns) of the refuse pile, and coal. These samples had a wide range of major element compositions, while their REE compositions were seen to be consistent across the sample set. Concentrations of light REEs were enriched with respect to heavy REES across the samples. The average concentration of REEs in the samples was 222.1 ppm, with a standard deviation of 43.6. The Department of Energy considers concentrations near 500 ppm to be economically viable for reclamation. Based on the results analyzed, the Eureka Mine 40 refuse pile would not be economically profitable to reclaim based on REE concentrations alone, however the critical minerals could provide an incentive to complete environmental remediation.