T25 The Changing Landscape of Energy Geology (Posters)

Sunday, 15 October 2023
8:00 AM - 5:30 PM
Hall B

REE CONTENT IN ANTHRACITE AND BITUMINOUS COAL WASTES FROM PENNSYLVANIA

Paper number: T25-5
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

Due to the current high demand but geographically limited supply of rare earth elements (REEs), potential alternative sources for these critical minerals (USGS, 2022) are being investigated. Certain instances of coal and coal byproducts/waste can show enrichment in REEs and could be economically important resources for REEs and other critical minerals.

Samples of coal and wastes from various phases of coal processing and combustion were sampled from facilities handling anthracite coal from northeastern Pennsylvania and facilities handling bituminous coal from southwestern Pennsylvania. Samples were analyzed for coal quality using proximate, ultimate, and sulfur forms analyses, and for major and trace elements. Trace element analysis included REEs by ICP-MS with fusion digestion. Sample fractions were also analyzed following density separation (ρ=1.60). Initial results indicated that the coal waste streams (refuse coal, process waste coal, and power plant ash) were enriched in REEs relative to average upper continental crust (UCC), whereas the processed coal (clean coal and dewatered slurry) had REE concentrations similar to or lower than average UCC. However, total REE concentrations were below the U.S. Department of Energy cutoff grade of 300 ppm (US DOE, 2017) in all samples analyzed.

For each waste type evaluated, REE concentrations were similar (generally ±10%) between the anthracite and bituminous samples. Based on correlations with ash yield and relatively higher concentrations in the denser sink fraction, REEs appear to be more abundant in the mineral fraction of the coal than in the organic fraction, which is consistent with many previous studies. These results suggest that the beneficiation process used to prepare coal for power generation could concentrate REEs through its waste streams. As much of this waste remains untapped, it is a potential resource for REE extraction using existing pilot-scale approaches based on waste coal as feedstock.

U.S. Geological Survey, 2022 list of critical minerals, https://www.usgs.gov/news/national-news-release/us-geological-survey-releases-2022-list-critical-minerals.

U.S. Department of Energy, National Energy Technology Laboratory, 2017, Rare Earth Elements, https://netl.doe.gov/sites/default/files/2017-11/Program-141.pdf.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-391518

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