231-6 Evaluating Rare Earth Element Potential and Mineralogical Associations in Acid Mine Drainage Systems, Flint Run, Jackson County, Ohio

Session: Critical Mineral Resources and Recovery in the Americas: Emerging Methods in Exploration and Sustainable Extraction (Posters)

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The mining of coal exposes associated Fe/S minerals to atmospheric oxygen and water which results in dissolution and precipitation of aforementioned minerals, known commonly as acid mine drainage (AMD). In some cases, AMD contains high concentrations of rare earth elements (REEs). REEs are important components of cleaner and renewable energy sources and AMD could be an alternative source of these elements. Here we show the mineralogical association and chemical constraints on REEs in an AMD system. Flint Run in Jackson County, Ohio is a coal spoils dump with prominent AMD history in the surface waters. Despite the AMD activity, we found that there is no REE enrichment in the sediment at Flint Run. The pH of sediment leachate at the surface is 6.77 while samples near the water table had a pH between 2.39–2.92­. Surface samples contained minerals such as calcite and gypsum, which have precipitated as a result of BYPRO, a paper mill byproduct used to buffer the acidity of the spoils. Mineralogically, a transition from montmorillonite to illite clay was seen at the water table. Pyrite, a mineral commonly associated with coal and important in AMD formation, is not found at water table depths (10 ft), but is present above and below the water table. The absence of pyrite is supported by the low pH, under which pyrite is not stable. The reappearance of pyrite suggests possible precipitation by sulfate-reducing bacteria. The lack of elevated REEs at this site are likely a result of the acidic conditions leaching concentrations from the sediment. Extraction of REEs from AMD fluids may be a more profitable approach in locations with acidic sediment like Flint Run.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8485

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