Recovery of Rare Earth Elements from Coal Mine Drainage

Technology Partner: West Virginia University Research CorporationAward Number: FE0026927
Project Duration: 3/1/2016 – 6/30/2019
Total Project Value: $4,339,414

Key Technology Area: Process Systems
Project Partners: Rockwell Automation; Tetra Tech, Inc.;

In Phase 2 of the project, West Virginia University and its partners will develop a cost-effective and environmentally benign process to recover rare earth elements (REEs) from solid residues (sludge) generated during treatment of acid coal mine drainage (AMD). This project will take advantage of autogenous processes that occur in coal mines and associated tailings which liberate, then concentrate, REEs. Phase 1 findings showed elevated concentrations of REEs, particularly in low-pH AMD, and nearly all precipitating with more plentiful transition metals in the AMD sludge. REE extraction using hydrometallurgical methods produced a concentrate with 4.6 percent total REE content. A techno-economic analysis also found that REE extraction from AMD sludge is economically attractive with a refining facility projected to generate positive cash flow within five years. During Phase 2, a

and Virginia Polytechnic Institute and State University

continuously operating bench-scale unit will be constructed and operated, yielding 3 grams per hour of REE concentrate. In Phase 1, AMD treatment residues were identified as a domestic source of REE feedstock. In addition, an economically attractive extraction and refining process was identified with the potential to generate significant income for operators of AMD treatment sites, and relieve the U.S. manufacturing industry’s reliance on foreign REE supplies. Estimates based on the volume of AMD generated in Pennsylvania and West Virginia suggest their AMD sludges represent approximately 610 to 2,700 tons of REEs per year— roughly sufficient to supply the 800 tons that the U.S. defense industry needs each year. In addition, a survey of 154 AMD treatment facilities found 225 tons of sludge (dry weight basis) in surface storage, with an inherent REE value of $122 million.

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AMD treatment and sludge storage. TREE: total rare earth elements. Ss: sludge solids. Major ions: Ca, SO4, Si, Fe, Mg, Mn.

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