Concentrating Rare Earth Elements in Acid Mine Drainage Using Coal Combustion Products Through Abandoned Mine Land Reclamation

Technology Partner: Ohio State UniversityAward Number: FE0031566

Project Duration: 12/1/2017 – 4/30/2019Total Project Value: $528,700

Key Technology Area: Separation Technologies

The project research team will develop an integrated process that first uses stabilized flue gas desulfurization material (sFGD) to recover rare earth elements (REEs) from acid mine drainage (AMD) and a sequential extraction procedure to produce a rare earth feedstock with above two percent by weight REE. The objectives are to (1) validate the effectiveness and feasibility of the integrated REE recovery/concentrating process, (2) determine mechanisms controlling the rare earth recovery process, (3) quantify the associated economic and environmental benefits, and (4) evaluate the full- scale application of the process. To achieve these objectives, tasks to be carried out are in four phases. In the first phase, the research team will collaborate with state agencies to carry out field investigations designed to screen and evaluate the seasonal changes of REEs from AMD discharges that have high recovery potential. Next, laboratory-scale tests will be carried out to study the recovery process under a range of percolation

conditions using AMD and sFGDs from selected sources. The associated water quality changes will be monitored. Advanced analytical techniques, including synchrotron based X-ray methods, will be used to identify the mineral forms of retained REEs. In the third phase, a highly selective sequential extraction procedure will be used to concentrate the REEs. In the final phase, techno-economic analysis and life-cycle assessment will be carried out to evaluate the economic and environmental benefits. The rare earth recovery and concentrating process can be integrated with abandoned mine land (AML) reclamation to create an approach that can (1) add economic incentives for AML reclamation, (2) remediate AMD discharge, (3) provide a long-term, high-volume beneficial use for coal combustion by-products, which otherwise needs to be disposed of in a landfill, and (4) eliminate public safety hazards and threats to local environment and ecological systems posed by AMLs.

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