Determination and prediction of micro scale rare earth element geochemical associations in mine drainage treatment wastes.

Autor: Hedin BC; Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, PA, 15260, United States; Hedin Environmental, Inc., 195 Castle Shannon Blvd., Pittsburgh, PA, 15228, United States. Electronic address: ben.hedin@hedinenv.com., Stuckman MY; National Energy Technology Laboratory, 626 Cochrans Mill Road, P.O. Box 10940, Pittsburgh, PA, 15236-0940, United States; National Energy Technology Laboratory Support Contractor, 626 Cochrans Mill Rd, Pittsburgh, PA, 15263, United States., Cravotta CA 3rd; U.S. Geological Survey, 215 Limekiln Rd, New Cumberland, PA, 17070, United States., Lopano CL; National Energy Technology Laboratory Support Contractor, 626 Cochrans Mill Rd, Pittsburgh, PA, 15263, United States., Capo RC; Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, PA, 15260, United States.
Jazyk: angličtina
Zdroj: Chemosphere [Chemosphere] 2024 Jan; Vol. 346, pp. 140475. Date of Electronic Publication: 2023 Oct 27.
DOI: 10.1016/j.chemosphere.2023.140475
Abstrakt: Acid mine drainage (AMD) has been proposed as a novel source of rare earth elements (REE), a group of elements that includes critical metals for clean energy and modern technologies. REE are sequestered in the Fe-Al-Mn-rich precipitates produced during the treatment of AMD. These AMD solids are typically managed as waste but could be a REE source. Here, results from AMD solids characterization and geochemical modeling are presented to determine the minerals/solid phases that are enriched in REE and identify the mechanism(s) of REE attenuation. AMD solids collected from limestone-based AMD treatment systems were subjected to sequential extraction and synchrotron microprobe analyses to characterize the binding nature of the REE. The results of these analyses indicated REEs were mainly associated with Al or Mn phases. Only selected REE (Gd, Dy) were associated with Fe phases, which were less abundant than Al and Mn phases in analyzed samples. The sequential extractions demonstrated that acidic and/or reducing extractions effectively mobilize REE from the AMD solids evaluated. The observed element associations in solids are consistent with geochemical model results that indicate dissolved REE can be effectively attenuated by adsorption on freshly precipitated Fe, Al, and Mn oxides/hydroxides. The model, which simulates dissolution of CaCO 3 and the precipitation of Fe, Al, and Mn oxides with increased pH, accurately predicts the pH dependent accumulation of dissolved REE with Al, Mn, and Fe oxides/hydroxides in the studied AMD treatment systems. The methods and results presented here can be used to identify conditions favorable for accumulation of REE-enriched AMD solids and possible passive or active treatment(s) to extract REE from AMD. This information can be used to design AMD treatment systems for the recovery of REE and is an opportunity to transform the challenges of addressing polluted mine drainage into an environmental and economic asset.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2023. Published by Elsevier Ltd.)
Databáze: MEDLINE
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