Abstract
Tailings from inactive uranium mine sites represent a potential secondary source of rare earth elements (REEs). For this study, two mine tailings (DT and RAT) from restored uranium sites in Ontario, Canada, were used. Bioleaching experiments were conducted with a mix of native sulfur- and iron-oxidizing bacteria to test the solubilization of REEs, U and Th at different temperatures (20, 30 and 40 °C). The selective recovery of REEs from bioleaching solution was evaluated using different ion exchange resins. The mineralogical characterization revealed that DT tailings were mainly composed of quartz, pyrite, gypsum and silicates, whereas RAT tailings were mainly composed of quartz. The maximum solubilization of heavy and light REEs (HREEs and LREEs, respectively), Th and U reached 54%, 6%, 60% and 51% for RAT after 35 days at pH 2, T = 30 °C and pulp density = 10% (w/v). Higher extraction yields were obtained for DT, with 58% of HREEs, 14% of LREEs, 85% of Th and 89% of U solubilized under the same conditions. The use of Lewatit TP272 resin for the recovery of Sc (94%) and U (99%) followed by the Lewatit SP112 resin for the recovery of Th (57%) and REEs (81% LREEs and 65% HREEs) seemed a promising method for the co-extraction of the key elements from the bioleaching solution.
Highlights
Published: 16 March 2021Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, BY) Commons licenseAttribution
There are two different types of biotechnologies applicable to extracting metals from mineralized material: heterotrophic leaching that requires an external carbon source, where microorganisms generate complexing ligands that bind the metals of interest; and autotrophic acidic bioleaching, where solubilization of the metals of interest occur by oxidation of reduced solid phases with ferric ion in combination with acid dissolution
To dissolve through bioleaching, while U from DT tailing is expected to be more. These results indicate that U from RAT, probably present as uranium carbonate comdifficult to extract, as more than 38.7% is present in the residual fraction, plexes, is expected to dissolve through bioleaching, while U from DT tailing is expected to be more difficult to extract, as more than 38.7% is present in the residual fraction, that is known to be more difficult to solubilize by diluted inorganic acids
Summary
Published: 16 March 2021Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, BY) Commons licenseAttribution (CC (https://creativecommons.org/licenses/by/ 4.0/).Bioleaching technologies are often considered for processing low-grade and waste material due to their relatively simple operation and low cost compared to conventional processing technologies. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Bioleaching technologies are often considered for processing low-grade and waste material due to their relatively simple operation and low cost compared to conventional processing technologies. There has been significant interest in applying bioleaching microorganisms to extract REEs from different types of metallic and mineralized wastes. There are two different types of biotechnologies applicable to extracting metals from mineralized material: heterotrophic leaching that requires an external carbon source, where microorganisms generate complexing ligands that bind the metals of interest; and autotrophic acidic bioleaching, where solubilization of the metals of interest occur by oxidation of reduced solid phases with ferric ion in combination with acid dissolution. The two pathways use a wide variety of microbial groups (e.g., chemolithoautotrophic bacteria and archaea, chemoorganoheterotrophic bacteria, archaea, and fungi); reviewed in [1,2]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
