Bioleaching of rare earth elements from monazite sand. Issue 2 (9th September 2015)

• Record Type: Journal Article
• Authors: Brisson, Vanessa L.; Zhuang, Wei‐Qin; Alvarez‐Cohen, Lisa
• Is Part Of: Biotechnology and bioengineering. Volume 113:Issue 2(2016)
• Page Start: 339
• Page End: 348
• Publication Date: 2015-09-09
• Subjects: bioleaching -- monazite -- rare earth elements -- phosphate -- fungi -- Aspergillus; Biotechnology -- Periodicals; Bioengineering -- Periodicals; 660.6
• DOI: 10.1002/bit.25823
• Languages: English
• ISSNs: 0006-3592

Abstract

ABSTRACT: Three fungal strains were found to be capable of bioleaching rare earth elements from monazite, a rare earth phosphate mineral, utilizing the monazite as a phosphate source and releasing rare earth cations into solution. These organisms include one known phosphate solubilizing fungus, Aspergillus niger ATCC 1015, as well as two newly isolated fungi: an Aspergillus terreus strain ML3‐1 and a Paecilomyces spp. strain WE3‐F. Although monazite also contains the radioactive element Thorium, bioleaching by these fungi preferentially solubilized rare earth elements over Thorium, leaving the Thorium in the solid residual. Adjustments in growth media composition improved bioleaching performance measured as rare earth release. Cell‐free spent medium generated during growth of A. terreus strain ML3‐1 and Paecilomyces spp. strain WE3‐F in the presence of monazite leached rare earths to concentrations 1.7–3.8 times those of HCl solutions of comparable pH, indicating that compounds exogenously released by these organisms contribute substantially to leaching. Organic acids released by the organisms included acetic, citric, gluconic, itaconic, oxalic, and succinic acids. Abiotic leaching with laboratory prepared solutions of these acids was not as effective as bioleaching or leaching with cell‐free spent medium at releasing rare earths from monazite, indicating that compounds other than the identified organic acids contribute to leaching performance. Biotechnol. Bioeng. 2016;113: 339–348. © 2015 Wiley Periodicals, Inc. Abstract : This article presents an investigation of bioleaching of rare earth elements from monazite as a more environmentally sustainable alternative to conventional rare earth extraction processes. The authors isolated and characterized microorganisms capable of biologically leaching rare earth elements from monazite sand and analyzed the contributions of organic acids in this bioleaching process. The authors also showed that bioleaching preferentially releases rare earth elements over radioactive Thorium also present in the monazite ore.