title: Concomitant Leaching and Electrochemical Extraction of Rare Earth Elements from Monazite.
abstract: Rare earth elements (REEs) have become increasingly important in modern day technologies. Unfortunately, their recycling is currently limited, and the conventional technologies for their extraction and purification are exceedingly energy and chemical intensive. New sustainable technologies for REE extraction from both primary and secondary resources would be extremely beneficial. This research investigated a two-stage recovery strategy focused on the recovery of neodymium (Nd) and lanthanum (La) from monazite ore that combines microbially based leaching (using citric acid and spent fungal supernatant) with electrochemical extraction. Pretreating the phosphate-based monazite rock (via roasting) dramatically increased the microbial REE leaching efficiency. Batch experiments demonstrated the effective and continued leaching of REEs by recycled citric acid, with up to 392 mg of Nd L-1and 281 mg of La L-1leached during seven consecutive 24 h cycles. Neodymium was further extracted in the catholyte of a three-compartment electrochemical system, with up to 880 mg of Nd L-1achieved within 4 days (at 40 A m-2). Meanwhile, the radioactive element thorium and counterions phosphate and citrate were separated effectively from the REEs in the anolyte, favoring REE extraction and allowing sustainable reuse of the leaching agent. This study shows a promising technology that is suitable for primary ores and can further be optimized for secondary resources.
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University , Coupure Links 653, B-9000 Gent, Belgium.
authors.forename: Synthia
authors.initials: S
authors.lastname: Maes
authors.affiliation: Department of Civil and Environmental Engineering, The University of Auckland , Auckland 1142, New Zealand.|Department of Civil and Environmental Engineering, University of California , Berkeley, California 94720-1710, United States.
authors.forename: Wei-Qin
authors.initials: WQ
authors.lastname: Zhuang
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University , Coupure Links 653, B-9000 Gent, Belgium.
authors.forename: Korneel
authors.initials: K
authors.lastname: Rabaey
authors.affiliation: Department of Civil and Environmental Engineering, University of California , Berkeley, California 94720-1710, United States.|Earth and Environmental Sciences Division, Lawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, California 94720, United States.
authors.forename: Lisa
authors.initials: L
authors.lastname: Alvarez-Cohen
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University , Coupure Links 653, B-9000 Gent, Belgium.|Department of Civil and Environmental Engineering, University of California , Berkeley, California 94720-1710, United States.
authors.forename: Tom
authors.identifier: 0000-0002-8346-5983
authors.initials: T
authors.lastname: Hennebel
mesh_terms: D019343:Citric Acid; D007811:Lanthanum; D008674:Metals, Rare Earth / Q000302:isolation & purification*; D009354:Neodymium; D010710:Phosphates; D059027:Recycling
chemical_list: D008674:Metals, Rare Earth; D010710:Phosphates; D019343:Citric Acid; D009354:Neodymium; D007811:Lanthanum