title: Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction.
abstract: The rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acid solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. The resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets.
authors.affiliation: †Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
authors.forename: Daejin
authors.initials: D
authors.lastname: Kim
authors.affiliation: †Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
authors.forename: Lawrence E
authors.initials: LE
authors.lastname: Powell
authors.affiliation: ‡Nuclear Materials Processing Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
authors.forename: Lætitia H
authors.initials: LH
authors.lastname: Delmau
authors.affiliation: §Center for Advanced Energy Studies, Idaho National Laboratory, Idaho Falls, Idaho 83415, United States.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Peterson
authors.affiliation: ∥Molycorp Magnequench, Greenwood Village, Colorado 80111, United States.
authors.forename: Jim
authors.initials: J
authors.lastname: Herchenroeder
authors.forename: Ramesh R
authors.initials: RR
authors.lastname: Bhave
mesh_terms: D004419:Dysprosium / Q000737:chemistry; D059346:Magnets; D008567:Membranes, Artificial; D008674:Metals, Rare Earth / Q000302:isolation & purification*; D008855:Microscopy, Electron, Scanning; D009354:Neodymium / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D008674:Metals, Rare Earth; D012997:Solvents; D004419:Dysprosium; D009354:Neodymium