Rare Metal Extraction and Processing: Processes for Rare Earth Elements
Sponsored by: TMS Extraction and Processing Division, TMS: Hydrometallurgy and Electrometallurgy Committee
Program Organizers: Takanari Ouchi, University of Tokyo; Gisele Azimi, University of Toronto; Kerstin Forsberg, KTH Royal Institute of Technology; Hojong Kim, Pennsylvania State University; Shafiq Alam, University of Saskatchewan; Neale Neelameggham, IND LLC; Alafara Baba, University of Ilorin; Hong (Marco) Peng, University of Queensland

Monday 8:30 AM
February 28, 2022
Room: 213B
Location: Anaheim Convention Center

Session Chair: Kerstin Forsberg, KTH Royal Institute of Technology; Hojong Kim, Pennsylvania State University; Takanari Ouchi, University of Tokyo

8:30 AM Introductory Comments

8:40 AM  Invited
EPD Distinguished Lecture: Rare Earth and Critical Material Recovery from Peralkaline Volcanic Ores: Minerals Processing, Hydrometallurgy and Solvent Extraction Separation: David Dreisinger1; 1University of British Columbia
    Rare earth elements are found in many geological settings. Peralkaline volcanic mineralization is found in the Port Hope Simpson Critical Materials District in Labrador, Canada. Minerals such as allanite and fergusonite are found in abundance along with minor chevkinite, bastnasite and monazite. In some deposits, zircon is present in significant concentrations. The complexity of these materials and the high intrinsic values contained require using every tool in the metallurgical toolkit in order to extract and recover the critical materials present. Conventional mineral processing, hydrometallurgical extraction and solvent extraction separation are all required to maximize the potential values of the natural deposits.

9:20 AM  
Two-phase Rare-earth Alloys as Reference Electrodes in Molten Chlorides for Reliable Electrochemical Measurements: Nathan Smith1; Stephanie Castro Baldivieso1; Timothy Lichtenstein1; Sanghyeok Im1; Hojong Kim1; 1Pennsylvania State University
    Electromotive force measurements were used to examine pure rare-earth reference electrodes (Nd, Gd) in molten chloride salts (LiCl-KCl-RECl3) over a temperature range of T = 400–800 C to determine the effects of disproportionation reactions (i.e., Nd + NdCl3 → NdCl2) and active metal dissolution on their longevity and stability. Several methods for developing and calibrating a stable two-phase Gd-Bi electrode were investigated including the use of a pure Gd metal reference electrode continuously submerged in the electrolyte, a pure Gd metal reference electrode intermittently dipped into the electrolyte, and a transient technique that deposited pure Gd onto an inert W wire. Electromotive force measurements were also employed to examine the lifetime of the two-phase alloy as the reference electrode in comparison to a pure rare-earth metal as the reference electrode. Pure rare-earth metal did not exhibit stability for more than 15 h, whereas two-phase Gd-Bi electrodes were found to be stable for over 24 days at T = 500–700 C.

9:40 AM  
Electrochemical Cell Design for Emf Measurements of Liquid Nd-Bi Alloys via Coulombic Titration in LiCl-KCl-NdCl3 Electrolyte: Sanghyeok Im1; Nathan Smith1; Stephanie Castro Baldivieso1; Hojong Kim1; 1The Pennsylvania State University
    Electrochemical properties of liquid Bi and Sn electrodes for Nd recovery were investigated in LiCl-KCl-NdCl3 at 773−973 K using a three-electrode configuration: a two-phase Nd-Sn alloy as the reference electrode and a liquid Nd-Bi alloy as the counter electrode. The electrode potentials of the liquid metals were measured during Nd deposition/removal cycles at various current densities to estimate round-trip coulombic efficiencies and to characterize current-dependent overpotentials. The overpotential measurements were corroborated by electrochemical impedance spectroscopy to study interfacial charge transfer and mass transport kinetics of liquid metal electrodes during electrolysis. After Nd electrodeposition experiments, the composition of the electrode was analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), and the recovery efficiency of Nd metal was estimated according to Faraday's law.

10:00 AM Break

10:20 AM  
Low-cost Distillation Technology for Rare Earth Recycling: Chinenye Chinwego1; Hunter Wagner1; Emily Giancola1; Jonathan Jironvil1; Adam Powell1; 1Worcester Polytechnic Institute
    As the need for high-technology applications and clean energy systems grow, extraction of rare earth elements (REEs) from secondary sources and end-of-life components has become far-reaching in various countries around the world. In proposing new methods or integrating new processes to existing methods, it is important to understand the cost implications of scaling up. This study will present an overview of the extraction of rare earth elements from secondary sources. In particular, it will present techno-economic analysis results for several different processes for utilizing various secondary sources. It will compare the costs of various recycling methods, focusing on a liquid metal extraction and distillation method. The effect of integrating a new continuous gravity-driven multiple effect thermal system (G-METS) metal distillation technology will be explored.

10:40 AM  Keynote
Extraction and Recovery of Rare-earth Elements and Critical Materials from Coal Waste Using Low Cost Processing Methods: Prasenjit Podder1; Michael Free1; Prashant Sarswat1; 1University of Utah
    Acid is an essential component for effective leaching of REEs (rare earth elements) bearing minerals and other sources. Acid can be generated using pyrite found with REE bearing materials. In the presence of A. Ferroxidans, pyrite (FeS2) is used as a source to generate ferric sulfate and sulfuric acid. Such microorganism-based bio-oxidation needs proper conditions for continuous acid generation. In this study, which involved pyrite to generate acid for leaching, a step-by-step analysis and associated details are presented. An automated bioreactor was used for bio-oxidation of pyrite of different level of purity. Morphology and elemental composition of precipitates were analyzed using scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, and the phase purity was identified using X-Ray diffraction analysis. Eh and pH measurements have been performed for different pyrite powders. FeS2 and Fe2+ reaction rate measurements were also done and pyrite usage efficiency was also estimated.

11:20 AM  
Selective Sulfidation for Rare Earth Element Separation: Caspar Stinn1; Antoine Allanore1; 1Massachusetts Institute of Technology
    Rare elements such as the lanthanides, selenium, tellurium, or scandium are critical components of advanced materials for energy, structural components, or transportation. These low-tonnage elements are sourced together with other metals, an imposition often accomplished through tedious, complete hydrometallurgical dissolution of primary or secondary processing streams. Herein, we present selective sulfidation as a novel, high-temperature alternative for separation of rare by- and co-product elements, either as compounds or for further reduction. We demonstrate the technical promise of selective sulfidation as applied to selenium and tellurium recovery from copper minerals, scandium separation from iron, and rare earth element processing. Meanwhile, sulfidation chemistry enables the employment of emerging new electro-metallurgical methods of reduction such as molten sulfide electrolysis. We also include technoeconomic and life cycle analysis in the context of rare earth element processing via selective sulfidation, illustrating improved process economics and sustainability compared to conventional liquid-liquid hydrometallurgical solvent extraction.