Rare Metal Extraction & Processing: REEs, Sc
Sponsored by: TMS Extraction and Processing Division, TMS: Hydrometallurgy and Electrometallurgy Committee
Program Organizers: Gisele Azimi, University of Toronto; Takanari Ouchi, University of Tokyo; Kerstin Forsberg, KTH Royal Institute of Technology; Hojong Kim, Pennsylvania State University; Shafiq Alam, University of Saskatchewan; Alafara Baba, University of Ilorin; Neale Neelameggham, IND LLC
Tuesday 2:00 PM
March 16, 2021
Room: RM 44
Location: TMS2021 Virtual
2:00 PM Keynote
Understanding the Feasibility for Secondary and by Product Sources to Supply Rare Earth Metals: Gabrielle Gaustad1; Eric Williams2; Alexandra Leader2; Ajay Gupta2; Saptarshi Das2; 1Alfred University; 2Rochester Institute of Technology
Sustainability strategies like urban mining, industrial symbiosis, and the circular economy suggest avenues to realize new supplies of critical metals. We explore the resource and economic potential for extracting rare earth elements (REEs) from industry byproducts (e.g. coal combustion products, red mud) and secondary sources (e.g. waste electronics and light bulbs). Combining materials flow analysis and characterization data, we find that while total REE concentrations in waste and byproduct streams are mostly much lower than current REE ores, some sources are richer than ores in high value REEs (eg. scandium). The quantities of REEs in secondary sources could meet global demand even with low extraction yield rates. Considering quality and quantity of contained REEs, phosphogypsum, coal ash and red mud stand out as candidates. Processes to extract REEs from secondary sources are under development, it is not yet clear which will be profitable at scale and at least environmental impact.
2:20 PM Invited
Uranium and Thorium Removal from Rare Earth Sulfate Solutions by Ion Exchange and Solvent Extraction: David Dreisinger1; Mike Johnson2; Niels Verbaan2; Greg Andrews2; 1University of British Columbia; 2SGS Minerals
The Search Minerals Direct Extraction Process involves direct acid treatment of crushed ore, water leaching and neutralization for iron and impurity removal and mixed carbonate precipitation. The rare earth carbonate is redissolved in sulfuric acid and treated by pH adjustment to remove silica and aluminum followed by ion exchange for uranium removal and solvent extraction for thorium removal. The treated solution is then sulfidized to remove zinc and subsequently processed to make either a mixed oxide rare earth or a mixed carbonate rare earth product for separation into high purity individual rare earths. The bench and pilot plant processing of rare earth sulfate solutions derived from the Foxtrot Deposit for uranium and thorium removal is described.
2:40 PM Invited
Rare Earth Elements Extraction from Coal Waste Using Biooxidation Approach: Prashant Sarswat1; Michael Free1; 1University of Utah
The rare earth elements (REEs)are exceptionally helpful in applications, for example, gas sensors, hybrid vehicles, metal alloys, semiconductors, fluorescent and LED lights, electrical equipment, and related magnets. REEs and related reserve in coal-related materials are huge. Under an assumption of typical production of coal ~ of 600 million short tons for each year with a normal REE ~ 200 ppm, the potential annual reserve is 120,000 tons. The majority of those REEs are found in ash or gangue derived or associated from coal-related materials. Under typical coal plant activity, the REEs frequently end up in reject heaps or tailings impoundments. By and large, variety of REEs can be extracted with ease utilizing suitable coal processing steps. In the current exploration, the preparing approach utilizes a characteristic pyrite stream, which was collected during coal cleaning and used to improve recovery. Biooxidation step was applied to coal-based materials for REE recovery.
3:00 PM Invited
Supercritical Extraction of Neodymium from NdFeB Magnet Using Organophosphorus Ligands: Nattanai Kunanusont1; Jiakai Zhang2; Kimberly Watada2; Yusuke Shimoyama1; Gisele Azimi2; 1Tokyo Institute of Technology; 2University of Toronto
Supercritical fluid extraction is a promising green technology for urban mining of rare earth elements. To dissolve a metal in non-polar supercritical carbon dioxide (sc-CO2), it must be bonded with a combination of negative and neutral ligands, called chelating agents. Here, we investigate the effect of organophosphorus reagents on the extraction of neodymium from a neodymium-iron-boron magnet in sc-CO2. We use COSMO-vacancy model to predict the solubility of triethyl phosphate (TEP), tri-n-butyl phosphate (TBP), tributyl phosphine oxide (TBPO), and trioctyl phosphine oxide (TOPO) in sc-CO2 and show a TEP>TBPO~TBP>TOPO trend. We examine the stoichiometry of neodymium-ligand complexes using UV-Vis spectroscopy, showing a 1:1 Nd–TEP, 1:3 Nd–TBP, 1:4 Nd-TBPO, and 1:5 Nd–TOPO complex chemistry. Supercritical fluid extractions show TEP results in highest neodymium extractions followed by TBP, TBPO, and TOPO, because of the increase in coordination number that result in larger micellar assemblies with lower solubility in sc-CO2.
3:20 PM Invited
Scandium Extraction from Bauxite Residue Using Sulfuric Acid and a Composite Extractant-enhanced Ion-exchange Polymer Resin: Efthymios Balomenos1; Ghazaleh Nazari2; Panagiotis Davris1; Gomer Abrenica2; Anastasia Pilichou3; Eleni Mikeli3; Dimitrios Panias3; Shailesh Patkar2; Wen-Qing Xu2; 1Mytilineos Metallurgy Buisness Unit; 2II-VI; 3NTUA
This work presents the results of Scandium extraction from Greek Bauxite Residue (BR) using sulfuric acid as the leaching agent and a solvent impregnated resin (SIR- developed by II-VI) as the extraction agent. The BR produced in Mytilineos’s plant contains app. 75-130 ppm of Sc and given the plant current production capacity, more than 100 t of Sc are discarded each year within the BR stream. Τhe optimum conditions for selective Sc extraction from BR were determined in lab scale in conjuction with the efficiency in Sc uptake, of the SIR resin. Under the SCALE research project, a BR leaching pilot plant (Mytilineos) and Sc extraction pilot plant (II-VI) have been erraected and operated at Mytilineos plant to demonstrate this process. Acknowledgements The research leading to these results has received funding from the European Community’s H2020 Programme SCALE-730105.
3:40 PM Invited
Scandium: Leaching and Extraction Chemistry: Dag Eriksen1; 1Primus.Inter.Pares As
One of the elements considered as key elements in the green economy is scandium. Scandium (Sc) is a rare earth element and as such, it is not very rare, but the concentration of it is always low making it a challenge to produce scandium at low cost. Compared to the other rare earth elements (REE), Sc3+ is a much smaller ion giving it properties closer to Al3+, Fe3+ and Zr4+. We therefore often do not find Sc together with the other REE, but instead in titanium-, aluminium- and uranium containing minerals. Processes involving Sc-separation are different from the usual REE-processes. Scandium is a critical metal as it is needed, but the market is not working properly. Exploitation of the mineral davidite is used as an example of small deposits to be utilized through green mining whereas other large operations like recovery from bauxite residues (red mud) are considered for comparison.
4:00 PM Invited
Environmentally Friendly Solid Phase Extraction of Critical Materials and REE from Unconventional Sources: Athanasios Karamalidis1; Jonathan Callura2; Madhav Patel1; 1Pennsylvania State University; 2Carnegie Mellon University
Critical materials, including rare earth elements (REE), are a group of valuable minerals with growing demand and supply chain concerns. Traditional sources of critical materials require significant capital investment and their refinement has caused widespread environmental contamination. Critical materials are also frequently present in secondary sources, such as brine water and industrial wastes. This work investigated the REE adsorption performance of polymer resins functionalized with phosphonate-based ligands. In multi-element competitive adsorption experiments the functionalized resins were highly selective, with REE separation factors up to two orders of magnitude higher than non-functionalized resins. Resin performance was also measured in fixed-bed adsorption columns to identify the impact of influent metal concentrations and flow rate on REE breakthrough. This work demonstrates the potential of these novel functionalized adsorbents for REE recovery from unconventional sources which can be used to augment existing REE supplies and offset environmentally harmful production methods.