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An Overview of Extraction Schemes for the Recovery of Erbium
Published in Abhilash, Ata Akcil, Critical and Rare Earth Elements, 2019
Shivendra Sinha, Abhilash, Pratima Meshram
Erbium being a critically important REE has immense applications in several technologically advanced areas, particularly in fusion reactors which require high purity erbium oxide/erbium-based compounds. However, its low concentration in monazite and xenotime deposits coupled with the presence of chemically similar elements make the task of devising separation schemes extremely tedious. This is corroborated by previous studies vis-à-vis separation processes such as solvent extraction, adsorption/IIPs, and electrolysis. There exists a lacunae in terms of selectivity, separation factor, ease of operation, low energy, and material costs, where research efforts can be aligned. To achieve high selectivity, molecular modeling and ab-initio modeling can be used by the simulation of erbium ion-selective functional moieties, which preferentially take erbium over other lanthanides. This approach can be extended to the design of new solvents, adsorbents, and IIP. Moreover, solvent-assisted membrane separation can also be promising in terms of augmenting the separation factor values. However, the cost of operation needs to be taken into account to achieve this new synthesized molecule to the tune of technological level. Considering the global demand for REOs, which was estimated to be 150,766 tons in 2020 at a CAGR of 3.8% due to escalating demands, research efforts in a modern circular economy are aligned to utilize end-of-life products; therefore, efforts can be made for the extraction of erbium from such products. Moreover, it was also seen that the potential of existing solvents, IIPs, and adsorbents are not yet fully explored from dilute solutions of erbium with other similar lanthanides and metal ions. Such studies will certainly help in the selection of separation schemes while utilizing end-of-life products.
The Taming of Plutonium: Plutonium Metallurgy and the Manhattan Project
Published in Nuclear Technology, 2021
Joseph C. Martz, Franz J. Freibert, David L. Clark
When the anomalously low plutonium melting point near 650°C was revealed in May 1944, it greatly simplified a number of the preparations for kilogram-scale processing. At this rather low temperature, magnesia was now an ideal crucible material. The difficult work of producing cerium sulfide crucibles undertaken at MIT was no longer necessary. A rather apologetic memo from C. S. Smith to John Chipman at MIT noted that this turn of events “must be very painful” for the MIT staff that had spent so much time, effort, and expense on developing these CeS crucibles (page 329 of Ref. 17). It should be noted, common crucible materials for plutonium today include not only magnesia, but tantalum and graphite! It was later found that coating graphite with materials such as erbium oxide (Er2O3) was sufficient to prevent crucible erosion in the melt.