Reversing Lanmodulin's Metal-Binding Sequence in Short Peptides Surprisingly Increases the Lanthanide Affinity.

Recycling of rare earths: a critical review

Highly Efficient and Precise Rare-Earth Elements Separation and Recycling Process in Molten Salt

Chapter 21 - Leaching of Rare Earth Elements: Review of Past and Present Technologies

Chirality transfer, induction, and circularly polarized luminescence (CPL) using supramolecular hosts, such as macrocycles and cages, have been explored for wide-ranging applications in chiral reco...

The use of rare earth elements (REEs) is increasing, mainly due to the growing demand for electric vehicles and new applications in green technology. This results in annual growth of the in-use REE stocks and the amount of End-of-Life (EoL) products containing REEs. REEs are considered critical elements by the EU, mainly because the rest of the world is dependent on China’s supply. Recycling of REEs can help alleviate the criticality of REEs, however, no REEs are currently functionally recycled. In this study, the time-dependent behavior of REEs in copper matte-slag system in primary copper smelting conditions was investigated experimentally at a laboratory scale. Lanthanum and neodymium were chosen to represent all REEs, as they are generally found in the highest concentrations in EoL products, and because REEs all have similar chemical behavior. The experiments were conducted as a function of time in air and argon atmospheres. SEM-EDS, EPMA and LA-ICP-MS methods were used for sample characterization. The results of this work indicate that the REEs strongly favor the slag and the deportment to the slag begins almost instantly when the system reaches high temperatures. With increasing contact times, the REEs distribute even more strongly into the slag phase, where they may be recovered and recycled, if their concentrations are sufficiently high and a suitable hydrometallurgical process can be found.

Quantifying provincial in-use stocks of rare earth to identify urban mining potentials in the Chinese mainland

Worker Safety in the Rare Earth Elements Recycling Process From the Review of Toxicity and Issues.

In an ongoing effort towards a more sustainable rare-earth element market, there is a high potential for an efficient recycling of rare-earth elements from end-of-life compact fluorescent lamps by physical separation of the individual phosphors. In this study, we investigate the separation of five fluorescent lamp particles by high-gradient magnetic separation in a rotary permanent magnet separator. We thoroughly characterize the phosphors by ICP-MS, laser diffraction analysis, gas displacement pycnometry, surface area analysis, SQUID-VSM, and Time-Resolved Laser-Induced Fluorescence Spectroscopy. We present a fast and reliable quantification method for mixtures of the investigated phosphors, based on a combination of Time-Resolved Laser-Induced Fluorescence Spectroscopy and parallel factor analysis. With this method, we were able to monitor each phosphors’ removal dynamics in the high-gradient magnetic separator and we estimate that the particles’ removal efficiencies are proportional to (d2·χ)1/3. Finally, we have found that the removed phosphors can readily be recovered easily from the separation cell by backwashing with an intermittent air–water flow. This work should contribute to a better understanding of the phosphors’ separability by high-gradient magnetic separation and can simultaneously be considered to be an important preparation for an upscalable separation process with (bio)functionalized superparamagnetic carriers.

Decision letter: Dynamic Na+/H+ exchanger 1 (NHE1) – calmodulin complexes of varying stoichiometry and structure regulate Ca2+-dependent NHE1 activation

Rare earth elements (REE) are essential in many green, modern technologies and play a critical role in a more sustainable future [1]. However, there is a substantial risk to their supply as the availability of REE deposits with minable concentrations are limited [2]. A better understanding of the mechanisms controlling REE concentration in minerals would have applications in more efficient practices as well as REE separation techniques and recycling.Our study investigated the reaction of multi-component REE (La, Ce, Pr, Nd, and Dy) aqueous solutions with carbonate grains of dolomite, aragonite and calcite at hydrothermal conditions (21-210 °C). Two different solutions were prepared (i) a solution with equal concentrations of each of the five REE: (ii) a solution with the concentrations of the five REEs normalized to a Post Archean Shale standard (PAAS), to mimic the rare earth element concentrations in continental crust and natural fluids.The interaction between the REE bearing fluids with each of the carbonate grains resulted in the replacement of the host carbonate grain with a series of REE minerals following a complex crystallization sequence (lanthanite → kozoite → bastnasite → cerianite). We have found that for most of the experiments at 165 °C, when using the equal concentration solutions, the crystallization of kozoite was promoted and the REE ratio in the newly formed solids was similar to the REE ratio in solution. In contrast, when PAAS solutions were used, REE-bearing crystals were zoned or had a heterogenous distribution of REEs, often coupled with the formation of discreet REE phases (e.g., cerianite). In addition, chemical signatures indicating the presence of metastable REE-bearing phases that transformed to more thermodynamically stable polymorphs were found in multiple samples as well as symplectite textures formed by the reaction of adjacent phases. Overall, our experiments demonstrate that the polymorph selection, crystallization pathway, the kinetics of mineral formation and the chemical texture of the newly formed rock during the mineral-fluid interaction process are dependent on the REE concentrations in solution, their ionic radii, temperature, time, and solubility of the host grains. References [1] Sinding-Larsen, R., Wellmer, F.W.,. Non-renewable resource issues: Geoscientific and societal challenges, Non-Renewable Resource Issues: Geoscientific and Societal Challenges 2012.[2] Jordens, A., Cheng, Y.P., Waters, K.E.,. A review of the beneficiation of rare earth element bearing minerals. Miner. 2013 Eng. 41, 97-114.

Sensitive determination of rare earth elements in liquid samples by spatial confinement assisted surface enhanced laser-induced breakdown spectroscopy

End-of-life recycling is promoted by OECD countries as a promising strategy in the current global supply crisis surrounding rare earth elements (REEs) so that dependence on China, the dominant supplier, can be decreased. So far the feasibility and potential yield of REE recycling has not been systematically evaluated. This paper estimates the annual waste flows of neodymium and dysprosium from permanent magnets, the main deployment of these critical REEs, during the 2011-2030 period. The estimates focus on three key permanent magnet waste flows: wind turbines, hybrid and electric vehicles, and hard disk drives (HDDs) in personal computers (PCs). This is a good indication of the end-of-life recycling of neodymium and dysprosium maximum potential yield. Results show that for some time to come, waste flows from permanent magnets will remain small relative to the rapidly growing global REE demand. Policymakers therefore need to be aware that during the next decade recycling is unlikely to substantially contribute to global REE supply security. In the long term, waste flows will increase sharply and will meet a substantial part of the total demand for these metals. Future REE recycling efforts should, therefore, focus on the development of recycling technology and infrastructure.

Yttrium is a heavy rare earth element (REE) that acquires remarkable characteristics when it is in oxide form and doped with other REEs. Owing to these characteristics Y2 O3 can be used in the manufacture of several products. However, a supply deficit of this mineral is expected in the coming years, contributing to its price fluctuation. Thus, developing an efficient, cost-effective, and eco-friendly process to recover Y2 O3 from secondary sources has become necessary. In this study, we used phage surface display to screen peptides with high specificity for Y2 O3 particles. After three rounds of enrichment, a phage expressing the peptide TRTGCHVPRCNTLS (DM39) from the random pVIII phage peptide library Cys4 was found to bind specifically to Y2 O3 , being 531.6-fold more efficient than the wild-type phage. The phage DM39 contains two arginines in the polar side chains, which may have contributed to the interaction between the mineral targets. Immunofluorescence assays identified that the peptide's affinity was strong for Y2 O3 and negligible to LaPO4 :Ce3+ ,Tb3+ . The identification of a peptide with high specificity and affinity for Y2 O3 provides a potentially new strategic approach to recycle this type of material from secondary sources, especially from electronic scrap.

An environmentally friendly process for the separation of the transition metals copper, cobalt, iron, manganese and zinc from rare earths by solvent extraction with the ionic liquid trihexyl(tetradecyl)phosphonium chloride has been developed. The solvent extraction process is carried out without the use of organic diluents or extra extraction agents and it can be applied as a sustainable hydrometallurgical method for removing transition metals from neodymium–iron–boron or samarium–cobalt permanent magnets. The recycling of rare earths is of high importance because of the possible supply risk of these elements in the near future. The method was tested for the removal of cobalt and iron from samarium and neodymium, respectively. The highest distribution ratios for cobalt and iron were found with 8.5 and 9 M HCl. At the tested conditions, the concentrations of neodymium and samarium in the ionic liquid were below 0.5 mg L−1 (0.5 ppm), even for feed concentrations of 45 g L−1. The separation factors of Nd/Fe and Sm/Co are 5.0 × 106 and 8.0 × 105, respectively. The percentage extraction of iron is still higher than 99.98% at loadings of the ionic liquids with 70 g L−1 of iron. The viscosity of the ionic liquid containing the tetrachloroferrate(III) complex [FeCl4]− is lower, and less depending on the feed concentration, than in the case with a tetrachlorocobaltate(II) anion [CoCl4]2−. After extraction, cobalt can be stripped very easily from the ionic liquid phase with water. However, due to the very high distribution ratio, iron could only be stripped by forming a water-soluble iron complex with ethylenediaminetetraacetic acid (EDTA). Also the possibility to extract chromium, nickel, aluminium, calcium and magnesium with trihexyl(tetradecyl)phosphonium chloride has been investigated, but the distribution ratios of these elements are very low in the tested conditions.

The formation of aqueous Cm(III) phosphate complexes was studied at room temperature by time-resolved laser-induced fluorescence spectroscopy (TRLFS) in 0.1 M NaClO4solutions. The experiments were perfomed at a fixed total Cm(III) concentration of 3 × 107or 2 × 108 M by varying the phosphoric acid concentration (3 × 105–0.1 M) and the pH (1.4–6.0). The red shift of the excitation and emission spectra, as well as the increase of luminescence lifetimes clearly showed the influence of phosphate on the aqueous Cm(III) speciation. In acidic phosphate solutions ([H3PO4] ≤0.1 M, pH 1.4–2.6) an increase in luminescence intensity was detected due to complexation with H2PO4−. At [H3PO4] ≥4 × 104 M and between pH 4.0 and 6.0 in general a decrease in luminescence intensity affiliates the complexation with HPO42−. Two Cm(III)-phosphate complexes could be identified from the emission data, CmH2PO42+and CmHPO4+, having peak maxima at 599.6 and 600.8 nm, respectively. TRLFS in combination with ultra-filtration (1 kD) showed that the formation of CmHPO4+is accompanied by the generation of Cm(III)-phosphate colloids especially at [H3PO4] ≥0.002 M and pH ≥ 5. Cm(III)-phosphate colloids formed at pH 5 and 6 are characterized by an emission maximum at 603.1 nm. Based on the factor analysis of the emission data the stability constants of the two complexes were calculated to be logβ121= 20.23 ± 0.13 and logβ111= 16.54 ± 0.80 at an ionic strength of 0.1 M (NaClO4).