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BACKGROUND: Prior to soil formation, phosphate liberated by rock weathering is often sequestered into highly insoluble lanthanide phosphate minerals. Dissolution of these minerals releases phosphate and lanthanides to the biosphere. Currently, the microorganisms involved in phosphate mineral dissolution and the role of lanthanides in microbial metabolism are poorly understood. RESULTS: Although there have been many studies of soil microbiology, very little research has investigated microbiomes of weathered rock. Here, we sampled weathered granite and associated soil to identify the zones of lanthanide phosphate mineral solubilisation and genomically define the organisms implicated in lanthanide utilisation. We reconstructed 136 genomes from 11 bacterial phyla and found that gene clusters implicated in lanthanide-based metabolism of methanol (primarily xoxF3 and xoxF5) are surprisingly common in microbial communities in moderately weathered granite. Notably, xoxF3 systems were found in Verrucomicrobia for the first time, and in Acidobacteria, Gemmatimonadetes and Alphaproteobacteria. The xoxF-containing gene clusters are shared by diverse Acidobacteria and Gemmatimonadetes, and include conserved hypothetical proteins and transporters not associated with the few well studied xoxF systems. Given that siderophore-like molecules that strongly bind lanthanides may be required to solubilise lanthanide phosphates, it is notable that candidate metallophore biosynthesis systems were most prevalent in bacteria in moderately weathered rock, especially in Acidobacteria with lanthanide-based systems. CONCLUSIONS: Phosphate mineral dissolution, putative metallophore production and lanthanide utilisation by enzymes involved in methanol oxidation linked to carbonic acid production co-occur in the zone of moderate granite weathering. In combination, these microbial processes likely accelerate the conversion of granitic rock to soil.

Coal resources represent an important potential source for the future extraction of rare earth elements (REEs). This study, combining microscopic characterization techniques and experimental analysis, investigates the occurrence characteristics of REEs in coal gangue and the roasting activation mechanisms. The study reveals that phosphate minerals are the primary carriers of REEs, and sequential chemical extraction results further confirm the close association between REEs and phosphate minerals. Roasting at around 600°C facilitates the release of REEs from organic matter and clay minerals like kaolinite, significantly improving leaching efficiency. Under leaching conditions of 20 g/L, 50°C, 0.5 M HCl, and 1000 RPM, the leaching of REEs can reach approximately 80%. However, when the roasting temperature exceeds 1000°C, the formation of mullite leads to mineral surface sintering, reducing the recovery of REEs. This study emphasizes the importance of optimizing roasting conditions and understanding mineral phase changes to maximize REEs recovery, which is crucial for sustainable resource management and environmental remediation. [ABSTRACT FROM AUTHOR]

The rollout of electric vehicles and photovoltaic panels is essential to mitigate climate change. However, they depend on technology‐critical elements (TCEs), which can be harmful to human health and whose use is rapidly expanding, while recycling is lacking. While mining has received substantial attention, in‐use dissipation in urban areas has so far not been assessed, for example, corrosion and abrasion of vehicle components and weather‐related effects affecting thin‐film photovoltaic panels. Therefore, the question arises to which extent TCEs dissipate during use and which potential non‐occupational human health impacts could occur. We assessed the available information on urban in‐use dissipation and human health concerns and conducted exploratory modeling of in‐use technology stocks, in‐ and outflows, and in‐use dissipation of neodymium, dysprosium, lanthanum, praseodymium, cerium, gallium, germanium, and tellurium contained in 21 vehicle and renewable energy technologies, for Vienna, Austria. In prospective scenarios, TCE dynamics in a trend‐continuation vis à vis official city policy plans and a more ambitious transition scenario were then assessed. We find that electrifying the vehicle fleet without demand‐reduction is the main driver of TCE consumption, effectively doubling cumulative end‐of‐life outflows to 3,073 [2,452–3,966] t and cumulative in‐use dissipation to 9.3 [5.2–15.7] t by the year 2060. Sufficiency‐based measures could reduce demand and in‐use dissipation well below levels with continued trends, thus highlighting the need to combine decarbonization with demand‐reducing measures. These results help assess potential future in‐use dissipation dynamics and inform discussions about potential public health hazards associated with exposure to TCEs accumulating in the urban environment. [ABSTRACT FROM AUTHOR]

The rare earth elements (REEs) are critical resources for many clean energy technologies, but are difficult to obtain in their elementally pure forms because of their nearly identical chemical properties. Here, an analogue of macropa, G‐macropa, was synthesized and employed for an aqueous precipitation‐based separation of Nd3+ and Dy3+. G‐macropa maintains the same thermodynamic preference for the large REEs as macropa, but shows smaller thermodynamic stability constants. Molecular dynamics studies demonstrate that the binding affinity differences of these chelators for Nd3+ and Dy3+ is a consequence of the presence or absence of an inner‐sphere water molecule, which alters the donor strength of the macrocyclic ethers. Leveraging the small REE affinity of G‐macropa, we demonstrate that within aqueous solutions of Nd3+, Dy3+, and G‐macropa, the addition of HCO3− selectively precipitates Dy2(CO3)3, leaving the Nd3+−G‐macropa complex in solution. With this method, remarkably high separation factors of 841 and 741 are achieved for 50 : 50 and 75 : 25 mixtures. Further studies involving Nd3+:Dy3+ ratios of 95 : 5 in authentic magnet waste also afford an efficient separation as well. Lastly, G‐macropa is recovered via crystallization with HCl and used for subsequent extractions, demonstrating its good recyclability. [ABSTRACT FROM AUTHOR]

Electronic waste (e-waste) contains valuable rare earth elements (REEs) essential for various high-tech applications, making their recovery crucial for sustainable resource management. This review provides an overview of the occurrence of REEs in e-waste and discusses both conventional and emerging green technologies for their recovery. Conventional methods include physical separation, hydrometallurgy, and pyrometallurgy, while innovative approaches such as bioleaching, supercritical fluid extraction, ionic liquid extraction, and lanmodulin-derived peptides offer improved environmental sustainability and efficiency. The article presents case studies on the extraction of REEs from waste permanent magnets and fluorescent powders, highlighting the specific processes involved. Future research should focus on developing eco-friendly leaching agents, separation materials, and process optimization to enhance the overall sustainability and efficiency of REE recovery from e-waste, addressing both resource recovery and environmental concerns effectively. [ABSTRACT FROM AUTHOR]

In this work, AZ31 and AZ31-1 wt.% RE (RE = Nd, Dy, Nd+Dy) alloys were prepared by conventional casting. The effect of single and co-addition of rare earth (RE) on the microstructure, mechanical properties and corrosion behavior of as-cast AZ31 magnesium alloys were investigated at ambient temperature, and after heat treatment at 400 °C for 1 h. The addition of 1 wt.% RE (RE = Nd, Dy, Nd+Dy) preferentially formed the Al2RE phase and completely suppressed the formation of the intermetallic β-Mg17Al12 phase. An excellent ultimate tensile strength (UTS)/ductility combination of 209 MPa/21% and 192 MPa/17% with an adequate yield strength (YS) of 90 MPa was observed for AZ31+Nd sample in as-cast and annealed states, respectively. The work-hardening rate of the AZ31 alloy containing Nd and Dy increased significantly after annealing compared to those of the as-cast state. Fracture analysis indicated that the additive RE did not obviously change the fracture mechanism of the Mg alloy. All specimens exhibit a hybrid fracture with cleavages and dimples. The weight loss test showed that the corrosion resistance of the AZ31 Mg alloy was improved with added RE as it interacts with Al to form Al-RE phase, which upgraded the corrosion resistance of the alloys. The co-addition of RE (RE = Nd+Dy) was proven to enhance corrosion resistance, and also stabilized the corrosion rate. In brief, the co-addition of Nd and Dy significantly improved the corrosion resistance of the AZ31 magnesium alloys than the counterpart of the mechanical properties. [ABSTRACT FROM AUTHOR]

Recent policy initiatives in the United States and beyond have called for decreasing reliance on China for rare earth elements and related downstream products, such as neodymium iron boron (NdFeB) magnets. Among these initiatives, recycling of rare earth elements and NdFeB magnets from electronic waste (e-waste) has emerged as an approach to reduce both import dependence on China and the environmental impacts of mining and refining these products. This paper highlights several methods for recycling NdFeB magnets from e-waste and assesses potential impacts on supply chains and the environment from the commercial adoption of these recycling techniques. [ABSTRACT FROM AUTHOR]

Background: Gallstone disease poses a global threat to human health and is strongly linked to environmental factors. However, there is currently no data on the presence of rare earth elements (REEs) in human gallstones. This paper investigates the concentration and distribution of REEs in gallstones for the first time, aiming to explore the environmental implications on human health. Methods: A total of 25 gallstone samples were collected in Shanghai and the content of REEs was measured by Inductively coupled plasma-Mass Spectrometry (ICP-MS) to explore the distribution of REEs in gallstones. Results: The concentration of REEs in gallstones ranged from 4.89 to 190.8 ng/g (mean 39.21). In most of the gallstone analyses, REEs have been detected and generally attributed to environmental exposure or food contamination. The Y/Ho ratio of gallstones was lower than that of continental rocks, similar to that in the blood, indicating limited fractionation during fluid transport processes in the gallbladder. Conclusions: The upper continental crust (UCC)-normalized REEs pattern in gallstones showed depletion of light REEs, while most showed enrichment of heavy REEs. Positive Gd anomalies were found in most samples, while few samples suggested anthropogenic influence. Whether exogenous inputs or in vivo biofractionation lead to changes in REEs fractionated patterns require further analyses. [ABSTRACT FROM AUTHOR]

Rare earth elements are an essential critical raw material in the development of modern technologies and are highly sensitive to both supply chain disruptions and market turbulence. The presented study examines the characteristics of fuel, fly ash, and bottom ash from lignite combustion in power plant units. Also, we attempted to determine the amount of amorphous glass in the ashes and whether and to what extent the glass from the ash samples is bound to REY. The suitability of the ash was assessed as an alternative source of REY. The fuel and ash samples were acquired from power plants in Poland. The tests determined the fuel quality parameters, including the chemical and phase composition, of amorphous glass using ICP-MS and XRD methods, respectively. The study showed that all ash samples dissolved in 4% HF were enriched in REY. The efficiency of REY enrichment varied, and its presence in the residue samples was found to be in similar proportions compared to the raw sample. All ash residue samples were enriched in critical elements. The obtained values of the Coutl prospective coefficient allowed for the classification of some of the analyzed ashes and their residues after dissolution in 4% HF as prospective REY raw materials. [ABSTRACT FROM AUTHOR]

Compositional screening is an important strategy to improve the oxidation resistance of high‐entropy diborides (HEB2), yet the related studies are limited. Here, we report a rare‐earth (RE) element compositional screening strategy to improve the oxidation resistance of HEB2. To be specific, the single‐phase (Hf0.28Zr0.28Ta0.28RE0.16)B2 (HEB2‐RE) samples with 12 different RE elements are fabricated via ultrafast ultrahigh‐temperature synthesis and spark plasma sintering techniques, and their oxidation resistance is explored by isothermal oxidation tests. The results show that the as‐obtained HEB2‐Sc samples possess the best oxidation resistance among all the as‐fabricated HEB2‐RE samples. Such outstanding oxidation resistance is ascribed to the enhanced viscosity of the generated B2O3 glass originating from the solid solution of (Zr, Me)0.84Sc0.16O2 complex oxides, as confirmed by transmission electron microscope observations and first‐principles calculations. [ABSTRACT FROM AUTHOR]

Surface water and sediment rare earth elements (REEs) concentrations can reflect the impact of human activities on aquatic ecosystems. Variations in formation time may result in changes in the geochemical characteristics of REEs in the water‒sediment system of coal mining subsidence lakes. However, our understanding of this phenomenon is limited. The spatial distribution, coexistence patterns, and fractionation characteristics of REEs were investigated in coal mining subsidence lakes with different subsidence times in the Huainan coalfield in eastern China. The results indicate that REEs concentrations in lake water are relatively low. Both compartments are enriched in light rare earth elements (LREEs), and the degree of enrichment increases with time, which can be attributed to the combined influences of natural processes and human activities. Under alkaline water conditions in the study area, LREEs are preferentially removed from the aqueous phase, leading to their enrichment in sediments. The anomalous behavior of Ce is associated with the oxidative environment under alkaline conditions, whereas the Eu anomaly is influenced primarily by the dissolution of feldspar minerals. Agricultural activities result in significant inputs of light rare earth elements (La) to farmlands each year through the application of rare earth fertilizers. These elements are ultimately released into coal mining subsidence lakes, resulting in noticeable anomalies of La in the majority of lakes within the study area. These findings indicate that the lakes in the subsidence area are strongly affected by agricultural activities. The difference between lakes with different numbers of sinking years is reflected mainly in the degree of enrichment of LREEs, and the older the lake is, the greater the degree of enrichment of LREEs. These research results provide a scientific basis for the treatment and protection of the water environment in coal mining subsidence lakes influenced by anthropogenic activities. Through this series of studies, we will improve our understanding of the behavior of REEs in the aquatic environment under the influence of human activities and to provide support for sustainable mineral resource development and environmental protection policy formulation. [ABSTRACT FROM AUTHOR]

The renewable energy industry is heavily reliant on rare earth elements, underscoring the need to develop resources and production. The objective of this work was to estimate coal ash resources and potential for extraction of rare earth elements using data for the US. Data on spatiotemporal variability in coal ash resources and disposition were compiled from various federal databases and rare earth elements levels in ash were compiled from the literature. Results show that ~ 52 gigatons (Gt) of coal were produced in the US (1950–2021). Power plants account for most of the coal use, particularly since 1980. Coal ash (5.3 Gt) represents a mean of 10% of coal by weight, ranging from 6% for subbituminous to 14% for lignite. About 70% of coal ash is potentially accessible for rare earth element extraction (1985–2021) and was disposed in landfills and ponds with the remaining coal ash used onsite or sold. Median values of total rare earth elements are much higher in ashes derived from the Appalachian Basin (median 431 mg/kg) than in the Illinois (282 mg/kg) or Powder River basins (264 mg/kg). Considering the market value of rare earth oxides, potentially accessible ash volumes, and percent rare earth element extraction (30% Appalachian and Illinois Basins; 70% Powder River Basin) results in an estimated $8.4 billion value. This study provides fundamental information on accessible coal ash resources in the US, linkages to coal sources, and preliminary estimates of rare earth element levels for future development within the US. [ABSTRACT FROM AUTHOR]

Background: Rare-earth sulfide nanoparticles (NPs) could harness the optical and magnetic features of rare-earth ions for applications in nanotechnology. However, reports of their synthesis are scarce and typically require high temperatures and long synthesis times. Results: Here we present a biosynthesis of terbium sulfide (TbS) NPs using microorganisms, identifying conditions that allow Escherichia coli to extracellularly produce TbS NPs in aqueous media at 37 °C by controlling cellular sulfur metabolism to produce a high concentration of sulfide ions. Electron microscopy revealed ultrasmall spherical NPs with a mean diameter of 4.1 ± 1.3 nm. Electron diffraction indicated a high degree of crystallinity, while elemental mapping confirmed colocalization of terbium and sulfur. The NPs exhibit characteristic absorbance and luminescence of terbium, with downshifting quantum yield (QY) reaching 28.3% and an emission lifetime of ~ 2 ms. Conclusions: This high QY and long emission lifetime is unusual in a neat rare-earth compound; it is typically associated with rare-earth ions doped into another crystalline lattice to avoid non-radiative cross relaxation. This suggests a reduced role of nonradiative processes in these terbium-based NPs. This is, to our knowledge, the first report revealing the advantage of biosynthesis over chemical synthesis for Rare Earth Element (REE) based NPs, opening routes to new REE-based nanocrystals. [ABSTRACT FROM AUTHOR]

AbstractA new ion-pairing HPLC method has been developed for the analytical separation of rare earth elements (REEs), utilizing the unique “diad-effect” of the lanthanides. A chemometric approach was used to optimize the separation process, examining the impact of mobile phase pH and ion-pairing reagent concentration on resolution and elution time. A triple gradient elution program was proposed, involving changes in the pH of the mobile phase from 3.5 to 4.5, the ion-pairing reagent concentration from 25 mM to 0.05 M, and the mobile phase complexing additive (hydroxyisobutyric acid) concentration from 0.05 M to 0.5 M. With the proposed method, all REEs, including pairs that are typically difficult to separate (Pr–Nd, Eu–Gd, and Dy–Y), were effectively separated in less than eight minutes. The method validation conducted following ICH guidelines showed accurate results, with an accuracy of 99–108% across a concentration range of 50–150% of the target concentration for REEs. It also exhibited good linearity (0.9998–0.9992) across a concentration range of 5–15 µg/mL for REEs and a detection limit of 0.27–0.98 µg/mL for the various species. The proposed HPLC method proved reliable and successfully separated a commercial sample of yttrium-group oxides. [ABSTRACT FROM AUTHOR]

A simple method was developed for the determination of REEs, Zr, Hf, Th and U in ultramafic rocks by inductively coupled plasma‐mass spectrometry with a combination of RE and UTEVA extraction resins for their separation and pre‐concentration. Ultramafic rocks were digested with HNO3‐HF‐HClO4 and finally turned into 11 mol l−1 HCl solutions together with H3BO3 to remove insoluble fluorides. The removal of matrix elements was achieved during the loading procedure. Following this, REEs on RE resin, and Zr, Hf, Th and U on UTEVA resin were eluted with 10 ml of 0.24 mol l−1 HCl, with recoveries better than 94.4%. This method was validated using reference materials JP‐1, DTS‐2B, OKUM, UB‐N, MUH‐1 and DZΣ‐2, and the measurement results for target analytes were comparable to literature values, indicating its applicability to the determination of REEs, Zr, Hf, Th and U at ultra‐trace level in ultramafic rocks. [ABSTRACT FROM AUTHOR]

The Na3Nd(BO3)2-NdBO3 phase diagram was investigated by the solid-state synthesis and DSC methods. Na3Nd(BO3)2, Na3Nd2(BO3)3 and NdBO3 were grown by spontaneous crystallization from the Na2O-B2O3-NaF flux. Typical Nd3+ luminescence of 4F3/2 → 4I9/2 and 4F3/2 → 4I11/2 electron transitions at 875 nm and 1054 nm were registered. Maximum integral intensity of the luminescence was observed for Na3Nd2(BO3)3 crystals, more than twice that of NdBO3, Na3Nd(BO3)2. [ABSTRACT FROM AUTHOR]

Lanthanum (La(III)) is one of the high-demand rare earth elements with applications in various products. However, La(III) in mining waste streams and electronic waste also poses environmental and health concerns. Therefore, the recovery of La(III) in the waste is needed. In the present study, the adsorption of La(III) with Dowex 50W-X8, Amberchrom50WX4, Amberlyst 15, and Amberchrom 50WX2 was evaluated using a shaker water bath. Dowex 50W-X8 was found to be the best adsorbent and was used to investigate the effect of the shaker speed (RPM = 50–150), adsorbent dosage (1.0–4.0 g), pH (2.0–7.0), and temperature (20–40 °C) on adsorption. La(III) adsorption was found to increase with the shaker speed, as expected. On the other hand, the adsorption capacity decreased with the adsorbent amount. Also, the highest La(III) adsorption was observed at pH = 6.0. La(III) percentage removal did not vary significantly with a temperature from 20 °C to 40 °C. However, the first-order kinetic rate constant decreased moderately with increases in temperature. The adsorption of La(III) by Dowex 50-X8 followed the Freundlich isotherm model better than the Langmuir model. In addition, the adsorption kinetics were represented well by the pseudo-first-order kinetic model. Moreover, enthalpy and Gibbs free energy changes were found to be negative, indicating an exothermic and thermodynamically favorable adsorption process. [ABSTRACT FROM AUTHOR]

Laboratory flotation tests carried out using an ore sample containing Rare Earth Elements (REEs) present as monazite and bastnaesite show that the flotation of monazite is slower and yielded lower recovery than that of bastnaesite. Results show that when studying the performances of a concentration process for an REE ore, it is essential to not look only at the behavior of the individual REEs but to convert elemental assays into mineral assays to obtain the mineral's actual response to the concentration process. The results of the laboratory flotation tests are used to calibrate a flotation simulator applied to study different circuit configurations for the concentration of the REE minerals. Indeed, it is shown that for the studied ore, two cleaning stages of a rougher concentrate are sufficient to produce a concentrate with a Total Rare Earth Oxide (TREO) grade above 40%, which is acceptable for the subsequent hydrometallurgical process. The simulation also shows that it may be feasible, if required for the hydrometallurgy step, to separate bastnaesite and monazite by taking advantage of the different flotation kinetics of the two minerals. [ABSTRACT FROM AUTHOR]

The aim of the research was to assess the potential of bottom ash from Polish coal-fired power plants as an alternative source of rare earth elements (REY). The potential of these ashes was compared with fly ash from the same coal combustion cycle. The phase and chemical composition, as well as REY, were determined using: X-ray diffraction and inductively coupled plasma mass spectrometry. The tested ashes were classified as inert-low pozzolanic and inert-medium pozzolanic, as well as sialic and ferrosialic, with enrichment in detrital material. The phase and chemical composition of bottom ash was similar to fly ash from the same fuel combustion cycle. The REY content in the ash was 199–286 ppm and was lower than the average for global deposits, and the threshold value was considered profitable for recovery from coal. Bottom ash's importance as a potential source of REY will increase by recovering these metals from separated amorphous glass and mullite and grains rich in Al, Mg, K, and P. The industrial value of bottom ash as an alternative source of REY was similar to fly ash from the same fuel combustion cycle. [ABSTRACT FROM AUTHOR]

As the 21st century advances, the demand for rare earth elements (REEs) is rising, necessitating more robust exploration methods. Our research group is using hyperspectral remote sensing as a tool for mapping REEs. Unique spectral features of bastnaesite mineral, has proven effective for detection of REE with both spaceborne and airborne data. In our study, we collected hyperspectral data using a Senop hyperspectral camera in field and a SPECIM hyperspectral camera in the laboratory settings. Data gathered from California's Mountain Pass district revealed bastnaesite-rich zones and provided detailed insights into bastnaesite distribution within rocks. Further analysis identified specific bastnaesite-rich rock grains. Our results indicated higher concentrations of bastnaesite in carbonatite rocks compared to alkaline igneous rocks. Additionally, rocks from the Sulphide Queen mine showed richer bastnaesite concentrations than those from the Birthday shonkinite stock. Results were validated with thin-section studies and geochemical data, confirming the reliability across different hyperspectral data modalities. This study demonstrates the potential of drone-based hyperspectral technology in augmenting conventional mineral mapping methods and aiding the mining industry in making informed decisions about mining REEs efficiently and effectively. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) comprises of a uniform group of lanthanides and scandium (Sc) and yttrium (Y) finding their key importance in agriculture sectors, electronic and defense industries, and renewable energy production. The immense application of REEs as plant growth promoters has led to their undesirable accumulation in the soil system raising concerns for REE pollution as upcoming stresses. This review mainly addresses the chemistry of REEs, uptake and distribution and their biphasic responses in plant systems and possible plausible techniques that could mitigate/alleviate REE contamination. It extends beyond the present understanding of the biphasic impacts of rare earth elements (REEs) on physio-biochemical attributes. It not only provides landmarks for further exploration of the interrelated phytohormonal and molecular biphasic nature but also introduces novel approaches aimed at mitigating their toxicities. By delving into innovative strategies such as recycling, substitution, and phytohormone-assisted mitigation, the review expands upon existing knowledge of REEs whilst also offering pathways to tackle the challenges associated with REE utilization. [ABSTRACT FROM AUTHOR]

The large loss of fine-grained bastnaesite has become an increasingly important issue restricting the development of rare earth ore flotation industry. To solve this issue, a new collector mixture that combines octyl hydroxamic acid (OHA) and octyl phenol ethoxylation (OP10, the number of ethylene oxide groups is 10) is proposed to be used to improve the flotation of bastnaesite. The flotation adsorption mechanism of OHA/OP10 on bastnaesite was investigated by a series of experimental and analytical tests. The results showed that when the molar ratio of OHA/OP10 was 3:1, the OHA/OP10 combination significantly improved the recovery of −74 + 38 μm and −15 μm bastnaesite compared with only OHA. Optical microscopy revealed that mixed OHA/OP10 had a beneficial effect on fine-grained bastnaesite aggregation. In addition, the results of the zeta potential test, fluorescence spectrum analysis, and XPS analysis showed that OHA and OP10 were co-adsorbed on the surface of bastnaesite. [ABSTRACT FROM AUTHOR]

Phosphorite deposit is a kind of marine sedimentary phosphate deposit with the francolite as the main ore mineral. These deposits were formed in the upwelling areas during six historical periods after Paleoproterozoic, and are generally related to the biological activity and the intensity of continental weathering. The formation of phosphorite deposits is controlled by marine transgressions and regressions, microbial activities and physical and chemical conditions of sediment pore water. The key factors for the formation of phosphorite deposits with high rare earth elements (REEs) content are low sedimentation rate and periodic submarine storms. Some phosphorite deposits are rich in medium and heavy REEs, which are potential important REE resources. The main host mineral of REEs in phosphorite is francolite. The REEs in francolite are mainly derived from seawater in sedimentary period and sediment pore water in early diagenetic period, and are incorporated into francolite via adsorption or lattice substitution. REEs can be adsorbed on the surface of marine particles by forming as REEs-carbonate complex and released by the marine particles decomposing that is induced by the change of redox conditions in the sediment pore water. Through the previous research, it is found that different marine particles preferentially adsorb different REEs, which results in the formation of different REEs patterns of pore water and then affects the patterns of francolite in phosphorite deposits. The enrichment of REEs in francolite is equal for light, medium and heavy REEs and different REEs patterns in francolite are derived from contrasting fluid sources. In general, seawater can produce a HREEs-enriched pattern, and pore water might yield a MREEs-bulge pattern (enrichment of medium REEs). As the phosphorite deposits with significant REEs contents are characterized by MREEs-bulge patterns that are consistent with Fe-Mn (oxyhydr) oxides input by the submarine hydrothermal process and the pore water in the early diagenetic process, which may indicates the influence of the submarine hydrothermal activities and the early diagenetic process on the REEs enrichment mechanism of phosphorite deposits. In this paper, the metallogenic process of phosphorite deposits is summarized from the characteristics, spatiotemporal distribution and metallogenic control factors of phosphorite deposits; the enrichment behavior and differentiation behavior of REEs in the process of phosphorite mineralization are analyzed from the content and anomaly of REEs in phosphorite deposits; and the possible enrichment mecha-nism of REEs in phosphorite rocks with abnormal enrichment of REEs is revealed. The study of metallogenic process and REEs enrichment mechanism of phosphorite deposits is of great significance for the prospecting and ex-ploitation of phosphorite deposits that are highly enriched in REEs. [ABSTRACT FROM AUTHOR]

Shifang-type phosphorite deposit is an important type of phosphorite deposit in China, which is characterized by large scale, high phosphorus grade, and enrichment in rare earth elements (REEs). However, the enrichment regularity and resource potential of REEs in this type of deposit are not studied in detail. This study takes the typical Shifang-type phosphorite deposit in Mianzhu, Sichuan Province, as the research object. Based on field geological investigation, the distribution and enrichment characteristics of REEs in the deposit are explored through microscopic petrographic observation, scanning electron microscope/energy disperse spectroscopy imaging, and whole-rock geochemical analysis for the phosphorus-bearing layers (phosphorite layer, dark grey and maroon S-P-Al-Sr-rich layers) and their roof and floor rocks (dolomite) in the mining area. In turn, the potential resource of REEs in Shifang-type phosphorite deposits in Sichuan Province is discussed. The results showed that the total REEs (La-Lu+Y) contents in the roof and floor dolomites of the phosphorus-bearing layers are very low (13.6x10-6 on average), the REEs contents in the phosphorite are medium (280.0x10-6 on average), while the REEs contents in the S-P-Al-Sr-rich layers are extremely high (2 053.9x10-6 on average), especially the maroon S-P-Al-Sr-rich layer (up to 3 257.2x10-6). Together with previously published REEs content data from adjacent phosphorite deposit, the average REEs content in S-P-Al-Sr-rich layers in the Shifang-type phosphorite deposits in Sichuan Province is 2 259. 4x10-6 with the maximum up to 3 286.8x10-6, of which the average concentration of medium and heavy REEs (Sm ~ Lu+Y) is 1 276.9x10-6 with the maximum up to 2 213.0x10-6, accounting for 55.1% of the total REEs. REEs contents in the Shifang-type phosphorite deposits in Sichuan Province are much higher than those in ion adsorption-type REEs deposits in southern China, Zhijin REEs-bearing phosphorite deposit, and REEs-rich deep-sea sediments. According to preliminary estimates, the total potential REEs resources associated with the Shifang-type phosphorite deposits in Sichuan Province can reach 252 000 tons, 156 000 tons of which are medium and heavy REEs. The potential medium and heavy REEs resources in the S-P-Al-Sr-rich layer alone can reach 96 000 tons. Therefore, the Shifang-type phosphorite deposits in Sichuan Province have important economic and social value, and the development and utilization of REEs in these deposits are expected to alleviate the current shortage of medium and heavy REEs in China. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) and their oxides have become seed of the modern technology. Lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), scandium (Sc), yttrium (Y) and their oxides La2O3, CeO2 and Y2O3 are utilized by researchers in order to enhance the microhardness, tensile strength, percentage elongation and wear resistance of the aluminum alloy composites and hybrid composites. Although aluminum boasts a lower weight-to-density ratio, high ductility, malleability and plasticity but the low strength, hardness and wear resistance limit its application. To address these shortcomings, various reinforcements have been employed. Among the available methods, powder metallurgy and stir casting are utilized by the researchers to process the aluminum metal matrix composites. The current study compiles the literature investigating the effect of rare earth elements and their oxides on mechanical properties and tribological behavior of aluminum alloys and hybrid composites. The addition of REEs and REOs to aluminum composites and hybrid composites resulted in properties suitable for applications in the aerospace, mobile phones, solar panels, fluorescent materials, marine and automobile components. [ABSTRACT FROM AUTHOR]

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Sediment transport to the sea by rivers is crucial for the stability of estuaries and coasts. The Yangtze River, the largest river in China, like many large rivers worldwide, is experiencing a decrease in sediment load reaching the coast. However, the tidal flat around Qidong Cape, located at the entrance of the North Branch of the Yangtze Estuary, is undergoing extensive siltation. The source of this sediment is unclear. In this study, a sediment core was collected and the geochemical characteristics of rare earth elements (REE) were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The results indicate the following: (1) The average content of REE is 178.57 μg/g, and the average ratio between LREE and HREE is 8.66, which is comparable to sediments from the South Yellow Sea. The chondrite-normalized and UCC-normalized patterns resemble those of the Yangtze River and the South Yellow Sea, indicating a negative gradient, a weak Ce-negative anomaly, and a distinct Eu-negative anomaly. (2) The continental shelf deposits in eastern China are primarily derived from sediment flux delivered by rivers. The sediments in the South Yellow Sea mainly originate from the Yangtze River and the Yellow River, exhibiting characteristics of a mixed source due to long-term geological processes, namely geochemical processes. The REEs in the tidal flat around Qidong Cape inherit the source area's characteristics and originate from the weathering of upper continental rock in mainland China. Moreover, the tidal flat around Qidong Cape is influenced by both runoff and tidal actions, leading to strong land–sea interactions and reducing the environment, explaining the Eu-negative anomaly. (3) Hydrodynamic forces in the North Branch of the Yangtze River have shifted from runoff to tidal dominance since the 1930s. However, marine hydrodynamics outside the estuary have remained unchanged. Consequently, the Subei coastal current plays a key role in sediment transport and diffusion. Sediments from the south wing of the Radiative Sand Ridge in the South Yellow Sea are transported southward by the Subei coastal current, and under tidal influence, suspended sediment is deposited in the tidal flat around Qidong Cape. Therefore, the sediment source has gradually shifted from the Yangtze River to the South Yellow Sea. [ABSTRACT FROM AUTHOR]

Copyright of Rare Metals is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Conventional mining of economically and strategically important critical rare earth elements (REEs) (such as neodymium, lanthanum and dysprosium), and chalcogens (such as selenium and tellurium) are associated with a huge economic and environmental cost. Therefore, the need to recover REEs as well as chalcogens from different waste streams including wastewaters is becoming urgent. Batch assays on synthetic chalcogen/REE-laden wastewater showed that the presence of REEs significantly improved the tellurite removal rate (> 80%) and enhanced selenate removal by 66% ± 10%. Three 3.9 L continuous upflow anaerobic granular sludge bed (UASB) reactors were operated at a hydraulic retention time of 24 h and 30 °C. Selenate reduction was achieved with a removal efficiency of ~ 98% with an influent pH of 4.0 for more than 28 days. The effect of REEs on tellurite removal in the UASB bioreactor could not be clearly established since a soluble tellurium removal efficiency of more than 98% was observed already before the addition of REEs at elevated tellurite concentrations. The complete REE removal in both batch assays and UASB reactors at higher pH (7.0 ± 0.5) was attributed to precipitation, whereas chalcogen oxyanions removal was due to microbial reduction. However, at acidic pH, biosorption was responsible for REE's removal, and the Se-enriched sludge exhibited a superior REE's removal efficiency than the non-enriched and Te-enriched sludge. [ABSTRACT FROM AUTHOR]

Our study aimed to assess the soil quality in Punjab's Hoshiarpur district through a meticulous analysis of nutrient and elemental composition. Using a variety of analytical techniques, including Neutron Activation Analysis (NAA), external Particle-induced Gamma-ray Emission (PIGE) an Ion beam analysis Technique, and energy-dispersive X-ray fluorescence (ED-XRF), we delved into soil characterization for 22 agricultural soil samples in the Punjab region. Within the NAA framework, utilizing the Pneumatic Carrier Facility and the self-serve facility at Dhruva reactor in Mumbai, a brief 1-min irradiation procedure identified pivotal elements—Na, Mg, V, Al, Mn, and K. Conversely, an extended neutron irradiation process of approximately 4 h within the self-serve facility enabled the estimation of nearly 12 elements, including Rare Earth Elements (REEs), Transition elements, and other significant elements. The external PIGE technique quantified low Z elements (Na, Mg, Al, and Si), contributing to our analytical arsenal. Rigorously validating both NAA and PIGE methodologies, we compared results meticulously against established geological standard reference materials—specifically USGS RGM-1 and USGS AGV-1.Instrumental in elemental analysis, ED-XRF spectroscopy fortified our investigative endeavors by quick assessment of ten crucial elements. The elemental analysis revealed notable accumulations of Mn and Zn in the soil, surpassing the suggested permissible limits, whereas Co, Cr, and Pb were found to be within the recommended thresholds set by WHO/UNEP. Beyond elemental profiling, our study extended to estimate the accumulation levels of various elements utilizing ecological risk factors such as Contamination Factor, Potential Ecological Risk Index, Pollution Load Index, and Geoaccumulation Factor. Our findings highlighted significant accumulation of REEs including La, Sm and Yb.. This evaluation sheds new light on the interplay between soil composition and environmental health, emphasizing the need for advanced accessible agricultural technologies to prevent and forecast contaminant discharge in arable soil. This commitment aligns with our broader goal of advancing sustainable practices in soil management. [ABSTRACT FROM AUTHOR]

Light‐emitting diodes (LED) are widely used for energy savings. A lot of different materials and especially metals are needed to produce LED. End‐of‐life LED contain critical metals like indium or rare earth elements. In this study, first a thermochemical step is used to recover the critical metal indium from LED with hydrochloric acid‐containing vapor from polyvinyl chloride as chlorine source. Then, the LED residue is leached with sulfuric acid and hydrogen peroxide. From the leachate, the heavy rare earth element lutetium can be extracted with n‐octanol and tributyl phosphate. [ABSTRACT FROM AUTHOR]

The successful adoption and widespread implementation of innovative acid mine drainage treatment and resource recovery methods hinge on their capacity to demonstrate enhanced performance, economic viability, and environmental sustainability compared to conventional approaches. Here, an evaluation of the efficacy of chromium-based metal–organic frameworks and amine-grafted SBA15 materials in adsorbing europium (Eu) from actual mining wastewater was conducted. The adsorbents underwent comprehensive characterization and examination for their affinity for Eu. Cr-MIL-PMIDA and SBA15-NH-PMIDA had a highest Langmuir adsorption capacity of 69 mg/g and 86 mg/g, respectively, for an optimum level of pH 4.8. Preferential adsorption tests followed using real AMD collected at a disused mine in the north of Norway. A comparative study utilizing pH-adjusted real AMD revealed that Cr-MIL-PMIDA (88%) exhibited slightly higher selectivity towards Eu compared to SBA15-NH-PMIDA (81%) in real mining wastewater. While Cr-MIL-PMIDA displays excellent properties for the selective recovery of REEs, practical challenges related to production costs and potential susceptibility to chromium leaching make it less appealing for widespread applications. A cost–benefit analysis was then undertaken to quantify the advantages of employing SBA15-NH-PMIDA material. The study disclosed that 193.2 g of EuCl3 with 99% purity can be recovered by treating 1000 m3 of AMD. [ABSTRACT FROM AUTHOR]

Basic study on burnt rock plays a crucial role in the prevention and control of burnt rocks water hazard. In order to understand the petrology and geochemical characteristics of the burnt rock, taking the Zhangjiamao mine field in Yushen mining area in northern Shaanxi as an example, the main elements, trace elements and rare earth elements of the burnt rock were determined and analyzed in detail through field investigation and core sampling in boreholes. The results indicate that the upper and lower parts of the rock mass, as well as the adjacent rock layers, belong to plate-like barbecue rocks, lava rocks, and layered barbecue rocks, respectively. The lithology, color, and pore development characteristics of different types of burnt rocks vary greatly with the degree of roasting. The main chemical composition of burnt rock is SiO2, followed by Al2 O3. The rock samples are mainly siliceous aluminum, with relatively low content of magnesium iron components. The average Fe2 O3 + MgO content is 4. 76%, and there is little difference between the original rock and the burnt rock, and between the original rock and the burnt lava sample. The content of lithophile elements Rb and Ba in the burnt rock is higher than that in the original rock, while the content of Sr is low, and Cs and Eu are relatively depleted. The Zr content in high field strength elements is generally higher in all samples, and different types of rock samples have the characteristics of Y, Zr, and Pb enrichment. The changes in high field strength elements under burning are not significant. The REE abundance trend curve of the sample shows a differential distribution, and the average value of standard sedimentary rock and upper crust is more similar than that of chondrite. The study results will provide basic support for studying the genesis and formation environment of burnt rocks. [ABSTRACT FROM AUTHOR]

The 2011 discovery of the first rare earth-dependent enzyme in methylotrophic Methylobacterium extorquens AM1 prompted intensive research toward understanding the unique chemistry at play in these systems. This enzyme, an alcohol dehydrogenase (ADH), features a La3+ ion closely associated with redox-active coenzyme pyrroloquinoline quinone (PQQ) and is structurally homologous to the Ca2+-dependent ADH from the same organism. AM1 also produces a periplasmic PQQ-binding protein, PqqT, which we have now structurally characterized to 1.46-Å resolution by X-ray diffraction. This crystal structure reveals a Lys residue hydrogen-bonded to PQQ at the site analogously occupied by a Lewis acidic cation in ADH. Accordingly, we prepared K142A-and K142D-PqqT variants to assess the relevance of this site toward metal binding. Isothermal titration calorimetry experiments and titrations monitored by UV-Vis absorption and emission spectroscopies support that K142D-PqqT binds tightly (Kd = 0.6 ± 0.2 μM) to La3+ in the presence of bound PQQ and produces spectral signatures consistent with those of ADH enzymes. These spectral signatures are not observed for WT-or K142A-variants or upon addition of Ca2+ to PQQ ⊏ K142D-PqqT. Addition of benzyl alcohol to La3+-bound PQQ ⊏ K142D-PqqT (but not Ca2+-bound PQQ ⊏ K142D-PqqT, or La3+-bound PQQ ⊏ WT-PqqT) produces spectroscopic changes associated with PQQ reduction, and chemical trapping experiments reveal the production of benzaldehyde, supporting ADH activity. By creating a metal binding site that mimics native ADH enzymes, we present a rare earth-dependent artificial metalloenzyme primed for future mechanistic, biocatalytic, and biosensing applications. [ABSTRACT FROM AUTHOR]

AbstractRare earth elements (REEs) are widely used in several high-tech modern industries. Quantification of REEs demonstrates a technical challenge that requires the use of special scientific techniques. These techniques commonly introduce uncertainties that may propagate not only during the sample preparation phase but also in subsequent measurement and analysis phases. The Jordan Atomic Energy Commission is starting up a REE investigation program utilizing many of its available physical and chemical analytical capabilities, one of which is the Neutron Activation Analysis Facility (NAAF) at the Jordan Research and Training Reactor (JRTR). The NAAF provides accurate and relatively quick analytical services for better estimations of REEs in the unknown samples of interest without the need for any chemical processing prior to or after sample activation. In this paper, we present analytical results of routinely conducted instrumental neutron activation analysis (NAA) experiments using REE certified samples. To optimize future NAA investigations, first, a time-dependent Monte Carlo code at the JRTR, named Monte Carlo Code for Advanced Reactor Design and Analysis (McCARD), is herein validated via comparing its calculation results of the activation process against the presented results of the NAA experiments. The certified REE samples were activated in a well-thermalized NAA vertical activation hole within the reactor reflector region. Detailed neutronics and burnup calculations as well as transmutations were performed using McCARD. Ultimately, this study aims to assess the accuracy and reliability of the McCARD calculation models as a part of the effort of setting up a dedicated REE analysis laboratory at the JRTR. This study shows very good agreement between both obtained results—NAA experiment and McCARD calculations—with confidence levels noted to be more than 90% for almost all REE elements. [ABSTRACT FROM AUTHOR]

This paper presents an in-depth investigation into the optimization of rare earth element (REE) separation through electrodialysis, leveraging a newly developed Class II phenomenological model. This study explores the pivotal roles of the HEDTA/Nd molar ratio and pH of feed solution on enhancing the separation efficiency of neodymium (Nd) and praseodymium (Pr) from lanthanum (La) and cerium (Ce). By integrating expanded Nernst-Planck equations and the concept of limiting current density, the model offers a sophisticated understanding of ion transport dynamics and the impacts of concentration polarization. Experimental validation confirms the model’s predictive accuracy, demonstrating its practical applicability for industrial-scale operations. The research delineates how operational parameters such as chelating agent concentration and pH critically influence the purity and yield of separated REEs. The dynamic nature of chelation chemistry is also examined, highlighting its evolution during the electrodialysis process and its effect on the system’s overall performance. Key findings illustrate that lower HEDTA/Nd molar ratios significantly enhance the purity of Nd + Pr by minimizing the chelation of La and Ce, thus facilitating their migration to the concentrate compartment. Conversely, higher ratios maximize yield by retaining more Nd + Pr in the feed compartment. This dual approach allows for optimized separation based on specific industrial requirements. The outcomes of this study not only advance the field of REE separation but also provide a framework for further research into more efficient and sustainable extraction methods. The developed model and its validation represent a step forward in the practical application of electrodialysis in REE processing, offering substantial benefits for the critical materials sector. [ABSTRACT FROM AUTHOR]

This study integrates map information projection methods with machine learning algorithms to analyze the distribution of rare earth mines in mainland China. The information obtained through the map information projection method includes the latitude and longitude of the deposits, deposit type labels, and deposit names. This approach helps to overcome challenges related to the sensitivity of geological information. The acquired information was organized into a simple dataset containing only latitude and longitude information and a complete dataset containing additional information. These datasets were used to simulate the early and later stages of the research project, respectively. The K-Means algorithm was applied to the simple dataset, and the results demonstrated good clustering performance through specific validation. The Support Vector Machine (SVM) algorithm was applied to the complete dataset, and the analysis showed excellent classification performance, with relevant metrics (Accuracy, Precision, Recall, F1 Score) all around 90%. The experiments demonstrate that K-Means and SVM are suitable for information analysis in earth sciences and that they complement each other in research projects, being particularly applicable to the early and later stages of the project, respectively.The findings contribute to a more nuanced understanding of rare earth mineral distributions and underscore the potential for machine learning techniques to revolutionize geological sciences. [ABSTRACT FROM AUTHOR]

Baitu AuPb Deposit is located at the intersection of the Kangshan - Shanggong Fault and Machaoying Fault on the southern margin of the North China Craton. The Au, Ag, and Pb ore bodies are in heterogeneous coexistence. They mainly occur in secondary fault zones in carbonate rocks in a vein-like and layered manner. This paper conducted rare earth and microelement tests on the main rocks. The characteristics of rare earth elements indicate widespread development of hydrothermal and metamorphic metasomatism. The specific characteristics are: w(REE) > 10 (REE) > 10(REE) >t(REEtek) > 10(REE mineralized dolomite) > 10W(REF-mineralind quarte vein), showing a feature of the greater the degree of alteration mineralization, the lower the total rare earth content; 2 The rare earth distribution curve shows that with mineralization, slope increases, enrichment degree of light rare earth decreases, and enrichment degree of heavy rare earth increases; 3 The influence of alteration on Eu element anomalies in rocks such as andesite tectonic rock and marble is not significant, while mineralization results in a significant negative anomaly of Eu element. Additionally, the alteration has a significant impact on Ce element anomalies in andesite, tectonic rock, and marble, causing the Ce element to evolve gradually from positive anomalies to negative anomalies. Mineralization further increases the degree of negative anomalies in Ce elements. Comparing the microelements of the main rocks and ores with that of the North China continental crust, it was found that andesite and marble are the main host rocks, and the ore-forming elements Ag. Sh, Pb, W, and Zn are enriched, providing high background value for lead mineralization. After alteration, Pb and W elements in andesite show obvious enrichment, suggesting that the hydrothermal fluid itself carries Ph and Wore-forming elements or has a hydrothermal metasomatic enrichment effect on the ore-forming elements in the wall rocks; In terms of anomalous intensity, tectonic rocks, quartz veins, quartz syenites, and (marble) dolomite have higher enrichment or depletion intensity compared to andesite rocks, and the anomalous intensity is sequentially strengthened, indicating a close relationship between the source of ore-forming matters and the carbonate rocks of Longjiayuan Formation. In summary, the genesis of Baitu AuPb Deposit is generally dominated by magmatic hydrothermal filling and metasomatism, but it is superimposed with later continental volcanic sedimentary transformation [ABSTRACT FROM AUTHOR]

Simple Summary: Rare earth elements (REEs) are widely used in various fields of human activity. However, data from many studies indicate the harmful effects of REEs on humans and animals, including the nervous system. In this study, we estimated the REE content in hair samples of children living on the Kola Peninsula (Murmansk region) in the vicinity of the Lovozersky REE Mining and Processing Plant, and we linked the REE content in children's bodies to the prevalence of the nervous system diseases in Lovozersky District. We observed a higher prevalence of nervous system diseases (episodic paroxysmal disorders (G40–G47), cerebral palsy (G80–G83), epilepsy and status epilepticus (G40–G41)) in children aged 15–17 years in Lovozersky District compared to other territories of the Murmansk region. Indirect evidence of the link between REE content in hair samples of children and nervous system diseases is provided by data in the literature. According to these data, REEs are deposited in the brain structures responsible for the function of the nervous system, thus impairing them. This investigation highlights the relevance of studying the role of REEs in nervous system diseases, and it points to the need for the further research in this area. The aim of this study is to assess the rare earth element (REE) content in hair samples of children living in Lovozero village, near an REE mining site, and the possible effects of REEs on the prevalence of nervous system diseases in Lovozersky District (Murmansk region, Kola Peninsula). Fifty-three school-age children were recruited for the analysis of REE content in hair samples. REE (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) content was estimated by means of inductively coupled plasma mass spectrometry (ICP-MS). The analysis of REE content in the hair of children living in Russia, Kazakhstan, and China indicated REE intake from the environment. The possible contribution of REEs to nervous system disorders is supported by the link between the REE content in hair samples of children living near REE mining areas (China) and the manifestation of cognitive disorders in these children. It is also found that the prevalence of nervous system diseases in children aged 15–17 years is higher in Lovozersky District compared to the other districts of the Murmansk region. In this paper, the possible contribution of REEs to the prevalence of episodic paroxysmal disorders (G40–G47), cerebral palsy (G80–G83), and epilepsy and status epilepticus (G40–G41) is discussed. [ABSTRACT FROM AUTHOR]

This article presents a Python‐based program, DFT2FEFFIT, to regress theoretical extended X‐ray absorption fine structure (EXAFS) spectra calculated from density functional theory structure models against experimental EXAFS spectra. To showcase its application, Ce‐doped fluorapatite [Ca10(PO4)6F2] is revisited as a representative of a material difficult to analyze by conventional multi‐shell least‐squares fitting of EXAFS spectra. The software is open source and publicly available. [ABSTRACT FROM AUTHOR]

Summary: This study investigated the variation in mineral elements in bracatinga (Mimosa scabrella Bentham) honeydew honeys produced biannually over three consecutive harvest years. The aim was to assess the relationship between the year of production and the concentration of fourteen rare earth elements and six trace elements analysed using ICP‐MS. The concentrations of the twenty elements varied (P < 0.001) among all the honey samples. The dominant rare earth elements were Eu, followed by Nd and La, while Pd and Au were the major trace elements. Cluster analysis (CA) and linear discriminant analysis (LDA) were performed using all the elements identified. The LDA categorised (83.3% accuracy) the bracatinga honeydew honey samples according to their harvest year. Discriminant functions, influenced by Ce, Tb, and Th, show distinct elemental patterns in bracatinga honeydew honeys, varying with harvest year. This reflects fluctuations in yearly climatic conditions and is important to guarantee accurate characterisation. [ABSTRACT FROM AUTHOR]

Acid baking treatment is widely used to extract rare earth elements (REEs) from refractory rare earth bearing minerals such as monazite and xenotime. Since these REE minerals have been identified in coal-based sources, a parametric study was conducted to evaluate the impact and optimize the parametric values associated with the acid-baking process when treating a bituminous coal source. The parameters studied using a three-level statistical experimental program were acid baking time, acid solution concentration, baking temperature, and acid solution-to-solids ratio and each were found to significantly impact REE and contaminant element recovery. An increase in baking temperature up to around 250°C improved the light and heavy REE recovery values by more than 50 absolute percentage points relative to performances achieved when direct leaching. Acid baking was needed to dehydroxylate the clays and liberate the REE minerals, which allowed access for the acid to solubilize the REEs. Acid concentration of the solution used for acid baking was studied as a means of minimizing the amount of acid needed to achieve a target REE recovery. However, thermo-gravimetric and differential scanning calorimetry analysis (TGA-DSC) of sulfuric acid under oxidizing atmosphere revealed that the addition of water decreased the evaporation temperature, which explains the lower REE recovery values obtained when using lower acid concentrations. Using pure sulfuric acid at an acid-to-solid ratio of 0.8:1 resulted in recovery values of around 70% for both LREEs and HREEs. The decomposition reaction time was relatively quick with 65% of the TREEs recovered within the first 10 minutes. Water leaching experiments performed on the acid-baked products under a temperature of 25°C instead of 75°C revealed an increase in REE recovery by 10 absolute percentage points, which was likely due to the high solubility of REE-sulfates at room temperatures. [ABSTRACT FROM AUTHOR]

Objective The study aimed to investigate the impact of rare earth elements (REEs) exposure on pregnancy outcomes of in vitro fertilization-embryo transfer (IVF-ET) by analyzing samples from spouses. Methods A total of 141 couples were included. Blood and follicular fluid from the wives and semen plasma from the husbands, were analyzed for REEs using inductively coupled plasma mass spectrometry (ICP-MS). Spearman's correlation coefficients and the Mann–Whitney U test were used to assess correlations and compare REE concentrations among three types of samples, respectively. Logistic models were utilized to estimate the individual REE effect on IVF-ET outcomes, while BKMR and WQS models explored the mixture of REE interaction effects on IVF-ET outcomes. Results Higher La concentration in semen (median 0.089 ng/mL, P = 0.03) was associated with a lower fertilization rate. However, this effect was not observed after artificial selection intervention through intracytoplasmic sperm injection (ICSI) (P = 0.27). In semen, the REEs mixture did not exhibit any significant association with clinical pregnancy. Conclusion Our study revealed a potential association between high La exposure in semen and a decline in fertilization rate, but not clinical pregnancy rate. This is the first to report REEs concentrations in follicular fluid with La, Ce, Pr, and Nd found at significantly lower concentrations than in serum, suggesting that these four REEs may not accumulate in the female reproductive system. However, at the current exposure levels, mixed REEs exposure did not exhibit reproductive toxicity. [ABSTRACT FROM AUTHOR]

The Marun–Keu complex plays a significant role in our understanding of the geological evolution of the Ural orogen; however, it remains poorly understood. This study aims to provide insights into the complex's age, protolith composition, rock formation conditions, and its position in the geological history. The zircons from the host granitic gneiss are characterized by magmatic cores with an age of 473 Ma and metamorphic rims with an age of approximately 370 Ma. We suggest that the metamorphic rims were formed during eclogite metamorphism and that the metagranitoids hosting the eclogites experienced eclogite metamorphism simultaneously with the basic and ultrabasic rocks that are common in this area. Heterogeneous zircons were also isolated from the selvage of a pegmatite vein, in which four domains are distinguished, two to three of which can be identified within single grains, as follows: (1) igneous cores with an age of approximately 470 Ma and the geochemical characteristics of zircon crystallized in basic rocks; (2) zircons recrystallized during eclogite metamorphism with geochemical characteristics intermediate between those of the magmatic cores and true eclogitic zircon; (3) pegmatitic zircon, exhibiting the most sharply differentiated REE spectra of all four domains, characterized by a prominent positive Ce anomaly and a weakly expressed negative Eu anomaly; and (4) eclogitic zircon, observed in the form of veins and rims, superimposed in relation to the other three domains. The age of the latter three domains is within the error range and is estimated to be approximately 370 Ma. This indicates that the processes of eclogite metamorphism and the formation of pegmatites occurred at approximately the same time in the studied area. [ABSTRACT FROM AUTHOR]

An econometric model was developed to analyze the contribution of various factors to the gross value added to the agricultural, manufacturing, and service sectors in the United States. The study found that variables such as rare earth element mining, the employment it generates, the domestic consumption, imports, and prices of certain elements significantly impact economic sectors. The models showed a good fit and met the necessary statistical assumptions. Rare earth elements are essential for a wide range of technological products, with China being the leading producer and consumer. This has raised concerns about the dependence on other countries. These elements significantly impact the economy's primary, secondary, and tertiary sectors used in agriculture, manufacturing, and services. Rare earth elements' mining and processing are complex and expensive processes, and demand is expected to continue to increase in the future. [ABSTRACT FROM AUTHOR]

The combined chemical extraction of rare earth elements from acid solutions and electrochemical separation of yttrium by electrodeposition from Estonian phosphorite ore samples containing rare earth elements has been conducted using ionic liquids at room temperature. It is shown that bis(2-ethylhexyl) phosphate can be used to selectively extract yttrium from other low rare earth elements, constituting the basis for further extraction. Electrochemical deposition can then be applied to the concentrated extraction product to separate valuable Y from the more abundant elements, such as Ca, from the natural sample. The addition of Bi salt to the working solution significantly aids REE's deposition. It is shown that this extraction method can be highly efficient as well as selective when well-controlled different electrodeposition conditions are applied. [ABSTRACT FROM AUTHOR]

We evaluated the effects of neodymium (0.000, 2.885, 5.770 and 8.655 mg · L−1) and zinc (0.1, 0.2 and 0.3 mg · L−1), as well as their interaction on lettuce plants in hydroponics. Applications of 2.885 mg Nd · L−1 and 5.770 mg Nd · L−1 increased plant height, number of leaves and leaf area, as well as fresh and dry stem, root and total biomasses. Root volume was greater in plants treated with 2.885 mg Nd · L−1. With 0.1 mg Zn · L−1, plant height, leaf area and fresh stem, root and total biomass were greater, while applying 0.3 mg Zn · L−1 increased the ratio of dry biomass of stems and roots. Plants exposed to 5.770 mg Nd · L−1 + 0.3 mg Zn · L−1 exhibited greater leaf length. The ratios of fresh and dry biomass of stems and roots increased in plants treated with 8.655 mg · L−1 Nd + 0.3 mg Zn · L−1. Dry biomass weights of stems, roots and total were the highest in plants treated with 20 mg Nd · L−1 + 0.1 mg Zn · L−1. Nd significantly increased foliar concentration of N, P and K. Hence, Nd and Zn improve growth and nutrition.

Abstract The renewable energy industry is heavily reliant on rare earth elements, underscoring the need to develop resources and production. The objective of this work was to estimate coal ash resources and potential for extraction of rare earth elements using data for the US. Data on spatiotemporal variability in coal ash resources and disposition were compiled from various federal databases and rare earth elements levels in ash were compiled from the literature. Results show that ~ 52 gigatons (Gt) of coal were produced in the US (1950–2021). Power plants account for most of the coal use, particularly since 1980. Coal ash (5.3 Gt) represents a mean of 10% of coal by weight, ranging from 6% for subbituminous to 14% for lignite. About 70% of coal ash is potentially accessible for rare earth element extraction (1985–2021) and was disposed in landfills and ponds with the remaining coal ash used onsite or sold. Median values of total rare earth elements are much higher in ashes derived from the Appalachian Basin (median 431 mg/kg) than in the Illinois (282 mg/kg) or Powder River basins (264 mg/kg). Considering the market value of rare earth oxides, potentially accessible ash volumes, and percent rare earth element extraction (30% Appalachian and Illinois Basins; 70% Powder River Basin) results in an estimated $8.4 billion value. This study provides fundamental information on accessible coal ash resources in the US, linkages to coal sources, and preliminary estimates of rare earth element levels for future development within the US.

Abstract Background Gallstone disease poses a global threat to human health and is strongly linked to environmental factors. However, there is currently no data on the presence of rare earth elements (REEs) in human gallstones. This paper investigates the concentration and distribution of REEs in gallstones for the first time, aiming to explore the environmental implications on human health. Methods A total of 25 gallstone samples were collected in Shanghai and the content of REEs was measured by Inductively coupled plasma-Mass Spectrometry (ICP-MS) to explore the distribution of REEs in gallstones. Results The concentration of REEs in gallstones ranged from 4.89 to 190.8 ng/g (mean 39.21). In most of the gallstone analyses, REEs have been detected and generally attributed to environmental exposure or food contamination. The Y/Ho ratio of gallstones was lower than that of continental rocks, similar to that in the blood, indicating limited fractionation during fluid transport processes in the gallbladder. Conclusions The upper continental crust (UCC)-normalized REEs pattern in gallstones showed depletion of light REEs, while most showed enrichment of heavy REEs. Positive Gd anomalies were found in most samples, while few samples suggested anthropogenic influence. Whether exogenous inputs or in vivo biofractionation lead to changes in REEs fractionated patterns require further analyses.

Abstract Background Rare-earth sulfide nanoparticles (NPs) could harness the optical and magnetic features of rare-earth ions for applications in nanotechnology. However, reports of their synthesis are scarce and typically require high temperatures and long synthesis times. Results Here we present a biosynthesis of terbium sulfide (TbS) NPs using microorganisms, identifying conditions that allow Escherichia coli to extracellularly produce TbS NPs in aqueous media at 37 °C by controlling cellular sulfur metabolism to produce a high concentration of sulfide ions. Electron microscopy revealed ultrasmall spherical NPs with a mean diameter of 4.1 ± 1.3 nm. Electron diffraction indicated a high degree of crystallinity, while elemental mapping confirmed colocalization of terbium and sulfur. The NPs exhibit characteristic absorbance and luminescence of terbium, with downshifting quantum yield (QY) reaching 28.3% and an emission lifetime of ~ 2 ms. Conclusions This high QY and long emission lifetime is unusual in a neat rare-earth compound; it is typically associated with rare-earth ions doped into another crystalline lattice to avoid non-radiative cross relaxation. This suggests a reduced role of nonradiative processes in these terbium-based NPs. This is, to our knowledge, the first report revealing the advantage of biosynthesis over chemical synthesis for Rare Earth Element (REE) based NPs, opening routes to new REE-based nanocrystals.