Rare Earth Minerals Research Articles

Geochemistry and Mineralogy of Rare-Earth Elements in Ferruginous Deposits and Bottom Sediments of the Laptev Sea

Abstract —The geochemical and mineralogical aspects of the distribution of rare-earth elements (REE) in ferruginous deposits (FD) and bottom sediments of the southeastern Laptev Sea are analyzed. The FD are dominated by biomorphs developed after polychaete tubes. The REE patterns depend on the proportion of ore and non-ore substances. The ore substance is represented mainly by iron hydroxides (limonite). It is a product of suboxic diagenesis enhanced by bioturbation and determines the slight enrichment of FD in MREE and cerium deficiency (Cean = 0.94). The non-ore substance comes from terrigenous sediments and has an (alumino)silicate composition. It controls the scandium content and is the source of REE mineral grains, among which monazite-(Ce) prevails. The sediments demonstrate a common similarity in REE patterns to shales and suspended material transported to the Laptev Sea by the Lena River, with elevated LREE and MREE contents and the value of Ce anomaly almost equal to unity (Cean = 1.06). In the sediments, REE minerals occur mostly in the silt fraction (<63 μm in size). The high content of organic matter (Corg of up to 2.15%) of predominantly terrigenous origin (OMter of up to 85%) in the sediments explains the oxygen deficiency and weak diagenetic mineral formation with low accumulation of trace elements, including REE, in the FD. The total REE content in the FD is lower than that in the sediments (on average, 173 ppm against 206 ppm).

The rare-earth yttrium induces cell apoptosis and autophagy in the male reproductive system through ROS-Ca2+-CamkII/Ampk axis

China has the world's largest reserves of rare earth elements (REEs), but widespread mining and application of REEs has led to an increased risk of potential pollution. Yttrium (Y), the first heavy REEs to be discovered, poses a substantial threat to human health. Unfortunately, little attention has been given to the impact of Y on human reproductive health. In this study, we investigated the toxic effects of YCl3 on mouse testes and four types of testicular cells, including Sertoli, Leydig, spermatogonial and spermatocyte cells. The results showed that YCl3 exposure causes substantial damage to mouse testes and induces apoptosis and autophagy, but not pyroptosis or necrosis, in testicular cells. Genome-wide gene expression analysis revealed that YCl3 induced significant changes in gene expression, with Ca2+ and mitochondria-related genes being the most significantly altered. Mechanistically, YCl3 exposure induced mitochondrial dysfunction in testicular cells, triggering the overproduction of reactive oxygen species (ROS) by impairing the Nrf2 pathway, regulating downstream Ho-1 target protein expression, and increasing Ca2+ levels to activate the CamkII/Ampk signaling pathway. Blocking ROS production or Ca2+ signaling significantly attenuates apoptosis and autophagy, while supplementation with Ca2+ reverses the suppression of apoptosis and autophagy by ROS blockade in testicular cells. Notably, apoptosis and autophagy induced by YCl3 treatment are independent of each other. Thus, our study suggests that YCl3 may impair the antioxidant stress signaling pathway and activate the calcium pathway through the ROS-Ca2+ axis, which promotes testicular cell apoptosis and autophagy independently, thus inducing testicular damage and impairing male reproductive function.

Rare Earth Elements Recovery from Primary and Secondary Resources Using Flotation: A Systematic Review

Rare earth minerals (REMs) contain rare earth elements (REEs) that are important in modern technologies due to their unique magnetic, phosphorescent, and catalytic properties. However, REMs are not only non-renewable resources but also non-uniformly distributed on the Earth’s crust, so the processing of REE-bearing secondary resources via recycling is one potential route to ensure the long-term sustainability of REE supply. Flotation—a method that separates materials based on differences in their surface wettability—is a process applied for both mineral processing and recycling of REEs, especially when the particles are fine and/or a high-purity product is required. In this review, studies about rare earth flotation from 2012 to 2021 were systematically reviewed using the PRISMA guideline. It was found that most REM flotation research works focused on finding better collectors and depressants while, for recycling, studies on advanced flotation techniques like froth flotation, ion flotation, solvent sublation, electroflotation, and adsorbing colloid flotation with an emphasis on the recovery of dissolved REEs from aqueous solutions dominated.

Roles and perspectives of A- and I-type magmas in rare earth element and gold mineralization

A- and I-type magmas are commonly associated with rare earth element (REE) and gold (Au) mineralization. However, the behavior and solubility of the REEs and gold within the A- and I-type magmas and their synchronous magmatism remain unclear. This study focused on the synchronous Early Cretaceous A- and I-type magmatism that formed alkaline and granodioritic complexes within the Luxi and Jiaobei terranes of the central-eastern North China Block, terranes that contain the third largest known REE deposit in China and the third largest gold province in the world. Our integrated whole-rock geochemical and Nd isotopic data and zircon Hf-O isotopic data provide new insights into the petrogenesis of these contemporaneous A- and I-type magmas and their role in the generation of the REE and gold mineralization in this area. The alkaline magmas that formed the intrusions in the Luxi terrane had A- and I-type affinities, were oxidized, were fluorine-, sulfur-, and copper-rich, were H2O-poor, and were generated by low-pressure partial melting of a source region containing enriched lithospheric mantle material and minor amounts of Paleoproterozoic A-type granitic crust. In comparison, the granodioritic magmas within the Jiaobei terrane had I-type affinities, were relatively reduced, were sulfur-rich, contained low concentrations of Cu, were hydrous, and were formed by high-pressure partial melting of a source region containing enriched mantle material and large volumes of Archean to Paleoproterozoic crustal material. The A- and I-type magmas within the Luxi terrane also have higher high field strength element (HFSE; e.g., Th, Nb, Ta) and total light rare earth element (ΣLREE) concentrations as well as higher ΣLREE/total heavy rare earth element (ΣHREE) ratios than the I-type magmas enriched in large ion lithophile elements (LILEs; e.g., Ba, Sr) in the Jiaobei terrane. These characteristics suggest that the diversity of REE and gold mineralization was the result of interaction between the lithospheric mantle and hybrid sediment-derived melts and aqueous fluids under rutile-bearing eclogite-facies (>2.0 GPa) conditions within the Luxi terrane and with aqueous fluids under amphibolite- to eclogite-facies (>1.5 GPa) conditions within the Jiaobei terrane. Our study strongly suggests that the interaction between the lithospheric mantle and sediment-derived melts, the presence of coexisting REE- and fluorine-rich magmas, and low-pressure partial melting were all crucial factors in the formation of A-type intrusion-related REE deposits, whereas high-pressure partial melting and contemporaneous sulfur and chalcophile element enrichment were critical processes in the formation of I-type intrusions prospective for gold mineralization.

Numerical Simulation Study on the Capture and Recovery of Rare Earth Mineral Particles in Bayan Obo Ore in a Superconducting Magnetic Field

Numerical Simulation Study on the Capture and Recovery of Rare Earth Mineral Particles in Bayan Obo Ore in a Superconducting Magnetic Field

Long-term effect of light rare earth element neodymium on Anammox process

During the mining of rare earth minerals, the application of neodymium-containing manures, and the treatment of spent neodymium iron boron magnet, the generation of ammonia wastewater containing neodymium is increasing. Thus, the effects of neodymium (Nd(III)) on anaerobic ammonium oxidation (Anammox) were investigated from the aspects of performance, kinetics, statistics, microbial community and sludge morphology, and the recovery strategy of EDTA-2Na wash was discussed. The nitrogen removal efficiency of the Anammox reactor decreased significantly and eventually collapsed at the Nd(III) dosing levels of 20 and 40 mg L−1, respectively. And the toxicity of Nd(III) to AnAOB was determined by the amount internalized into the cells. The EDTA-2Na wash successfully increased the total nitrogen removal rate (TNRR) of Nd(III)-inhibited Anammox to 41.60% of its initial value within 30 days, and the modified Boltzmann model accurately simulated this recovery process. The transient and extended effects of Nd(III), self-recovery, and EDTA-2Na wash on Anammox were effectively assessed using a one-sample t-test. 16S rRNA gene sequencing indicated that Nd(III) remarkably decreased the relative abundance of Planctomycetes and Candidatus Brocadia. The scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) revealed crystal-like neodymium particles on the surface of Anammox sludge. The above-mentioned results demonstrate that the concentration of Nd(III) should be below the toxicity threshold (20 mg L−1) when treating ammonia wastewater containing neodymium by Anammox, and also emphasize the importance of an appropriate recovery strategy.

A dynamic connectedness analysis between rare earth prices and renewable energy

Current world environmental challenges put pressure on clean energy produced mostly through renewables. There is an undeniably important role of rare earth minerals in renewable energy technologies. This study aims to infer the relationship between rare earth, clean energy, renewable energy technologies, and carbon emissions, focusing on daily stock price index data and applying the novel quantile time-frequency connectedness model, and the cross-quantilogram dependence approach during 2012–2022. Results show that spillovers among rare earth minerals and renewable energy are dependent on market conditions, time horizons, and analyzed quantiles. They also highlight the net receiver role of rare earth, especially in the short term. Findings might help investors understand diversification benefits and support policymakers in developing strategies for lessening import dependence on rare earth metals, as important as they are for renewable technology adoption to ensure green growth.

Exploitation alters microbial community and its co-occurrence patterns in ionic rare earth mining sites

The exploitation of ion-adsorption rare earth elements (REEs) deposits results in serious ecological and environmental problems, which has attracted much attention. However, the influences of exploitation on the prokaryotic communities and their complex interactions remain poorly understood. In the present study, bacterial and archaeal communities, as well as ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), in and around REEs mining area were investigated through high throughput sequencing and quantitative polymerase chain reaction (qPCR). Our results indicated that mining soil was characterized by poor soil structure, nutrient deficiency, and high concentrations of residual REEs. Oligotrophic bacteria (e.g., Chloroflexi and Acidobacteriota) were dominant in unexploited soil and mining soil, while copiotrophic bacteria (Proteobacteria and Actinobacteriota) were more abundant in surrounding soil. Nutrient was the key factor affecting microbial variation and abundance in mining soil. The bacterial community was more sensitive to REEs, while the archaeal communities were relatively stable. As the key members for ammonia oxidation, AOA outnumbered AOB in all the soil types, and the former was significantly influenced by pH, nutrients, and TREEs in mining soil. The microbial co-occurrence network analysis demonstrated that exploitation significantly influenced topological properties, decreased the complexity, and resulted in a much unstable network, leading to a more fragile microbial ecosystem in mining areas. Notably, the abundance of keystone taxa decreased after exploitation, and oligotrophic groups (Chloroflexi) replaced copiotrophic groups (Proteobacteria and Actinobacteriota) as the key to rebuilt a co-occurrence network, suggesting potentially important roles in maintaining network stability. The current results are of great significance to the ecological risk assessment of REEs exploitation.

Petrochemistry, rare metals-bearing minerals and spectrometric exploration in Khour Abalea, Abu Rusheid area, Eastern Desert, Egypt

On the Red Sea coast, Abu Rusheid area is located south Marsa Alam City (90 km) in the south Eastern Desert. Khour Abalea as a part of the Abu Rusheid area extends for about 1.0 km in E-W direction. It is subdivided into two main branches; the first one (the longest) extends about 0.7 km in E-W direction with 10–30 m in passing through mylonites, whereas the second branch extends about 0.5 km in ENE-WSW with about 5–20 m in width and passing through mylonites and ultra-mylonites. Microscopically, this rock is composed mainly of k-feldspars, plagioclases, biotite, and quartz as the main minerals, while the accessories include fluorite, allanite, secondary uranium (kasolite), and zircon. The hydrothermal alteration that occurs during the interaction of hydrothermal fluid and rock results in an M-W type tetrad effect range of 1.72–3.66 in the normalized REE chondrite patterns of the Khour Abalea mylonite rocks. The identified heavy minerals associated with Khour Abalea mylonite rocks can be categorized as a) radioactive minerals (soddyite, kasolite, thorite and uranothorite), b) rare earth minerals (monazite, xenotime and rare earth silicate), c) Nb–Ta minerals (columbite, fergusonite, ishikawaite and aeschynite), d) precious metals (gold, silver minerals (argentite, arcubisite and matildit), e) base metals (cassiterite, wolframite, chalcocite, galena, sphalerite pyrite and Bi minerals (bismite, bismuthinite and perite) and f) accessory mineral (zircon). According to the uranium mobilization equations, there are uranium enrichment in Khour Abalea mylonite.

Utilizing N-hydroxy-9-octadecenamide as a collector in flotation separation of bastnaesite and fluorite

Bastnaesite ((Ce,La,Pr,Nd)CO3F) is a significant light rare earth mineral found in nature, known for its fine-grained properties. Flotation is commonly employed for the recovery of fine-grained bastnaesite particles. Collectors serve as an essential flotation reagent that enhance the surface hydrophobicity of target minerals. A novel collector, N-hydroxy-9-octadecenamide (N-OH-9-ODA), was synthesised in this study. N-OH-9-ODA exhibits superior selectivity compared to the traditional collector oleic acid in the flotation separation of bastnaesite and fluorite. The experimental and computational results indicate that N-OH-9-ODA exhibits superior selectivity due to its higher adsorption affinity for bastnaesite surface compared to fluorite surface. The zeta potential and the binding energies of the Ce 3d peaks in the X-ray photoelectron spectrum (XPS) of bastnaesite surface exhibit significant shifts. Conversely, fluorite surface demonstrates minimal alterations in its zeta potential and the binding energies of the Ca 2p peaks in its XPS after its interaction with N-OH-9-ODA.

Tracing the material flows of dysprosium in China from 2010 to 2020: An investigation of the partition characteristics of different rare earth mining areas

Dysprosium, a critical rare earth element, is widely used in industries such as electric vehicles, wind power generation and electronic products. China leads dysprosium mining. However, the dysprosium supply cannot satisfy the demand due to mining restrictions. This study traced dysprosium flows and stocks in China from 2011 to 2020 by adopting a dynamic material flow approach. Compared to existing studies, dysprosium mining was divided into nine provincial mining areas, revealing the dysprosium mining characteristics and facilitating more realistic supply and demand balance value estimation. Moreover, the typically overlooked issue of dysprosium final product recycling was addressed. The results showed that (1) the dysprosium supply mainly results from mining, with the largest mining contribution in Jiangxi Province, accounting for 46% of the total mining amount; (2) from 2011 to 2020, the total dysprosium demand was 132828 tons, of which 25% was exported; (3) the dysprosium supply–demand gap was mainly due to dysprosium mining, with the supply gap accounting for approximately 46% of the total supply from 2011 to 2020; and (4) with increasing dysprosium in-use stocks, China exhibited a vast dysprosium recycling potential.

Russian Arctic Mineral Resources Sustainable Development in the Context of Energy Transition, ESG Agenda and Geopolitical Tensions

The Arctic region is well-known as a source of energy and mineral resources. Developing these resources by means of responsible practices could provide the world’s economy with strategically and critically important types of minerals. As a result, the role of the Arctic’s resource potential and the approaches used to develop it are gradually changing. In current conditions, it is crucial to strike a balance between existing needs and long-term demand for traditional energy sources or critical materials, such as rare and rare-earth minerals. Achieving this balance will result in sustainable growth, meeting ESG agenda targets while considering national security priorities, and devising novel approaches to sustainable project financing. However, there is controversy between existing strategies and plans based on low-carbon development and reality, which creates new macroeconomic and geopolitical obstacles that need to be overcome. The primary goal of this research is to substantiate the necessity of transforming the Russian Arctic’s mineral resource exploration in the context of global and national changes. The article presents a comprehensive analysis of the contemporary trends and tendencies influencing the exploration of the Arctic’s resources, as well as a general vision of the current situation in the energy sector. Research methods include content analysis and synthesis, generalization, decomposition, elements of strategic analysis, planning and forecasting, statistical methods, econometric modeling methods, and scenario planning. An upgraded concept of sustainable development based on six key components is proposed and discussed. Recommendations are provided on how to improve the existing system of long-term planning and forecasting to reduce the high level of macroeconomic and geopolitical uncertainty. The role of Russian Artic resources is determined in light of the shift in resource use.

Effect of grain size distribution of tailings during the formation of technogenic deposit on the fragmentation index

The most important link in the process chain for creating waste-free technology at concentrating plants is to ensure the possibility of using tailings, where the bulk of non-metallic minerals, rare earth minerals or overburden is concentrated. Increasingly, mining enterprises store their waste, forming man-made deposits. Thus at present time, the development of section technogenic deposits containing tailings is becoming a pressing challenge. The characteristic feature of such deposits is the polydispersity of the developed material, which makes it difficult to determine the fragmentation index. Therefore, the objective of this paper is to study the influence of the grain size distribution of tailings on the fragmentation index during the formation of an technogenic deposit, wherein said index affects the performance of mining and transport equipment, as well as the safety of mining operations. This paper is prepared with the application of the method of mathematical analysis, as well as a laboratory method, including determination of the volume of the pore space by displacement of the liquid phase from a container with a polydisperse mixture and measuring of weight indicators. The polydisperse mixture is represented by a fraction of 0–0,2 mm, 0,2–0,8 mm, 0,8–2,0 mm, 2,0–4,0 mm. 4,0–8,0mm, 3,0–12,0mm. An analysis was made of the influence of 5 indicators on the loosening coefficient. As a result of the study, it was found that the main criterion affecting the loosening coefficient is the ratio of coarse to fine class in the mixture, and not the size of the weighted average particle in it, and the smaller this ratio, the lower the loosening coefficient approaches 1. Class 1 reception in subsequent calculations. The results obtained will become the basis for studying the loosening factor in the development of man-made deposits, represented by tailings, and require further improvement of the theoretical foundations and industrial use.

Excellent, steady and economical nitrogen removal in highly variable mining wastewater via three-stage partial-denitrification/partial-nitrification/anammox system: A pilot-scale demonstration

In this study, a novel three-stage partial-denitrification/partial-nitrification/anammox (PD/PN/Anammox) system was established. Results showed that the excess of COD and the reduction of nitrite in PD process caused by the instability of influent nitrate are avoided through real-time influent COD/N ratio of 2.1. The extending the aeration interval in PN process enhanced the inhibition of nitrite oxidizing bacteria and promoted the activity of ammonia oxidizing bacteria under low free ammonia (FA, 1.1 ± 0.2 mg/L). In the upflow porous-plate anaerobic reactor (UPPAR), anammox bacteria (Candidatus_Kuennia) was rapid natural enriched from 0 % to 48.4 %, and granular anammox was formed by the increased of filamentous bacteria, α-d-glucose and a-helix. Moreover, the removal and robustness of ammonia nitrogen (98.9 ± 1.8 %) and total nitrogen (87.0 ± 2.3 %) in this system are better than those of the single stage PN/PD/Anammox process, and its cost of oxygen consumption, COD consumption and sludge treatment is far lower than that of nitrification denitrification process and PN/Anammox/denitrification process. This study provides a series of feasible start-up and operation strategies of PD, PN, Anammox and PD/PN/Anammox processes for the application of anammox in rare earth mining wastewater, which proposes upgrading and renovation plans for local wastewater treatment plants.

Assessing the Efficiency of Ion Exchange Resins for the Recovery of Scandium from Sulfuric Acid Leaching Solutions

Scandium, a valuable element with restricted production sources mainly situated in China and Russia, is typically obtained as a by-product during the production of various materials. As the demand for scandium grows in the expanding aluminum and fuel cell industries, and with significant investments in rare earth mining in the USA and Australia, there is a need to explore alternative recovery sources. This research investigates the recovery of scandium from an acid pregnant leaching solution using ion exchange resins. The pregnant leaching solution was obtained after the leaching of bauxite residue with sulfuric acid. Commercial resins with different functional groups were tested for their performance in scandium extraction. In addition, the co-adsorption of impurities, such as iron and titanium, was studied. The feed solution consisted of 12.7 mg/L Sc and main impurities of 272 mg/L Fe and 33.6 mg/L Ti and was pretreated before the ion exchange process by acidification with sulfuric acid and iron powder addition to suppress silica gel formation and minimize the Fe(III) content in the solution accordingly. Among the tested resins, a D2EHPA-impregnated resin had high selectivity for Sc towards Ti, while a monophosphonic resin was also a promising option since it had a higher capacity for Sc but co-extracted Ti. These findings offer promising opportunities for the recovery of scandium from acid leaching solutions and could contribute to addressing the growing demand for this valuable element.

Free Energy Calculations and Conformational Analysis of Dibenzo-30-crown-10 with Sm2+, Eu2+, and Three Halide Salts in THF Using the AMOEBA Force Field.

Crown ether complexes have been tailored for use in industrial separations of lanthanides (Ln) as a part of rare earth mining and refining. Dibenzo-30-crown-10 (DB30C10) is one of the most efficient complexants for the separation of rare earth mixtures based on the cation size. To understand the origin of this complexation, molecular dynamics (MD) simulations of DB30C10 have been performed using different combinations of divalent Sm and Eu and three halide salts Cl-, Br-, and I- in tetrahydrofuran (THF) solvent. DB30C10 was parameterized here for the polarizable atomic multipole optimized energetics for biomolecular simulation (AMOEBA) force field, and the existing parameters of THF, Sm2+, and Eu2+ were employed from our previous efforts. The large conformational fluctuations present in the DB30C10 systems were found to be dependent both on the identity of the lanthanide and halide complexes. For Cl- and Br- systems, there were no observed conformational changes at 200 ns, while in I- systems, there were two conformational changes with Sm2+ and one with Eu2+ within that same timeframe. In SmI2-DB30C10, there were three stages of conformational changes. In the first stage, the molecule is unfolded, in the second stage, the molecule is partly folded, and finally, in the third stage, the molecule is completely folded. Lastly, the Gibbs binding free energies of DB30C10 with SmBr2 and EuBr2 have been computed, which resulted in nearly identical ΔGcomp values for each lanthanide with Sm2+ being slightly more favorable. Considering the folding mechanism of the SmI2 system with DB30C10, the Gibbs binding free energies of DB30C10 and dicyclohexano-18-crown-6 (DCH18C6) with SmI2 were calculated separately and compared to probe their complexation affinities, in which the former was found to be more favorable.

Ageing of Pb in Farmland Soil near an Ionic Rare Earth Mine

Ageing of Pb in Farmland Soil near an Ionic Rare Earth Mine

The giant ShangzhuangREE‐rich apatite deposit, western China: Genesis by ultramafic magma differentiation

The origin of giant rare earth element (REE)‐rich phosphorus deposits related to ultramafic rocks is unclear. To characterize the genetic linkage between ultramafic rocks and P–REE mineralization, we investigated the whole‐rock geochemistry, geochronology and Hf isotopic compositions, along with previously published data of barren and ore‐bearing clinopyroxenites from the giant Shangzhuang REE‐rich apatite deposit (containing about 51.1 million tonnes of P2O5and 157,400 tonnes of REEs) in the Lajishan suture, Western China. The P–REE ores and barren biotite clinopyroxenites are composed predominantly of clinopyroxene and biotite, with high levels of apatite, amphibole, allanite, sulfide and oxide minerals in the ore‐bearing samples. Zircon and allanite U–Pb ages for the barren and ore‐bearing clinopyroxenites indicate they were formed between 467 and 465 Ma. The barren and ore‐bearing samples are characterized by high CaO and low SiO2contents, as well as similar Hf isotope ratios (εHf[t]: +3.4 to +7.7), indicating that they represent an ultramafic magma system and have been derived from a similar source. They are enriched in light REEs and depleted in Nb–Ta–Zr–Hf–Ti, similar to arc‐related lavas found worldwide. The weakly evolved barren samples have high Ba/La, Rb/Y and Dy/Yb values, and their ages are coeval with calc‐alkaline granitic plutons in the belt, which postdate the formation of the Lajishan ophiolite by ~30 myr. This suggests that the primary magma originated from garnet peridotite mantle modified by subducted Proto‐Tethys oceanic crust‐derived fluids in an arc setting. The presence of apatite intergrowth with cumulus clinopyroxene without alteration features indicates that the deposit has a magmatic origin. The ore‐bearing clinopyroxenite contains higher contents of P, REEs, and high‐field‐strength elements than the barren clinopyroxenite, which could be attributed to the in situ accumulation of apatite and allanite in the residual magma. Thus, the formation of the P‐dominated orebodies results from phosphate saturation due to the extensive fractionation crystallization of clinopyroxene and biotite during magmatic evolution. REEs were primarily enriched in the late‐stage melt, which was compatible with apatite and allanite. We propose that the formation of the Shangzhuang REE‐rich apatite deposit can be attributed to a simple differentiation of ultramafic melts in an evolved magmatic system.

Spatial Heterogeneity of Rare Earth Elements: Implications for the Topsoil of Regional Ion-Adsorption Type Rare Earth Deposit Areas in Southern China

The migration and spatial distribution characteristics of topsoil rare earth elements (REEs) are significant for the risk assessment of the external environment. However, the spatial distribution of REEs in the topsoil of ion-adsorption type rare earth element (REE) mining areas is poorly studied. We aimed to determine the differences and control factors of the spatial distribution of REEs in the topsoil of typical rare earth mines in South Jiangxi, South China. Sixty-five topsoil samples and eighteen profile samples were collected and analyzed for their rare earth content to elucidate spatial autocorrelation and heterogeneity using statistical analysis software (IBM SPSS Statistics 26.0.0.0, GS+9.0, and Arcgis10.2.0.3348). Moran index analysis showed that the positive correlation between sampling points was significant within the range of 0–500 m. The best fitting models of the semi-variance variogram were the exponential model, Gaussian model, and spherical model. The sequence of the spatial structure (C0 + C) was Ho > Tb > La > Pr > Nd > Sm > Gd > Tm > Lu > Dy > Er > Yb > Ce > Eu. The spatial fractal distribution pattern was Ho > Tb > Lu > Er > Dy > Yb > Tm > Gd > Ce > La > Eu > Sm > Pr > Nd. This indicated that the light rare earth elements (LREEs) and heavy rare earth elements (HREEs) in the topsoil were significantly different from the other sediments. This study provides new evidence for the environmental quality assessment of the in situ leaching of ionic rare earth ores into the topsoil layer.

Effects of superabsorbent polymers (SAPs) incorporated with organic and inorganic fertilizer on the water and nutrient retention of soil in rare earth mine tailing areas

Effects of superabsorbent polymers (SAPs) incorporated with organic and inorganic fertilizer on the water and nutrient retention of soil in rare earth mine tailing areas