Rare Earth Elements And Yttrium Research Articles

Rare earth element and yttrium geochemistry in sinking particles and sediments of the Jiaozhou Bay, North China: Potential proxy assessment for sediment resuspension

To exploit the resolving ability of rare earth element and yttrium (REY) in resuspension binary mixing model, and discover potential new REY-related resuspension proxy, this preliminary research studied the geochemical signature of REY in different Jiaozhou Bay samples including surficial/core sediments and settling trap-collected particles. Close quantitative relation for bulk concentration in particles, sediments and fine-grained fraction of major river sediments around the Yellow Sea, approved the priority contribution of catchment detrital materials. Moreover, common characteristics occurred for compartment-specific partitioning REY signatures in six operated-defined fractions, and multiple REY normalization pattern indexes (i.e. Y/Ho divergence, and Ce/Eu anomalies). All constrain the application of REY in resuspension discrimination of marginal shallow seas. However, linearity with different slopes and intercepts were plotted for the MREE bulge index versus HREE/LREE figure in reducible amorphous Fe-oxides fraction, which could provide new discrimination perceptions.

Geochemistry of Rare Earth Elements in Lower Gondwana Coals of the Talchir Coal Basin, India

This study investigated the concentration, distribution, and modes of occurrences of rare earth elements in coal from the Talchir coal basin, Odisha State. This basin comprises two coal bearing Formations i.e. Barakar and Karharbari. Samples, collected from one borehole, were analyzed by X-ray diffraction, X-ray fluorescence, electron microprobe and inductively coupled plasma mass spectrometry (ICP-MS). The coals are medium to high volatile, high ash and low sulphur. The Rare Earth Elements and Yttrium (REY) of the 34 coal samples varies from 29.6 ppm to 179.4 ppm with an average value of 91.0 ppm. The average value of total REY of the Barakar Formation (53.6 ppm) is considerably lower than the average value of Karharbari Formation (127.4 ppm). The average of the ratio of light to heavy rare earth elements (LREE/HREE) is also much higher in the Karharbari Formation (8.1) than in the Barakar Formation (4.4). Coals from both Formations show negative europium anomalies while only coals from the Karharbari Formation show a positive cerium anomaly. These differences indicate differences in depositional conditions between the coals of the two Formations within the coal basin. Through EPMA analysis, REY-bearing phosphates are found to be present in this coal in clay minerals. Monazites are found in Mg aluminosilicate matrix as dispersed minerals which may be detrital and monazite-bearing chlorite indicates that the monazites are formed by hydrothermal alteration during coalification. Ag, Ba and Zr are found as replacements or substitution in the REY phosphates.

Differentiation of rare earth elements and yttrium in different size and density fractions of the Reshuihe coal, Yunnan Province, China

Rare earth elements and yttrium (REY) in coal, fly ash as well as coal preparation products have attracted much attention due to the increasing demand worldwide. In this paper, the distribution of REY in different size and density fractions, their mode of occurrence, and the insight they provide on the sediment source region of the Reshuihe coal in southern China are studied. The results show that the physical separation method caused light-REY (LREY) to be enriched in the low-density and large-sized coal particles, whereas medium-REY (MREY) and heavy-REY (HREY) are enriched in small-sized and high-density fractions. In addition, LREY are more closely associated with organic matter, while MREY and HREY occur more often in aluminosilicate minerals. Moreover, the sediment source of the Reshuihe coal was mainly derived from the felsic–intermediate rocks at the top of the Emeishan basalt sequence. Further, REY in the feed coal are generally not enriched, though REY are enriched in density fractions of 1.4 kg/L. The combustion products of coal with a density of 1.4 kg/L obtained by gravity separation have a potential economic value as promising raw materials for REY.

Abundance and distribution pattern of rare earth elements and yttrium in vitrain band of high-rank coal from the Qinshui basin, northern China

Vitrain bands are clean and contain less ash than the bulk coal. A comprehensive study on rare earth elements and yttrium (REY) in vitrain may provide insights into the REY affinity. In this study, abundance and distribution pattern of REY in bulk coal, vitrain band and HCl-HF demineralized vitrain band was investigated. The coal studied in the present work was low-ash (ash yields ranging from 4.13 to12.86%, with 8.59% as the average), high-rank (anthracite to semi-anthracite, with volatile matter yields of 7.52–13.42%, 9.58% on average) coal of Permian Shanxi Formation, collected from the Sihe and Zhaozhuang mines, southern Qinshui Basin. The major minerals identified by powder XRD are illite and kaolinite, with small amount of ankerite, chlorite, calcite, siderite and pyrite. In comparison to the bulk coal, vitrain band displays a lower REY content and smaller compositional range. The bulk coal has N-, H- and L-type REY patterns based on Seredin-Dai’s classification, while the REY distribution for the vitrain band is commonly characterized by an H-type pattern. Moreover, the LaN/LuN ratio in the vitrain band is usually lower than that in the bulk coal. This probably suggests that the organic component has a higher HREY association than LREY compared to the inorganic part. The limited impact of HCl-HF demineralization on content and distribution pattern of REY in vitrain band probably reflects the weak acid solubility of REY in the vitrain band. The sequential chemical extraction procedure reveals that the clays and the residual organics, which have a stronger association with LREY and HREY respectively, are the dominant carriers of total REY in the studied bulk coals.

Geochemical and hydrogeochemical characteristics and evolution of Kozaklı geothermal fluids, Central Anatolia, Turkey

Kozaklı is one of the most important areas of Central Anatolia in terms of geothermal potential and it is characterized by thrust and normal faults. These faults, accommodating deep circulation of hydrothermal fluids of meteoric origin, are the primary controls of the geothermal systems in this region. Chemical and isotopic composition of the hot springs and geothermal fluids was monitored throughout 2017. The surface temperature of the fluid ranges from 24.9 to 96 °C. The cold spring waters are mostly of the Ca-Mg−HCO3 type in the study area. Major element chemistry of the water reveals that the deep geothermal fluids are mostly of the Na-Ca-Cl-SO4 type while the shallow geothermal well waters are Ca-Na−HCO3 waters. Silica geothermometers suggest that the reservoir temperature ranges from 103 to 173 °C. Based on the δ18O–δD relationship, water samples have a high-altitude meteoric origin. Stable isotopic data indicate that the geothermal fluids are formed by local recharge and deep circulation of meteoric waters. The Rare Earth Elements and Yttrium (REY) composition showed that Eu, Ce and Y anomalies are related both to inheritance from geological host materials and the fractionation of these elements during water-rock interactions.

Calcium phosphate control of REY patterns of siliceous-ooze-rich deep-sea sediments from the central equatorial Pacific

Abstract Rare earth elements and yttrium (REY) are often used as proxies for (paleo)environmental conditions and for the reconstruction of element sources and transport pathways. Many geological systems are well described with respect to the behavior of REY but deep-sea sediments with their manifold processes impacting the sediment during early diagenesis leave some questions about the origin and development of the shale-normalized REY (REYSN) patterns unanswered. Here we report REY data for sediment solid phase and pore water from the upper 10 m of deep-sea sediments from the Clarion Clipperton Zone (CCZ) in the central equatorial Pacific. The solid-phase REY profiles show highest concentrations at depth below 5–8 m. The REYSN patterns show an enrichment in middle REY (MREY) (LaSN/GdSN between 0.35 and 0.60; GdSN/YbSN between 1.19 and 1.47) and either no or negative CeSN and YSN anomalies (i.e. chondritic to sub-chondritic Y/Ho ratios between 24.7 and 28.7). Based on correlation analyses of bulk sediment element concentrations and sequential extractions, we suggest that a Ca phosphate phase controls the distribution and the patterns of REY in these silty clay pelagic sediments rich in siliceous ooze. The MREY enrichment develops at the sediment-water interface and intensifies systematically with depth. The negative CeSN anomaly intensifies with depth possibly because Ce is mostly bound to Mn- and Fe-(oxyhydr)oxides. Therefore, Ce concentrations remain relatively constant throughout the sediment core, while its trivalent REY neighbors are mostly hosted by the Ca phosphate phase that continuously incorporates REY from ambient pore waters. The non-redox-sensitive trivalent REY concentrations increase with depth, producing or enhancing a negative CeSN anomaly through coupled substitution of REY3+ and Na+ for Ca2+. The solid-phase REYSN pattern is therefore determined by the pore-water REYSN pattern and not suitable for paleoceanographic interpretation. The similarity of the pore-water and solid-phase REYSN patterns suggests, however, that only minor fractionation occurs during REY incorporation into the Ca phosphate crystal structure.

The rare-earth elements distribution in the Bazhenov shales

The rare-earth elements and yttrium (REY) distribution data with depth in the Bazhenov formation are given for the case of the one well in the Nizhnevartovsk arch of the Western Siberia, Russian Federation. According to the correlation analysis, it was found that REY (mainly LREE) is concentrated in apatite more than in clays or plagioclase, while HREE is preferably accumulated in clay minerals. It was estimated that the water extracts from the Bazhenov formation contain REY up to 0.014 ppb, while LREE is contained in 3.6 times more than HREE. An attempt to estimate the REY content in the pore water of the Bazhenov formation was made using water extract composition data.

Controls on the chemical composition of ferromanganese nodules in the Clarion-Clipperton Fracture Zone, eastern equatorial Pacific

Ferromanganese nodules have long been considered an attractive source for Mn, Co, Ni and Cu and, potentially, for the rare earth elements and yttrium (REY). Sixteen exploration contracts have recently been granted for the Clarion-Clipperton Fracture Zone (CCFZ) in the eastern equatorial Pacific and, because of concern about the environmental impacts of seafloor mining, some parts of the CCFZ have been designated ‘Areas of Particular Environmental Interest’ (APEI) from which mining will be excluded. As the APEIs were selected based on surface ocean characteristics and seafloor topography, estimated from satellite altimetry, the abundance and composition of nodules in these areas are unknown, and as a result their relevance as an intended baseline for mining disturbance has not been demonstrated.To fill this gap, we have undertaken a detailed study of the chemical composition of nodules and seafloor sediments in the UK Contract area in the CCFZ and its closest APEI, APEI-6. There are distinct differences between the two sites: nodules from the UK Contract area are larger (10–15 cm in diameter) compared to those from APEI-6 (2–4 cm diameter), and they have faster growth rates (~11 vs ~3 mm/Ma). Nodules from APEI-6 have, on average, higher contents of Fe (7.2 vs. 5.7 wt%), Co (0.28 vs. 0.13 wt%) and total REY (1120 vs. 715 ppm) relative to those from the UK Contract area. Analyses of individual growth layers reveal that nodules from the UK Contract area contain a greater proportion of Mn-rich phases that are also enriched in Ni and Cu. Although pore waters in the uppermost sediments are oxygen replete today, these layers likely precipitated from suboxic sediment pore waters indicating that the supply of organic material to the sediments in this area has been higher in the past. Sediments from the UK Contract area, in turn, have higher Mn/Al ratios compared to sediments from APEI-6 and have a higher proportion of Mn in easily-reducible phases. Nodules from APEI-6 have a greater proportion of Fe-rich layers that are also enriched in Co and the REY, and likely precipitated from seawater. These differences in the chemical composition of nodules from the UK Contract area and APEI-6, as well as differences in the oxygen penetration depth in the sediments, mean that APEI-6 does not provide a relevant geochemical baseline for mining disturbance in the UK Contract area, or for many other contract areas within the CCFZ.

Minerals and Enrichment of W, Rb, and Cs in Late Permian Coal from Meitian Mine, Meitian Coalfield, Southern China by Magmatic Hydrothermal Fluids

We report on the effects of magmatic hydrothermal fluids on the mineralogical and geochemical compositions of 12U and 12L Coals from the Meitian Mine in the Meitian Coalfield, southern China. The minerals in 12U Coal are predominantly chlorite, quartz, and calcite, while the minerals in 12L Coal consist mainly of illite, quartz, chlorite, kaolinite, and mixed-layer illite/smectite (I/S). The vesicle- and fracture-filling illite, chlorite, I/S, pyrite, and fluorite, cleat- and fracture-filling carbonate minerals (i.e., calcite, and dolomite), and cleat-filling tremolite, diopside, and talc have epigenetic hydrothermal origins. Tremolite, diopside, and talc were probably formed from the reaction between dolomite and Si-rich magmatic hydrothermal fluids. Elevated Pb–Zn–Sn–Cd assemblages are characteristic for the 12U Coal, while 12L Coal is enriched in W, Rb, Cs, Th, V, Zn, and Zr, most notably W, Rb, and Cs. REY (Rare Earth Elements and Yttrium) plots for almost all coals, partings and host rocks are similar, showing an M-type REY distribution, Gd-maximum, positive Y anomalies, and negative Ce anomalies, suggesting acid hydrothermal circulation in the coal-bearing strata. Rubidium and cesium in the coal is clearly associated with K-rich clay minerals (illite + I/S), and to a lesser extent with silicate minerals that were precipitated from hydrothermal solutions. W in the coals mainly occurs in the inorganic constituents of illite and pyrite, especially illite. Enrichment of W, Rb, and Cs in the coal and host rocks is genetically associated with magmatic hydrothermal fluids. Specifically, magmatic hydrothermal fluids of relatively high temperatures that are rich in volatile matter can extract abundant W, Rb, and Cs from granitic melts. The enrichment of these rare metals in the coal is mainly related to illitization. Our study results suggest that, for coal intruded by magmatic rocks, the type of hydrothermal alteration may greatly influence the enrichment of elements.

Study on the modes of occurrence of rare earth elements in coal fly ash by statistics and a sequential chemical extraction procedure

Rare earth elements and yttrium (REY) are strategically important materials in the defense, aerospace, automation and electronic industries, and therefore, REY has been referred as the “vitamin of industries.” The recovery of REY from coal fly ash has been recognized as a promising way to expand REY sources, and characterization of REY in coal fly ash will be critical for its subsequent exploitation and utilization. The work reported here investigates the modes of occurrences of REY in fly ash. Coal fly ash samples were collected from Guizhou Province. The results of the particle size classification showed that the content of total REY as well as that of individual components increased with a decrease in the particle size, and REY showed a moderate degree of enrichment in the smaller particles. The REY content was found to be a strongly and positively correlated with the content of silicon and aluminum through Pearson correlation and regression correlation analysis. A mathematical model between REY and Si/Al was established and this can be used to predict the content of REY with known Si and Al content. A sequential chemical extraction procedure for REY in coal fly ash was designed, and results from these tests showed that the silicate & aluminosilicate form was the dominant mode of occurrence of REY; this form accounted for 80% of the material. Hence the silicate & aluminosilicate form, which contains the most REY, must be the focus of subsequent recovery processes.

The effects of lithology on trace element and REE behavior during tropical weathering

The thick regolith developed in the humid tropics represents an endmember of critical zone evolution, where shallow and deep biogeochemical cycles can be decoupled in terms of the predominant source of trace elements (atmospheric input at the surface, weathering at depth) and of the processes that control their cycling. To investigate the influence of lithology on trace element behavior and in this potential decoupling, we studied two deep (9.3 and 7.5 m), highly-leached, ridgetop regolith profiles at the Luquillo Critical Zone Observatory, Puerto Rico. These profiles have comparable internal (degree of weathering, topography) and external (vegetation, climate) characteristics, but differ in their underlying bedrock (andesitic volcaniclastic and granitic). At these two sites, we analyzed a large suite of trace elements and used the rare earth elements and yttrium (REY) as tracers of critical zone processes because they are fractionated by the chemical reactions involved in weathering and pedogenesis (e.g., sorption, dissolution, colloidal transport) and by redox fluctuations.We found that both regolith profiles show atmospheric inputs of trace elements at the surface and evidence of bedrock dissolution at depth, as expected. We also found noticeable differences in the re-distribution of trace elements and REY within the profiles, indicative of different geochemical environments with depth and lithology. In the volcaniclastic profile, trace element and REY behavior is controlled mainly by redox-mediated, sorption/desorption reactions, whereas pH-controlled dissolution/precipitation and sorption reactions predominate in the granitic profile. The most noticeable difference between the two regolith profiles is in the long-term redox conditions, inferred from redox-sensitive elements and Ce anomaly variations, which are more variable and stratified in the volcaniclastic profile and change gradually with depth in the granitic profile. The contrasting redox conditions and the different sources of elements (dust vs. bedrock) produce a decoupling between the surface and deep geochemical environments of the volcaniclastic regolith. The difference in redox conditions between the two lithologies likely stems from the finer grain size and higher clay content of the volcaniclastic regolith.

Trace element and Nd isotope composition of shallow seawater prior to the Great Oxidation Event: Evidence from stromatolitic bioherms in the Paleoproterozoic Rooinekke and Nelani Formations, South Africa

Pure, stromatolitic limestones from the ∼2.44 to 2.43 Ga old Rooinekke Formation, Transvaal Supergroup (South Africa), provide unique insight into the geochemistry of Paleoproterozoic shallow seawater and, therefore, into the evolution of ambient redox-levels of the Earth’s atmosphere-hydrosphere system. In contrast to the stromatolitic Klipput dolostones from the overlying Nelani Iron Formation (IF), the stromatolitic Rooinekke limestones do not show post-depositional alteration and are virtually free of detrital contamination. This makes them excellent geochemical archives of proxies of ambient shallow-marine Transvaal seawater. Shale-normalized (SN) rare earth element and yttrium (REY) patterns of pure Rooinekke limestones show seawater-like REY distributions with positive LaSN and GdSN anomalies, super-chondritic Y/Ho ratios and a depletion of the light (LREY) relative to the heavy REYSN (HREY). However, the lack of negative CeSN anomalies implies that redox conditions at the Earth’s surface were not oxidizing enough to stabilize significant amounts of Ce(IV). In contrast to the majority of Archean marine chemical sediments, the pure Early Paleoproterozoic Rooinekke limestones lack positive EuSN anomalies, suggesting that the fraction of REY derived from high-temperature (>250 °C) hydrothermal fluids in shallow Rooinekke seawater was negligible. The predominance of continental sources in the geochemical REY budget of Rooinekke seawater is corroborated by unradiogenic εNd(2.44 Ga) values close to those of contemporaneous upper crustal material. The Rooinekke limestones, therefore, reveal the absence of a high-temperature hydrothermal component from shallow seawater already at least 100 million years prior to the Great Oxidation Event. In contrast, older chemical sediments from the Transvaal Supergroup, such as the Campbellrand carbonates and the Penge and Kuruman IFs, show positive EuSN anomalies and more radiogenic εNd(t) values, indicating a significant contribution of mantle-derived REY via high-temperature hydrothermal fluids to the late Neoarchean shallow marine REY inventory on the Kaapvaal Craton. The declining impact of high-temperature hydrothermal fluids on surface seawater, that is recorded by the late Neoarchean to Paleoproterozoic shallow water Transvaal carbonates, is similar to the general trend of decreasing positive EuSN anomalies with decreasing depositional age, that is observed in Eoarchean to Proterozoic IFs which recorded the composition of deeper marine waters.

Rare earth element and yttrium content of coal in the Banko coalfield, South Sumatra Basin, Indonesia: Contributions from tonstein layers

The South Sumatra Basin is one of the most prolific coal basins in Indonesia. Most of the coal from this area is used as thermal coal. Seredin and Dai (2012) explained the importance and significance of coal deposits as potential sources for rare earth elements and yttrium (REY); the concentrations of these elements in coal are similar to their abundances in conventional REY deposits. Production of the REY in coal deposit is mainly from the coal's fly/bottom ash. Examination of coal with high REY concentrations is becoming a very important issue. The study area is located in the Banko coalfield, Sumatra, Indonesia. This area is one of the best candidates for studying REY in coal because there are tuffaceous mudstone layers (tonsteins) reported by previous researchers that may have enriched the coal in REY. For this study, coal and non-coal beds from the same stratigraphic interval were sampled and analyzed using thin and polished section, X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and inductively coupled plasma mass spectrometry (ICP-MS). Special attention was given to coals near the tonstein layers. Based on the data collected, it was concluded that all the tonsteins studied are of volcanic origin and are silicic and alkali tonsteins. The elements Al and Si are higher in coal samples collected just beneath the tonstein layers and the highest REY concentration found was in a sample beneath a silicic tonstein layer. These data suggest that there is an opportunity to extract REY from coal's fly/bottom ash because the REY content of the ash is as much as 10 times higher than the REY content of the coal feed to power plants.

Mineralogical and Geochemical Characteristics of Trace Elements in the Yongdingzhuang Mine, Datong Coalfield, Shanxi Province, China

Fifteen samples of No. 4 coal from the Yongdingzhuang Mine in Datong Coalfield were tested for their elemental compositions, modes of occurrence, and mineralogical compositions, using X-ray powder diffraction, X-ray fluorescence spectrometry, inductively coupled plasma mass spectrometry, and scanning electron microscopy equipped with an energy-dispersive X-ray spectrometer. The samples have low sulfur content (0.63%). The major minerals are kaolinite and quartz, followed by pyrite and anatase. Compared with averages for the Chinese coals, the percentages of SiO2 (15.11%), TiO2 (0.7%), and Al2O3 (10.39%) are much higher. In No. 4 coals, Li (62.81 μg/g), Be (6.94 μg/g), Zr (235 μg/g), Ga (17.04 μg/g), F (165.53 μg/g), Tl (1.93 μg/g), and Hg (0.34 μg/g) are some potentially valuable and toxic trace elements with higher concentrations than Chinese coals and World hard coals. Lithium and F mainly have kaolinite associations. With the exception of kaolinite, Li, and F also partly occur in anatase, gorceixite and goyazite. Beryllium largely occurs in anatase; gallium is mainly associated with kaolinite and to a lesser extent, with gorceixite and goyazite; zirconium is associated with kaolinite, gorceixite and goyazite; and thallium and Hg occur in in pyrite. Potentially valuable elements (including Al, Li, Ga, and Zr) might be recovered as value-added byproducts from coal ash. Toxic elements (e.g., Be, F, Tl, and Hg) might have potential adverse effects to the environment and human health during coal processing. In addition, the distribution patterns of rare earth elements and yttrium (REY) indicate that the REY in No. 4 coals originated from the granite of Yinshan Oldland, and natural waters or hydrothermal solutions that may circulate in coal basins.

Mineral and chemical composition of some claystones from the Troyanovo-3 mine, Maritsa East lignite basin, Bulgaria

This paper presents the results of a detailed mineralogical and geochemical study on five types of claystones from the Maritsa East lignite basin in Bulgaria. The studied samples of each claystone type are composite, taken from outcrops at the operated pre-stripping and stripping horizon of the mine. Most of the minerals in claystones, such as quartz, illite, montmorillonite, kaolinite, plagioclase, feldspar, zircon, and mica have terrigenous origin. Pyrite, arsenopyrite, barite, calcite, apatite, gypsum, and goethite are authigenic. A total of 66 elements were analyzed in samples. Based on coefficient of enrichment of elements compared to Clarke values for clays, the samples can be arranged as follows: yellow claystone (43 elements), black claystone 1 (42 elements), blue claystone (25 elements), black claystone 2 (20 elements), and white claystone (17 elements). The black and yellow claystone have highest content of rare earth elements and yttrium (REY). Gold, Ag, Pt, and Pd are highly and unusually enriched in some samples. The dominant mode of occurrence of elements is mineral matter as sorbed on clay minerals (illite, montmorillonite, and kaolinite), structurally bound in other silicates (plagioclase, feldspar), apatite, and goethite. A portion of the studied elements also show affinity to organic matter (Ca, Sr, Mg, P, S, Mo, Sc, Cr, Cu, Cd, Hg, Tl, As, Ag, and HREE+Y). Mercury also has clear relation to kaolinite, as does U - to calcite. The La/Lu, Sm/Lu, and Gd/Lu refer the claystones to mix L-M type (yellow, blue, and black claystones) and H-type (white claystone). The ΣREY in claystones is as follows: black claystone 1 (400 ppm), yellow claystone (366 ppm), blue claystones (188 ppm), black claystone 2 (162 ppm), and white claystone (146 ppm). These concentrations do not imply that the claystones would be a possible source for extraction of REY.

Rare earth elements and yttrium in ferromanganese deposits from the South China Sea: distribution, composition and resource considerations

Ferromanganese nodules and crusts contain relatively high concentration of rare earth elements (REE) and yttrium (REY), with a growing interest in exploitation as an alternative to land-based REY resources. On the basis of comprehensive geochemical approach, the abundance and distribution of REY in the ferromanganese nodules from the South China Sea are analyzed. The results indicate that the REY contents in ferromanganese deposits show a clear geographic regularity. Total REY contents range from 69.1×10–6 to 2 919.4×10–6, with an average value of 1 459.5×10–6. Especially, the enrichment rate of Ce content is high, accounting for almost 60% of the total REY. This REE enrichment is controlled mainly by the sorption of ferromanganese oxides and clay minerals in the nodules and crusts. Moreover, the total REY are higher in ferromanganese deposits of hydrogenous origin than of diagenetic origin. Finally, Light REE (LREE) and heavy REE (HREE) oxides of the ferromanganese deposits in the study area can be classified into four grades: non-enriched type, weakly enriched type, enriched type, and extremely enriched type. According to the classification criteria of rare earth resources, the Xisha and Zhongsha platform-central deep basin areas show a great potential for these rare earth metals.

Estimating REY content of eastern Kentucky coal samples based on their associated ash elements

Coal and coal combustion byproducts can be considered as an alternative source of rare earth elements and yttrium (REY). The study of relationships between REY and other main coal properties could have several advantages such as estimating REY content of coal particles and designing beneficial extraction method. In this investigation, inter-correlations between REY content with coal parameters (proximate and ash elements) for a wide range of eastern Kentucky coal samples (708 records) were explored. Results demonstrate that zircon and monazite are the main source of heavy and light rare earth elements (HREE and LREE), respectively. Zr has the highest correlation with Y and Th has the strength relationship with Ce and La. In general, LREE have higher interaction with coal ash content in comparison with HREE. Results indicated that REY can be estimated quite satisfactorily by using their associated elements in coal ash.

Rare earth elements and yttrium (REY) variability with water depth in hydrogenetic ferromanganese crusts

The origins of ferromanganese (Fe–Mn) crusts that form in seawater and elemental partitioning into these crusts have previously been studied using samples from water depths shallower than 4 km. Here we report geochemical analyses of Fe–Mn crusts sampled from petit-spot volcanoes within the Pacific Ocean at water depths of 5.2–6.0 km. The Fe–Mn crusts have low Mn/Fe ratios (0.63–1.5), high contents of Co, Ni, and rare earth elements and Y (REY), and positive Ce anomalies, indicating a hydrogenetic origin. The Fe–Mn crusts are characterized by lower shale-normalized La/Pr ratios (LaSN/PrSN) than typical hydrogenetic Fe–Mn crusts from the Pacific Ocean. Despite negative LaSN/PrSN and NdSN/SmSN and positive EuSN/GdSN and DySN/HoSN correlations with water depth, the distribution coefficients of the REY are constant. This indicates that the observed REY variability with water depth in these hydrogenetic Fe–Mn crusts reflects that of seawater. In particular, a strong correlation between LaSN/PrSN and water depth has potential for use as a (paleo)ocean hydro-barometer. The variety of REY compositions of Fe–Mn crusts should be interpreted on the basis of distribution coefficients calculated for each water depth.

Linkages between the Genesis and Resource Potential of Ferromanganese Deposits in the Atlantic, Pacific, and Arctic Oceans

In addition to iron and manganese, deep sea ferromanganese deposits, including nodules and crusts, contain significant amounts of economically interesting metals, such as cobalt (Co), nickel (Ni), copper (Cu), and rare Earth elements and yttrium (REY). Some of these metals are essential in the development of emerging and new-generation green technologies. However, the resource potential of these deposits is variable, and likely related to environmental conditions that prevail as they form. To better assess the environmental controls on the resource potential of ferromanganese deposits, we have undertaken a detailed study of the chemical composition of ferromanganese nodules and one crust sample from different oceanic regions. Textural and chemical characteristics of nodules from the North Atlantic and a crust from the South Pacific suggest that they acquire metals from a hydrogenous source. These deposits are potentially an economically important source of Co and the REY. On the other hand, nodules from the Pacific Ocean represent a marginal resource of these metals, due to their relatively fast growth rate caused by diagenetic precipitation. By contrast, they have relatively high concentrations of Ni and Cu. A nodule from the Arctic Ocean is characterised by the presence of significant quantities of detrital silicate material, which significantly reduces their metal resource.

Biosorption of Rare-Earth Elements and Yttrium by Heterotrophic Bacteria in an Aqueous Environment

This paper reports the results of the experimental determination of the coefficient of sorption of rare-earth elements and yttrium (REY) under conditions of acidic pH using several strains of heterotrophic bacteria (Microbacterium sp., Curtobacterium sp., Bacillus subtilis, Pseudomonas putida, and Bacillus pumilis) that are widespread in natural and technogenic waters of the Far East (Russia). Insignificant fractionation between heavy and light rare-earth elements, negative cerium and dysprosium anomalies, and a positive europium anomaly were revealed. The selectivity of REY biosorption by gram-positive and gram-negative bacteria, as well as inertia of the biosorption process under more acidic conditions of the medium, were shown.