Yttrium Source Research Articles

Trends in Extraction of Rare Earth Elements from Coal Ashes: A Review

The demand for novel, cost-effective, and environmentally friendly rare earth element and yttrium (REY) sources is essential. The recovery of REY and other valuable components from coal fly ash (CFA) may result in securing alternative resources, decreased disposal costs, and environmental protection, all of which may have positive effects. However, research on the recovery of REY from CFA is underway, and it is still necessary to assess its viability from an economic and environmental standpoint. The authors have reviewed some of the most recent advances in extracting rare earth elements from CFA. However, most techniques reported for the treatment of CFA are still at the laboratory scale. Nevertheless, there are several pathways for industrial-scale applications. Therefore, CFA treatment and the extraction of valuable products from it have considerable potential for reducing both its carbon footprint and environmental burden.

РЕДКОЗЕМЕЛЬНАЯ МИНЕРАЛИЗАЦИЯ В АРГИЛЛИЗИРОВАННЫХ ГРАНИТАХ ЮЖНОГО ПРИМОРЬЯ (НОВЫЕ ДАННЫЕ)

Rare earth element (REE) mineralization in the weathered granites of Primorye is localized in the basement rocks and rocks along the periphery of the coal-bearing basins, which have been recently tectonically faulted and folded and have undergone argillisite metasomatism. It was shown that the clay material from the zones of intense argillization can be a source of scarce REE and yttrium. The ion-sorption and carbonate forms of REE+Y in them in combination with the clay composition of most of the ores make it possible to use cheap and low-toxic salt and hydrochloric acid solutions during heap leaching.

The potency of rare earth elements and yttrium in Konawe coal ashes, Indonesia

Fly ash and bottom ash (FABA), which not utilized is considered waste, has been regarded as the promising source of rare earth elements and yttrium (REY). REY has been recognized as critical raw materials to several modern high-technology applications. This research aims to identify the potential resource of REY in FABA, by investigating FABA samples from two different coal-fired power plant (KNW-1 and KNW-2) in Konawe, Southeast Sulawesi Province, Indonesia. The geochemical compositions of coal and FABA include major elements and REY determined by ICP-MS and ICP-AES. The major elements in coal and FABA samples showed the highest concentration in SiO2, Al2O3, Fe2O3, CaO, and MgO. The individual REY contents in FABA from KNW-1 are about 17-21 times higher than in coal samples while FABA from KNW-2 are about 57-73 times higher than in coal. The total REY concentration in FABA KNW-1 ranged from 227.34-276.41 ppm while the concentration in FABA KNW-2 ranged from 278.49-356.45 ppm. The total REO content of KNW-1 FABA samples ranged from 274.08-333.45 ppm. These values are lower than the REO content of the KNW-2 FABA (335.67-429.80 ppm). The percentage critical REY (30% ≤ REYdef ≤ 51%) and coefficient outlook (0.7 ≤ Cou tl ≤ 1.9%), showed all FABA samples are potential for promising raw material REY.

Thermal Atomic Layer Deposition of Yttrium Oxide Films and Their Properties in Anticorrosion and Water Repellent Coating Applications

The thermal atomic layer deposition (ThALD) of yttrium oxide (Y2O3) was developed using the newly designed, liquid precursor, Y(EtCp)2(iPr2-amd), as the yttrium source in combination with different oxygen sources, such as ozone, water and even molecular oxygen. Saturation was observed for the growth of the Y2O3 films within an ALD window of 300 to 450 °C and a growth per cycle (GPC) up to 1.1 Å. The resulting Y2O3 films possess a smooth and crystalline structure, while avoiding any carbon and nitrogen contamination, as observed by X-ray photoelectron spectroscopy (XPS). The films showed strong resistance to fluorine-containing plasma, outperforming other resistant materials, such as silicon oxide, silicon nitride and alumina. Interestingly, the hydrophilic character exhibited by the film could be switched to hydrophobic after exposure to air, with water contact angles exceeding 90°. After annealing under N2 flow at 600 °C for 4 min, the hydrophobicity was lost, but proved recoverable after prolonged air exposure or intentional hydrocarbon exposure. The origin of these changes in hydrophobicity was examined.

Hydrothermal Resource-saving Processes in Complex Processing of Bauxite and Red Mud


 
 
 The Bayer bauxite residue (red mud, RM) is environmentally hostile and hazardous to human health. Red mud can be viewed as an important and promising source of scandium, yttrium, zirconium and other elements rather than a solid waste. Due to a high content of iron in bauxites and especially in RM, the conversion of hematite into magnetite in Bayer liquor plays a key role in the exploration of a cleaner technology of alumina production. Thus, RM and raw bauxite were used for hydrothermal digestion in an original one-stage method of magnetite production during co-recovery of alumina. The yield of alumina reaches 80% from RM and more from bauxites during digestion with addition of lime and Fe(II) or Fe . The saturation magnetization of a bulk sample of magnetized bauxite is 40.5 emu/g, two orders of magnitude higher than that of a raw red mud sample. Moreover, magnetite containing a residue has a high crystallinity, which contributes to better deposition and magnetic separation in the development of an overall flowsheet for RM utilization.
 
 
 
 Keywords: Red mud, bauxite, hydrothermal treatment; enrichment, extraction, magnetization, hematite, magnetite, rare elements
 
 
 
 
 

REE+Y patterns and positive europium anomalies recorded in limestones from zone XX of the Tlayúa Quarry Konservat-Lagerstätte (Tlayúa Formation, Lower Cretaceous; Tepexi de Rodríguez, Mexico)

Major and trace element concentrations of thirteen limestone samples from zone XX of the Tlayua Quarry Fossillagerstatte were analysed with the aim of elucidating the source of rare earth elements plus yttrium (REE+Y) as well as some palaeoenvironmental conditions attributable to them. The concentrations of cortex-derived elements/element oxides (SiO2, Al2O3, Zr), as well as of phosphorus, show no significant contamination by means of terrigenous material and/or phosphates, which means that the REE+Y concentrations can be interpretable. REE+Y patterns display partly typical modern seawater signals, particularly positive La and Y anomalies, mostly superchondritic Y/Ho ratios (between 42.34 and 56.38) and moderate depletions of light rare earth elements (LREE) and middle rare earth elements (MREE) in comparison to heavy rare earth elements (HREE) (x PrSN/YbSN = 0.12, x NdSN/YbSN = 0.14 and x DySN/YbSN = 0.42, respectively). Negative cerium anomalies could also be identified [(Ce/Ce*SN) = 0.73], which indicate oxidising conditions. In addition, positive Eu anomalies [(Eu/Eu*SN) = 2.53] were detected. Since no convincing evidence for diagenesis, hydrothermal or aeolian input exists, the origin of these anomalies can, to some extent, be attributable to the influence of the dissolution of plagioclases in the water column, which can be inferred from the bivariate correlation of (Eu/Eu*)SN and Na/Al. Despite depicting modern seawater-like signals, an important difference between the REE+Y patterns from zone XX of the Tlayua Quarry and modern seawater REE+Y patterns can be determined. For instance, modern seawater does not display significant europium anomalies. Nevertheless, REE+Y patterns from zone XX of the Tlayua Formation can altogether be reliable palaeoenvironmental proxies for the Cretaceous. The inferred palaeoenvironment for zone XX from these proxies is represented by an open-marine setting, showing oxidising conditions, evidence of plagioclase dissolution and overall negligible terrigenous influence. The palaeoecological interpretation from these patterns does not exclude, however, the probability of monsoonal or tidally influenced sedimentation in other sediments from zone XX or from other zones in Tlayua, as previous works suggest.

Thermal and Plasma-Enhanced Atomic Layer Deposition of Yttrium Oxide Films and the Properties of Water Wettability.

The atomic layer deposition (ALD) of yttrium oxide (Y2O3) is investigated using the liquid precursor Y(EtCp)2(iPr-amd) as the yttrium source with thermal (H2O) and plasma-enhanced (H2O plasma and O2 plasma) processes, respectively. Saturation is confirmed for the growth of the Y2O3 films with each investigated reactant with a similar ALD window from 150 to 300 °C, albeit with a different growth rate. All of the as-deposited Y2O3 films are pure and smooth and have a polycrystalline cubic structure. The as-deposited Y2O3 films are hydrophobic with water contact angles >90°. The water contact angle gradually increased and the surface free energy gradually decreased as the film thickness increased, reaching a saturated value at a Y2O3 film thickness of ∼20 nm. The hydrophobicity was retained during post-ALD annealed at 500 °C in static air for 2 h. Exposure to polar and nonpolar solvents influences the Y2O3 water contact angle. The reported ALD process for Y2O3 films may find potential applications in the field of hydrophobic coatings.

Magnetic properties of evenly mixed Fe-Y2O3 nanocomposites synthesized by a facile wet-chemical based route

Abstract Evenly mixed Fe-Y2O3 magnetic nanocomposites have been successfully prepared through a facile and rapid wet-chemical based route with two steps. First, a sheet-like mixed oxide precursor was synthesized by solution combustion synthesis using ferric nitrate, yttrium nitrate and glycine as the iron source, yttrium source and fuel, respectively. Subsequently, Fe-Y2O3 nanocomposites with evenly dispersed Y2O3 nanoparticles were prepared through hydrogen reduction of the as-synthesized sheet-like mixed oxide precursor. The phase constituents, morphology, specific surface area and magnetic properties of the Fe-Y2O3 nanocomposites synthesized at different temperatures were studied in details. The Fe-Y2O3 nanocomposite reduced at 400 °C presents a rod-like morphology with a short axis size of ~20 nm and a length of ~60 nm. With the reduction temperature increasing, the average grain size and saturation magnetization of the Fe-Y2O3 nanocomposites gradually increase, while the coercivity and specific surface area decrease. The saturation magnetization value of the Fe-Y2O3 nanocomposite reduced at 600 °C reaches 190.3 emu/g, with an average crystalline size of ~64 nm.

Control of Dopant Distribution in Yttrium-Doped Bioactive Glass for Selective Internal Radiotherapy Applications Using Spray Pyrolysis.

In this study, we demonstrate the fabrication of Y-doped bioactive glass (BG), which is proposed as a potential material for selective internal radiotherapy applications. Owing to its superior bioactivity and biodegradability, it overcomes the problem of yttrium aluminosilicate spheres that remain in the host body for a long duration after treatment. The preparation of Y-doped BG powders were carried out using a spray pyrolysis method. By using two different yttrium sources, we examine the change of the local distribution of yttrium concentration. In addition, characterizations of phase information, particle morphologies, surface areas, and bioactivity were also performed. The results show that both Y-doped BG powders are bioactive and the local Y distribution can be controlled.

Dados geoquímicos e gamaespectrométricos na avaliação do potencial de corpos ígneos brasilianos para gerar concentrações de elementos terras raras do tipo ion adsorption clay (Terreno Apiaí-Guaxupé, estados de Minas Gerais e São Paulo, Brasil)

Os elementos terras raras apresentam crescente importância na economia mundial devido as suas aplicações na indústria de tecnologia, resultando em um crescente interesse pela prospecção de fontes minerais para esses elementos. Nesse âmbito, um tipo particular de mineralização conhecido na China se destaca por representar a principal fonte de elementos terras raras pesados (Eu a Lu) e ítrio (Y), menos comuns do que de elementos terras raras leves (La a Sm). Esse tipo de depósito, denominado ion adsorption clay, é composto de perfis de intemperismo desenvolvidos a partir de biotita e/ou muscovita sienogranitos, com a concentração exógena dos elementos terras raras originando-se pela adsorção desses elementos em argilominerais neoformados pelo processo intempérico. Características diversas afetam a gênese desses depósitos, onde a presença de minerais de elementos terras raras muito susceptíveis ao intemperismo e as características de desenvolvimento da alteração exógena são de grande importância para esse tipo de enriquecimento de elementos terras raras. O Terreno Apiaí-Guaxupé, onde foram selecionados corpos ígneos para a presente avaliação, é portador de uma diversidade de corpos ígneos, os quais foram afetados por processos de intemperismo cenozóicos, representando uma região com potencial prospectivo para esse tipo de depósito. Os corpos ígneos avaliados não apresentam informações descritivas sobre minerais (fluor)carbonáticos de elementos terras raras, muito susceptíveis ao intemperismo e importantes para a gênese desses depósitos de concentração exógena. Dessa forma, faz-se necessário o uso de informações químicas, descrições de minerais acessórios e de sobreposição de processos de alteração hidrotermal na busca de definir a possibilidade de formação dos minerais (fluor)carbonáticos de elementos terras raras. A investigação da potencialidade de enriquecimento de elementos terras raras do tipo

Highly improved visible-light-driven photocatalytic removal of Cr(VI) over yttrium doped H-Titanate nanosheets and its synergy with organic pollutant oxidation

Rare earth metal (yttrium-Y) doped H-Titanate nanosheets (Y-HTNSs) were synthesized via a facile (one-pot) hydrothermal route. The samples exhibit a lamellar structure with the surface area ranging from 336 to 371 m2/g and smaller thickness. The process of the structural transformation of the P25 nanoparticles from three dimensions (3D) to two dimensions (2D) of the H-Titanate nanosheets was controlled by changing the weight percent of the yttrium source. The proportion of Ti3+ in the Y-HTNS samples gradually increased with the concentration of doped yttrium. The Y doping of H-Titanate nanosheets leads a shift in the absorption edge toward higher wavelengths, improving the utilization of the energy in the visible region of the solar spectrum. The photocatalytic performance of Y-HTNSs for the solution with RhB and Cr (VI) was enhanced initially with the concentration of Y up to 1.0 at.%, showed optimal performance at 1.0 at.% and then decreased for concentrations higher than 1.0 at.%. It was demonstrated that the appropriate amount of Y (≤1.0 at.%) effectively improves the separation efficiency of the photoelectron-hole pairs. However, for heavy doping (Y > 1.0 at.%), yttrium ions serve as electrons/hole pair recombination centers, resulting in a reduction in the efficiency of charge separation. In addition, the co-existence of RhB significantly promoted the photocatalytic degradation of Cr(VI), suggesting a synergy between the degradation of RhB and Cr(VI). Combining the surface photocurrent and electrochemical impedance spectral investigations, the mechanism of enhanced photocatalytic performance of Y-HTNS samples was proposed and explained.

Modes of Occurrence of Rare Earth Elements in Coal Fly Ash: A Case Study

Coal fly ash (CFA), the main byproduct of coal combustion, has been regarded as an attractive source of rare earth elements plus yttrium (REY). Understanding how REY occurs in CFA is essential for ...

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.

A novel synthesis method of delafossite-type CuYO<sub>2</sub> using a layered yttrium hydroxide as an yttrium source

A novel synthesis method of delafossite-type CuYO<sub>2</sub> using a layered yttrium hydroxide as an yttrium source

Preparation of YAG nanopowder by different routes and evaluation of their characteristics including transparency after sintering

Yttrium aluminium garnet (YAG) nanopowder has been synthesized by five different routes: three of them are co-precipitation with different combinations of aluminium and yttrium sources as well as the precipitating agents, and the rest are by solid state synthesis with certain variation. They are designated as: process-1 (Al-nitrate, yttria, HNO3, NH4HCO3), process-2 (Al-nitrate, Y-nitrate, NH4HCO3), process-3 (Al-nitrate, Y-nitrate, NH4OH,), process-4 (Al-nitrate and Y-nitrate heated to 1000 °C), and process-5 (alpha-alumina and yttria heated to 1100 °C). Of them, process-2 develops the highest surface area (31 m2/g), soft agglomerated and near spherical crystalline YAG nanopowders through minimum mass loss, and excellent cation homogeneity. Pseudo solid state reaction between aluminium nitrate/yttrium nitrate (process-4) and solid state reaction of alumina/yttria (process-5) requires high-calcination temperature and results in hard agglomerates. In most cases, highly crystalline YAG is formed together with the formation of an intermediate metastable phase of YAP. Powder prepared by process-2 leads to 99.6% dense and 60% transparent YAG ceramics on hot isostatic pressing.

Rare earth element resources in coal mine drainage and treatment precipitates in the Appalachian Basin, USA

Drainages from abandoned coal mines in the Appalachian Basin represent a potential source of rare earth elements and yttrium (REY), many of which are considered to be critical resources due to their use in electronics and batteries. We report REY data from coal mine drainage (CMD) sites and precipitates from CMD treatment systems throughout Pennsylvania. Most CMD discharges are enriched in total rare earth elements relative to concentrations expected in unaffected surface or ground waters, generally by 1–4 orders of magnitude. Relative to the North American Shale Composite (NASC), which approximates the rock with which mine waters interact, CMD waters generally show a pattern of enrichment in the middle REE, including several identified as critical resources (Nd, Eu, Dy, Tb). Low-pH discharges tend to have higher REY concentrations than circumneutral discharges, and a precipitous drop in concentration around pH6.6 suggests adsorption of REY in the mine water flow path at near-neutral pH values. Treatment precipitates, including Fe oxy-hydroxides, CaMg lime slurries, and Si- and Al-rich precipitates, are enriched in REY relative to the average CMD discharge value by factors of 103–104. While the discharges and precipitates analyzed in this study did not overlap in space and time, the overall REY pattern of the precipitates approximate those of the CMD, but with a slight depletion in light rare earth elements. The higher REY concentrations in precipitates from systems treating low-pH discharges most likely reflects the generally higher REY concentrations in these discharges, but this needs to be established through direct comparisons over multiple seasonal cycles. We estimate that coal mine drainage outflows in the Appalachian Basin generate a total of about 538 metric tons of REY per year in a dissolved state, with ~83% of that from low pH (<5) discharges. A portion of these discharges could be targeted for resource recovery by mine drainage treatment systems engineered to optimize high-REY precipitates.

Selective separation of yttrium and europium using Cyanex 572 for applications in fluorescent lamp waste processing

The quest for a circular economy has directed attention towards processing of end-of-life products and industrial streams to recover the valuable fractions these contain. Fluorescent lamp waste is acknowledged to be an important source of yttrium and europium, two of the rare earth elements presently regarded as having critical supply risk. In this study, a commercial extractant for solvent extraction separations of REEs, Cyanex 572, was successfully applied to separate yttrium and europium from solutions obtained during processing of fluorescent lamp waste streams. Yttrium was selectively separated from europium at pHeq=0, followed by further recovery of europium at pHeq=1. Better extraction efficiencies of REEs were achieved using aliphatic diluents e.g. kerosene in comparison to aromatic diluents or long chain alcohols. Increases in temperature in the range 25–65°C led to decreases in the separation factors between yttrium and europium. Stripping with hydrochloric acid solutions at concentrations higher than 3M led to complete recovery of extracted yttrium and europium. Precipitation of these elements from their respective stripping products with oxalic acid, followed by calcination of the precipitate, led to yttrium and europium oxides of 99.82% and 91.60% purity, respectively. A flowsheet that encompass the main steps for fluorescent lamp waste processing is also presented.

Domestic Yttrium Consumption Trends in Japan

SummaryYttrium tends to occur in the same ore deposits as the lanthanides and exhibits similar chemical properties as rare earth elements. Yttrium sources are typically concentrated in China, and there are concerns about supply security. Yttrium is used in small, but essential, quantities in a variety of advanced industrial sectors, for example, in phosphors, advanced ceramics, optical glasses, and batteries. In terms of resource security, it is important to verify the domestic yttrium consumption trends. In order to characterize the domestic yttrium consumption trends in Japan, we tracked the historical yttrium consumption patterns from 2001 to 2011 by applying the bottom‐up approach and illustrated the recent domestic yttrium flow by using a substance flow analysis. The results showed that the total yttrium consumption has remained steady over 10 years, from 1,124 tonnes (t) in 2001 to 967 t in 2011. Recent consumption in 2011 was driven primarily by the use of yttrium in fluorescent lamps (462 t), nickel metal hydride batteries (185 t), and optic glasses (149 t).

Microwave dielectric properties of YAG ceramics prepared by sintering pyrolysised nano-sized powders

YAG ceramics with good dielectric properties were prepared via a modified pyrolysis method, with yttrium nitrate as the yttrium source and combined aluminium sulphate and aluminium nitrate as aluminium sources, and subsequent sintering in a muffle furnace. The effects of the different aluminium sources on the powder characteristic and the impact of sintering temperature, sintering aids (TEOS) and additive (TiO2) on the dielectric properties of the ceramics were studied. The results show that well-dispersed pure YAG nano-powders can be obtained after calcination at 1000°C with an aluminium sulphate and aluminium nitrate molar ratio of 1.5:2. The relative density, permittivity (εr) and quality factor (Q×f) of the YAG ceramics increase with sintering temperature and TEOS addition. TiO2 can greatly promote τf to near-zero but decreases Q×f. The relative density, εr, Q×f and τf of the YAG–1wt% TEOS–1wt% TiO2 ceramic obtained at 1520°C are 97.6%, 9.9, 71, 738GHz and −30ppm/°C, respectively.

Template-free synthesis of mesoporous anatase yttrium-doped TiO2 nanosheet-array films from waste tricolor fluorescent powder with high photocatalytic activity

A novel mesoporous anatase yttrium-doped TiO2 nanosheet-array film was prepared via a low-cost, facile and template-free solvothermal method by employing Waste Tricolor Fluorescent Powder (WTFP) as a dopant yttrium source and acetic acid as a mesopore creator. The as-prepared Y–TiO2 film exhibited large specific surface area, high pore volume and high temperature anatase phase stability. The significant increase of photocatalytic activity was confirmed by the degradation of Methyl Orange (MO) aqueous solution under simulated solar light irradiation. The large enhancement of photocatalytic activity could be due to the synergistic effect of Y-doping and high specific surface area as well as the developed mesoporous structure.