Recovery Of Rare Earth Metals Research Articles

Efficient Adsorption and Elimination of Tm3+ for Enhanced Seed Germination Using Pillar[5]Arene Polymer.

While rare earth elements (REEs) are essential for modern technology, their production methods raise concerns for agriculture. Researchers are now exploring ways to control and recycle REEs pollution, aiming to minimize agricultural impacts and potentially even develop methods to utilize these elements for improved crop yields. Regarding this issue, a new type of pillar[5]arene polymer (Pol-P[5]-BTZP) has been designed and synthesized by click reaction to enhance the efficiency of adsorption and recovery of rare earth metals. This polymer incorporates the unique structure of 2,6-di-1,2,3-triazolyl-pyridine. The results of various analyses revealed that Pol-P[5]-BTZP exhibits excellent thermal stability, a high specific surface area, and well-distributed networks of micropores and mesoporous structures. The adsorption capacity of Pol-P[5]-BTZP for Tm3+, a representative REE, was evaluated using the Langmuir and Freundlich isothermal adsorption models with a maximum adsorption capacity (Qmax) of 127.71 mg/g. Furthermore, the versatility of Pol-P[5]-BTZP in adsorption and recovering various REEs was tested. In addition to its adsorption capabilities, the potential of Pol-P[5]-BTZP for rare earth recovery and reuse was assessed through experiments on the impact of Tm3+ and La3+ on seed germination. These experiments demonstrated the wide-ranging applicability of Pol-P[5]-BTZP in recovering and reusing REEs for green agriculture.

Overview on Hydrometallurgical Recovery of Rare-Earth Metals from Red Mud

Aluminum is produced from its primary bauxite ore through the Bayer process. Although Al is important nowadays in the development of humanity, its production leads to the generation of a huge amount of waste, called red mud. Globally, the estimation of the stock of red mud is about 4 billion tons, with about 10 million tons located in Turkey. The presence of rare-earth elements (REEs) in crucial materials such as red mud makes it a major source of these elements. A number of methods have been developed for treating red mud, which are employed globally to recover valuable products. The application of a suitable method for REE extraction from red mud is a way to overcome the supply risk, contributing to reducing the environmental issues linked to red mud pollution. The current review summarizes the research on red mud processing and examines the viability of recovering REEs from red mud sustainably, utilizing hydrometallurgy and biohydrometallurgy.

Effectiveness Evaluation of Pyrometallurgy and Hydrometallurgy Methods in The Recycling Process of Nd-Fe-B Permanent Magnet and Rare Earth Metals Recovery : A Review

Effectiveness Evaluation of Pyrometallurgy and Hydrometallurgy Methods in The Recycling Process of Nd-Fe-B Permanent Magnet and Rare Earth Metals Recovery : A Review

The distribution coefficients of Nd3+ and Y3+ between 0.1 and 2.1 M HNO3 and HDEHP at 298.15 K

Rare earth metals are considered to be some of the most critical raw materials on the planet due to their use in many products and technologies, the difficulty in isolating the individual elements from ores and each other, and the market restrictions that threaten their supply. However, despite this, the recycling rates for rare earth metals remain low. Hydrometallurgy has been proposed to hold the greatest potential for the recovery of rare earth metals from waste materials. However, the design of hydrometallurgical processes for the recovery of rare earth elements from waste requires a good understanding of the behaviour of the rare earth metals between different phases.In this study, the distribution coefficients of two rare earth metals, yttrium, and neodymium, between an organic solvent; bis(2-ethylhexyl) phosphate, diluted in n-dodecane at between 0.25 M and 1 M; and an aqueous nitric acid solution at concentrations of between 0.1 M and 2.8 M were measured. Distribution measurements were performed using a series of liquid–liquid extraction cells at a constant temperature of 298.2 K. The concentration of the rare earth metals was measured using ICP-OES analysis. The distribution coefficients and the acid concentration were found to be inversely related to each other. Conversely, the distribution coefficients were directly proportional to the concentration of the solvent in the organic phase.The data reported in this paper will be used to design a counter-current liquid–liquid extraction column for the recovery of neodymium from waste permanent magnet powder.

Explorative Research Course: Recovering Rare Earth Elements from Electronic Waste Using Deep Eutectic Solvents

This study aims to demonstrate how a course design approach based on explorative research involving systems thinking can be implemented through the recovery of rare earth elements utilizing deep eutectic solvents. The method used in this research is design based research (DBR). The instruments used were questions regarding the measurement results/characterization of leaching samples, short questions about concept maps, and student response questionnaires. Data from measurements of leaching samples was measured using an Fouier Transform Infrared Spectrometer (FTIR), data about concept maps was measured by the number of component and process concepts in the context recovery of electronic waste that students were able to identify, and student response data was measured using a Likert scale. Based on the research results, recovery of rare earth metals can be leached using DES. This can be shown by a shift in the peak vibration of 497.65 cm-1 from the standard sample at vibration of 449.43 cm-1. In addition, this study yields new insights into the perceptions of future pre-service chemistry teachers regarding the possibility of new types of eutectic based ionic liquids in the context of chemistry learning. According to pre-service chemistry teachers, the recovery of rare earth metals from electronic waste and the application of DES are an interesting new context for laboratory learning. Context-based design of research activities can enhanced system thinking and interest in the study of chemistry. Students showed increased systems thinking abilities, this can be shown by the component and process concepts that emerged from the pretest by 652 concepts while the posttest increased by 1208 concepts.

Novel devices for the extraction and recovery of rare-earth metals through recycling of waste

Novel devices for the extraction and recovery of rare-earth metals through recycling of waste

LiNO3-assisted electrochemical extraction of metallic Sm from a molecular liquid-based electrolyte

Developing efficient, green, and cost-effective methods for extracting rare earth (RE) metals is essential to accelerate breakthroughs in critical technologies in the field of RE-based functional materials. In this study, a low-cost aprotic polar molecular liquid, N,N-Dimethylformamide (DMF), was used for electrowinning metallic Sm with upstream SmCl3 as the raw material, inspired by previous applications of diverse specialised ionic liquids for the electrochemical recovery of RE metals. Cyclic voltammetry and electrodeposition experiments demonstrated that metallic Sm cannot be obtained from the binary DMF-SmCl3 system, but can be electrodeposited with LiNO3. Therefore, the mechanism underlying the observed electrochemical behaviour is elucidated and discussed in detail. Sm and Sm–Co metallic elements were successfully electrodeposited on an Al substrate at a relatively high current density, characterised, and evaluated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Moreover, a unique two-step method involving electrodeposition and direct smelting is prospectively described for the continuous preparation of bulk RE-containing alloys to stabilise highly active RE elements. Therefore, this study provides valuable insights into practical solvometallurgical processes for RE metal extraction, refinement, and recycling.

NdFeB magnet scrap valorization by leaching and recovery of rare earth metals by sorption on low-cost expanded clay

The search for new sources of rare earth metals (REM), such as neodymium and dysprosium, has ensued globally due to their strategic value for the sustainability of the energy sector. In this context, this work explored the potential of vermiculite as a sorbent for recovering rare earth cations from the leachate of end-of-life NdFeB magnets by kinetic, equilibrium, and desorption investigations. In which the REM uptake on vermiculite occurred by fast kinetics, and the significant sorbate-sorbate interactions at the equilibrium indicated that the REM sorption was a cooperative process; vermiculite sorbed the metals from the acid leachate in the following order: Fe(III) > Nd(III) > Zn(II) > Pr(III) > Co(II) > Dy(III) > Ni(II) > Al(III) > Mn(II); and the chelating agent ethylenediaminetetraacetic acid desorbed Nd(III) preferably over other metals, indicating the potential for further selective recovery processes. The characterization analyses indicated that the loaded vermiculite preserved the original structure, composition, functional groups, and thermal stability. Also, X-ray photoelectron spectroscopy corroborated the cation exchange mechanism between interlayer magnesium in the REM sorption. Thus, the experimental findings and a cost analysis compared to the literature demonstrated the cost-effectiveness and potential of vermiculite for the valorization of NdFeB magnet leachates.

The recovery of rare-earth metals from fly ash using alkali pre-treatment with sodium hydroxide

The recovery of rare-earth metals from fly ash using alkali pre-treatment with sodium hydroxide

Selective recovery of rare earth metals from acid mine drainage by pyrrolidine diglycolamide silica column

We developed an adsorption column that can be used for rare earth recovery from acid mine drainage (AMD). 2-[2-oxo-2-(1-pyrrolidinyl)ethoxy] acetic acid was used as a functional ligand grafted onto amino silica gel, resulting in an adsorbent selective for rare earth metals. Adsorption columns for the enrichment of rare earth metals have been made using this functional silica. A flow rate of 500 µL min−1 and an eluent of pH= 2 0.013 mol L−1 DTPA were determined as the optimum operating conditions. The recovery of actual AMD using SiO2 @PYRDGA adsorption column achieved 82.29%, 75.66%, 85.10%, 78.43% for Er, Gd, Nd and La, and the purity of rare earth in AMD can be increased about 10 times after recovery. In addition, the thermodynamics, kinetics, adsorption mechanism, and theoretical calculations of the adsorption process were investigated in detail.

Properties of Rare-Earth Element in Magnetic Material and Its Processing

Rare-earth metal is one of the critical elements because of its small amount with a lot of demand for this metal in a variety of the latest technologies, which are currently developed fast and intensively. The use of rare-earth metals can contribute to the development of innovations in the production of new materials in various fields, because these metals have strong, hard and heat-resistant properties. Rare-earth metals are found in complex compounds that makes it difficult to separate from ore. Obtaining of the rare-earth metals is realized by recycling the product from a secondary source of magnets containing rare-earth metals, such as NdFeB and SmCo magnets. Hydrometallurgical and pyrometallurgical processes can carry out the process of recovering of the rare-earth metals from secondary materials. There is a new research using bacteria as a rare-earth metal extractor to minimize environmental impact. Oxalic acid and other organic acids have potential in the recovery of rare-earth metals. As alternative, the rare-earth-free materials as candidates for permanent magnets are also mentioned.

Challenges and opportunities for sustainable valorization of rare earth metals from anthropogenic waste.

Progressively and projected integration of rare earth metals (REMs) in modern technologies, especially in the clean energy, consumer electronics, aerospace, automotive, and defense sectors, place REMs as critical raw materials in the supply chain and strategic metal from the fourth industrial revolution perspective. Current REM production from the primary mineral resources in the supply chain versus industrial demand is at a bottleneck. Alternatively, REM-bearing anthropogenic wastes are pertinent and potent to addressing the critical supply chain bottleneck. Although secondary REM resources are prudent to address the critical supply chain bottleneck, the absence of effective and efficient technologies to recover these REMs from anthropogenic waste imposes challenges and provides opportunities. Hence, this review analyses and discusses the significance of anthropogenic wastes for REM recovery, the status of recycling technologies for sustainable valorization of REMs, challenges, and opportunities. The current review covers the potential quantitative REM wealth locked in various anthropogenic waste like (i) spent rare earth permanent magnets, (ii) spent batteries, (iii) spent tri-band REM phosphors, (iv) bauxite industry residue red mud, (v) blast furnace slag and (v) coal mines, and coal byproducts and status of valorization technologies for circularizing the REMs. In industrial waste like red mud, steelmaking slag, blast furnace slag, and coal fly ash typically 109,000, 2000, 39,000, and 354,000 tons of REM get scrapped, respectively, in a conservative estimation. In the years 2020 and 2021, respectively, 240,000 and 280,000 tons of REM were produced by mine production in contrast to 504,000 tons of REM that were scrapped with REM-bearing industrial waste. This review revealed that total REM currently getting scrapped with anthropogenic waste versus projected REM demand for the years 2022, 2023, 2024, and 2025 could be standing at 2.66, 2.51, 2.37, and 2.23, respectively. Our investigation revealed that efficient recovery of REMs from anthropogenic waste is significant and promising but associated with challenges like lack of industrial-scale valorization process, lack of a clear strategy, road map, policy, effort, funding, and diversified research.

Utilization of Ashes from Biomass Combustion

Biomass is one of the most important sources of renewable energy in the energy industry. It is assumed that by 2050 the global energy deposit could be covered in 33–50% of biomass combustion. As with conventional fuels, the combustion of biomass produces combustion by-products, such as fly ash. Therefore, along with the growing interest in the use of biomass as a source of energy, the production of ash as a combustion by-product increases every year. It is estimated that approximately 476 million tons of ashes per year can be produced from biomass combustion. For example, the calorific value of dry wood mass tends to be between 18.5 MJ × kg−1 and 19.5 MJ × kg−1, while the ash content resulting from thermal treatment of wood is from 0.4 to 3.9% of dry fuel mass. However, biomass ash is a waste that is particularly difficult to characterize due to the large variability of the chemical composition depending on the biomass and combustion technology. In addition, this waste is, on the one hand, a valuable fertilizer component, as it contains significant amounts of nutrients, e.g., calcium (Ca), potassium (K) and microelements, but on the other hand, it may contain toxic compounds harmful to the environment, including heavy metals and substances formed as a result of combustion, such as polycyclic aromatic hydrocarbons (PAHs) or volatile organic compounds (VOCs). PAHs and VOCs are formed mainly in the processes of incomplete combustion of coal and wood in low-power boilers, with unstable operating conditions. However, it is important to remember that before the fly ash is used in various industries (e.g., zeolite synthesis, recovery of rare earth metals or plastic production) as an additive to building materials or fertilizers for cultivation, a number of analyses are to be conducted so that the by-products of combustion could be used to allow the by-product of combustion to be used. It is important to conduct tests for the content of heavy metals, chlorides, sulphates, microelements and macroelements, grain and phase composition and organic compounds. If such ash is characterized by low pollution levels, it should be used in agriculture and reclamation of degraded land and not directed to landfills where it loses its valuable properties. The purpose of this review is to present the properties of ashes generated as a result of biomass combustion in Poland and the world, to discuss factors influencing changes in its composition and to present the possibilities of their reuse in the environment and in various branches of industry.

Recovery of Some Rare-Earth Elements by Sorption Technique onto Graphene Oxide

In this work, graphene oxide (GO), prepared using the Hummers method, is physically characterized and used for rare-earth metals recovery from monazite ores. Batch study for sorption of 152+154Eu radionuclide onto GO carried out to assess the optimum reaction parameters for recovery process. The optimum pH is 2.09, the equilibrium time achieved after 5 h, humic acid enhances the sorption efficiency but if its concentration increases it opposes the sorption process. The kinetic reaction mechanism is regulated by pseudo-2nd order and the sorption isotherms show Langmuir applicability. The maximum sorption capacity for 152+154Eu at 20 °C is 59.81 mg g−1. Desorption studies were performed to determine a proper eluent with a suitable concentration for the recovery process and 0.1 M HCl was selected as an efficient eluent. The sorption process is favorable and endothermic. Finally, GO is used as a sorbent for rare-earth elements accumulated in monazite ore. The sorption efficiency of REE is 69.03% with initial concentration 1149.57 mg L−1 at monazite leachate and the recovery percentage is 20.32%. These results promised the use of GO for REE recovery from monazite ore.Graphical

Sustainable composite material based on glutenin biopolymeric-clay for efficient separation of rare earth elements

Rare earth metals (REEs) are crucial for modern industries and technological development. Their extraction from non-renewable primary sources has almost reached its threshold due to excessive global demand. An effectual approach for REEs recovery is recycling secondary sources governed by separation materials. In this work, a novel glutenin-based Na-bentonite (Gle@Na_Bex:y) composite was produced via the in-situ hydrothermal route followed by a subsequent freeze-drying process. Additionally, a possible production route for the composites was proposed. The novel Gle@Na_Bex:y composites were characterized with Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) surface area, and zeta potential (ZP) measurements. FTIR results complemented with SEM images and XRD measurements confirmed the successful incorporation of glutenin into the Na-bentonite clay. The separation of REEs from aqueous solution was used as a model system to demonstrate the material’s ability for selective metal recovery. The best conditions (T, pH, time) for REE sorption were assessed using equilibrium batch adsorption experiments. The kinetics of REE adsorption were effectively explained by a pseudo-second-order model; all the adsorption equilibrium data followed the Langmuir model. Thermodynamic investigations revealed that the adsorption is endothermic and spontaneous, and the adsorption of REEs occurred through a chemisorption process. The sorption mechanism of REE ions was investigated using molecular modelling. The results of this study demonstrate the feasibility of utilizing Gle@Na_Be50:50 composite as an efficient material for REEs removal. The maximum adsorption capacities of Y3+, La3+, and Nd3+ achieved with Gle@Na_Be50:50, were 76.87, 56.71, and 74.61 mg/g, respectively. This work offers a new route for engineering, valuable composite materials for the separation of REEs from diverse sources.

A Preliminary Economic Evaluation of Rare Earth Element and Yttrium (REY) in Indonesian Coal: Progress and Future Prospect

Coal deposits have fascinated much attention in recent years due to its by-product waste as promising alternative sources for rare earth metals. Rare earth metals concentration in many coals and coal ashes are known have equal to or higher than those found in conventional ore. Indonesia is one of the most extensive coal-bearing sedimentary basins in SE Asia with unique tectonic and geological control that might be significance as prospective country of rare metals recovery from coal. This study shows recent progress from several Indonesian coal-bearing sedimentary basins: Ombilin, South Sumatra and Pasir basin. Surprisingly, the REY concentration in Ombilin, South Sumatera and Pasir basin has higher than the average world-coal with 126.15 ppm, 203.72 and 285.53 ppm, respectively. Based on the relationship market demand and supply of individual REY in recent years proposed by Seredin and Dai (2012), all of coal samples were clustered into Promising (II) type with base of critical outlook is 0.7 and cut-off grade is 1000 ppm in coal ashes. It comprises the various REY distribution types and can be regarded as promising REY raw metrials for economic development. REY-enrichment processes in Indonesian coal are different due its tectonic and geological processes that control the basin formation, both of pre-, syn- and post-forming. Genetically, major REY-enrichment processes in Indonesian coal are controlled by tuffaceous; infiltrational; and terrigenous process. Tuffaceous process is related to volcanism that produce tonstein layer during coal peatification, this type is determined in South Sumatera and Pasir basin. Terrigenous process is controlled by provenance sediment-source during coal-bearing formation is formed; basaltic-igneous basement is major controlled REY-enrichment in Ombilin and Pasir basin. Injections of marine water during coal peatification also known that lead REY-enrichment, this type called infiltrational type and its presence in all three basins. Recent study about REY-rich in Indonesian coal shows significance prospect for future rare earth metals recovery. Further study is needed in unexplored coal-bearing sedimentary basin such as Tarakan, Asem-asem, Barito, Ketungau, Melawi, Salawati and Bintuni basin.

Recovery of Rare Earth Metals (REMs) from Nickel Metal Hydride Batteries of Electric Vehicles

Nickel metal hydride (NiMH) batteries are extensively used in the manufacturing of portable electronic devices as well as electric vehicles due to their specific properties including high energy density, precise volume, resistance to overcharge, etc. These NiMH batteries contain significant amounts of rare earth metals (REMs) along with Co and Ni which are discarded due to illegal dumping and improper recycling practices. In view of their strategic, economic, and industrial importance, and to mitigate the demand and supply gap of REMs and the limited availability of natural resources, it is necessary to explore secondary resources of REMs. Therefore, the present paper reports a feasible hydrometallurgical process flowsheet for the recovery of REMs and valuable metals from spent NiMH batteries. More than 90% dissolution of REMs (Nd, Ce and La) was achieved using 2 M H2SO4 at 75 °C in 60 min in the presence of 10% H2O2 (v/v). From the obtained leach liquor, the REMs, such as Nd and Ce, were recovered using 10% PC88A diluted in kerosene at eq. pH 1.5 and O/A ratio 1/1 in two stages of counter current extraction. La of 99% purity was selectively precipitated from the leach liquor in the pH range of 1.5 to 2.0, leaving Cu, Ni and Co in the filtrate. Further, Cu and Ni were extracted with LIX 84 at equilibrium pH 2.5 and 5, leaving Co in the raffinate. The developed process flow sheet is feasible and has potential for industrial exploitation after scale-up/pilot trails.

Increasing the efficiency of rare earth metal recovery from technological solutions during processing of apatite raw materials

The issues of complex processing of mineral resources are relevant due to the depletion of available raw materials. So, it is necessary to involve technological waste, generated during the processing of raw materials, to obtain valuable components. In the process flow of apatite concentrate treatment using the sulfuric acid method, a large amount of phosphogypsum is produced with an average content of light rare earth metals (REMs) reaching 0.032-0.45 %. When phosphogypsum is treated with sulfuric acid solutions, a part of REMs is transferred to the sulfate solution, from which it can be extracted by means of ion exchange method. The study focuses on sorption recovery of light REMs (praseodymium, neodymium and samarium) in the form of anionic sulfate complexes of the composition [ln(SO4)2]– on polystyrene anion exchanger AN-31. The experiments were performed under static conditions at a liquid-to-solid ratio of 1:1, pH value of 2, temperature of 298 K and initial REM concentration in the solutions ranging from 0.83 to 226.31 mmol/kg. Thermodynamic description of sorption isotherms was carried out by the method based on linearization of the mass action equation, modified for the ion exchange reaction. As a result of performed calculations, the authors obtained the constants of ion exchange equilibrium for Pr, Nd and Sm, as well as the values of the change in the Gibbs energy for the ion exchange of REM sulfate complexes on the AN-31 anion exchanger and the values of total capacity of the anion exchanger. Calculated separation factors indicated low selectivity of AN-31 anionite exchanger for light REMs; however, the anion exchanger is suitable for effective recovery of a sum of light REMs. Based on the average value of ion exchange equilibrium constant for light REMs, parameters of a sorption unit with a fluidized bed of anion exchanger were estimated.

Development of Hydrometallurgical Process for Recovery of Rare Earth Metals (Nd, Pr, and Dy) from Nd-Fe-B Magnets

Non-availability of rich primary resources of rare earth metals (REMs) and the generation of huge amounts of discarded magnets containing REMs, compelled the researchers to explore the possibilities for the recovery of REMs from discarded magnets. Therefore, the present paper reports the recovery of REMs (Nd, Pr, and Dy) from discarded Nd-Fe-B magnets. The process consists of demagnetization, pre-treatment, and hydrometallurgical processing to recover REMs as salt. Leaching studies indicate that 95.5% Nd, 99.9% Pr, and 99.9% Dy were found to be dissolved at the optimized experimental condition i.e., acid concentration 2 M H2SO4, temperature 75 °C, pulp density 100 g/L, and mixing time 60 min. Solvent extraction technique was tried for the selective extraction/separation of REMs and Fe. The result indicates that 99.1% (24.42 g/L) of Nd along with 90% (1.08 g/L) of Pr and total Fe were co-extracted using 35% Cyanex 272 at organic to aqueous (O/A) ratio 1/1, eq. pH 3.5 in 10 min of mixing time. It requires multistage separation and therefore, not feasible in view of economics. Thus, direct precipitation of REMs salt and iron oxide as pigment was studied using two stages of precipitation at different pH. The obtained precipitate of REMs and Fe hydroxides were dried separately to remove the moisture and further treated at elevated temperature to get pure REMs oxide and red oxide.

LiNO3-Supported Electrodeposition of Metallic Nd from Nd-Containing Solvate Ionic Liquid

Inexpensive electrolyte systems and readily available rare-earth (RE) precursors are necessary for the facile recovery of RE metals at the lowest temperature, which will allow the sustainable devel...