Extraction Of Lanthanides Research Articles

Influence of the Structure of Carbamoylmethylphosphine Oxides on the Extraction of Lanthanides(III) from Nitric Acid Solutions in the Presence of Dinonylnaphtalenesulfonic Acid

It was found that the extraction of lanthanides(III) from nitric acid solutions with solutions of carbamoylmethylphosphine oxides increases significantly in the presence of dinonylnaphthalene sulfonic acid. The stoichiometry of the extracted complexes was determined, and the influence of the composition of the aqueous phase, the nature of the organic solvent, and the structure of carbamoylmethylphosphine oxides on the efficiency of extraction of metal ions into the organic phase was considered.

Liquid-liquid extraction and separation of light and heavy rare earth elements from chloride solution using a mixture of tertiary amine and phosphinic acid: recycling strategies for NdFeB magnet

ABSTRACT This piece of work aims to study the extraction behavior of light and heavy rare earth elements, which are often found in permanent magnets, using a mixture of tri-octyl amine and bis-(2,4,4-trimethylpentyl) phosphinic acid from a chloride medium. The study showed that the extraction efficiency of Dy(III) is more than that of Nd(III) and Pr(III). Benzene proved to be an effective diluent. Increasing the pH of the aqueous phase improved the extraction percentages, with maximum extractions of 98.4% for Dy(III), 61.2% for Nd(III), and 58.3% for Pr(III) at pH 5.04 using 0.1 mol/L of each extractant. Adding sodium chloride enhanced the extraction efficiency due to the salting-out effect. The extraction mechanism has been proposed based on the slope analysis and FTIR data. From thermodynamic variables, the process was found to be exothermic. The simulated leach liquor of NdFeB magnets showed the highest separation factors of 67.7 (Dy/Pr) and 56.9 (Dy/Nd) at pH 2.05 with 0.25 mol/L extractants. The counter-current study showed that 4.15 mg/L Dy(III) was left behind in the raffinate indicating 97.4% removal of Dy(III) in two stages at unity phase ratio. Testing with actual leach liquor from hard disk magnets revealed a preference for iron extraction, which impeded REE extraction.

Towards the bioleaching of bauxite residue by gluconobacter oxydans.

This project evaluated a biologically-mediated strategy to solubilize several rare earth elements and critical raw materials, including scandium, from bauxite residue. This work seeks to expand on previous research on contact leaching with bauxite. In this study, Gluconobacter oxydans was shown to secrete mixed organic acids, including gluconic acid, which was superior to pure gluconic acid in the dissolution of bauxite residue, even at low molarities. In situ contact leaching with G. oxydans significantly promoted the dissolution yield (recovery of metal present in the ore) of yttrium, aluminum, calcium, and titanium (41.18, 67.79, 80.16 and 59.41%, respectively) but allowed for only marginal dissolution yield of scandium, lanthanum, cerium, and neodymium (13.40, 14.74, 24.41 and 10.67%, respectively) at relatively low pulp densities. In addition, the dissolution yields of rare earth elements were reduced further with time, presumably as the oxides of these elements fell out of solution. This work builds on previous research that seeks to extract rare earth elements and critical raw materials from bauxite residue through contact leaching with organic acids. Some elements such as yttrium, aluminum, calcium, and titanium could be effectively solubilized, however some elements showed reduced solubility, possibly due to tight association with the iron phase of the residue. However, the relative ease and speed of leaching, and suggestions for improved solubilization suggest this could be a viable method for securing critical raw material supplies.

System analysis with life cycle assessment for NiMH battery recycling.

The nickel metal hydride (NiMH) battery technology has been designed for use in electric vehicles, solar-powered applications and power tools. These batteries contain the critical and strategic raw materials cobalt, nickel and several rare earth elements (REE). When designing a battery recycling process, there are several choices to be made regarding end-products and process chemicals. The aim of this study is to investigate and compare the environmental and economic sustainability of different recycling options for NiMH batteries by taking projected market developments into consideration and by applying life cycle assessment and life cycle costing methods. The comparative study is limited to recovery of the REEs. Two hydrometallurgical processes for recovery of the REEs from the anode material are compared with extraction of REEs from primary sources in China. The processes compared are a high-temperature sulfation roasting process and a process based on hydrochloric acid leaching followed by precipitation of REE oxalates. By comparing the different recycling approaches, the hydrochloric acid process performs best. However, the use of oxalic acid has a large impact on the overall sustainability footprint. For the sulfation roasting process, the energy, sodium hydroxide and sulphuric acid consumption contribute most to the total environmental footprint. This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

Extraction of rare earth elements from ion adsorption clay using bio-based ionic liquid via COSMO-RS: computational and experimental validation

The study introduces eco-friendly leaching agents as alternatives to traditional rare earth element (REE) extraction solvents, addressing environmental concerns associated with ammonium sulfate. Bio-based ionic liquids (ILs), known for their non-toxic and biodegradable properties, were screened using the COSMO-RS software. Initially, 105 ILs involving 7 cations and 15 anions were computationally screened to find the best ILs for REE extraction. The chosen criteria were based on hydrogen bond formation, affinity screening, hydrophobicity, viscosity, and eco-toxicity test. Based on the COSMO-RS screening, choline oleate, choline decanoate, and choline hexanoate exhibit high solubility for REEs, with a chemical potential of 17.60, 17.01, and 18.37 kcal/mol at REE oxidation state +2. Choline glycinate, choline oleate, choline decanoate, choline hexanoate, choline lysinate, and choline leucinate were selected for their strong affinity to extract REE dissociate ions. Experimental results show slightly higher REE extraction from ammonium sulfate (3.17 ppm) compared to choline glycinate (3.15 ppm). For long-term applications, choline glycinate offers a promising eco-friendly and cost-effective alternative to traditional leaching agents, promoting economic feasibility and environmental friendliness.

Eco-friendly synthesized zeolitic imidazolate framework-8 enables one-step cerium recovery from water

The rapid pace of technology advancement has quickly depleted valuable rare earth elements (REEs), which are critical for the function and performance of electric and electronic components, and there is thus a need for REE extraction from secondary sources rather than from virgin mines. This study presents an approach involving the ball-milling-induced construction of zeolitic imidazolate framework-8 (ZIF-8) that integrates REE extraction and recovery processes. ZIF-8 demonstrates remarkable extraction capacities for various REEs, and notably promotes nanoscaled CeO2 formation. Ball-milling-prepared ZIF-8 (ZIF-8-BM) effectively concentrates cerium (III) ions (CeIII), and a purity of 99.34% is achieved by controlling the processing parameters, offering a comprehensive solution for efficient Ce retrieval from wastewater. The superior Ce extraction performance is attributed to the greater numbers of structural defects and surface hydroxyl (–OH) groups and the enhanced phase transformation efficiency. Moreover Ce extraction by ZIF-8-BM is found to be efficient in both low and high Ce concentration ranges. ZIF-8-BM nanoparticles spontaneously oxidize CeIII in solution to insoluble CeO2, thereby facilitating the efficient extraction and subsequent recovery of cerium from complex matrices. The findings of this study provide an environmentally benign approach for the safe and efficient recovery of REEs from waste streams, supported by a scientifically sound and economically feasible processing strategy.

Pilot-scale bioremediation of rare earths wastewater by Chlamydomonas sp. YC

The extraction of rare earth elements (REEs) through in-situ leaching with ammonium sulphate [(NH4)2SO4] had resulted in the production of a large volume of ammonium-rich wastewater, causing severe environmental pollution. This study aimed to assess the ability of an indigenous microalga Chlamydomonas sp. YC, isolated from REEs wastewater, to directly treat real REEs wastewater under outdoor conditions in 50 L airlift photobioreactors (AL-PBRs) and 5.0 m3 open race-way photobioreactors (ORWPs). Additionally, the harvested Chlamydomonas sp. YC biomasses from these two pilot photobioreactors were comprehensively analyzed to evaluate the nutritional values. The results showed that Chlamydomonas sp. YC in AL-PBRs exhibited higher biomass production (1.1 g/L), greater removal efficiencies in NH4+-N (24.9%) and total nitrogen (20.4%), as well as higher CO2 fixation rate (125.0 mg/(L·d)), compared to those of ORWPs. Moreover, the Chlamydomonas sp. YC biomasses obtained from the two pilot photobioreactors contained 44.5% and 49.4% protein, 9.1% and 14.3% lipids. Moreover, Chlamydomonas sp. YC in the two pilot photobioreactors displayed essential amino acid indexes (EAAI) of 0.900, which was higher than that of soybean protein (0.657), indicating superior nutritional values. In conclusion, the implementation of the process involving Chlamydomonas sp. YC in AL-PBRs under outdoor conditions holds promise as a coupled microalgal biotechnology for the simultaneous removal of NH4+-N from REEs wastewater, and the capture of CO2 for the production of valuable biomass.

Mechanisms of roasting for improving rare earth element leaching from coal gangue

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

Bipyridyldicarboxamides and f-metals: the influence of electron effects on the structure, stability, separation, and photophysical properties of their complexes.

In this work, three isomeric fluorinated bipyridyldicarboxamides were studied to evaluate the impact of the fluorine atom position on the structure, stability, Am(III)/Ln(III) separation, and photophysical properties of their complexes. The complexes of the fluorinated amides have a metal-to-ligand composition of 1 : 1, which is independent of the fluorine atom position or lanthanide metal. The bipyridyl fragments in the fluorinated complexes are flattened compared with those in unsubstituted ones. Ln-to-heteroatom distances are more affected by steric hindrance in the ligand and further by lanthanide ion radius contraction. This leads to significant effectivity of heavy lanthanide extraction compared with the light ones, particularly for 4F diamide. Fluorination leads to a slight variation in the excited triplet state of the complexes, and hence, the effectiveness of luminescence increases for Eu, Sm, and Tb complexes. Moreover, fluorination significantly affects the CIE chromaticity coordinates for the complexes.

Microalgae for the Extraction and Separation of Rare Earths: An STXM Study of Ce, Gd, and P

Microalgae for the Extraction and Separation of Rare Earths: An STXM Study of Ce, Gd, and P

Extraction of rare earth elements from phosphogypsum and uranium in situ leaching solutions

Extraction of rare earth elements from phosphogypsum and uranium in situ leaching solutions

Ionic Liquids and its Potential as a New Green Solvent for REE Extraction in Philippine Bauxite Residues

Abstract Rare earth elements (REEs) have become necessary for high-technology applications. This has prompted an increase in demand for REE exploration, production, and extraction. Despite its name, REEs are fairly rich in the Earth’s crust. REEs are estimated to have a crustal abundance of 9.2 ppm relative to other elements in our crust. In the Philippines, deposits are found to give adequately high concentrations of REE, ranging from approximately 200 ppm to 600 ppm. Samar bauxite deposits especially had around 500 ppm REE. In line with the planned bauxite production in the Philippines, it is of interest to further uncover ways to maximize its recovery. One of the possible optimizations in its extraction is to utilize its residue. There have been a number of methods to extract REE in bauxite residues. The use of ionic liquids (IL) to recover REE in bauxite offers a possibility of an effective and environmentally safe recovery process. ILs are molten salts that have melting points below 100degC. They exhibit high electrochemical stability, non-flammability, non-volatility, and can be tailored to the desired application. Hence, they have been the topic of study for different research regarding REE extraction in bauxite residues. Herein, the potential of ILs as a green solvent for REE extraction in bauxite is reviewed for future use in the extractive metallurgy of bauxites in the Philippines.

Moderate strategy for efficient recovery of rare earth elements from scintillation crystal waste

The lutetium has been known to be used in medical imaging materials, but its scarcity in the Earth’s crust makes it expensive. In this work, we present a process for efficient lutetium recovery from the lutetium-yttrium oxyorthosilicate crystals (LYSO) waste. The process involves preliminary mechanical activation, followed by rare earth extraction via acid leaching. The key factors for activation and leaching were studied and optimized. The mechanism of mechanical activation promoting rare earth leaching was revealed by employing the characterizations of morphology and crystal structure of LYSO. It was found that the mechanical activation process could destroy the crystal structure of LYSO waste, forming numerous amorphous phases and grain boundaries, which facilitated the breaking of existing bonds and mass transfer of acid. It was also discovered that the formation of silica gel during leaching impedes the leaching of rare earth, and low concentrations of hydrochloric acid, combined with stirring during acid leaching, could reduce the impact of silica gel. Ultimately, following a mechanical activation pretreatment at 300 rpm for 90 min, 98.7 % of lutetium could be leached after 60 min of acid leaching in 3 mol/L hydrochloric acid. This process addresses the problems associated with high energy consumption and excessive usage of acidic and alkaline reagents in conventional recycling techniques. Compared to conventional methods, the mechanical activation-acid leaching method has a minimum economic benefit improvement of 20.8 % in the process of recovery from LYSO waste. It offers an alternative and more energy-efficient and economical recycling route for waste scintillation crystals.

Rare earth elements enrichment and extraction potential of bauxite deposits in Samar, Philippines

Abstract Rare earth elements (REE) play an integral part of modern life, from smartphones to satellites. Dubbed ‘critical metals’, the demand for REE has significantly increased, driven by the growth in global production for green technologies such as e-vehicles, solar panels, wind turbines, and other energy-economic infrastructure. Therefore, there is a need to explore alternative REE sources to ensure continued development of emerging green technologies. A possible alternative REE source is bauxite, which is soil that forms from intense weathering of aluminum oxide-rich rocks exposed to tropical climate. This paper investigates the REE enrichment and extraction potential from bauxite deposits in Paranas, Samar, Philippines. The sampling survey included collection of rock and soil on surface exposures, test pits, and drill cores from accessible portions of the bauxite mineral reservation site. The soil and parent rock samples collected were then subjected to various geochemical and mineralogical analyses. The main ore minerals of aluminum are gibbsite and boehmite; with minor goethite, hematite, and magnetite. Investigation of the geochemical composition of the bauxite reveals a total REE content of up to ~300 ppm, which is one of the highest REE and critical metal content among geological deposits in the country. These results will provide inputs in the design of a green and economical process to recover REE from bauxites. If the bauxite deposits prove to be a valuable REE resource, this study will help maximize the economic potential of the mineral resource in the Philippines and contribute to an economically efficient and environment-friendly way to produce e-tech elements for the country.

Interpretation of vertical migration and enrichment processes of rare earth elements (REEs) in ion-adsorption-type mineralization in Japan based on REE speciation analyses

Typical vertical profiles of ion-adsorption-type rare earth element (REE) deposits discovered in southwest Japan were studied by conducting speciation analyses, including X-ray absorption fine structure and laser-induced fluorescence spectroscopy combined with transmission electron microscopy and adsorption/desorption experiments. The results revealed that REE speciation, migration, and enrichment in weathered granite is largely controlled by soil pH, which in turn controls the variable charges of kaolinite, the REE host phase. Both the distribution coefficient Kd and the soil pH increase with depth. As a result, (i) REE dissolution and migration occur in the near-surface acidic environment of the upper layers, where hydroxyls of kaolinite basal surfaces and edges are deprotonated to a lesser degree, and (ii) REEs accumulate in the relatively high-pH environment below the surface, where hydroxyls of kaolinite basal surfaces and edges are deprotonated to a larger degree, producing REE adsorption sites with variable charges. An increase of soil pH to greater than 6 in deeper layers promotes inner-sphere complexation of REEs. Although inner-sphere complexation inhibits the ion-exchange extraction of REEs, the inner-sphere complexes can be still extracted by lowering the pH of the extraction solution. This fact, which indicates that the adsorption of both inner- and outer-sphere complexes is reversible, is important in terms of both (i) understanding vertical REE profiles in which the pH varies and (ii) the efficient recovery of REEs from REE-enriched layers at all depths in weathered granite.

Lipophilic EDTA-based ligands in different diluents for the extraction of rare earths: Preliminary results with Nd(III), Dy(III) and Pr(III) in chloride and nitrate media

A separation method for the recovery of neodymium(III) from two different media, chloride and nitrate, by implementing solvent extraction technique with a novel lipophilic diamide derivative of ethylenediamine tetraacetic acid (EDTA), namely 2,2’-N,N′-didecyl-dioxo-N,N′,N″,N″’-tetraazatetratriacontane-N″,N″’-diyl diacetic acid (H2E4C10), has been investigated. Initial screening results demonstrated acceptable solubility (ca. 15 mM) of the diamide in 1,3-diisopropylbenzene (DiPB) and in a 93:7 v:v n-dodecane:n-octanol mixture (DOm) as non-polar diluents. Further investigations aiming at determining operational parameters associated with the befitted extractant systems were conducted at pH ranging from 2 to 4 in chloride and nitrate media. A pH-dependent performance of the proposed systems revealed loading capacity peaking at pH = 3 with the respective values of 1.7 and 2.0 g L−1 in nitrate and chloride media. The extraction efficiency, the distribution coefficients, and the separation factor (E%,D and SF, respectively) were determined for an equimolar mixture of neodymium and two other potential competitive lanthanides, namely dysprosium and praseodymium. The best selectivity was observed in the chloride medium at pH = 4 yielding SFNd/Pr = 1.48 and SFNd/Dy = 2.03. Neodymium-to-extractant stoichiometry was evidenced in chloroform to be 1:1 H2E:Nd at pH = 2. Thermodynamic constants related to the considered extraction equilibrium have been determined by using the Van't Hoff relation and the slope analysis method. It appeared within the selected pH-range that the mechanism of the Nd3+ transfer was strongly influenced by the nature of the diluent. This was illustrated by the enthalpy-driven transfer when Nd3+ was extracted with the H2E-4C10-Dom system (aliphatic diluent) while the transfer became entropy-driven when the extraction was performed with the H2E-4C10-DiPB system (aromatic diluent). The complexation of Nd3+ involved mainly the participation of both the amide and carboxylic functional groups. The transfer of the cation to the organic phase might occur through the formation of the Nd(HE)A2 complex (where A is either a nitrate or a chloride anion), allowing for the lowest associated standard Gibbs free energy of transfer (−28 < ΔG° < −24 kJ mol−1) regardless of the aqueous feed.

Extraction of Rare Earth and CaF2 from Rare Earth Calcium Thermal Reduction Slag by Using CaO Roasting–Acid Leaching Method

The rare earth calcium thermal reduction slag (RCS) generated during the production of heavy rare earth metal contains large amounts of rare earth and fluoride compounds. In this study, rare earth elements (REEs) and fluorine in the RCS were recovered by the CaO roasting–hydrochloric acid leaching method. Firstly, the thermodynamic feasibility of converting rare earth fluoride to rare earth oxides through CaO roasting was demonstrated. The influence of roasting conditions and leaching conditions on the leaching rate of the REEs was investigated. Optimal results, a 95.48% leaching rate of the REEs, were obtained under the following conditions: a CaO dosage of 15%, a roasting temperature of 1000 °C, and a roasting duration of 90 min. XRD, SEM, and EDS results revealed that during the calcination process, the REEs present in fluorite (CaF2) in isomorphic form were transformed into acid-soluble rare earth oxides; furthermore, the rare earth metallic in the RCS remained unchanged even after roasting. In the leaching process, rare earth metals and rare earth oxides are efficiently extracted, while CaF2 rarely dissolves. The leaching slag contained 97.31% CaF2 with a F recovery of 96.92%. The kinetics of the rare earth leaching process was analyzed, and the results show that the three-dimensional diffusion control at the phase interface of the kinetic model best fits the process. The calculated apparent activation energy for the leaching rate of REEs is 20.869 kJ/mol. Therefore, efficient comprehensive recovery of rare earth and fluorite from RCS can be achieved by using the CaO roasting–hydrochloric acid leaching method.

INVESTIGATION OF RARE AND RARE-EARTH ELEMENTS LEACHING PROCESSES FROM THE WEATHERING CRUST ORES OF THE KUNDYBAY DEPOSIT

The weathering crust ore of the Kundybay deposit is a hard-enriched ore that contains such minerals as cherchite, bastnesite, kaolinite, etc., which are embedded in the matrix structure of other silicate rocks. These minerals contain rare earth (RE) and rare earth elements (REE). The multi-component structure and dense packing of minerals in the aluminosilicate matrix of the ore make it difficult to be blocking out. Determination of the optimal ore blocking method in order to extract RE and REE is an urgent task for today. The purpose of this work is to develop an effective method of leaching RE, REE and "white soot" from the weathering crust ores of the Kundybay deposit. Methods. Processing with soluble ammonium, magnesium and aluminium salts will allow estimation of the state of RE and REE in the ore. The indicator of RE and REE blocking out during leaching with sodium hydroxide is the transfer of silica into solution, due to which RE and REE form their own hydroxides, which can be subsequently transferred into solution by acid treatment. Acid leaching with sodium pyrosulfite, hydrofluoric acid and sulfuric acid will allow the RE and REE to be immediately transferred into solution. Results and Discussion. The main characteristics of the Kundybay deposit weathering crust ore were determined, such as: silica content, moisture content, base metals, RE and REE. Conclusion. The degree of extraction of RE and REE by soluble salts of ammonium, magnesium and aluminium did not exceed 2%, which indicates the existence of RE and REE in the form of their own minerals. Leaching with sodium hydroxide showed low recovery of silica, with RE and REE remaining in a difficult-torecover form. Leaching with a mixture of sodium pyrosulfite, hydrofluoric and sulfuric acids is a promising method for RE and REE recovery due to the complex effect of the components of this mixture.

A Review of the Occurrence and Recovery of Rare Earth Elements from Electronic Waste.

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

Extraction and separation of rare earth elements using LN resins in hydrochloric acid

Extraction and separation of rare earth elements using LN resins in hydrochloric acid