Separate Rare Earth Research Articles

Synthesis of magnetic manganese-based adsorbent for rapid adsorption of selenium ions from water

Selenium (Se) is one of the natural elements, and it is widely studied because of its complex behavior, especially in its involvement in the metabolism of organisms. In addition, Se contamination at high concentrations has been reported to affect human health. In this study, an adsorbent material based on manganese-magnetic (Mn-Fe3O4) has been developed, which was prepared by impregnation methods. The developed material was characterized by spectroscopy, microscopy, magnetometry, and N2 gas adsorption to investigate its surface and paramagnetic properties. A batch adsorption test was used to investigate the removing Se ions in an aqueous medium. The experimental result showed that the Se equilibrium adsorption onto Mn-Fe3O4 material could be reached within 120 min at pH 7.0 with a maximum adsorption capacity (qe) of 12.50 mg g−1 and %removal of Se at 99 % at room temperature conditions. In addition, the material is easy to regenerate under alkaline conditions. This study provides strategies for fabricating magnetic materials to separate rare earth metals efficiently and rapidly.

Size Selective Ligand Tug of War Strategy to Separate Rare Earth Elements.

Separating rare earth elements is a daunting task due to their similar properties. We report a "tug of war" strategy that employs a lipophilic and hydrophilic ligand with contrasting selectivity, resulting in a magnified separation of target rare earth elements. Specifically, a novel water-soluble bis-lactam-1,10-phenanthroline with an affinity for light lanthanides is coupled with oil-soluble diglycolamide that selectively binds heavy lanthanides. This two-ligand strategy yields a quantitative separation of the lightest (e.g., La-Nd) and heaviest (e.g., Ho-Lu) lanthanides, enabling efficient separation of neighboring lanthanides in-between (e.g., Sm-Dy).

Environmentally sound technology development for processing of rare earth elements from waste permanent magnets synthetic leach solutions: recovery and separation perspectives

Overall environmentally sound technology development for the waste permanent magnets (PMs) processing for the recovery of the rare earths. • The present research and development is concern to recover the rare earths from waste permanent magnets leach liquors. • From this study appropriate experimental condition for crowding studies were optimized. • Based on crowding effect, to enrich the as maximum as separation of rare earths each other. • Extraction isotherm was constructed for dysprosium. • Maximum extraction and predicted the A/O 1, 2 and 3 ratios requires 3, 5 and 8 extraction stages. An environmentally sound process was investigated as feasible to extract and separate rare earths from the synthetic leach liquors prepared based on waste permanent magnets composition analogs. Solvent extraction methods were used to screen different extractants to optimize and suggest the proper extraction system to recovery the different rare earth elements (REEs). Various experimental factors, equilibrium pH and impact of the extractant concentration were studied to select the optimum extraction system. Waste permanent magnets were treated in the initial stages with plating separation, sulfuric acid leaching and double salt precipitation. A second leaching process was implemented by hydrochloric acid; the leach liquor was treated by hydrometallurgy processes for the reprocessing and separation of rare earths present. Three phosphorous based commercial extractants Cyanex 272 (bis (2, 4, 4-trimethylpentyl) phosphinic acid), D2EHPA (bis (2, 4, 4-tri-methyl-pentyl) phosphinic acid) and PC 88A (2-ethyl-hexyl-phosphonic acid mono-2-ethyl-hexyl ester) were applied in the present study. Initial experiments suggested that Cyanex 272 is the best reagent for recovery and potential separation between REs, therefore the crowding studies were carried on. From this study appropriate experimental conditions for crowding were optimized to maximize the enrichment of rare earths while separating them.

Ionic Liquids [M3+ ][A- ]3 with Three-Valent Cations and Their Possible Use to Easily Separate Rare Earth Metals.

We introduce a simple way to liquify rare earth metals (REM) by incorporating the corresponding cations, in particular Eu3+, La3+, and Y3+, into polyvalent ionic liquids (ILs). In contrast to conventional methods, this is achieved not by transforming them into anionic complexes, but by keeping them as bare cations and combining them with convenient, cheap and commercially available anions (A) in the form [REM3+][A − ]3. To do so, we follow the COncept of Melting Point Lowering due to EThoxylation (COMPLET) with alkyl polyethylene oxide carboxylates as anions. We provide basic properties, such as glass transition temperatures, viscosities, electrical conductivities, as well as water‐octanol partition constants P and show that these ILs have remarkably different properties, despite the similarity of their cations. In addition, we show that the ionic liquids possess interesting luminescent properties as non‐conventional fluorophores.

A novel MagLev-based separation approach for heavy metal recycling

Separation is crucial for recycling heavy metals, however, most of the reported processes focus on separating metals from non-metals. Here we propose a magnetic levitation (MagLev) configuration to separate heavy metals from metallic mixtures. The novel configuration is able to levitate substances with specific densities over 5.00 g/cm3, while the extant MagLev devices can only handle materials that have specific densities no more than 3.00 g/cm3. We mathematically model the proposed MagLev configuration and apply the approach to separate rare earth metals from fluorescent powders as well as indium contents from indium-tin oxide (ITO)/glass mixtures, mechanically processed liquid crystal displays (LCDs) and ITO powder. The results show that the recovery rates of ITO from ITO/glass mixtures are over 95%, the concentrations of indium in separated LCD shreds are doubled (from 912.0 ppm to 1873.1 ppm), and the purities of separated In2O3 from ITO powder are around 90%. The method is controllable and requires no energy or chemical inputs, and it thereby has tremendous prospects in heavy metal recycling.

Sorption of rare earth coordination compounds

Rare earth elements (REEs) are valuable and strategically important in many high-technology areas, such as laser technology, pharmacy and metallurgy. The main methods of REE recovery are precipitation, extraction and sorption, in particular ion exchange using various sorbents, which allow to perform selective recovery and removal of associated components, as well as to separate rare earth metals with similar chemical properties.
 The paper examines recovery of ytterbium in the form of coordination compounds with Trilon B on weakly basic anion exchange resin D-403 from nitrate solutions. In order to estimate thermodynamic sorption parameters of ytterbium anionic complexes, ion exchange process was carried out from model solutions under constant ionic strength specified by NaNO3, optimal liquid to solid ratio, pH level, temperatures 298 and 343 K by variable concentrations method. Description of thermodynamic equilibrium was made using mass action law formulated for ion exchange equation and mathematically converted to linear form. Values of equilibrium constants, Gibbs free energy, enthalpy and entropy of the sorption process have been calculated. Basing on calculated values of Gibbs energy, a sorption series of complex REE ions with Trilon B was obtained over anion exchange resin D-403 from nitrate solutions at temperature 298 K. Sorption characteristics of anion exchange resin have been estimated: total capacity, limiting sorption of complex ions, total dynamic capacity and breakthrough dynamic capacity.

Extraction of Rare Earth Metal Ions with an Undiluted Hydrophobic Pseudoprotic Ionic Liquid

Recovering and concentrating rare earth metals (Nd and Dy) from waste permanent magnets rather than discarding them into the environment without pretreatment is critical for metal recycling and environmental responsibility. In this work, we used an undiluted hydrophobic pseudoprotic ionic liquid composed of trioctylamine and decanoic acid as an extractant to separate rare earth metals from aqueous media with a solvent extraction technique. This ionic liquid proved to be excellent with low viscosity and extractability reaching 100% for Nd and Dy in the presence of salts like sodium chloride and sodium nitrate. In acidic media, extractability decreased with increasing acid concentrations. Under all our experimental conditions, the rare earth metals (Nd and Dy) were found to be preferentially extracted compared to nickel with the distribution ratios of Dy higher than those of Nd.

Investigation of Elemental Composition Change by Laser Ablation of a Rare‐Earth Containing Material

Rare earth doped materials, in the form of nanoparticles, have attracted extensive attention in photonic and biomedical applications. Separation of rare earth elements in a clean way has been also topic of great interest. Laser ablation has been actively examined to convert the rare earth containing bulk materials into functional nanoparticles as a potentially clean, efficient production method. However, elemental composition change during laser ablation based rare earth containing nanoparticle conversion process has not been studied extensively despite its significance. In this study, an ultraviolet nanosecond pulsed laser is used to ablate an erbium containing glass material with a major aim of tracking elemental composition in collected nanoparticles. The effect of laser fluence and laser beam spot is experimentally investigated by morphological, optical, spectroscopic, and elemental analyses. The results indicates the careful choice of laser parameters for the laser ablation can either preserve the elemental composition of bulk materials for applications dealing with rare earth containing materials or separate rare earth elements from bulk materials.

Concentration of rare earth elements from monazite by selective precipitation

Pure rare earth elements and their compounds play a unique role in a wide range of green technology and different industrial applications such as medicine, aerospace and clean energy production. The aim of this study was to concentrate and separate rare earth elements from the monazite matrix. Monazite was digested using a mixture of Na2HPO4/NaH2PO4·H2O fluxes at 900 °C. Precipitation of rare earth elements was investigated with biphenyldicarboxylic acid and acetyl acetone chelating agents. The precipitates were re-dissolved in sulphuric acid and analysed together with the filtrate solutions using inductively coupled plasma optical emission spectrometry. Analytical results indicated selective precipitation of rare earth elements with both biphenyldicarboxylic acid and acetyl acetone. The results also revealed a negative Na+ influence (from the flux) on the rare earth elements recovery in solution which is attributed to easily ionisable behaviour of Na which affects the flame properties of the inductively coupled plasma optical emission spectrometry. Na was removed as NaCl by addition of concentrated HCl prior rare earth elements precipitation. This step improved the rare earth elements recovery in the precipitate from 90.2(1) and 101.68(3) %, while the impurities concentrations remained below 30 %. These results indicated the successful concentration and separation of most rare earth elements from monazite by selective precipitation.

Simulating producer responses to selected chinese rare earth policies

This study explores the effects of Chinese rare earth stockpiling, environmental taxation, and improvements in recovery rates on rare earth markets. It uses a Stackelberg model with a leading producer (legal Chinese producers) and two sequential followers (illegal Chinese producers and the Mount Weld mine in Australia), each producing multiple rare earths. The model is parameterized for the production and prices of separated rare earth oxides (REOs) from ore. Counterfactuals involving Chinese policies are compared to the no-policy, business-as-usual (BAU) scenario. The five counterfactuals are: (1) further Chinese State Reserve Bureau (SRB) stockpiling of neodymium, (2) further SRB stockpiling of dysprosium, (3) an environmental tax on the production of legal Chinese rare earths, (4) increased recovery rates of neodymium at legal Chinese operations, and (5) increased recovery rates of dysprosium also at legal Chinese operations. The BAU scenario and five counterfactuals are run with (a) four different levels of reference illegal Chinese production and (b) with and without the Chinese production quota, yielding 48 total outcomes (6×4×2). The first finding is that any SRB stockpile purchase increases the price of the stockpiled REO and increases legal Chinese ore production. However, given co-production, increased ore production involves more production of all REOs, and the prices of non-stockpiled REOs decrease. Thus if the stockpiled REO represents a large (small) portion of illegal Chinese and Mount Weld revenue, then illegal Chinese producers and the Mount Weld mine will increase (decrease) their production. An environmental tax decreases legal Chinese production, increases production by illegal Chinese producers and Mount Weld, and increases prices of all REOs. Increased legal Chinese recovery rates lead to increased legal Chinese production, decreased production by illegal Chinese producers and Mount Weld, and decreased REO prices. Increased levels of reference illegal Chinese production (a) exacerbate the policy-driven production increases or dampen production reductions of illegal producers and (b) conversely, for legal Chinese producers, reduce policy-driven production increases and further increase production reductions.

A reactive distillation process for the treatment of LiCl-KCl eutectic waste salt containing rare earth chlorides

The pyrochemical process, which recovers useful resources (U/TRU metals) from used nuclear fuel using an electrochemical method, generates LiCl-KCl eutectic waste salt containing radioactive rare earth chlorides (RECl3). It is necessary to develop a simple process for the treatment of LiCl-KCl eutectic waste salt in a hot-cell facility. For this reason, a reactive distillation process using a chemical agent was achieved as a method to separate rare earths from the LiCl-KCl waste salt. Before conducting the reactive distillation, thermodynamic equilibrium behaviors of the reactions between rare earth (Nd, La, Ce, Pr) chlorides and the chemical agent (K2CO3) were predicted using software. The addition of the chemical agent was determined to separate the rare earth chlorides into an oxide form using these equilibrium results. In the reactive distillation test, the rare earth chlorides in LiCl-KCl eutectic salt were decontaminated at a decontamination factor (DF) of more than 5000, and were mainly converted into oxide (Nd2O3, CeO2, La2O3, Pr2O3) or oxychloride (LaOCl, PrOCl) forms. The LiCl-KCl was purified into a form with a very low concentration (<1 ppm) for the rare earth chlorides.

Perspectives for the Brazilian Industry of Rare-Earth Magnets

The Brazilian reserves of rare earths were updated. Brazil is among the countries with the largest reserves of rare earths in the world. Rare earths present a series of applications in the high technology industry. Magnet production is one of the applications requesting largest volumes of rare earths. Another relevant application is catalysis and Petrobras needs 1000 tons/year of La2O3 for petroleum refining. CBMM mine has a pilot plant able to produce tons of separated rare earth oxides, notably didymium (a mixing of Nd and Pr oxides) used in magnet manufacture. Serra Verde mine in Goiás also produced separated rare earth oxides. The magnet production in Brazil can be important for the high efficiency electrical motors industry and also for the automotive industry.

Separation of lanthanides and yttrium as aniomic complexes by isocratic ion-interaction chromatography

Rare earth elements in nitric acid solution can be individually separated by ion-interaction chromatography. The separation is achieved by isocratic elution with oxalic acid as the complexing agent in the eluent and tetra- n-butylammonium hydroxide as the ion-pairing reagent. The separated rare earth elements are measured spectrophotometrically after post-column reaction with Arsenazo III, and can be determined at levels ⩾ 0.5 mg/1 with a relative standard deviation of 0.01% for the individual rare earth elements at the 10 mg/1 level. The order of elution is from lanthanum to lutetium, yttrium being eluted immediately after terbium.

Reversed-phase chromatgraphic separation of the rare earth elements

Chromatographic behaviour of the rare earth elements on C-18 bonded silica reversed-phase material has been investigated in aqueous lactate media. The lactatocomplexes of the rare earths are distributed and fractionated on the bonded silica column by a mobile phase gradient technique in the presence of hydrophobic ions. The effects of the lactate concentration pH, methanol and hydrophobic ion concentrations in the eluents have been investigated in detail to have the best resulution of the adjacent rare earth elements. Port-column reaction with arsenazo(III) is used to detect the separated rare earth lactatocomplexes. This reversed-phase partition system is suited to separate and detect all rare earth elements within 40 min with good reproducibility.

Rare earth and uranium minerals present as daughter crystals in fluid inclusions, Mary Kathleen U-REE skarn, Queensland, Australia

AbstractAt least six separate rare earth and uranium-bearing daughter crystals occur in fluid inclusions hosted by andraditic garnet from the Mary Kathleen REE-U ore skarn, Queensland, Australia. The daughter minerals are particularly high in La, Nd and Ce which reflects the relatively high concentration of these in the bulk ore (La2O3 = 33.5%, Nd2O3 = 9.1% and Ce2O2 = 51.5% of the 2.6 wt. % REE common in the ore). The host garnets themselves contain up to 7600 ppm REE and 5 to 2700 ppm U. The energy-dispersive spectra (EDS) are consistent with the following minerals: a (Y, Ce, U, Ca, Fe, Nb, Ta) mineral; a (Ca, Fe, Ce) carbonate(?) mineral; a (Fe, Ca, Y, Ce, Nb, Ta) mineral; a possible carbonate of La, Mn and Nd; a chlorite of Mn and La as well as a possible chloride or oxychloride of K, Mg, Mn and La. Their occurrence infers that relatively high concentrations of REE and U prevailed in the original, oxidized, concentrated (30–70 wt. % total dissolved salts), high-temperature (550–670°) ore solutions. Their presence as daughter crystals may be due to the fact that CaCl2 is a dominant salt in the solutions and that the latter's solubility was sufficiently high to ‘salt out’ the less soluble REE-U components.

Dosage par activation neutronique des terres rapes dans des roches uraniferes

The determination of rare earths by activation analysis in uranium containing rocks is disturbed either by fission-produced rare earths, or by neptunium-239 originating from uranium-238. In order to eliminate of these interferences the chemical separation of rare earths from uranium prior to activation should be performed. The purpose of this work was the elaboration of a chemical process to separate rare earths prior to irradiation in a nuclear reactor. The rock sample is fused with sodium borate, then, after addition of hydrochloric acid, the resulting solution is passed through a Dowex 1×8 column. Uranium is retained on the resin and rare earths and scandium are eluted. Aluminium is added as a carrier to the solution and rare earths and scandium are coprecipitated with aluminium hydroxide. This precipitate is irradiated in the nuclear reactor. Gamma spectrometry is used for the determination of each radionuclide. Activities measurements are performed in successive steps during one month. The following elements are determinated: Pr, La, Sm, Nd, Yb, Lu, Ce, Tb, Eu, and Sc. The chemical yield is measured by using scandium as an internal standard.

Retention Time in Rumen and Degradation of Protein Supplements Fed to Lactating Dairy Cattle

In part 1 of this experiment, six lactating Holstein cows were used to determine rate of passage of soybean meal, corn gluten meal, and brewer's dried grains through the gastrointestinal tract and also to compare chromiumethylenediaminetetraacetic acid and cobalt-ethylenediaminetetraacetic acid as liquid digesta markers. Cows were offered a basal diet containing 60% alfalfa hay and 40% of a grain mix twice daily. In addition, all cows received 2.7kg daily of a mixture of soybean meal, corn gluten meal, and brewer's dried grains. At a designated feeding, each of the protein supplements was labeled with a separate rare earth marker element (samarium, cerium, or lanthanum). Mean ruminal turnover of liquid was 11.4 and 9.9%/h when chromium-ethylenediaminetetraacetic acid and cobalt-ethylenediaminetetraacetic acid were used as markers. Treatment means for ruminal turnover of soybean meal, corn gluten meal, and brewer's dried grains were 4.9, 5.3, and 4,8%/h.In part 2, nitrogen disappearance from soybean meal, corn gluten meal, and brewer's dried grains placed in Dacron bags suspended in the rumen of a fistulated cow was determined at intervals of 1, 4, 8, 12, 16, and 24h. These measurements, along with information on the amount of protein supplement remaining in the rumen at various intervals (derived from the rate of passage data), were used to estimate protein degradability in the rumen. Protein degradabilities by this approach for soybean meal, brewer's dried grains, and corn gluten meal were 72, 42, and 14%. Results for soybean meal and brewer's dried grains matched in vivo results in the literature, but corn gluten meal was underestimated grossly.

Microstructure and magnetism in amorphous rare earth–transition metal thin films

We have examined UHV vapor deposited and sputtered films of various amorphous alloys by transmission electron microscopy (TEM). All of the films exhibited an anisotropic microstructure composed of columnar regions surrounded by a low density network. The structure is produced by shadowing of the incident vapor by the growing film. Films produced by vapor deposition from separate rare earth (RE) and transition metal (TM) sources may possess an easy axis of magnetization in the film plane that is not present when the substrate is rotated or when the film is produced by sputtering. All of the films possess a high tensile stress which may be reduced and eventually converted to a compressive stress by vapor deposition in an oxygen containing ambient or by negative bias sputtering. The appearance of compressive stresses is coincident with the development of a perpendicular easy axis in Gd-Co. A perpendicular easy axis is also induced in vapor deposited and zero volt bias sputtered Gd-Co films upon heating within the TEM. Our results indicate that perpendicular anisotropy may be produced by the formation of an inhomogeneous structure via removal of ferromagnetic Gd, either by oxidation or preferential resputtering.

A rapid carrier-free separation method for divalent rare earths

A separation of carrier-free divalent rare earths by electrolytic reduction and amalgamation is described. The separation is carried out in a water-jacketed cell, 1 cm diameter by 10 cm long, fitted with a stopcock at the bottom. The cell utilizes a Pt anode and Hg cathode. The electrolyte used is potassium citrate-rare earth acetate at a concentration of 10 mg rare earth oxide per ml. The decontamination factor observed for Lu in a typical separation for Yb is ≥104. Sm, Eu, and Yb are all amalgamated if present in the sample. For the present study, the parameters have been evaluated primarily for the case of Yb. A current of 100 mA is applied to 0.5 ml of electrolyte containing 1–1000 μg of Yb(III) for 5 min. The amalgam is decomposed and the Yb recovered by shaking for 1 min with 6M HCl. The overall time required is about 10 min and the yield is reproducible at 84–85%. Under these conditions, the electrolyte may contain up to 3.5 mg of Yb although at 2 mg the yield begins to decrease. The effects of current time, density and electrolyte concentration are discussed. This method has the advantage of being rapid and carrier-free, and the separated rare earth is in a form suitable for further chemical separation if required.

Knorre氏法&lt;SUP&gt;1)&lt;/SUP&gt;の適用性について

Recently, in order to improve hot workability of high grade stainless steel, adding rare earth metals in a bath have been widely taken in stainless-steel melting practice. As regards determination of Ce in steels, W. Westwood and A. Mayer2) reported in their paper that Ce in cast iron was separated from iron by using citric acid ammonia buffer solution, then extracted with chloroform and at last determined by oxine colorimetry.To determinate Ce in stainless steel which was treated with misch-metal, the author made some experiments concerning the following matters:(i) Separability of all rare earth metals from the steel using HF solution.(ii) Applicability of Knorre's method to Ce in separated rare earth metals.As a result of experiments, the author ascertained applicability of Knorre's method to determine the Ce in steel.