Neodymium Metal Research Articles

Preparation of Neodymium Metal by Pyro-Metallurgical Process Using Fluoride Salt

The neodymium fluoride was reduced to metal by thermal reduction or pyro-metallurgical process using calcium as reducing agent. Thermal reduction was carried out in a sealed reactions chamber in inert atmosphere with a nickel crucible having dry calcium fluoride lining. The stoichiometric mixture of neodymium fluoride and calcium metal chips were used in the form of pallets for pyro-metallurgical reactions. Small iodine was also added to increase heat available during ignition and to yield a lower melting and more fluid slag. The contents were heated electrically at a predetermined rate until ignition took place. The reaction was self-supporting and neodymium metal was obtained with fairly good efficiency.

Assessing the environmental footprint of the production of rare earth metals and alloys via molten salt electrolysis

Much attention has been given in recent years to the rare earth elements, considering their significance in a number of high-tech and clean energy applications. Despite the environmental destructive operations to produce rare earth elements, limited life cycle assessment investigations have yet been carried out. This is specifically true regarding the reduction of rare earth compounds to produce rare earth metals and alloys. In combination with mass/energy balance and stoichiometry, life cycle inventories of molten slat electrolysis process were developed in this study using industrial datasets gathered from different facilities in China and the Ecoinvent v3 database. The results showed that although mining, chemical treatment, and solvent extraction stages are the dominant contributors to the whole neodymium metal production process for most impact categories, molten salt electrolysis significantly impacts ecotoxicity, carcinogenics, non-carcinogenics, and eutrophication categories. Moreover, neodymium fluoride production, electricity consumption, and molybdenum use in cathodes are the dominant contributors in the molten salt electrolysis process. In addition, the neodymium metal production at facilities which produce larger amounts of heavy rare earth metals/alloys demonstrates relatively lower impacts on all impact categories compared to the production of neodymium metal at refining facilities which produce light rare earth metals/alloys.

Thermodynamic simulation and validation experiment of neodymium oxide reduction into metallic neodymium by metallothermic process

Neodymium (Nd) is one of the rare-earth elements (REEs) found in significant amount within monazite and bastnasite minerals. Nd is a ferromagnetic metal that is often used as a material to produce magnet, commonly known as a permanent magnet. Neodymium is alloyed with other metals such as iron and boron to form one of the strongest types of permanent magnet. This research aim is to study the reduction process of Nd-oxide into Nd-metal through the metallothermic process. The Nd metal product is expected to fulfill the material specification for a permanent magnet. Thermodynamics simulation of Nd reduction into its metal was conducted using ITB’s licensed Factsage software. A validation experiment was conducted only to the Nd metal resulting simulation. The simulations involved some parameters, i.e. temperatures (600, 700, 800, 900, 1000, 1100 and 1200 °C), types of fluxes (CaCl 2 and Ca(OH) 2 ), composition of the reducing agent (1x, 2x dan 3x of the stoichiometric calculations), types of the reducing agents (Ca and Mg), and types of feeds used (Nd-oxide and Nd-chloride). The thermodynamic simulation shows that Nd metal was produced in a condition where the temperature should be1100-1200 °C using Ca as the reducing agent and CaCl 2 as the flux, while the amount of reducing agent has no effect on the resulted product. Validation result of the simulations shows that the Nd metal is formed up to 49% metal in a non-oxidative condition.

Recovery of rare-earth metal neodymium from aqueous solutions by poly-γ-glutamic acid and its sodium salt as biosorbents: Effects of solution pH on neodymium recovery mechanisms

For recovery of metals from low-concentration sources, biosorption is one of promising technologies and poly-γ-glutamic acid (γ-PGA) has been known as a potential biosorbent for recovery of heavy metals from aqueous solutions. Effects of solution pH on recovery of rare-earth metal Nd are systematically examined to clarify mechanisms of Nd recovery by γ-PGA and its sodium salt (γ-PGANa). The recovery efficiency of Nd by γ-PGA increases from 2.4 to 19.6% as pH increases from 2 to 4. Subsequently the Nd recovery efficiencies for γ-PGA and γ-PGANa remain almost constant in the range of pH from 4 to 7. For pH > 7 the increase in Nd recovery is significant and 100% recovery of Nd is achieved at pH 9. The pH dependency on Nd recovery by γ-PGANa is similar to that by γ-PGA. Contributions of adsorption and precipitation/coagulation to Nd recovery process are quantified. Whereas the adsorption dominates Nd recovery at lower pH (<∼4), the precipitation/coagulation controls Nd recovery process for pH > 7. At higher pH, purple gel precipitates are observed. The maximum adsorption capacities for γ-PGA and γ-PGANa are 215 mg-Nd/(g-γ-PGA) at pH 4 and 305 mg-Nd/(g-γ-PGANa) at pH 3, respectively. From the spectra of FT-IR and XPS, the biosorption of Nd onto γ-PGA and γ-PGANa via electrostatic interaction with carboxylate anions at pH 3 is verified. The Nd complexation with amide and carboxylate anion groups on γ-PGA and γ-PGANa may also contribute to the Nd recovery. The biosorption isotherms for Nd recovery by γ-PGA and γ-PGANa can be satisfactorily fitted by the Langmuir model. The thermodynamic studies suggest that the biosorptions of Nd by γ-PGA and γ-PGANa are endothermic. The utilization of γ-PGA and γ-PGANa as potential and eco-friendly biosorbents for the highly effective recovery of Nd from aqueous solution is confirmed.

Model studies on the separation of Ca2+ and Nd3+ ions using ethylenediaminetetraacetic acid

Studies on the separation of calcium and neodymium ions by using ethylenediaminetetraacetic acid (H4EDTA) as a complexing agent were performed. This research was undertaken due to the possibility of H4EDTA applying to isolate rare earth elements from the solution after acidic leaching of phosphogypsum, and because of the similarity of coordination properties of calcium and lanthanides ions. The experiment was carried out in model systems containing Ca2+ and Nd3+ ions in hydrochloric or sulphuric acid. The content of calcium and neodymium metals, phase composition and thermal behaviour of the obtained products were determined by ICP-OES, FTIR, XRD and TG/DTA techniques. During the separation process, the precipitates of a light pink colour were obtained. The obtained results show that the neodymium ethylenediaminetetraacetate has been successfully formed and that the isolation of neodymium ions was more efficient in chloride medium. The precipitate included 72.2 and 3.9% of the starting amount of neodymium and calcium used in the experiment, respectively. However, in sulphates medium, these amounts were equal to 73.8 and 53.5%, respectively. Moreover, the obtained powder was polluted with sulphates. The addition of the EDTA in an excess (15%) contributed only to an increase in calcium content in the complex.

New extraction process for recovery of metals in glass deposits

A new process, named salt extraction process, has been developed to enable recovery of metal values from secondary sources e.g. scrap and waste materials such as slag and flue dust. It is also feasible in extracting metals from certain ores that normally are difficult to enrich and process by traditional metallurgy – two examples are nickel and cobalt. The salt extraction process has also been applied in the recovery of metals from silicates including lead from glass wastes.The process is based on the extraction of metal values from the raw materials into a molten salt bath consisting of NaCl, LiCl, and KCl corresponding to the ternary eutectic composition and with AlCl3 dissolved in the salt melt acting as the chlorinating agent. This is followed by the electrolysis of the salt bath in the same reactor. The normal processing temperature is in the range 973 K (700 °C) to 1173 K (900 °C). The aluminium chloride in the salt bath reacts with the metals in the fine comminuted raw material and metal ions are formed in the chloride bath. During the electrolysis, the metal ions reach the solid cathode and get deposited in metallic form. Liquid aluminium is used as the anode. Chlorine gas formed at the anode reacts with aluminium forming aluminium chloride in situ, which gets dissolved in the salt melt supplying the required amount of the flux.The salt extraction process has been used successfully in the extraction of Cr and Fe from electric arc furnace (EAF) silicate slag. Experiments have also been carried out in which lead has been recovered with high yield from spent cathode ray tubes. The process was shown to be successful in the extraction of the rare-earth metals neodymium and dysprosium from permanent magnet scrap. The method is a highly promising process route for the recovery of strategic metals. It also has the added important advantage of being environment-friendly, with only small amount recyclable, potentially useful rest products like alumina and silica as with limited energy consumption.

Electrodeposition of Neodymium from NdCl3-Containing Eutectic LiCl–KCl Melts Investigated Using Voltammetry and Diffusion-Reaction Modeling

Electrodeposition of neodymium (Nd) metal from NdCl3–containing molten LiCl–KCl eutectic melts was investigated using voltammetry and diffusion–reaction modeling. Voltammetry studies confirmed that Nd electrodeposition is a two–step reduction process involving first a reversible one–electron transfer reduction of Nd3+ to Nd2+, followed by quasi–reversible reduction of Nd2+ to Nd metal. In the electrode potential range where Nd3+ is reduced to Nd2+, the peak current density measured in a voltammetry scan showed good agreement with the classical Randles–Sevcik model for reversible soluble–soluble redox transitions. However, in the potential range where Nd2+ is reduced to Nd metal, the experimentally measured peak currents in the voltammogram were substantially lower than those predicted by applying the Berzins–Delahay model for reversible soluble–insoluble redox transitions. In the present work, this discrepancy was addressed using transient diffusion–reaction modeling, which accounted for the multivalent (Nd2+ and Nd3+) species transport and their multi–step reduction to Nd metal. The diffusion–reaction model accurately predicts the voltammetric response during Nd electrodeposition in a broad range of operating conditions (species concentrations and voltammetry scan rates), while providing access to the kinetic parameters governing Nd electrodeposition from halide melts. The approach presented herein may also be applied to other electrodeposition systems which undergo multivalent redox transitions at the electrode–electrolyte interface.

Investigation of electrodeposition behavior for Nd(III) in [P2225][TFSA] ionic liquid by EQCM methods with elevated temperatures

The electrodeposition behavior of Nd(III) in an ionic liquid, triethyl-pentyl-phosphonium bis(trifluoromethyl-sulfonyl) amide ([P2225][TFSA]), was investigated on an electrochemical quartz crystal microbalance (EQCM) at elevated temperatures. Cyclic voltammetry with EQCM measurements of Nd(III) in [P2225][TFSA] at 363, 373 and 378K were performed. A clear cathodic peak with increasing mass and decreasing ηρ (where η is the viscosity and ρ is the density) was observed at −2.79V. Considering the results of our previous investigations, this peak indicated the reduction of Nd(III) to Nd(0) as [Nd(III)(TFSA)5]2−+3e−→Nd(0) + 5[TFSA]−. In addition, the apparent molar mass, Mapp, between −2.49 and −2.94V calculated from the mass change was 140.4gmol−1, which was close to the theoretical value for the electrodeposition reaction of Nd(III)/Nd(0), 144.2gmol−1.Moreover, controlled potential electrolysis with EQCM (CPE/EQCM) measurements at −3.20V was performed for 0.05 and 0.10M Nd(III) in [P2225][TFSA] at 373K. The calculated Mapp values in 0.05 and 0.10M Nd(III) in the initial stage of CPE/EQCM analysis were 147.3 and 148.8gmol−1, respectively, which were close to the theoretical value for reduction of Nd(III) to Nd(0), 144.2gmol−1; thus, electrodeposition of Nd(0) metal was also proved by the CPE/EQCM analysis. Furthermore, energy-dispersive X-ray and X-ray photoelectron spectroscopy analyses of the blackish electrodeposits obtained by the CPE/EQCM measurements were identified as primarily metallic neodymium because the Nd 3d5/2 spectrum was detected within 980.5–981.5eV.

Study of Morphological Behavior of Hydroxyapatite, EDTA Hydroxyapatite and Metal Doped EDTA Hydroxyapatite Synthesized by Chemical Co-Precipitation Method via Hydrothermal Route

Hydroxyapatite Ca10(PO4)6(OH)2: (HAp) with stoichiometric composition and Ca/P (ratio) = 1.67 has attracted much attention in the context of bone transplant due to its similarity with the mineral constituent of mammals bone and teeth. It is frequently used as a filler to replace amputated bone or as a coating to promote bone ingrowth into prosthetic implants. Biomimetics or biomimicry is the imitation of the models, systems, and elements of nature for the purpose of solving complex human problems. Living organisms have evolved well-adapted structures and materials over geological time through natural selection. Biomimetics has given rise to new technologies inspired by biological solutions at macro and nanoscales. Nanostructure modification of dental implants has long been sought as a means to improve osseointegration through enhanced biomimicry of host structures. Several methods have been proposed and demonstrated for creating nanotopographic features.In the present investigation hydroxyapatite and metals (scandium, magnesium and neodymium) doped hydroxyapatite were successfully synthesized in laboratory by chemical precipitation using hydrothermal route and also by taking ethylene diamine tetra-acetic acid as a complexing reagent. The crystal, grain, and bonding structures of resulting HAp were characterized structurally using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques and spectroscopically using Fourier transform infrared (FT-IR) techniques. From SEM analysis it was found that the irregular structure of HAp changes to nanorods with EDTA HAp which further gets converted to dandelium structure with scandium doping, plate structure with magnesium doping and whiskers structure on doping with neodymium.

Reducing Greenhouse Gas Emission from the Neodymium Oxide Electrolysis. Part I: Analysis of the Anodic Gas Formation

Neodymium metal is produced nowadays only via Chinese technology, by the electrolysis of neodymium oxide in a NdF3–LiF electrolyte at about 1050 °C. The process is not automated and is known to emit a large amount of perfluorocarbons (PFCs), with a tremendous greenhouse gas potential. The electrochemical system is analyzed by calculating the theoretical voltages of formation of the relevant anodic gas products. Linear voltammograms are conducted together with a simultaneous off-gas measurement to determine the dynamic behaviors of CO, CO2, CF4, and C2F6 in relation to the electrochemical behavior. The measurements show that the PFC emission starts with the occurrence of a partial anode effect, where the first CF4 is detected, and the anode is passivated partially. The direct enabling of CF4 formation activates the anode again, and at higher voltages, also C2F6 is formed. The critical current density and voltage of this partial anode effect are determined depending on the oxygen content of the electrolyte to be able to define a process window, with no PFC formation. An estimation of the off-gas emission continuously containing 7 % CF4 and 0.7 % C2F6 leads to an emission of about 20 million t CO2-eq. per year during the production of 30,000 t/a neodymium, which can explain a part of the gap between the amounts of atmospheric measured PFCs and the data from the aluminum and semiconductor industry. Minimizing the PFC emission must be the primary goal for the whole rare earth electrolysis.

Removal of Iron and Boron by Solvent Extraction with Ionic Liquids and Recovery of Neodymium Metal by Direct Electrodeposition

ABSTRACTIn this study, the mechanism of Fe3+ ion extraction was investigated in the tri-n-butyl phosphate (TBP)/triethyl-pentyl-phosphonium (P2225) bis(trifluoromethyl-sulfonyl)amide (TFSA) system. According to the performed analysis, the Fe3+ extraction is based on cation exchange with ionic liquids:Moreover, the removal of Fe and B by continuous extraction was investigated. It was determined that nine extraction cycles led to the removal of all B and most of the Fe and increased the concentration of rare earth ions in the organic phase by a factor of 2.2.The electrochemical behavior of the extracted [Fe(III)(TBP)3(TFSA)3] complex was investigated at 373 K, and two reduction steps were detected:Based on these results, potentiostatic electrodeposition from an electrolytic bath was carried out at −1.75 V at 373 K after the ninth cycle of continuous extraction. Electrodeposits with 0.8–0.9 μm diameter were recovered on the Cu substrate, and metallic Fe in these deposits was identified by their energy dispersive X-ray spectrometry (EDX) spectra. Finally, the effectiveness of solvent extraction and direct electrodeposition in the recovery process was demonstrated in this study.

Purification of rare earth bis(trifluoromethyl-sulfonyl)amide salts by hydrometallurgy and electrodeposition of neodymium metal using potassium bis(trifluoromethyl-sulfonyl)amide melts

This paper reports a novel bench-scale hydrometallurgical procedure and electrodeposition using potassium bis(trifluoromethyl-sulfonyl)amide (KTFSA) melts for the recovery of rare earth (RE) elements from Nd-Fe-B magnet waste. The investigations were performed at bench scale to assess the potential of a process based on leaching, deironization, and purification of RE amide salts. In the leaching process using 3.4 kg of oxidized Nd-Fe-B and 14.2 L of an aqueous solution of 1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide (HTFSA), 83.0% Nd and 0.98% Fe were leached in 13 h, indicating that selective leaching of RE elements was performed at bench scale. Then, KOH or oxidized Nd-Fe-B was used as a precipitation agent in the deironization process and 100.0% Fe was successfully separated from RE components. Moreover, 4.07 kg of purified amide salts (M(TFSA)3, M = Pr, Nd, Dy, B, Al, and trace elements) were recovered from a spray dryer. The electrochemical behavior of Nd(III) in KTFSA melts containing M(TFSA)3 (molar fraction of RE components: xRE = 0.1) was investigated in this study. Electrochemical analysis revealed that the reduction peak of Nd(III) at around +1.0 V vs. K/K+ was due to the following reaction: Nd(III) + 3e− → Nd(0). The diffusion coefficient of Nd(III) was estimated to be 3.14 × 10−10 m2 s−1 at 483 K by semi-differential analysis, which is similar to that of Nd(III) in KTFSA melts containing pure Nd(TFSA)3 salts (xNd = 0.1). The electrodeposition of Nd was performed under potentiostatic conditions of +0.8 V vs. K/K+ at 483 K. The electrodeposits had a fine surface morphology with small metal particles. The electrodeposits were confirmed to be Nd metal in the middle layer analyzed by scanning electron microscopy/energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Finally, we demonstrated the effectiveness of the novel recovery process for practical use by estimating whole material flow.

ChemInform Abstract: Neodymium Electrowinning into Copper‐Neodymium Alloys by Mixed Oxide Reduction in Molten Fluoride Media.

AbstractGalvanostatic electrolysis of Nd2O3—CuO pellets in molten LiF—CaF2 eutectics containing Li2O between 900 and 1040 °C leads to the formation of metallic neodymium in the form of liquid Cu—Nd alloys.

Plasma characteristics and target erosion profile of racetrack-shaped RF magnetron plasma with weak rubber magnets for full circular target utilization

Abstract We have developed the racetrack-shaped RF magnetron plasma with weak rubber magnets (ferrite and neodymium) for the full utilization of the circular target and the reduction of the magnet weight. The magnetic field simulations are analyzed for the ferrite rubber magnets, the neodymium rubber magnets, and the neodymium rubber magnets including the neodymium metal magnets. The magnetic flux density indicates a mountain like profile between the magnets, having a maximum for the neodymium rubber and metal magnets. It is found that the ion flux to the target has a peak in the gap between two rubber magnets and the value remarkably increases with the addition of neodymium metal magnets. The erosion of the circular copper target, with 100 mm in diameter, has been studied by rotating the racetrack-shaped RF magnetron plasma for the neodymium rubber magnets including the neodymium metal magnets. It is seen that radial profile of the erosion depth keeps roughly constant until r = 20 mm and then decreases gradually away from the center for RF power of 40 W, Ar gas pressure of 2 Pa and sputtering time of 4 h. The target utilization is approximately 72% estimated from the erosion profile.

Neodymium electrowinning into copper-neodymium alloys by mixed oxide reduction in molten fluoride media

The possibility of neodymium electrowinning from neodymium oxide using a reducing agent (RA) produced in-situ by solvent reduction was investigated in molten LiF⿿CaF2⿿Li2O between 900 °C and 1040 °C. Nd2O3 galvanostatic electrolyses were performed and reaction products were analyzed by SEM, XRD and electron-probe microscopy. Metallic neodymium was not directly obtained, due to several limitations for Nd2O3 reduction: low electrical conductivity, unfavourable Pilling⿿Bedworth coefficient and formation of a dense insulating CaO layer on the sample surface. Consequently, the reduction of a pellet made of a neodymium oxide-metallic oxide mixture was carried out as an alternative pathway. Nd2O3-CuO reduction led to metallic neodymium production in the form of liquid Cu-Nd alloys. A reaction mechanism was proposed based on these experimental results:

Application of spark plasma sintering for fabricating Nd-Fe-B composite

Constant magnets are applied in such fields as electric equipment and electric generators with fixed rotor. Rare earth metal neodymium is well known as promising material. Production of magnets by sintering three elements (neodymium, iron and boron) is one the most promising methods. But there are difficulties in choosing the right temperature for sintering and further processing. Structure and properties of the product, consisted of rare earth metals, was analyzed. X-ray analysis of the resulting product and the finished constant magnet was performed. Vickers microhardness was obtained.

Modeling the Neodymium Metallic Reduction from Molten Salts

A model for simulating the reduction of metallic neodymium from molten salts is presented. The model was formulated with basis on the Navier-Stokes equations coupled with the Maxwell's relations. The model is useful for predicting optimum parameters of processing, as for example cell geometry and current density.

Rare-Earth-Metal Allyl Complexes Supported by the [2-(N,N-Dimethylamino)ethyl]tetramethylcyclopentadienyl Ligand: Structural Characterization, Reactivity, and Isoprene Polymerization

Rare-earth-metal half-sandwich allyl complexes bearing an amino-functionalized cyclopentadienyl ligand (CpNMe2 = 1-[2-(N,N-dimethylamino)ethyl]-2,3,4,5-tetramethylcyclopentadienyl) were synthesized in a two-step salt-metathesis reaction. Treatment of LnCl3(THF)x with LiCpNMe2, followed by an in situ reaction with the Grignard reagent C3H5MgCl, generated the bis(allyl) half-sandwich complexes CpNMe2Ln(η3-C3H5)2 only for the smaller rare-earth metals (Ln = Y, Ho, Lu) in good yields (82–88%). In case of the larger neodymium, the dimeric mono(allyl) chlorido half-sandwich complex [CpNMe2Nd(η3-C3H5)(μ-Cl)]2 was obtained in 68% yield. All complexes show moderate to high activity in isoprene polymerization upon cationization with organoborates [Ph3C][B(C6F5)4] and [PhNMe2H][B(C6F5)4], the yttrium, holmium, and neodymium metal centers yielding mainly 3,4-microstructures (maximum 79%). Addition of 10 equiv of AlMe3 to the catalyst systems CpNMe2Ln(η3-C3H5)2 (Ln = Y, Ho)/[PhNMe2H][B(C6F5)4] and [CpNMe2Nd(η3-C3H5)(μ...

Electrochemistry and the mechanisms of nucleation and growth of neodymium during electroreduction from LiCl–KCl eutectic salts on Mo substrate

The electrochemical behavior of NdCl3 was studied on a Mo electrode in molten LiCl–KCl eutectic salts. The electroreduction of Nd(III)/Nd(0) involved two reaction steps, as confirmed by three different electrochemical techniques. In the first reaction step, Nd(III) is converted into soluble Nd(II), which undergoes further reduction into metallic Nd(0) in the second reaction step. The standard reaction rate constants for each reaction step were determined by Nicholson method. The rate constant values were used in Matsuda-Ayabe’s criteria for testing the electrochemical reversibility. Accordingly, both reaction steps were quasi-reversible redox reactions.The nucleation mechanisms of neodymium metal deposited on a Mo substrate were predicted by using Scharifker–Hill model, and tested for the first time by scanning electron microscopy (SEM) studies of the electrode surface. The SEM studies confirmed that for the low initial concentration of NdCl3, neodymium nucleates and grows progressively, while for higher NdCl3 concentrations, the related mechanism is instantaneous. Both are governed by the aggregative growth mechanisms based on surface mobility of formed nanoclusters.

산화네오디뮴(Nd2O3) 기도투여에 따른 흡입독성

산화네오디뮴(Nd2O3) 기도투여에 따른 흡입독성