The solubility of neodymium in the systems NdCl3LiCl and NdCl3LiClKCl

Kvam, K.R.; Bratland, D.; Øye, H. A.

doi:10.1016/s0167-7322(99)00078-1

Cited by 5 publications

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“…These studies include the examination of the solubility of Nd 3+ in molten LiCl-KCl eutectic mixtures. [19][20][21] Furthermore, Sridharan et al constructed a phase diagram of the NdCl 3 -LiCl-KCl melt. 22 Of particular relevance to electrowinning and electrorefining, it has been demonstrated (using cyclic voltammetry and potentiometric measurements) that Nd electrodeposition from NdCl 3 -LiCl-KCl melts proceeds via a two-stage reduction process: 18,19,[22][23][24][25][26] Nd 3+ + e − → Nd 2+…”

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confidence: 99%

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

Shen

Akolkar

2017

J. Electrochem. Soc.

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Electrodeposition of neodymium (Nd) metal from NdCl 3 -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 Nd 3+ to Nd 2+ , followed by quasi-reversible reduction of Nd 2+ to Nd metal. In the electrode potential range where Nd 3+ is reduced to Nd 2+ , 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 Nd 2+ 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 (Nd 2+ and Nd 3+ ) 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. Rare earth elements enable important functions in numerous applications. They are used in permanent magnets in electric motors and electronic memory storage, in catalysts for automobile catalytic converters and for petroleum refining, and in phosphors for energyefficient lighting and color displays. 1 Due to their rare occurrence in nature and the complexity associated with extracting and refining them, rare earth metals are very expensive and face potential supply risks. For future sustainable use of rare earth metals, the recovery and recycling of these materials from product waste is of great practical importance. 2 For energy-efficient recovery of rare earth elements, one promising technique is the electrolytic refining of these metals from waste streams such as electronic waste. 3 Electrochemical processing, i.e., electrowinning or electrorefining, using high temperature molten salt electrolytes is particularly attractive, because molten salts offer high ionic conductivity, 4 good electrochemical stability, 5,6 and low interfacial charge transfer resistance. 7,8 These are desirable attributes for industrial scale process implementation. Furthermore, high-temperature molten salt electrochemical systems offer industrially relevant rates of processing (high current densities) and ease of scalability to large-volume manufacturing at low cost. 9,10 Consequently, the characterization of the electrochemical behavior of rare earth metals in molten salts is important, bec...

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confidence: 99%

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

Shen

Akolkar

2017

J. Electrochem. Soc.

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“…The solubility of neodymium metal has been determined to be very low in this type of melts (7). Therefore, we may conclude that the wave B can only be attributed to the reduction of Nd ions.…”

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confidence: 70%

Extraction of Rare Earth Metals from Nd-based Scrap by Electrolysis from Molten Salts

et al. 2013

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The possibilities of recovery of rare earth metals and alloys from Nd-based scrap by electrolysis from high temperature molten salts were investigated. The realization of such a process will eliminate the oxide or halide conversion steps, leading to a more effective and environmental process, as many hydrometallurgical steps are avoided. The NdFeB compound (which could be scrap from the magnet production or demagnetized spent magnet) is placed in the anode compartment from where the rare earth elements present in the material (Nd, Dy, Pr) will be anodically dissolved in the form of ions, which will be discharged at the cathode as metals and/or magnetic alloys. Different electrolyte compositions and temperatures are tested and the feasibility, kinetics, and efficiency of the process are evaluated.

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“…However, this surprising observation is in accordance with solubility measurements of neodymium in NdCl 3 -LiCl-KCl solutions by Kvam, Bratland and Øye. 27 They found that the equilibrium Nd þ 2NdCl 3 ¼ 3NdCl 2 shifts to the right with decreasing KCl content. At the composition of the eutectic LiCl-KCl a solution (NdCl 2 ) 0.05 (eut.-LiCl-KCl) 0.95 has to be more suitably written in the form: (Nd) 0.007 (NdCl 2 ) 0.030 (NdCl 3 ) 0.013 (eut.-LiCl-KCl) 0.95 , i.e.…”

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confidence: 98%

Raman spectroscopic study of mixed valence neodymium and cerium chloride solutions in eutectic LiCl–KCl melts

Rodriguez-Betancourtt

Nattland

2005

Phys. Chem. Chem. Phys.

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We have studied the Raman spectra of (NdCl 2 )-(NdCl 3 ) and Ce-(CeCl 3 ) mixtures in eutectic (LiCl) 0.58 (KCl) 0.42 as solvent in the temperature range up to 600 1C. For the highly corrosive samples a windowless cell in connection with a Raman microscope was utilised. To our knowledge the Raman spectra of the solutions of NdCl 2 , CeCl 3 and (most likely) CeCl 2 in eut.-LiCl-KCl are shown here for the first time. In accordance with other rare earth halides described in the literature the Raman spectra of the pure trivalent systems are dominated by octahedral LnCl 6 3À species which show a typical broad polarized band centred at 245 cm À1 for NdCl 3 and 240 cm À1 for CeCl 3 , respectively. NdCl 2 in (LiCl-KCl) eu shows a complex Raman spectrum consisting of depolarized bands. In mixtures of divalent and trivalent neodymium chlorides both spectra can be observed in parallel and no additional Raman bands appear. Solutions of cerium in CeCl 3 -(eut.-LiCl-KCl) show temporarily new Raman bands which are presumably due to divalent cerium chloride. These bands disappear in our samples after about 1 h since CeCl 2 is not stable under the experimental conditions. Our findings are discussed in the light of the strongly different electronic transport properties in the neodymium and cerium systems.

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The solubility of neodymium in the systems NdCl3LiCl and NdCl3LiClKCl

Cited by 5 publications

References 1 publication

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

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

Extraction of Rare Earth Metals from Nd-based Scrap by Electrolysis from Molten Salts

Raman spectroscopic study of mixed valence neodymium and cerium chloride solutions in eutectic LiCl–KCl melts

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The solubility of neodymium in the systems NdCl3LiCl and NdCl3LiClKCl

Cited by 5 publications

References 1 publication

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

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

Extraction of Rare Earth Metals from Nd-based Scrap by Electrolysis from Molten Salts

Raman spectroscopic study of mixed valence neodymium and cerium chloride solutions in eutectic LiCl–KCl melts

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

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