Extraction Of Nd Research Articles

Extraction of ND scattering lengths from the Λb → π−pD0 decay and properties of the Σc(2800)+

The isovector and isoscalar ND s-wave scattering lengths are extracted by fitting to the LHCb data of the pD0 invariant-mass distribution in the decay Λb→π−pD0, making use of the cusp effect at the nD+ threshold. The analysis is based on a coupled-channel nonrelativistic effective field theory. We find that the real part of the isovector ND scattering length is unnaturally large due to the existence of a near-threshold state with a mass around 2.8 GeV. The state is consistent with the Σc(2800)+ resonance observed at Belle. Our results suggest that it couples strongly to the ND channel in an s-wave, and that its quantum numbers are JP=1/2−. The strong cusp behavior at the nD+ threshold can be verified using updated LHCb data.

FTIR spectroscopic investigations on the aggregation behaviour of N,N,N′,N′-tetraoctyldiglycolamide and N,N-dioctylhydroxyacetamide in n-dodecane during the extraction of Nd(III) from nitric acid medium

Fourier Transform Infra Red (FTIR) spectroscopy is an excellent tool for probing the co-ordination chemistry of the solvent extracted metal complexes in organic phase. The organic phase containing tetraoctyldiglycolamide (TODGA) and N,N-dioctylhydroxyacetamide (DOHyA) ligands dissolved n-dodecane was employed for the extraction of Nd(III) from nitric acid medium. The extracted organic phase was probed by FTIR spectroscopy to understand the coordination chemistry and aggregation behaviour of Nd(III)-ligand complex in the binary solution. The results were compared with those obtained in the individual solvent system. The extraction of Nd(III) and nitric acid in organic phase was accompanied by shifting and broadening of amidic carbonyl stretching bands of TODGA and DOHyA, and the degree of shift or broadening was dependent on the amount of Nd(III) or nitric acid loaded in organic phase. Near complete shift of amidic carbonyl transmittance bands from 1660 cm−1 to 1610 cm−1 was observed prior to the undesirable event known as organic phase splitting. The results showed the possibility of employing the FTIR spectroscopic technique for understanding the extraction and for the prevention of organic phase splitting during the course of solvent extraction.

Hydrometallurgical Process for Selective Extraction of Nd and Rare-Earth Metals from End-of-Life Hard Disk Drives NdFeB Magnet Scrap

This paper proposed a recycling process for neodymium-iron-boron (NdFeB) magnet scrap from the end-of-life (EOL) of hard disk drives by using hydrometallurgical process. Initial chemical composition of NdFeB magnet scrap was consisted of 25.37%Nd, 6.53%Pr, 0.90%Co, 3.63%B and 63.57%Fe. After de-magnetization and crushing into proper size, magnet scraps were directly leached by H2SO4 solution. More than 90% dissolved into acid solution with remaining small amount of residuals and Ni-coated metal. Neodymium precipitated from leached solution by pH-control to the optimum condition at pH 0.6 using NaOH solution. Solid Nd-precipitates XRD pattern was observed in form of NaNd (SO4)2.(H2O) and FeSO4.(H2O). Elemental analysis of Nd-precipitates by WD-XRF. The precipitates contained 26.50%Nd, 8.46%Pr and 1.19%Fe. In order to elimination of Fe, Nd-precipitates was leached by using H2SO4 solution to dissolve FeSO4.(H2O) into acid solution to obtain high concentration of Nd and rare-earth metals (REMs) compound. As a result, XRD pattern of Nd-compound after Fe-removal confirmed that the high purity NaNd (SO4)2.(H2O) compound was obtained. The final composition of precipitates analyzed by WD-XRF was 26.36%Nd, 8.13%Pr with Fe as low as 0.14%Fe.

Extraction of Lanthanides(III) along with Thorium(IV) from Chloride Solutions by N,N-di(2-Ethylhexyl)-Diglycolamic Acid

ABSTRACT The extraction of Nd(III), Gd(III), and Er(III), which represent light, middle, and heavy lanthanides, respectively, from chloride solutions has been carried out by using N,N-di(2-ethylhexyl)-diglycolamic acid (HDEHDGA, HA) diluted in kerosene as the organic phase. The results from the slope analysis method indicate that the extraction of Ln(III) with HDEHDGA is mainly governed by the cation-exchange reaction mechanisms in the low pH region (pH 1.2–2.7). The obtained data reveal that the extracted species in the organic phase might be LnA3∙HA(1~2), which consist of a core of 1:3 LnA3 complex and one additional neutral HA molecule for light Ln(III) or two for heavy Ln(III) associated with the core in the outer coordination sphere. The dependency on the temperatures indicates that the extraction of Ln(III) with HDEHDGA is exothermic and is mainly driven by the exothermic enthalpies crossing the whole Ln(III) series. The extraction of the whole Ln(III) series (except for Pm(III)) and Th(IV) has also been evaluated. HDEHDGA provides remarkable extraction capability with considerable separation factors (SF) for adjacent light Ln(III) pairs (SFCe/La = 6.8, SFPr/Ce = 3.3, SFNd/Pr = 2.5, and SFSm/Nd = 3.5), but relatively poor selectivity for the adjacent heavy Ln(III) pairs. It also presents very good selectivity/extractability for Th(IV) over the light Ln(III) ions (SFTh/La = 1362 and SFTh/Ce = 200). These properties make HDEHDGA a promising extractant for separating Th(IV) from light Ln(III) ions and for separating light Ln(III) ions from each other, which coexist significantly in some Rare Earth (RE) minerals, especially monazite and bastnaesite.

Unraveling the role of phase modifiers in the extraction of Nd(III) from nitric acid medium in tetra-bis(2-ethylhexyl)diglycolamide in n-dodecane containing long chain aliphatic alcohols

Tetra-bis(2-ethylhexyl)diglycolamide (TEHDGA) alone in n-dodecane (n-DD) is unsuitable for the solvent extraction of trivalent actinides from high-level liquid waste due to the occurrence of third phase formation during the course of solvent extraction. Significant concentration of long chain aliphatic alcohols ranging from 5% to 15% (V/V) have been added to the solvent phase, TEHDGA/n-DD, to control the undesirable third phase formation. The alcohols investigated were n-octanol, n-decanol, and isodecanol. To understand the role of alcohols in controlling the third phase formation, the extraction behaviour of the trivalent metal ion, Nd(III), from nitric acid medium was studied in a solution of 0.2 M TEHDGA + 1 M alcohol in n-DD. The equilibrium concentration of Nd(III) and nitric acid present in organic and aqueous phases were determined. The organic phase obtained after extraction was subjected to dynamic light scattering studies to unravel the role of alcohol phase modifiers in organic phase. The aggregate size and their distribution in organic phase was determined as a function of various parameters such as concentrations of nitric acid, Nd(NO3)3 and the nature of alcohol. The results revealed that the presence of long chain alkyl aliphatic alcohols interact with the polar acid-solvates and metal-solvates by solvation and prevents these solvates undergoing aggregation in organic phase. In view of this, the aggregate size was controlled much below the limiting aggregate size required for third phase formation by these alcohol phase modifiers. Even though all the alcohols investigated in the present study could bring down the aggregate size much below the limiting value, n-decanol was found to be superior to other alcohols.

Studies on the radiolytic degradation of N,N-dioctyl-2-hydroxyacetamide using dynamic light scattering and ATR-FTIR spectroscopy

Abstract The bulk extraction of Nd(III) from 4 M nitric acid medium was studied in a solution of N,N-di-octyl-2-hydroxyacetamide (DOHyA) in n-dodecane as a function of γ absorbed dose up to 750 kGy. The average size of reverse micellar aggregates in the irradiated and un-irradiated DOHyA samples after the extraction of Nd(III) was measured by dynamic light scattering (DLS) spectroscopy. The effect of absorbed dose of γ radiation and concentration of Nd(III) in the organic phase on the aggregation behavior of DOHyA was investigated by DLS measurements and ATR-FTIR spectroscopy. The data on irradiated and un-irradiated samples were compared. FT-IR analysis of the irradiated samples of DOHyA showed the formation of degradation products which were mainly identified as hydroxyacetic acid and primary or secondary amines.

Extraction of neodymium from other fission products by co‐reduction of Sn and Nd

High temperature processing is an important method for recovering long‐lived elements from spent nuclear fuel. Electrolysis is the key technology for high temperature processing. The electrochemical behaviors of Sn2+, Nd3+ and the mechanisms of Sn‐Nd alloy formation were investigated on a Mo electrode at 873 K by conducting a series of electrochemical techniques. The results showed the deposition of Nd on inert electrode is a two‐step process in LiCl‐KCl‐SnCl2 (2.0 wt.%) melt system. Subsequently, the electrochemical extraction of Nd from molten chlorides were carried out on the Mo electrode at temperature of 873 K by the potentiostatic electrolysis at −1.2 V for 40 hr. Besides, the extraction efficiency is 97.6%. A series of potentiostatic electrolysis were carried out at potential range between −1.0 and − 1.4 V. The NdSn3 alloy was obtained by electrolysis at −1.2 V. This deposition potential is consistent with the predicted results of the mathematical model. The micro‐chemical analysis and morphology analysis of the deposits was characterized by energy dispersive spectrometry (EDS) with scanning electron microscopy (SEM) equipped. The composition of the deposits was analyzed by X‐ray diffraction (XRD) and inductive coupled plasma atomic emission spectrometer (ICP‐AES).

Extraction kinetics of neodymium from chloride medium using HEH/EHP saponified with magnesium bicarbonate solution

Magnesium bicarbonate solution is considered as an environmentally friendly extractant saponification agent for the solvent extraction of rare earth elements due to its advantage of minimum water pollution. In order to reveal the extraction regularity, optimize production-process and guide the use of this new extraction system, the extraction of Nd(Ⅲ) in chloride medium with HEH/EHP saponified by magnesium bicarbonate solution was investigated with the self-designed constant interfacial area cell. Besides, the effects of stirring rate, temperature, specific interfacial area and concentration of Mg-HEH/EHP on the extraction rate of Nd(Ⅲ) were systematically investigated. Results show that, the rate of extraction is governed by both diffusion and chemical reaction, and the extraction reaction takes place at the interface. The apparent activation energy of the extraction reaction is 16.88 kJ/mol. The corresponding rate equation is deduced. The mechanisms and rate-determining step are speculated based on interfacial reaction models, which is consistent with the experimental results.

Aggregation Behavior of Alkyldiglycolamides in n-Dodecane Medium during the Extraction of Nd(III) and Nitric Acid

Diglycolamides (DGAs) are promising reagents for the separation of trivalent actinides and lanthanides from the nitric acid medium. The alkyl group attached to DGAs plays an important role in deciding the extraction and third phase formation behavior of trivalents in DGAs. To understand the role of alkyl group (varied from hexyl to dodecyl) attached to DGA, the extraction behavior of Nd(III) from the nitric acid medium was studied in 0.2 M alkyl DGA in n-dodecane (n-DD). The organic phase obtained after extraction was subjected to dynamic light scattering (DLS) studies to explore the behavior of reverse micelles (or aggregates) formed in the organic phase. The data were compared with the self-aggregation behavior of DGAs in n-DD. The results revealed that the aggregate size and their distribution in n-DD increased with increase in the extraction of nitric acid and Nd(III) in organic phase for all DGAs. However, at certain conditions of loading of HNO3 and Nd(III) the organic phase underwent splitting into...

Solvent Selection for Extraction of Neodymium Concentrates of Monazite Sand Processed Product

The extraction of neodymium concentrates of monazite sand processed product has been done. The objective of this investigation was to determine the best solvent to separate Nd from Nd concentrate. As an aqueous phase was Nd(OH)3 concentrated in HNO3 and as solvent or the organic phase was trioctylamine (TOA). tryibuthyl phosphate (TBP). trioctylphosphine oxyde (TOPO) and di-ethyl hexyl phosphoric acid (D2EHPA) in kerosene. The investigated variables were HNO3 concentration. feed concentration. solvent concentration or solvent in kerosene. time and stirring speeds. From the investigation on the selection of solvent for the extraction of Nd(OH)3 concentrate with various solvents. it was concluded that the extraction of Nd could be carried out by using TBP or TOA. Extraction of Nd using TOA at the optimum HNO3 concentration of 2M. feed concentration of 5 gram/10 mL. TOA in kerosene concentration of 6 %. stirring time of 15 minutes. stirring speed of 200 rpm was chosen if the Y concentration in Nd concentrate is small. In these condition DNd obtained was 0.65; extraction efficiency of Nd (ENd)=37.10%. the concentrations of Nd2(C2O4)3 = 67.14%. Ce2(C2O4)3 = 1.79%. La2(C2O4)3 = 1.37% and Y2(C2O4)3 = 24.70%. Extraction of Nd using TBP at the optimum HNO3 concentration of 1M. feed concentration of 5 gram/10 m. the TBP concentration in kerosene of 15%. stirring time of 15 minutes and stirring speed of 200 rpm was chosen if the Ce concentration in Nd concentrate is small. In these condition DNd obtained was 0.20. extraction efficiency of Nd (ENd)=17%. concentration of Nd2(C2O4)3 = 70.84%. Ce2(C2O4)3=15.53%. La2(C2O4)3 = 0.00% and Y2(C2O4)3 = 8.63%.

Dynamic Light Scattering and FTIR Spectroscopic Investigations on the Reverse Micelles Produced During the Extraction of Nd(III) and Nitric Acid in Tetra Ethylhexyl Diglycolamide

AbstractThe aggregation behaviour of reverse micelles, formed during the extraction of neodymium nitrate and nitric acid, in an organic phase composed of tetra‐bis(2‐ethylhexyl) diglycolamide (TEHDGA) in n‐dodecane (n‐DD) was studied, at various temperatures. The organic phase, 0.2 M TEHDGA/n‐DD was equilibrated with aqueous solutions of nitric acid in the presence and absence of neodymium nitrate. At certain nitric acid and Nd(III) concentration in aqueous phase, the organic phase underwent splitting into two phases, with top phase known as “diluent rich phase”, the other one known as “third phase” or “metal ion rich phase”. Dynamic light scattering, attenuated total reflectance (ATR) ‐Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopic methods were employed for probing the size and distribution of aggregates present in the organic phase before and after splitting. The investigations revealed that the aggregates, formed in organic phase, interact efficiently with the extracted metal ions and these interactions increased with increase in the concentration of nitric acid and neodymium nitrate in organic phase. In addition, the interaction among the reverse micelles in third phase appear to be very strong as compared to that observed in the organic phase before third phase formation, and such strong interactions resulted in a merger and narrow distribution of reverse micelles in third phase.

Experimental and modelling studies of neodymium solvent extraction from chloride media with methyl-tri(octyl/decyl)ammonium oleate ionic liquid diluted in kerosene

A study of the solvent extraction process of Nd(III) from chloride solutions has been carried out using an ionic liquid (AliOle) prepared from Aliquat 336 (Methyl-tri(octyl/decyl)ammonium chloride) and Oleic Acid. The IL was chosen among other homemade ionic liquids and commercial extractants due to its high Nd(III) extraction ability and good phase separation. Increasing AliOle concentration improves the extraction of Nd(III) as expected. The pH of the aqueous phase strongly influences the extraction process. The appropriate equilibrium pH region has been established in the range 5–6.5. The effect of chloride concentration in the aqueous phase has been investigated. High concentrations of Cl− anion contribute to increasing the extraction yield by promoting neodymium(III) speciation in the aqueous phase.Two extraction models are proposed from experimental data. Chloride concentration in the aqueous phase determines the Nd(III) extraction mechanism. The models consider extraction of Nd3+ species when chloride concentration in the solution is low and NdCl2+ species when chloride concentration is high. Competitive extraction between HCl and the metal ions is also included in the models. They are able to reproduce feasibly the experimental Nd(III) extraction extension.

Recovery of neodymium and dysprosium from NdFeB magnet swarf

The rare earth elements neodymium and dysprosium were separated and recovered from NdFeB permanent magnet swarf by hydrometallurgical route. The magnet swarf was leached with HCl after crushing and grinding, and from the leach liquor, Nd and Dy were separated by solvent extraction using NaCyanex 302. The separation factor (β) of Dy/Nd with NaCyanex 302 was high at low equilibrium pH. So Dy was first separated from the leach liquor at pH0.5 (equilibrium pH1.2). After separation of Dy, the separation of Nd was also carried out with the same extractant. The effect of equilibrium pH and extractant concentration on the extraction of Nd and Dy with NaCyanex 302 was studied. The McCabe-Thiele plots for extraction of both Dy and Nd with NaCyanex 302 were constructed and the number of stages for quantitative extraction was determined. The stripping of loaded organic was carried out with three different mineral acids and it was observed that the stripping efficiency followed the order HCl<HNO3<H2SO4. The McCabe-Thiele plots for stripping of loaded organic were also constructed. The reaction mechanism of both Nd and Dy was determined from the slope analysis method and the extracted species was found to be MA3.5HA.

Electrochemical Extraction of Nd from NaCl-KCl Melt by Formation of Cu-Nd Alloys

Electrochemical behavior of Nd was studied in NaCl-KCl melt on W and Cu electrodes via cyclic voltammetry and chronopotentiometry. Generally, the reduction of Nd3+ takes place in two consecutive steps in molten chlorides, such as LiCl-CaCl2, LiCl-BaCl2, CaCl2-NaCl, LiCl-KCl melts. However, the reduction of Nd3+ ions was found to be through a one-step process: Nd3+ + 3e− → Nd. The co-reduction behavior of Nd3+ and Cu2+ ions and the mechanisms of alloy formation were investigated in NaCl-KCl melt on W electrodes at 988 K (715 °C). Four potential plateaus corresponding to four different kinds of Cu-Nd intermetallic compounds were detected. Cu-Nd alloys were prepared on Cu electrodes at 988 K (715 °C) and 1143 K (870 °C). At 988 K (715 °C), Cu5Nd phase was identified by X-ray diffraction. The morphology and micro-zone chemical analysis of the alloys were characterized by scanning electron microscopy equipped with energy-dispersive spectrometry. The alloy film was observed on the Cu electrodes. Moreover, at 1143 K (870 °C), a globate bulk Cu-Nd alloy with Cu5Nd, Cu4Nd, Cu2Nd, CuNd, and Cu phases, as liquid in the melt, was obtained at the bottom of the crucible.

Micelle Mediated Extraction of Neodymium and Electrochemical Characterization of AOT Reverse Micelles

The surfactant bis(2-ethylhexyl) sulfosuccinate (AOT) effects on neodymium (Nd) extraction from aqueous phase in electric field-imposed extraction processes were studied. With the application of an external electric field (0 – 1.4 kV m-1) and gentle stirring, a slight to moderate increase in the extraction of Nd was observed relative to the Nd extracted without applied field for AOT, HDEHP and AOT+HDEHP. Electrochemical impedance spectroscopy technique showed that as the reverse micelles molar water content (Wo), increased, conductivity increase. Addition of HDEHP caused a significant drop in solution conductivity. Temperature had a mild effect on increasing the conductivity.

Synergistic extraction of Nd(III) with mixture of 8-hydroxyquinoline and its derivative with di-2-ethyl hexyl phosphoric acid in different diluents

Solvent extraction of neodymium (III) from chloride medium with synergistic mixture of 8-hydroxyquinoline or 2-methyl-8-hydroxyquinoline and di-2-ethyl hexyl phosphoric acid was investigated in different diluents. Effect of various experimental parameters such as pH, extractant concentration, diluents and temperature was studied. Role of diluents on extraction of neodymium is explained in terms of activity coefficient adopting Hildebrand regular solution theory. The negative value of enthalpy change suggests that the extraction of ternary system is exothermic. The IR data for the extracted species also substantiated the nature of extracted species as observed by slope analysis method.

Extraction of rare earth elements from nitrate solution using novel unsymmetrical diglycolamide

ABSTRACTA novel unsymmetrical diglycolamide (DGA), namely N,N-dihexyl-N’,N’-didecyldiglycolamide (DHD2DGA), was synthesized for the extraction of Nd(III), Sm(III), Gd(III), Dy(III), Ho(III) and Er(III) in nitric acid solutions. The effects of HNO3, HCl or H2SO4 on the distribution ratio of the investigated metal ions were investigated. A systematic investigation was carried out using DHD2DGA in n-dodecane from nitric acid solutions. The main extracted species of Nd(III), Sm(III), Gd(III), Dy(III), Ho(III) and Er(III) were studied at different nitric acid concentrations by the slope analysis method and the enthalpy change of the extraction reactions was determined. The IR spectra of the extracted species were also investigated. The values of thermodynamic functions for the extraction of the lanthanides were calculated. The obtained results indicated that the effective separation of Ln(III) from Fe(III), Ni(II), Co(II) and Cs(I) can be obtained.

Efficient extraction of Nd(III) by calix[4]arene derivatives containing diethyl phosphite

Calix[4]arene derivatives including diethyl phosphite groups were used for the first time for separating Nd(III) from nitrate media. Calix[4]arene derivatives were synthesized and characterized by infrared spectroscopy (IR), mass spectroscopy (MS), and 1H NMR. Four calix[4]arene derivatives, CalixF (①), DCalixF (②), PCalixF (⑤), and POCalixF (⑥), were used in a solvent extraction method. The effects of aqueous acidity, diluent, temperature, shaking time, and Nd(III) concentration were investigated. The results showed that the extraction ability of ⑤ and ⑥ with a phosphate functional group at the upper rim were best for the extraction of Nd(III). Derivative ⑥ had better complexing capacities than ⑤ for the generation of a phenolic hydroxyl group at the lower rim. The enthalpy (∆HO), Gibbs free energy (∆GO), and entropy (∆SO) changes for the extraction were obtained from a thermodynamic study. The results showed that the extraction of Nd(III) from a nitric acid system might be an endothermic reaction since the process was naturally spontaneous and increasing the temperature during extraction was determined to be thermodynamically feasible. The extraction of Nd(III) was governed by a two-stage chemical reaction and diffusion process. In the first stage, the process was controlled by a fast chemical reaction at the liquid-liquid interface. The composition of the Nd(III)-calix[4]arene derivative complex was determined to be [Nd(NO3)3]2 [L]. The second stage was the diffusion of extracted products towards equilibrium. Calix[4]arene derivative ⑥ was found to be an efficient extractant for the separation of Nd(III) and would be a potential extractant for the disposal of radioactive waste in spent fuel.

Recovery of Nd and Pr from NdFeB magnet leachates with bi-functional ionic liquids based on Aliquat 336 and Cyanex 272

The separation of neodymium and praseodymium was carried out from a chloride solution containing the similar composition of NdFeB magnet leach liquor. A comparative study between extractants demonstrated that the extraction efficiency of bi-functional ionic liquids (Bif-ILs) tri octylmethylammonium bis(2,4,4-trimethylpentyl)phosphate (R4NCy) and trioctylmethylammonium di(2-ethylhexyl)phosphate (R4ND) was higher than the conventional extractants such as tri-octyl methyl ammonium chloride (Aliquat 336), bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) and di-2-ethylhexyl phosphoric acid (D2EHPA) under same experimental condition. The extraction efficiency of different extractants for Nd and Pr was in the order: R4NCy>R4ND>Cyanex 272>D2EHPA>Aliquat-336. As the extraction of Nd and Pr was maximum with R4NCy Bif-ILs, the McCabe-Thiele diagram was constructed with R4NCy which showed 2 stages at 1:1 phase ratio. A 2-stage counter current simulation study showed 98.97% Nd and 99.02% Pr extraction. The loaded organic phase was stripped with H2SO4 acid and the stripping efficiencies for Nd and Pr were 98.11% and 98.75%, respectively. The extracted species was found to beMCl3⋅3R4NCy. The thermodynamic parameters were also determined for extraction of Nd and Pr with ionic liquid.

Tributyl phosphate-[C&lt;sub&gt;n&lt;/sub&gt;min][Tf&lt;sub&gt;2&lt;/sub&gt;N]を用いた塩酸溶液からの希土類元素の抽出および逆抽出

Mutual separation of rare earth ions is very difficult because of their similar chemical properties. In this study, extraction of Nd (III), Dy (III), and Pr (III) from hydrochloric acid solution and their back extraction have been investigated using the mixture of tributyl phosphate, TBP, and 1-alkyl-3-methylimidazoliumbis[ (trifluoromethyl) sulfonyl]imide, [Cnmim][Tf2N] (n, the alkyl chain length, was 2, 4, and 6), in order to clarify the possibility of mutual separation and recovery of these elements. Synergistic effect between TBP and [Cnmim][Tf2N] was found because the extraction was highly enhanced using their mixture, while the extraction by the individual reagent was very low. Although the extraction was increased with a decrease in the n value, mutual separation was difficult because the extraction behavior was similar to one another. Ammonium formate was found to be effective as a back extraction reagent because Pr (III) and Nd (III) were precipitated out as formates while Dy (III) was quantitatively back extracted without precipitation. Precipitation formation was faster in Pr (III) than Nd (III). Based on these results, a possibility of the mutual separation among these three ions was shown.