Separation of Scandium and Rare Earths with the Method of PSO-Extraction Chromatography

Separation of scandium and rare earths was investigated by using a new extraction chromatography which PSO was used as a stationary phase,while HCl-NH_4SCN solution as a mobile phase.The separation conditions were studied.In this system, the separation factor(β_(Nd)^(Sc))can reach up to 1.3×10~4.The method can be applied to the purposes of separation,purification and analysis of microquantity of Sc in the mixed rare earth.

Study on the Separation of Rare Earths with the Method of H(DEHP)-Extraction Chromatography

Separation of rare earths was investigated by extraction chromatography where H(DEHP)was used as a stationary phase,while HCl and H_2SO_4 solutions as a mobile phase.The average separation fac- tors of rare earths,β_(HCl) and β_(H_2SO_4),are 3.79 and 4.57.respectively.The β_(La)^(Ce) in HCl and H_2SO_4 systems are as high as 28.5 and 26.3,respectively.The elution acidity in the study can be down to one tenth and one four- teenth of that in HEH(EHP)system.

Progress in the extraction and separation of rare earths and related metals with novel extractants: A review

Rare earths(REs) play a key role in high-tech fields and the associated thorium is a vital element for nuclear energy. However, to be used in high-tech industry or nuclear energy, these elements must first be recovered from the deposits and purified. As solvent extraction is the main technology for the recovery and purification of the metals, the review mainly presents our recent works on the extraction and separation of tetravalent cerium cation by neutral α-aminophosphonates, the individual rare earth separation by α-aminophosphonic acids, and the continuous preparation of high-purity thorium. The extraction and separation of some other metals are also discussed.

Separation of middle rare earths by solvent extraction using 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant

The extraction of the trivalent middle rare earths from chloride media by kerosene solutions of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant was studied. The separation factors between the elements using solution simulating wastes from NiMH spent batteries have been evaluated: the order of the extractive ability of extractant can be confirmed in Tb>Gd>Eu>Sm.

STUDY ON THE SEPARATION AND EXTRACTION MECHANISM OF RARE EARTH ELEMENTS BY MEANS OF REVERSED-PHASE PAPER CHROMATOGRAPHY

Reversed-phase paper chromatography technique is used for study on the extraction mechanism and sep- aration of rare earth elements.As the stationary phase,chromatographic paper strips are impregnated with a solution of monomyristyl phosphoric acid (MPA) in chloroform.Mineral acids are used as developers. The effect of concentration of acids and/or salts upon R_f has been investigated.According to the re- sults of R_f values for a given rare earth element in various acids,the order of extraction ability is HCl>HNO_3>H_2SO_4.A tetrad effect is clearly observed.for the R_f value of rare earth elements.The effects of other parameters on the R_f value,such as the quantities of extractant retained by the paper and the temperature are also examined.Based on the determination of the molar ratio of MPA to rare earth elements and the number of H^+ ions released in extraction reaction,a reasonable mechanism is proposed.The mutual separation of heavy rare earth elements will be better than that of the light rare earth group because of the larger separation coefficient of the former.A mixture of Ho-Er-Tm-Lu is successfully separated by the present method.

Development course of separating rare earths with acid phosphorus extractants: A critical review

This paper reviews the development course of separating rare earths with acid phosphorus extractants,including extraction chemistry(thermodynamics and kinetics), separation process and industrial application, the loss/degradation of extractants, etc.

Separation of Red (Y_2O_3: Eu^(3+)), Blue (Sr,Ca,Ba)_(10)(PO_4)_6Cl_2: Eu^(2+) and Green (LaPO_4:Tb^(3+),Ce^(3+)) Rare Earth Phosphors by Liquid/Liquid Extraction

A novel process for separation of red （Y2O3： Eu^3＋）, blue （Sr, Ca, Ba）10（PO4）6Cl2： Eu^2＋ and green （LaPO4： Tb^3＋, Ce^3＋） fine tricolor phosphor powders was established. First, the green phosphor was extracted and separated from three phosphor mixtures in heptane/DMF（N, N-Dimethylformamide） system using stearylamine or laurylamine （DDA） as the cationic surfactant. Then, after being treated with 99.5% ethanol, the blue and red phosphors could be separated in Heptane/DMF system in presence of 1-octanesulfonic acid sodium salt as the anionic surfactant. Satisfactory separation results have been achieved through two steps extractions with their artificial mixtures. The grades and recovery of separated products reached respectively as follows： red product was 95.3% and 90.9%, blue product was 90.0% and 95.2%, and green product was 92.2% and 91.8%.

Separation of Red (Y_2O_3:Eu^(3+)), Blue (BaMgAl_(10)O_(17):Eu^(2+)) and Green (CeMgAl_(10)O_(17):Tb^3) Rare Earth Phosphors by Liquid/Liquid Extraction

A novel process for separation of red （Y2O3：Eu^3＋）, blue（BaMgAl10O17：Eu^2＋） and green （CeMgAl10O17：Tb^3） rare earth fluorescent powders was proposed. At first, the blue powder can be extracted selectively from an aqueous solution using a chelating collector 2-thenoyltrifluoroacetone （TTA） dissolved in heptane at alkaline pH condition, then, chloroform was used for extracting the green powder into organic phase. The red phosphor remains in aqueous phase with potassium sodium tartrate depressant （PST）. Therefore, three phosphors can be separated successfully from their artificial mixtures by liquid/liquid extraction, and grades and recovery of separated products reach respectively as follows： red is 96.9% and 95.2%, blue is 82.7% and 98.8%, green is 94.6% and 82.6%.

A review on yttrium solvent extraction chemistry and separation process

This paper reviewed various systems such as neutral phosphorus and acid phosphorus, carboxylic acid and amine extractant for solvent extraction chemistry of yttrium, including thermodynamics, kinetics and yttrium extracting separation process containing the development course and new separation process.

Progress in Solid-Liquid Extraction Resin for Separation of Rare Earth Elements

The latest development in solid-liquid extraction resin for the separation of REE was reviewed. The chemistry of inorganic supports based on diatomite, silica gel or alumina as well as organic supports based on cellulose, chitosan natural macromolecular support and poly(styrene-divinylbenzene), polyacrylate, aldehyde polymer, polyurethane, polyacrylonitrile synthetic macromolecular supports was covered, low molecular weight extractants such as acidic, organophosphorus, amine, macrocyclic compounds as well as macromolecular extractants were outlined. The different approaches involving ion exchange, ion-pair and chelating separation mechanisms were discussed. Physical adsorption, enclosing and chemical bonding mechanisms about extractants immobilized on solid supports were presented. The relation between resin shape and the property of packed columns was highlighted. Modern synthetic techniques such as molecular assembly, ionic imprinting, chemical modification for the preparation of resins were described. Basic fundamentals, advantages and synthetic methods of novel solid-liquid extraction resins as well as possibilities to improve resins performance were introduced.

A novel process of extraction and separation of RE and Mn from Panxi rare earth mud

A novel process to extract and separate rare earth (RE) and manganese (Mn) from Panxi rare earth mud was developed. The process involves roasting the mud at 480?℃ with NH 4Cl as chlorinating agent, and leaching the calcine with hot water to obtain a rare earth chloride solution. After the solution was further purified, HD(DIBM)P (P 507 ) was applied as extractant to separate RE and Mn. By seven stages of fractional extraction, the RECl 3 and MnCl 2 solutions with 99.8% purity were obtained. Finally, the purified RECl 3 and MnCl 2 solution were precipitated by NH 4HCO 3 to obtain a crystal RE 2(CO 3) 3 and MnCO 3 products respectively.

Breakthrough in the China's Separation Technology for Extraction of Rare Earth Elements

Separation technology of rare earth elements （REEs）, as the critical step in the separation process, had long been fraught with technical difficulty. A research project conducted by Baotou Shibo Rare Earth Extraction ＆ Equipment Co. Ltd., Baotou REE Research Institute, and Baotou Steel ＆ REE Group Hi-Tech Co. Ltd （Inner Mongolia）, has successfully solved the problem using a centrifugal extractor and advanced techniques to achieve a key breakthrough.

EXTRACTION OF AMERICIUM AND LIGHT RARE EARTHS BY 2－ETHYL HEXYL PHOSPHONIC ACID 2－ETHYL HEXYL ESTER

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Rare Earth Separation with 1-Hexyl-4-Ethyloctyl Isopropylphosphonic Acid Extractant

A new extractant 1 hexyl 4 ethyloctyl isopropylphosphonic acid (HHEOIPP or HA) in heptane was employed to extract rare earths from hydrochloric acid medium. The dependence of extraction distribution ratio on equilibrium aqueous pH and the concentration of extractant were investigated. On the basis of slope analysis, it was proposed that two different kinds of extracted species were formed. For rare earth elements (La～Ho) the extracted species was LnA 3(HA) 3 and for heavy rare earth elements (Er～Lu) the species was LnClA 2(HA) 3. The steric hindrance plays an important role in forming the species. The extraction constants and separation factors of the adjacent rare earths were calculated too. Compared with HDEHP and HEH/EHP, HHEOIPP is a valuable extractant with high separation selectivity. The “tetrad effect” between K ex and atomic number was observed.

Study on Scandium Separation from Rare Earth Ore in Yunnan Province

Chemical components, main mineral content and mineral composition of rare earth ore in Yunnan Province was measurated by the analysis of the spectrum and the chemical components. The study shows that main metals mineral in the rare earth ore are magnetite, tatanomagnetite, limonite; less metals mineral are ilmenite, hematite; some minim minerals were iron pyrites, zircon, scheelite, and so on. Main nonmetals mineral are quartz, feldspar(plagioclase, K-feldspar); less nonmetals mineral are hopfnerite, biotite, titanite; some minim minerals are kaolinite and dolomite. Ilmenite has the highest content of Sc as 175 g·t -1, next is titanite as 81.2 g·t -1. Based on this result, A new method of extracting Sc is put forward. The technological flowsheet of separating Sc of low-intensity magnetic separation,tabing, gravity concentrate, high-gradient magnetic separation, and electrostatic separation was prepared. Amplified experiment obtained Sc concentrate with Sc content of 148.54 g·t -1, the yield of 7.92%,recovery of 69.20%, at the same time, a Fe concentrate with the grade of 63.88% and the yield of 5.91% is obtained.

Progress of Separation and Determination Methods for Rare Earth Elements

This review covers the developments in rare earth elements analysis over the period from 2003 to 2005. Some novel separation and determination methods and their applications in rare earth elements analysis were presented and discussed in detail. Some new materials, such as ionic liquids, nanometer materials and ion-imprinted polymers, and some new technologies, such as cloud point extraction, membrane extraction and capillary electrophoresis were successful used in rare earth elements analysis. The determination methods of NAA, ICP-OES and ICP-MS were also discussed in detail.

Monoalkyl Esters of Isoalkylphosphonic Acid as Extractants in Rare Earth Separation

Four monoalkyl esters of isoalkylphosphonic acids have been studied for the chromatographic separation of rare earths (RE).The relationship between distribution ratios and acid concentration of the eluants for samarium and ytterbium has been explored.The characteristics of these extractants loaded onto macroreticular poly (methyl methacrylate) resin beads for the separation of lanthanum,cerium,praseodymium and neodymium have been compared.Among the extractants studied,mono(1-methylheptyl) ester of isooctylphosphonic acid was found to be the best for RE separation.The acidity for separation is lower than any known P-containing extractants for the same purpose.For instance,with 1.73 mol·L^(-1) nitric acid as eluent,thulium,ytterbium and lutetium can be separated quantitatively.The extractant-loaded resins possess high column efficiency with good kinetic characteristics.The extraction mechanism was also explored.

Evaluation study on properties of a macroporous silica-based CMPO extraction resin to be used forminor actinides separation from high level liquid waste

Basic properties of a silica-based octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) extraction resin (CMPO/SiO2-P) was investigated.Adsorption behavior for some rare earth elements (RE) which are constituents of high level liquid waste (HLLW) and the long-term stability of the extraction resin in nitric acid solution were examined.The CMPO extraction resin was significantly stable in 3 mol·L?1 HNO3 solution at 50oC.Furthermore,the RE(III) were efficiently separated from non-adsorptive fission product (FP) elements such as Sr(II) in a column experiment using a highly nitric acid solution.The separation behaviors of the elements are considered to result from the difference in their adsorption and elution selectivity based on the complex formation with CMPO.There was no strong dependency of RE(III) separation efficiency on feed solution flow rate.Only from the perspectives of the acid-resistant behavior of CMPO extraction resin and the elution kinetics for the metal ions with the extraction resin,the CMPO extraction resin can be used in the modified MAREC process for HLLW partitioning.

Efficient enrichment and selective recovery of rare earths from sulfate leachate of ion-adsorption type rare earth ore by extraction with HPOAc

The efficient enrichment and separation of rare earth elements(REEs) from sulfate leachates of ionadsorption type rare earth ore(IATREO) is still a challenge.This work presents a novel extractant 2-(bis((2-ethylhexyl)oxy)phosphoryl)-2-hydroxyacetic acid(HPOAc) for the selective extraction and efficie nt enrichment of REEs from sulfate leachates of IATREO.HPOAc exhibits higher extraction ability for all fifteen REEs(Ⅲ) than naphthenic acid(NA) at pH_(ini)=1,56.Furthermore,it has no drawbacks of di-(2-ethylhexyl) phosphoric acid(P204) and 2-ethylhexyl phosphoric acid mono-2-ethylhexylester(P507)such as weak extraction ability towards light REEs(Ⅲ) and high stripping acidity for heavy REEs(Ⅲ).It has better separation performance for metal ion impurities than P204 and P507,especially for the typical impurity Al(Ⅲ).Furthermore,the HPOAc system has better phase separation behavior and extraction pheno mena.A simulated operation with two-stage counte r-current extraction and single-stage stripping of REEs was carried out using unsaponified HPOAc.The recovery of REEs reaches 98.7%.The concentration of REEs increases from 0.44 to 130.35 g/L,indicating a nearly 300-fold increase.Furthermore,the content of REEs increases from 77.8 wt% to 97.6 wt%.So HPOAc has the potential to selectively recover REEs from sulfate leachates of IATREO.

Research and Application Progress in Countercurrent Solvent Extraction

In this article, the recent progress made by Peking University is briefly introduced. Based on Theory of Countercurrent Extraction established by Prof. Guangxian Xu, the static equilibrium and dynamic process for two- and three-outlet countercurrent extractions, and designed the optimized parameters for the real cascades to separate different rare earth minerals, which can be scaled-up to the industrial process without any further experimental verification were systematically investigated. In order to stabilize the quality of products and improve the capability of automation for extraction process, we have also established an (()^(241)Am) stimulated X-ray fluorescent energy dispersive method to detect the elemental composition in both organic and aqueous phases, which can be used as an on-line analysis method in practice. Furthermore, the expert system and the control software with open- and close-loop models have been set up. Combined with the detected data from on-line analysis, the flow-rates of extracting, feeding, scrubbing and stripping solutions can be (controlled) in an optimum status for the industrial cascades. In addition, we have developed a new multi-input and multi-output countercurrent extraction process for separating multi-component rare earth mixture with lower chemical cost and pollution.