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Sample records for acidic rare earths

  1. Separation of rare earths from solutions of phosphoric acid

    International Nuclear Information System (INIS)

    Jones, E.A.

    1977-01-01

    Rare earths are separated from 6M phosphoric acid by adsorption onto cation resin BIORAD AG50W-X8. The phosphoric acid is then washed from the column, and the rare earths are eluted with 4M hydrochloric acid

  2. Extraction studies on rare earths using dinonyl phenyl phosphoric acid

    International Nuclear Information System (INIS)

    Anitha, M.; Singh, D.K.; Kotekar, M.K.; Vijayalakshmi, R.; Singh, H.

    2011-01-01

    Rare earths are widely used in phosphor materials, magnetic substances, alloys, catalyst, lasers, superconductors, solid oxide fuel cells and in nuclear applications. The high value of these elements depends on their effective separation into high purity compounds. The separation into individual rare earths is very difficult to achieve, due to the very low separation factors between two adjacent rare earths arising due to similar chemical properties. Taking the advantage of variation in basicity, the separation is generally accomplished by solvent extraction or ion exchange. There are several references on the separation of rare earth in different media employing various types of extractants such as 2-ethylhexyl 2-ethyhexylphosphonic acid (EHEHPA) and di-2-ethyl hexyl phosphoric acid (D2EHPA) which have been widely used for the separation and purification of rare earths. Dinonyl phenyl phosphoric acid (DNPPA) is an organo phosphorus extractant (pKa = 2.54) and is an aromatic analogue of D2EHPA, which extracts metal ion by cation exchange mechanism. DNPPA was explored to recover rare earths from phosphate media such as wet process phosphoric acid and merchant grade acid. However, there is no information available in literature on DNPPA for RE extraction from chloride medium. Therefore, an attempt has been made in the present study to investigate the feasibility of using DNPPA for extraction of La(III), Dy(III) and Y(III) from chloride medium

  3. Preparation and Property of Acrylic Acid Rare Earth Complex and Its Hydrosilylation

    Institute of Scientific and Technical Information of China (English)

    Zhang Ming; Chen Haiyan; Chen Xiaosong; Dai Shaojun; Inoue Shinich; Okamoto Hiroshi

    2004-01-01

    Acrylic acid rare earth complex was prepared. Its chemical composition was determined by chemical and elemental analysis, and its structure as well as properties was characterized using IR, Fluorescence and UV spectrum, and its solubility was also investigated. Meanwhile a kind of elastic functional polymer with rare earth units in the side chains was produced. It is confirmed by IR spectrum that the Si-H bonds really react with acrylic acid rare earth.

  4. Rare earth sulfates

    International Nuclear Information System (INIS)

    Komissarova, L.N.; Shatskij, V.M.; Pokrovskij, A.N.; Chizhov, S.M.; Bal'kina, T.I.; Suponitskij, Yu.L.

    1986-01-01

    Results of experimental works on the study of synthesis conditions, structure and physico-chemical properties of rare earth, scandium and yttrium sulfates, have been generalized. Phase diagrams of solubility and fusibility, thermodynamic and crystallochemical characteristics, thermal stability of hydrates and anhydrous sulfates of rare earths, including normal, double (with cations of alkali and alkaline-earth metals), ternary and anion-mixed sulfates of rare earths, as well as their adducts, are considered. The state of ions of rare earths, scandium and yttrium in aqueous sulfuric acid solutions is discussed. Data on the use of rare earth sulfates are given

  5. Solvent Extraction of Rare Earths by Di-2 Ethylhexyl Phosphoric Acid

    International Nuclear Information System (INIS)

    Srinuttrakul, Wannee; Kranlert, Kannika; Kraikaew, Jarunee; Pongpansook, Surasak; Chayavadhanangkur, Chavalek; Kranlert, Kannika

    2004-10-01

    Solvent extraction has been widely applied for individual rare earth separation because the separation time is rapid and a large quantity of products is obtained. In this work, this technique was utilized to extract mixed rare earths, obtained from monazite digestion process. Di-2-ethylhexyl phosphoric acid (D2EHPA) was used as an extractant. The factors affected the extraction including HNO 3 concentration in mixed rare earth nitrate solution and the amount of D2EHPA were studied. The appropriate concentrations of HNO 3 and D2EHPA were found to be 0.01 and 1.5 M, respectively. From the result of equilibrium curve study, it was observed that heavy rare earths were extracted more efficient than light rare earths. A 6-stage continuous countercurrent solvent extraction was simulated for rare earth extraction. The optimum ratio of solvent to feed solution (S/F) was 2. Because of the high cost of D2EHPA, 1.0 M of D2EHPA was suitable for the rare earth extraction by the continuous countercurrent solvent extraction

  6. Rare Earth Extraction from NdFeB Magnet Using a Closed-Loop Acid Process.

    Science.gov (United States)

    Kitagawa, Jiro; Uemura, Ryohei

    2017-08-14

    There is considerable interest in extraction of rare earth elements from NdFeB magnets to enable recycling of these elements. In practical extraction methods using wet processes, the acid waste solution discharge is a problem that must be resolved to reduce the environmental impact of the process. Here, we present an encouraging demonstration of rare earth element extraction from a NdFeB magnet using a closed-loop hydrochloric acid (HCl)-based process. The extraction method is based on corrosion of the magnet in a pretreatment stage and a subsequent ionic liquid technique for Fe extraction from the HCl solution. The rare earth elements are then precipitated using oxalic acid. Triple extraction has been conducted and the recovery ratio of the rare earth elements from the solution is approximately 50% for each extraction process, as compared to almost 100% recovery when using a one-shot extraction process without the ionic liquid but with sufficient oxalic acid. Despite its reduced extraction efficiency, the proposed method with its small number of procedures at almost room temperature is still highly advantageous in terms of both cost and environmental friendliness. This study represents an initial step towards realization of a closed-loop acid process for recycling of rare earth elements.

  7. Rare earth octacyanomolybdates(4)

    International Nuclear Information System (INIS)

    Zubritskaya, D.I.; Sergeeva, A.N.; Pisak, Yu.V.

    1980-01-01

    Optimal conditions for synthesis of rare-earth octacyanomolybdates(4) of the Ln 4 [Mo(CN) 8 ] 3 xnH 2 O composition (where Ln is a rare-earth element, other than Pr, Pm, Lu, Tb) have been worked out. The synthesis has been accomplished by neutralization with octacianomolybdic acid with rare-earth carbonates. The composition and structure of the compounds synthesized have been studied by infrared-spectroscopy. It has been established that rare-earth octacyanomolybdates(4) form three isostructural groups

  8. Utilization of hydrochloric acid wastes of titanium-magnesium plants for reprocessing of rare earth mineral raw material

    International Nuclear Information System (INIS)

    Nikonov, V.N.; Troyanker, L.S.; Mikhlin, E.B.

    1979-01-01

    The possibility of using hydrochloric acid wastes of gas purifying plants in rare earth production is studied in laboratory conditions. It is shown that during sorption leaching of a rare earth product using the KU-2X8 cationite instead the reactive hydrochloric acid one may use hydrochloric acid wastes; rare earth element and yttrium extraction in both cases is identical

  9. Solvent extraction of uranium, thorium, and rare earths with dialkyldithiophosphoric acids

    International Nuclear Information System (INIS)

    Haiduc, I.; Curtui, M.

    1986-01-01

    The separation conditions for throium (IV) in the presence of trivalent rare earths was investigated. The distribution ratios (D), extraction effectivity values (E%) and separation factor(S) were calculated for binary systems Th-La, Th-Ce, Th-Pr, Th-Sm. Di-(2-ethyl-hexyl)dithiophosphoric acid (HEhdtp) alone or mixtures of HEhdtp and trioctylphosphoshine oxide (TOPO) can be successfully used for separation of Thorium (IV) and rare earths

  10. Acid pressure leaching of a concentrate containing uranium, thorium and rare earth elements

    International Nuclear Information System (INIS)

    Lan Xinghua; Peng Ruqing.

    1987-01-01

    The acid pressure leaching of a concentrate containing rinkolite for recovering uranium, thorium and rare earth elements is described. The laboratory and the pilot plant test results are given. Under the optimum leaching conditions, the recovery of uranium, thorium and rare earth elements are 82.9%, 86.0% and 88.3% respectively. These results show that the acid pressure leaching process is a effective process for treating the concentrate

  11. Synthesis of amino acid rare earth complexes and its application in agriculture

    International Nuclear Information System (INIS)

    Luo, G.-T.; Lian, P.; Hu, Y.H.; Guo, G.-R.

    1998-01-01

    Full text: The application of rare-earth compounds in agriculture has been widely reported. So far, most rare-earth compounds used in agriculture were inorganic salt and they were difficult to be absorbed by croup. The synthesis method and structure of amino acid rare-earth complexes have been reported. In this paper, we reported the preparation of mixed amino acids rare-earth complexes and their application in agriculture. The mixed amino acids were obtained by hydrolysis of waste natural protein. Rare earth was lanthanum oxide(99%). Mixed amino acids lanthanum complexes(MALa) was prepared according to the previous method. Investigation to the effect of croup by MALa, we have make tests of citrus, rice and mung bean. The results show as follows: 1) When the experiment group citrus was sprinkled twice 400ppm MALa at bouquet stage and young fruit stage, the sugar, morose, sucrose, soluble solid matter and vitamin C of fruit were increased 21%, 20%, 22%, 22% and 6% as compared to the control group, respectively. The area of leaf and foliage branch in Spring were also increased 4.6% and 2.2%. 2) When the rice was sprinkled 300ppm MALa at early tillering stage, the productively of rice was addition to 10-15%, and the relative effect of prevention was 45.61% for sheath and culm blight of rice. 3) In the test of mungbean growth, the low consistency of MALa ( 250ppm) retain from sprouting seed. As the same time, it was similar action to seeding growth. Preliminary results indicated MLAa could used as the plant growth regulation agent on the croup. Investigation to the effect of MALa on other croup and the mechanism of biological effect on the croup are still going on

  12. Recovery and separation of rare-earth elements, barium, and strontium from bastnasite with sulfuric acid

    International Nuclear Information System (INIS)

    Eisele, J.A.; Bauer, D.J.

    1974-01-01

    A bench-scale investigation was made of a concentrated H 2 SO 4 reaction for recovering and separating rare earth elements, barium, and strontium from a bastnaesite ore and byproduct. Barium and strontium were dissolved in the concentrated acid and precipitated as a mixed product by water dilution. Separation of strontium from barium was effected by reaction with Na 2 CO 3 solution, followed by a dilute acid leach of the SrCO 3 formed. After removing the barium and strontium from bastnaesite ore, the rare-earth elements were roasted to water-soluble sulfates. The rare earth sulfate solution was subsequently processed by solvent extraction to produce rare-earth oxides low in lead and magnesium. (U.S.)

  13. Rare earth elements recycling from waste phosphor by dual hydrochloric acid dissolution

    International Nuclear Information System (INIS)

    Liu, Hu; Zhang, Shengen; Pan, Dean; Tian, Jianjun; Yang, Min; Wu, Maolin; Volinsky, Alex A.

    2014-01-01

    Highlights: • The article provides a new method for recycling rare earth (RE) from waste phosphor. • When compared with the traditional methods, leach rate was much higher. • Y–Eu concentrate and Tb–Ce concentrate were obtained successively. • It would reduce the burden of later extraction, separation and purification. - Abstract: This paper is a comparative study of recycling rare earth elements from waste phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red rare earth phosphor (Y 0.95 Eu 0.05 ) 2 O 3 in waste phosphor is dissolved during the first step of acid leaching, while the Green phosphor (Ce 0.67 Tb 0.33 MgAl 11 O 19 ) and the Blue phosphor (Ba 0.9 Eu 0.1 MgAl 10 O 17 ) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO 2 are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the rare earth elements was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications

  14. Rare earth elements recycling from waste phosphor by dual hydrochloric acid dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hu [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, Shengen, E-mail: zhangshengen@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Pan, Dean; Tian, Jianjun; Yang, Min; Wu, Maolin [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Volinsky, Alex A. [Department of Mechanical Engineering, University of South Florida, Tampa, FL 33620 (United States)

    2014-05-01

    Highlights: • The article provides a new method for recycling rare earth (RE) from waste phosphor. • When compared with the traditional methods, leach rate was much higher. • Y–Eu concentrate and Tb–Ce concentrate were obtained successively. • It would reduce the burden of later extraction, separation and purification. - Abstract: This paper is a comparative study of recycling rare earth elements from waste phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red rare earth phosphor (Y{sub 0.95}Eu{sub 0.05}){sub 2}O{sub 3} in waste phosphor is dissolved during the first step of acid leaching, while the Green phosphor (Ce{sub 0.67}Tb{sub 0.33}MgAl{sub 11}O{sub 19}) and the Blue phosphor (Ba{sub 0.9}Eu{sub 0.1}MgAl{sub 10}O{sub 17}) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO{sub 2} are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the rare earth elements was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications.

  15. Synthesis and physicochemical study of rare earth complexes with o-hydroxyphenoxymethylphosphonic acid

    International Nuclear Information System (INIS)

    Alibaeva, Z.M.; Snezhko, N.I.; Pechurova, N.I.; Martynenko, L.I.; Alekseeva, N.A.; Bovin, A.N.

    1987-01-01

    Rare earth complexes with o-hydroxyphenoxymethylphosphonic acid (C 7 H 9 PO 5 , N 2 L) of the HMl 2 xnH 2 O composition are synthesized. The compounds separated are studied by IR spectroscopy, X-ray phase and elementary analysis methods. The data obtained permit to suppose on the polymer structure of rare earth complexes, except HLaL 2 x2H 2 O which is evidently of the island structure

  16. New Trident Molecule with Phosphoric Acid Functionality for Trivalent Rare Earth Extraction

    Directory of Open Access Journals (Sweden)

    Keisuke Ohto

    2017-11-01

    Full Text Available Tripodal extraction reagent with three phosphoric acid groups, together with the corresponding monopodal molecule has been prepared to investigate some metals extraction behavior, in particular, trivalent rare earth elements (REEs. The tripodal reagent exhibited extremely high selectivity for metals with high valency such as Zr(IV, In(III, Lu(III, and Fe(III. Tripodal reagent also exhibited exceptionally high extraction ability compared with the corresponding monopodal one in the extraction of trivalent rare earths. The result for the stoichiometry of tripodal reagent to heavy rare earths showed the inflection point between Er (2:1 for a ligand with ion and Tm (1:1. The extraction reactions were determined for all rare earths with both reagents. The extraction equilibrium constants (Kex, the separation factors (β, half pH values (pH1/2, difference half pH values (ΔpH1/2 for extraction of REEs with both reagents are estimated.

  17. Stepwise hydrochloric acid extraction of monazite hydroxides for the recovery of cerium lean rare earths, cerium, uranium and thorium

    International Nuclear Information System (INIS)

    Swaminathan, T.V.; Nair, V.R.; John, C.V.

    1988-01-01

    Monazite sand is normally processed by the caustic soda route to produce mixed rare earth chloride, thorium hydroxide and trisodium phosphate. Bulk of the mixed rare earth chloride is used for the preparation of FC catalysts. Recently some of the catalyst producers have shown preference to cerium depleted (lanthanum enriched) rare earth chloride rather than the natural rare earth chloride obtained from monazite. Therefore, a process for producing cerium depleted rare earth chloride, cerium, thorium and uranium from rare earth + thorium hydroxide obtained by treating monazite, based on stepwise hydrochloric acid extraction, was developed in the authors laboratory. The process involves drying of the mixed rare earth-thorium hydroxide cake obtained by monazite-caustic soda process followed by stepwise extraction of the dried cake with hydrochloric acid under specified conditions

  18. Preparation of rare earth fluorides from apatite concentrate

    International Nuclear Information System (INIS)

    Mulyarchuk, I.F.; Voloshchenko, M.V.; Zen'kovich, E.G.; Sumenkova, V.V.; AN Ukrainskoj SSR, Kiev. Inst. Problem Lit'ya)

    1980-01-01

    The processes of preparation of the rare earths element sum from apatite concentrate of the Khibins, connected with preliminary extraction of rare earth phosphates from nitric acid extract using solvent extraction or direct precipitation from the extract by solution of potassium and ammonium fluorides. The sequence of the processes of the first variant is the following: solvent extraction of rare earths by tributylphosphate from clarified nitric acid extract of apatite with subsequent reextraction of rare earths with water and precipitation of rare earth phosphates from aqueous solution during neutralization by ammonia. In case of fluoride preparation from rare earth phosphate the main attention is paid to precipitation and filtration of fluorides. Technological scheme and cost price of industry for the production of 1800 t of rare earth trifluorides a year are calculated. When taking account of TBP losses according to its solubility the industry cost price is 1O times lower the modern cost of rare earth fluorides

  19. The effect of acid rain stress on chlorophyll, peroxidase of the conservation of rare earth elements

    International Nuclear Information System (INIS)

    Chongling, Y.; Yetang, H.; Xianke, Y.; Shunzhen, F.; Shanql, W.

    1998-01-01

    Full text: Based on pot experiment, the effect of acid rain stress on chlorophyll, peroxidase of wheat, the relationship of them and the conservation of rare earth elements has been studied. The result showed: stress of acid rain resulted in decrease of chlorophyll content and a/b values, chlorophyll a/b value and chlorophyll content is positive correlation with pH value of acid rain: peroxidase activity was gradually rise with pH value decrease, which indirectly increased decomposition intensity of chlorophyll. Decreased content and a/b value of chlorophyll further speeded blade decay affected the transport and transformation of light energy and metabolism of carbohydrates. After being treated by rare earth elements content and pH value of chlorophyll and peroxidase activity could be relatively stable. Therefore, under lower acidity condition, rare earth elements can influence the effect of acid rain on chlorophyll and peroxidase activity of wheat

  20. The effect of acid rain stress on membrane protective system of spinach and the conservation of rare earth elements

    International Nuclear Information System (INIS)

    Chongling, Y; Yetang, H.

    1998-01-01

    Full text: Based on pot experiments, the effect of acid rain stress on membrane protective system of spinach and the effect of rare earth elements has been studied. The results showed, stress of acid rain resulted in decrease of over all level of superoxide dismutase activity, catalase activity and increase of peroxidase (POD) activity. After being treated by rare earth elements, the overall level of superoxide dismutase activity and catalase activity were increased and the peak value of activity variation curve moved toward to the direction of higher acidity. POD activity increased slightly, comparing with the plants that hadn't been treated by rare earth elements under same acid rain condition; the three important enzymes of membrane protective system could be kept on a relatively stable level. It was clear that in relative lower acidity condition, rare earth elements can reduce the impact of acid rain on the membrane protective system

  1. Determination of aminoglycoside antibiotics using complex compounds of chromotropic acid bisazoderivatives with rare earth ions

    International Nuclear Information System (INIS)

    Alykov, N.M.

    1981-01-01

    Studies of complex formation of bisazo derivatives of chromotropic acid with rare earth ions and aminoglycoside antibiotics have made it possible to choose carboxyarsenazo, orthanyl R and carboxynitrazo as highly sensitive reagents for determining aminoglycoside antibiotics. Conditions have been found for the formation of precipitates of different-ligand complexes containing rare earth ions, bisazo derivatives of chromotropic acid and aminogylcoside antibiotics. A procedure has been worked out of determining the antibiotics in biological samples with carboxyarsenazo [ru

  2. Bioleaching of rare earth elements from monazite sand.

    Science.gov (United States)

    Brisson, Vanessa L; Zhuang, Wei-Qin; Alvarez-Cohen, Lisa

    2016-02-01

    Three fungal strains were found to be capable of bioleaching rare earth elements from monazite, a rare earth phosphate mineral, utilizing the monazite as a phosphate source and releasing rare earth cations into solution. These organisms include one known phosphate solubilizing fungus, Aspergillus niger ATCC 1015, as well as two newly isolated fungi: an Aspergillus terreus strain ML3-1 and a Paecilomyces spp. strain WE3-F. Although monazite also contains the radioactive element Thorium, bioleaching by these fungi preferentially solubilized rare earth elements over Thorium, leaving the Thorium in the solid residual. Adjustments in growth media composition improved bioleaching performance measured as rare earth release. Cell-free spent medium generated during growth of A. terreus strain ML3-1 and Paecilomyces spp. strain WE3-F in the presence of monazite leached rare earths to concentrations 1.7-3.8 times those of HCl solutions of comparable pH, indicating that compounds exogenously released by these organisms contribute substantially to leaching. Organic acids released by the organisms included acetic, citric, gluconic, itaconic, oxalic, and succinic acids. Abiotic leaching with laboratory prepared solutions of these acids was not as effective as bioleaching or leaching with cell-free spent medium at releasing rare earths from monazite, indicating that compounds other than the identified organic acids contribute to leaching performance. © 2015 Wiley Periodicals, Inc.

  3. Determination of rare earths in their extraction processing

    International Nuclear Information System (INIS)

    You Jiannan; Zhang Yuqin

    1989-01-01

    A method for determination of rare earths in ores, ion-exchange resins and solution samples has been developed. The ore is molten with sodium peroxide and the molten sample is leached with triethenol amine and sodium citrate. In weak acid medium, the rare earths can be extracted by PMBP-phenol solution, and stripped with formic acid. In the acetic acidsodium acetate buffer medium of pH3, the spectrophotometric determination of rare earths with arsenazo M has been made. The rare earths in ion-exchange resins can be directly determined by spectrophotometry after being leached with hydrochloric acid and at heated condition. The rare earths with arsenazo M or a red complex. The maximum absorption of the complex is at 640 nm, and the molar absorption is 8.0 x 10 4 L centre dot mol -1 centre dot cm -1 . While the range of determination is 0.005%-0.5% and 0.001-1.0 g/L, the relative standard deviation is less than 5%, and recovery of rare earths is 98.5-105%. The method is rather simple and rapid

  4. Leaching of rare earth elements from bentonite clay

    OpenAIRE

    van der Watt, J.G; Waanders, F.B

    2012-01-01

    Due to increasing concerns of global rare earth element shortfalls in the near future, possible alternative sources of rare earth elements have recently become of economic interest. One such alternative is decanting acid mine water originating primarily from abandoned old mines in the Witwatersrand region of the Republic of South Africa. In this study, a novel way of rare earth element removal from the acid mine drainage was employed, making use of bentonite clay, which has very good adsorben...

  5. Process for lead removal from rare earth

    International Nuclear Information System (INIS)

    Bollat, A.; Sabot, J.L.

    1987-01-01

    An aqueous solution of rare earth chlorides and lead chlorides, with a chloride concentration of at least 2 moles/liter and a pH between 2 and 4, is extracted by an alkylphosphonic acid ester and rare earth(s) is (are) recovered from the organic phase [fr

  6. Synthesis and study of rare earth complexonates with ethylenediaminedisuccinic acid

    International Nuclear Information System (INIS)

    Mitrofanova, N.D.; Martynenko, L.I.; Kolleganov, M.Yu.

    1986-01-01

    Solid complexonates with ethylenediaminedisuccinic acid of HMZxnH 2 O and KMLxnH 2 O composition are synthesized for the Y, Sc and rare earths. The compounds were studied by different physicochemical methods. According to data on IR and electron spectroscopy the conclusion is made on-COOH-group coordination in protonated HML complexes. The complexes are X-ray amorphous, they have polymeric structure

  7. Rare earth metals, rare earth hydrides, and rare earth oxides as thin films

    International Nuclear Information System (INIS)

    Gasgnier, M.

    1980-01-01

    The review deals with pure rare earth materials such as rare earth metals, rare earth hydrides, and rare earth oxides as thin films. Several preparation techniques, control methods, and nature of possible contaminations of thin films are described. These films can now be produced in an extremely well-known state concerning chemical composition, structure and texture. Structural, electric, magnetic, and optical properties of thin films are studied and discussed in comparison with the bulk state. The greatest contamination of metallic rare earth thin films is caused by reaction with hydrogen or with water vapour. The compound with an f.c.c. structure is the dihydride LnH 2 (Ln = lanthanides). The oxygen contamination takes place after annealing at higher temperatures. Then there appears a compound with a b.c.c. structure which is the C-type sesquioxide C-Ln 2 O 3 . At room atmosphere dihydride light rare earth thin films are converted to hydroxide Ln(OH) 3 . For heavy rare earth thin films the oxinitride LnNsub(x)Osub(y) is observed. The LnO-type compound was never seen. The present review tries to set the stage anew for the investigations to be undertaken in the future especially through the new generations of electron microscopes

  8. Extraction of rare earths and hydrochloric acid by trialkylphosphine oxide

    International Nuclear Information System (INIS)

    Mikhajlichenko, A.I.; Karmannikov, V.P.; Klimenko, M.A.; Fedulova, T.V.

    1983-01-01

    Extraction of rare earth chlorides and hydrochloric acid by trialkylphosphine oxide with different radicals (POR) (RR' 2 PO-POR, where RR'=alkyl of a normal structure, containing 7 to 9 carbon atoms, R=isoamyl) has been studied. Distribution of lanthanum-, neodymium-, lutetium- and yttrium chlorides during extraction with 1.28 mol/l POR solution in white spirit is investigated in the salt concentration range in the equilibrium aqueous phase from 0 to 2.8 mol/l. Lanthanide distribution coefficients increase with an increase in the order number of elements, with the separation coefficients of two extreme members of the series (Lu and La) for chlorides and nitrates constituting 100 and 80, respectively microquantities of Ln against the background of macroquantities of La is 2.6 mol/l. According to the results of measurements of viscosity, electric conductivity and water content in the extracts a conclusion is made on the state of salt in the organic phase. In the systems POR-LnCl 3 -HCl-H 2 O the hydrochloric acid extraction increases with an increase in the rare earth chloride concentration and order number of the element

  9. Chemical analysis of rare earth elements

    International Nuclear Information System (INIS)

    Tsukahara, Ryoichi; Sakoh, Takefumi; Nagai, Iwao

    1994-01-01

    Recently attention has been paid to ICP-AES or ICP-MS, and the reports on the analysis of rare earth elements by utilizing these methods continue to increase. These reports have become to take about 30% of the reports on rare earth analysis, and this is because these methods are highly sensitive to rare earth elements, and also these methods have spread widely. In ICP-AES and ICP-MS, mostly solution samples are measured, therefore, solids must be made into solution. At the time of quantitatively determining the rare earth elements of low concentration, separation and concentration are necessary. Referring to the literatures reported partially in 1990 and from 1991 to 1993, the progress of ICP-AES and ICP-MS is reported. Rare earth oxides and the alloys containing rare earth elements are easily decomposed with acids, but the decomposition of rocks is difficult, and its method is discussed. The separation of the rare earth elements from others in geochemical samples, cation exchange process is frequently utilized. Also solvent extraction process has been studied. For the separation of rare earth elements mutually, chromatography is used. The spectral interference in spectral analysis was studied. The comparison of these methods with other methods is reported. (K.I)

  10. Environmental aspects in the processing of rare earth ores and minerals

    International Nuclear Information System (INIS)

    Bhattacharya, R.

    2011-01-01

    In India, rare earths are extracted from the mineral monazite which occurs abundantly along with other heavy minerals in the coastal beach sands. Monazite, apart from rare earths, also contains uranium and thorium. Rare earths can be obtained from monazite either by acid digestion route or by alkaline digestion route. In India, although pilot scale studies have been carried out extraction of rare earths by acid digestion route, however, alkali digestion route has been predominantly followed for commercial extraction of rare earths

  11. Recovery of fluorine, uranium, and rare earth metal values from phosphoric acid by-product brine raffinate

    International Nuclear Information System (INIS)

    Wamser, C.A.; Bruen, C.P.

    1976-01-01

    A method for recovering substantially all of the fluorine and uranium values and at least 90 percent of the rare earth metal values from brine raffinate obtained as by-product in the production of phosphoric acid by the hydrochloric acid decomposition of tricalcium phosphate minerals is described. A basically reacting compound is added to the brine raffinate to effect a pH 9 or greater, whereby fluorine, uranium and rare earth metal values are simultaneously precipitated. These values may then be separately recovered from the precipitate by known processes

  12. Rare earth elements materials production from apatite ores

    International Nuclear Information System (INIS)

    Anufrieva, A V; Buynovskiy, A S; Makaseev, Y N; Mazov, I N; Nefedov, R A; Sachkov, V I; Valkov, A V; Andrienko, O S; Stepanova, O B

    2016-01-01

    The paper deals with the study of processing apatite ores with nitric acid and extraction of the rare earth elements. The rare earth elements can be successfully separated and recovered by extraction from the nitrate- phosphate solution, being an tributyl phosphate as extraction agent. The developed scheme of the processing apatite concentrate provides obtaining rare earth concentrates with high qualitative characteristics. (paper)

  13. Kinetics studies of solvent extraction of rare earths into DEHPA

    International Nuclear Information System (INIS)

    Lim, T.M.; Tran, T.

    1996-01-01

    The kinetics of rare earth solvent extraction into di(2-ethylhexyl) phosphoric acid have been studied using radiotracers ( 141 Ce, 152 Eu, 153 Gd, 160 Tb and 88 Y) in a modified Lewis cell. The experimental procedure involved continuous monitoring of both aqueous and organic phases using an automated γ- counting system. Using this method, highly reproducible results were obtained without chemical analysis or disturbance of the system. The initial rate extraction was first order with respect to individual rare earth concentration. At low acidities ([H+] < 0.01 M), the extraction rates of rare earths were equal and independent of pH. However, at high acidities, the extraction rate was strongly dependent on pH and varied between the rare earths. Similarly, differences in the extraction rate of individual rare earths were apparent at low DEHPA concentration. (authors)

  14. Rare earth element recycling from waste nickel-metal hydride batteries

    International Nuclear Information System (INIS)

    Yang, Xiuli; Zhang, Junwei; Fang, Xihui

    2014-01-01

    Highlights: • Leaching kinetics of REEs has rarely been reported. • A new method, including hydrochloric acid leaching and oxalic acid precipitation, was proposed. • REEs recovery rate of 95.16% and pure rare earth oxides of 99% were obtained. • Leaching process was controlled by chemical reaction. • The kinetic equation was determined. - Abstract: With an increase in number of waste nickel-metal hydride batteries, and because of the importance of rare earth elements, the recycling of rare earth elements is becoming increasingly important. In this paper, we investigate the effects of temperature, hydrochloric acid concentration, and leaching time to optimize leaching conditions and determine leach kinetics. The results indicate that an increase in temperature, hydrochloric acid concentration, and leaching time enhance the leaching rate of rare earth elements. A maximum rare earth elements recovery of 95.16% was achieved at optimal leaching conditions of 70 °C, solid/liquid ratio of 1:10, 20% hydrochloric acid concentration, −74 μm particle size, and 100 min leaching time. The experimental data were best fitted by a chemical reaction-controlled model. The activation energy was 43.98 kJ/mol and the reaction order for hydrochloric acid concentration was 0.64. The kinetic equation for the leaching process was found to be: 1−(1−x) 1/3 =A/ρr 0 [HCl] 0.64 exp((−439,800)/(8.314T) )t. After leaching and filtration, by adding saturated oxalic solution to the filtrate, rare earth element oxalates were obtained. After removing impurities by adding ammonia, filtering, washing with dilute hydrochloric acid, and calcining at 810 °C, a final product of 99% pure rare earth oxides was obtained

  15. Thermochemical properties of rare earth complexes with salicylic acid

    International Nuclear Information System (INIS)

    Yang Xuwu; Sun Wujuan; Ke Congyu; Zhang Hangguo; Wang Xiaoyan; Gao Shengli

    2007-01-01

    Fourteen rare earth complexes with salicylic acid RE(HSal) 3 .nH 2 O (HSal = C 7 H 5 O 3 ; RE = La-Sm, n = 2; RE = Eu-Lu, n = 1) were synthesized and characterized by elemental analysis, and their thermal decomposition mechanism were studied with TG-DTG technology. The constant-volume combustion energies of complexes, Δ c U, were determined by a precise rotating-bomb calorimeter at 298.15 K. Their standard molar enthalpies of combustion, Δ c H m 0 , and standard molar enthalpies of formation, Δ f H m o , were calculated

  16. Rare earths

    Energy Technology Data Exchange (ETDEWEB)

    Cranstone, D A

    1979-01-01

    Rare earth elements are commonly extracted from the minerals monazite, bastnaesite, and xenotine. New uses for these elements are constantly developing; they have found applications in glass polishing, television tube phosphors, high-strength low-alloy steels, magnets, catalysts, refractory ceramics, and hydrogen sponge alloys. In Canada, rare earths have been produced as byproducts of the uranium mining industry, but there was no production of rare earths in 1978 or 1979. The world sources of and markets for the rare earth elements are discussed.

  17. Corrosion resistance of chromium-nickel steel containing rare earths

    International Nuclear Information System (INIS)

    Asatiani, G.N.; Mandzhgaladze, S.N.; Tavadze, L.F.; Chuvatina, S.N.; Saginadze, D.I.

    1983-01-01

    Effect of additional out-of-furnace treatment with complex alloy (foundry alloy) calcite-silicon-magnesium-rare earth metal on corrosion resistance of the 03Kh18N20M3D3C3B steel has been studied. It is shown that introduction of low additions of rare earths improves its corrosion resistance improves its corrosion resistance in agressive media (in 70% - sulfuric acid) in the range of transition from active to passive state. Effect of additional introduction of rare earth metals is not considerable, if potential of steel corrosion is in the range of stable passive state (32% - sulfuric acid). Additional out-of-furnace treatment with complex foundry alloy, containing rare earth metals, provides a possibility to use a steel with a lower content of Cr, Ni, Mo, than in conventional acid-resistant steels in highly agressive media

  18. Rapid analysis of some rare earth magnets

    Energy Technology Data Exchange (ETDEWEB)

    Raoot, K N; Raoot, S; Rukmani Desikan, N [Defence Metallurgical Research Lab., Hyderabad (India)

    1978-12-01

    A simple complexometric method for the quick analysis of the constituent elements in some quaternary rare earth magnets of the type RE-Co-Cu-Fe and RE-Ni-Cu-Fe is described. The technique is based on a total titration, subsequent release of EDTA from rare earth with ammonium fluoride and that from copper (II) with ascorbic acid and thiourea followed by determination of the excess and liberated EDTA by lead nitrate in a weak acid medium using xylenol orange indicator. In another, aliquot iron (III) and rare earth are first masked with sodium fluoride, and copper (II) with ascorbic acid and thiourea before cobalt (II) or nickel (II) is estimated by back titration. Iron is calculated by difference. The new method yields accurate and reproducible results with error not exceeding 1%. A set of three samples can conveniently be analysed in two hours.

  19. Rapid analysis of some rare earth magnets

    International Nuclear Information System (INIS)

    Raoot, K.N.; Raoot, Sarala; Rukmani Desikan, N.

    1978-01-01

    A simple complexometric method for the quick analysis of the constituent elements in some quaternary rare earth magnets of the type RE-Co-Cu-Fe and RE-Ni-Cu-Fe is described. The technique is based on a total titration, subsequent release of EDTA from rare earth with ammonium fluoride and that from copper (II) with ascorbic acid and thiourea followed by determination of the excess and liberated EDTA by lead nitrate in a weak acid medium using xylenol orange indicator. In another, aliquot iron (III) and rare earth are first masked with sodium fluoride, and copper (II) with ascorbic acid and thiourea before cobalt (II) or nickel (II) is estimated by back titration. Iron is calculated by difference. The new method yields accurate and reproducible results with error not exceeding 1%. A set of three samples can conveniently be analysed in two hours. (author)

  20. A novel approach for acid mine drainage pollution biomonitoring using rare earth elements bioaccumulated in the freshwater clam Corbicula fluminea.

    Science.gov (United States)

    Bonnail, Estefanía; Pérez-López, Rafael; Sarmiento, Aguasanta M; Nieto, José Miguel; DelValls, T Ángel

    2017-09-15

    Lanthanide series have been used as a record of the water-rock interaction and work as a tool for identifying impacts of acid mine drainage (lixiviate residue derived from sulphide oxidation). The application of North-American Shale Composite-normalized rare earth elements patterns to these minority elements allows determining the origin of the contamination. In the current study, geochemical patterns were applied to rare earth elements bioaccumulated in the soft tissue of the freshwater clam Corbicula fluminea after exposure to different acid mine drainage contaminated environments. Results show significant bioaccumulation of rare earth elements in soft tissue of the clam after 14 days of exposure to acid mine drainage contaminated sediment (ΣREE=1.3-8μg/gdw). Furthermore, it was possible to biomonitor different degrees of contamination based on rare earth elements in tissue. The pattern of this type of contamination describes a particular curve characterized by an enrichment in the middle rare earth elements; a homologous pattern (E MREE =0.90) has also been observed when applied NASC normalization in clam tissues. Results of lanthanides found in clams were contrasted with the paucity of toxicity studies, determining risk caused by light rare earth elements in the Odiel River close to the Estuary. The current study purposes the use of clam as an innovative "bio-tool" for the biogeochemical monitoring of pollution inputs that determines the acid mine drainage networks affection. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Rare earth element recycling from waste nickel-metal hydride batteries.

    Science.gov (United States)

    Yang, Xiuli; Zhang, Junwei; Fang, Xihui

    2014-08-30

    With an increase in number of waste nickel-metal hydride batteries, and because of the importance of rare earth elements, the recycling of rare earth elements is becoming increasingly important. In this paper, we investigate the effects of temperature, hydrochloric acid concentration, and leaching time to optimize leaching conditions and determine leach kinetics. The results indicate that an increase in temperature, hydrochloric acid concentration, and leaching time enhance the leaching rate of rare earth elements. A maximum rare earth elements recovery of 95.16% was achieved at optimal leaching conditions of 70°C, solid/liquid ratio of 1:10, 20% hydrochloric acid concentration, -74μm particle size, and 100min leaching time. The experimental data were best fitted by a chemical reaction-controlled model. The activation energy was 43.98kJ/mol and the reaction order for hydrochloric acid concentration was 0.64. The kinetic equation for the leaching process was found to be: 1-(1-x)(1/3)=A/ρr0[HCl](0.64)exp-439,8008.314Tt. After leaching and filtration, by adding saturated oxalic solution to the filtrate, rare earth element oxalates were obtained. After removing impurities by adding ammonia, filtering, washing with dilute hydrochloric acid, and calcining at 810°C, a final product of 99% pure rare earth oxides was obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Batch Simulation of Rare Earths Extractive Separation by Di (2-Ethylhexyl) Phosphoric Acid and Tributylphosphate in Kerosene

    International Nuclear Information System (INIS)

    Kraikaew, Jarunee; Srinuttakul, Wanee

    2004-01-01

    Liquid-liquid extraction is applied to separate individual rare earths. In this research, 6-stage continuous countercurrent solvent extraction was simulated to extract rare earths from rare earth nitrate solution, which was obtained from monazite processing, to estimate the possible optimum operating conditions for pilot or industrial plants. The solvent(S) per feed(F) ratio (S/F) was varied from 1 to 3. The organic are 1.0 and 1.5 Molars (M) Di (2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene. 50% tributylphosphate (TBP) in kerosene was applied for comparison. It was found that D2EHPA was a good extracting agent for heavy rare earths while TBP extracted well both light and heavy rare earths. After extraction with TBP and D2EHPA, the extraction efficiency at solvent per feed ratio (S/F) =2 and 3 showed a slight difference. S/F =2 was selected commercially for operation

  3. Separation of rare earths by means of acid organophosphorous compounds. Structure-activity study by molecular simulation

    International Nuclear Information System (INIS)

    Fourcot, Fabrice

    1991-01-01

    The increasing number of industrial applications of rare earths has resulted in an increased demand in purified rare earths whereas their separation is difficult due to their high chemical similarity. The search for a better separation leads to the search for more selective extraction agents. Organophosphorous compounds appear to be the most selective. As the search for new extraction agents resulting in high lanthanide extraction efficiency or in a better selectivity between rare earths has been mainly empiric, this research thesis aims at developing a molecular simulation method which allows the number of molecules to be synthesized and tested to be reduced. After having briefly recalled general knowledge on liquid-liquid extraction and on rare earths, and described calculation methods (quantum methods, methods based on molecular mechanics, conformational analysis, methods of charge calculation), the author proposes a critical review of literature related to rare earth liquid-liquid extraction by organophosphorous acids with respect to the used extraction agent. The molecular modelling issue is then addressed by describing ways to apply it to extraction problems, faced problems, brought solutions and obtained results

  4. Rare earth germanates

    International Nuclear Information System (INIS)

    Bondar', I.A.; Vinogradova, N.V.; Dem'yanets, L.N.

    1983-01-01

    Rare earth germanates attract close attention both as an independent class of compounds and analogues of a widely spread class of natural and synthetic minerals. The methods of rare earth germanate synthesis (solid-phase, hydrothermal) are considered. Systems on the basis of germanium and rare earth oxides, phase diagrams, phase transformations are studied. Using different chemical analysese the processes of rare earth germanate formation are investigated. IR spectra of alkali and rare earth metal germanates are presented, their comparative analysis being carried out. Crystal structures of the compounds, lattice parameters are studied. Fields of possible application of rare earth germanates are shown

  5. Processing of monazite at the rare earth division,Udyogamandal

    International Nuclear Information System (INIS)

    Narayanan, N.S.; Thulasidoss, S.; Ramachandran, T.V.; Swaminathan, T.V.; Prasad, K.R.

    1988-01-01

    The processing techniques adopted at the Rare Earth Division of the Indian Rare Earths Limited at Udyogamandal, for the production of rare earth compounds of various compositions and purity grades are reviewed. Over 100 different compounds are produced and marketed, and these include mixed rare earths chloride, crude thorium concentrate, cerium oxide, cerium hydrate, rare earths carbonate, didymium salts and individual rare earth oxides and salts. Also, the trisodium phosphate obtained as byproduct in the processing of monazite, is recovered and marketed. The process scheme for monazite essentially involves alkaline digestion of ground monazite, removal of the by-product trisodium phosphate, separation of thorium through preferential dissolution of rare earths hydroxide in hydrochloric acid under controlled pH and temperature conditions followed by purification, and evaporation of the chloride solution to yield pure rare earths chloride. Part of the chloride is utilised for the production of individual rare earth compounds after separation by solvent extraction and ion exchange processes. Individual rare earth compounds of 99.99 %+ purity are regularly produced to cater to the demand within the country. (author) 8 figs., 1 tab

  6. Rare Earth Polyoxometalates.

    Science.gov (United States)

    Boskovic, Colette

    2017-09-19

    variable-temperature studies have revealed the temperature dependence of the POM-based sensitization, which is relevant for potential applications in phosphor thermometry. Novel RE-POM coordination polymers demonstrate the promise of higher-dimensional materials for catalytic and sensing applications that can make use of either or both rare earth and polyoxometalate capabilities. Finally, structural, electrochemical, and density functional theory studies on a family of modular RE-POMs that incorporate molybdotungstates with amino acid coligands have revealed how closed Mo-oxo loops that are reduced preferentially can act as electron reservoirs in mixed-metal molybdotungstates. This has important implications for mixed-metal polyoxometalates in redox and photoredox catalysis. Notably, these hybrid RE-POMs are stable in solution and maintain the chirality induced by amino acid ligands. The RE-POMs surveyed in this Account provide a glimpse of possible structural features that are accessible with this family of compounds. The studies of the ensuing chemical and physical properties reveal the promise of RE-POMs for diverse and varied applications and lay an excellent foundation for the future development of this new class of functional materials.

  7. Equilibrium studies on interactions of rare earth ions with phytic acid

    International Nuclear Information System (INIS)

    Siddiqi, K.S.; Shah, S.A.; Aqra, F.M.A.M.; Tabassum, S.; Zaidi, S.A.A.; Benlian, D.

    1993-01-01

    The interaction between phytic acid and trivalent rare earth metal ions, viz., Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Gd 3+ , Tb 3+ , Dy 3+ and HO 3+ has been investigated potentiometrically at 25degC. The proton-ligand stability constants (pK Y H ) of phytic acid and the stability constants (logK) of metal complexes formed in aqueous medium (μ = 0.1 M NaClO 4 ) have been evaluated. The results indicate that eight protons of phytic acid are highly acidic, two are weakly acidic and two very weakly acidic, titrable in the pH ranges 1.2-4.9, 5.0-8.15 and 8.3-11.0 respectively. The stability of each phytic acid-lanthanide ion complex decreases with an increase in pH and follows the usual trend through the series. (author). 11 refs., 2 tabs

  8. A study on the separation method of total rare earth oxides in Xenotime

    International Nuclear Information System (INIS)

    Shim, Sang Kwon; Park, Hea Kyung; Kim, Kyung Lim

    1990-01-01

    This study is concerned with the separation method of total rare earth oxides in Xenotime by acid digest method. Thioacetamide was used as a carrier, tartaric acid was used as a masking agent and oxalic acid was used as a precipitant. So the effects of three acid digest methods, pH of the solution, digesting time,tartaric acid, oxalic acid and aging time were oberved. The results showed that the best acid digest method was sulfuric acid leaching and mixed acid digest method, and that pH of the solution was 2, digesting time was 4 hours, tartaric acid was 100 ml of 2% solution, oxalic acid was 8 gr. and aging time was 1 hour. Through this experiment, it was confirmed by X-ray diffractometer that the separated total rare earth oxides consisted of the Yttrium and the other rare earth elements : Gadolinium, Dysprosium, Erbium, Ytterbium and trace rare earth elements. The pure rare earth oxides being separated by this method were dried and ignited at 900 deg C (Author)

  9. Enhancement in extraction rates by addition of organic acids to aqueous phase in solvent extraction of rare earth metals in presence of diethylenetriaminepentaacetic acid

    International Nuclear Information System (INIS)

    Matsuyama, Hideto; Azis, A.; Fujita, Mamoru; Teramoto, Masaaki.

    1996-01-01

    It is well known that the selectivity of rare earth metals by solvent extraction is increased by the addition of a chelating agent such as diethylenetriaminepentaacetic acid (DTPA) in the aqueous phase. One of the disadvantages of this method is the decrease in extraction rates due to complexation in the aqueous phase. In this paper, further addition of organic acids to the aqueous phase was examined for the purpose of enhancing the extraction rates in solvent extraction with DTPA. The addition of several kind of organic acids such as formic acid, acetic acid, malonic acid, lactic acid and citric acid was investigated for a Er/Y separation system. A remarkable enhancement in extraction rates was observed with a slight decrease in the selectivity by the addition of citric acid or lactic acid. Extraction rates in the presence of both DTPA and citric acid increased with the increase in citric acid concentration and with the increase in proton concentration. A 150 times enhancement in extraction rates was found in the low proton concentration condition. In order to analyze the extraction rates and selectivities obtained, mass transfer equations were presented by considering both the dissociation reaction of rare earth metal-DTPA complexes and the complex formation between rare earth metal and organic acid in the aqueous phase. The experimental data were analyzed by these equations. (author)

  10. Some regularities of extraction of rare earth elements by organophosphoric acid

    International Nuclear Information System (INIS)

    Korpusov, G.V.; Keimirov, M.A.; Danilov, N.A.; Djumauradov, B.

    1988-01-01

    Consideration is given to results of investigation of extraction of rare earth macroquantities from nitrate solutions by D-2-isopropyl-5-methylhexylphosphoric and 2-isopropyl-5-methylhexylphosphoric acids. It is shown that extractant selectivity decreases with increase of aqueous phase acidity. The selectivity is usually higher against the background of macroquantities of weakly extracted component, but some times another dependence is observed. It is noted that substitution of the diluent for more polar one which monomerizes extractants, leads to the loss of selectivity. But in small guantities polar diluents provide the stability of the extraction system for formation of sediments. Both sampls of organophosphoric acids provide for extraction process at low HNO 3 concentrations without rick of sediment formati on of extracted compounds in organic phase

  11. Activation analysis of trace amounts of rare earth in high purity tantalum

    International Nuclear Information System (INIS)

    Ishibashi, Wataru; Saito, Shinichi; Hirayama, Tooru.

    1975-01-01

    It is necessary to separate rare earth from tantalum by rapid methods in order to remove effects of a strong radioactivity and a short half-life. Tantalum is extracted with 10%N-lauryl (trialkylmethyl) amino-benzene pre-equilibrated with a solution of 9 M hydrochloric and 0.15 M hydrofluoric acid. A non-radioactive rare earth element is added to this aqueous solution, a precipitate of trace amounts of radioactive rare earth in aqueous solution is formed by this addition of rare earth. Some factors in the determination are: 1) the effect of the irradiation position of the sample in the atomic reactor, 2) the effect on the extraction with 10%N-lauryl (trialkylmethyl) amino-benzene for the radioactive rare earth, 3) the effect of the concentration of hydrofluoric acid, ammonia water and nitric acid on co-precipitation. As a result of the investigation we obtained the following satisfactory results: 1) Rare earth was not effected by the extraction of tantalum with 10%N-lauryl (trialkylmethyl) amino-benzene. 2) The recovery of rare earth by co-precipitation increases when an ammonium ion coexists, and when the concentration of hydrofluoric acid decreases, but the recovery decreases with the increase of nitric acid concentration. 3) The time required for the extraction is 9 hours. In case of determination for dysprosium, tantalum extracted with 10%N-lauryl (trialkylmethyl) amino-benzene before activation and the time for separation is 2 hours. (auth.)

  12. Equilibrium studies on interactions of rare earth ions with phytic acid

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqi, K S; Shah, S A; Aqra, F M.A.M.; Tabassum, S; Zaidi, S A.A. [Aligarh Muslim Univ. (India). Dept. of Chemistry; Benlian, D [Centre de St Jerome, Cedex (France). Laboratoire de Chimie de Coordination

    1993-05-01

    The interaction between phytic acid and trivalent rare earth metal ions, viz., Ce[sup 3+], Pr[sup 3+], Nd[sup 3+], Sm[sup 3+], Gd[sup 3+], Tb[sup 3+], Dy[sup 3+] and HO[sup 3+] has been investigated potentiometrically at 25degC. The proton-ligand stability constants (pK[sub Y][sup H]) of phytic acid and the stability constants (logK) of metal complexes formed in aqueous medium ([mu] = 0.1 M NaClO[sub 4]) have been evaluated. The results indicate that eight protons of phytic acid are highly acidic, two are weakly acidic and two very weakly acidic, titrable in the pH ranges 1.2-4.9, 5.0-8.15 and 8.3-11.0 respectively. The stability of each phytic acid-lanthanide ion complex decreases with an increase in pH and follows the usual trend through the series. (author). 11 refs., 2 tabs.

  13. Geochemical processes assessed by Rare Earth Elements fractionation at “Laguna Verde” acidic-sulphate crater lake (Azufral volcano, Colombia)

    International Nuclear Information System (INIS)

    Inguaggiato, Claudio; Burbano, Viviana; Rouwet, Dmitri; Garzón, Gustavo

    2017-01-01

    The geochemical behaviour of major elements, Fe, Al, Mn, and Rare Earth Elements (REE) was investigated in the “Laguna Verde” acidic crater lake of Azufral volcano (Colombia). The cold lake water (T close to 10 °C) is sulphate-dominated, due to absorption and oxidation of H_2S (pH 2.1–2.7, Eh 196–260 mV), and Na-enriched (Total Dissolved Solids 0.79 g L"−"1). The total amount of REE dissolved in the lake ranges from 3.3 to 9.1 ppb. The REE patterns normalized to the local rocks show a Light Rare Earth Elements (LREE) depletion quite constant in the 15 samples. Similar patterns were already found in the acidic sulphate springs of Nevado del Ruiz volcano-hydrothermal system, caused by the precipitation of alunite and jarosite, absorbing LREE and hence removing them from solution. Alunite and jarosite minerals are not oversaturated at chemical-physical conditions within the lake itself, but alunite becomes oversaturated for temperatures above ≈100 °C, reigning in the underlying hydrothermal system. Water temperatures close to 75 °C were found in the northern part of the lake. Coupling the distribution of REE in lake water (LREE depleted) and the saturation indexes, we suggest that the distribution of REE in the lake water is the result of the alunite precipitation in the northern part of the lake and/or in the deeper hydrothermal system. The acidic hydrothermal fluids mobilize the REE with contents up to ≈5 orders of magnitude higher than seawater; acidic-hydrothermal systems, such as acidic crater lakes, can hence be considered potential REE “reservoirs”. - Highlights: • Acidic crater lakes can be considered potential Rare Earth Elements reservoirs. • Alunite precipitation removes Light Rare Earth Elements. • Rare Earth Elements identify geochemical processes in volcano-hydrothermal systems.

  14. Rare earths

    International Nuclear Information System (INIS)

    1984-01-01

    The conference was held from September 12 to 13, 1984 in Jetrichovice, Czechoslovakia. The participants heard 16 papers of which 4 were inputted in INIS. These papers dealt with industrial separation processes of rare earths, the use of chemical methods of separation from the concentrate of apatite and bastnesite, the effect of the relative permittivity of solvents in the elution of rare earth elements from a cation exchanger, and the determination of the content of different rare earth elements using X-ray fluorescence analysis and atomic absorption spectroscopy. (E.S.)

  15. Spectrographic determination of some rare earths in thorium compounds

    International Nuclear Information System (INIS)

    Brito, J. de.

    1977-01-01

    A method for spectrographic determination of Gd, Sm, Dy, Eu, Y, Yb, Tm and Lu in thorium compounds has been developed. Sensibilities of 0.01 μg rare earths/g Th02 were achieved. The rare earth elements were chromatographycally separated in a nitric acid-ether-cellulose system. The solvent mixture was prepared by dissolving 11% of concentrated nitric acid in ether. The method is based upon the sorption of the rare earths on activated cellulose, the elements being eluted together with 0.01 M HNO 3 . The retention of the 152 , 154 Eu used as tracer was 99,4%. The other elements showed recoveries varying from 95 to 99%. A direct carrier destillation procedure for the spectrochemical determination of the mentioned elements was used. Several concentrations of silver chloride were used to study the volatility behavior of the rare earths. 2%AgCl was added to the matrix as definite carrier, being lantanum selected as internal standard. The average coefficient of variation for this method was +- -+ 7%. The method has been appleid to the analysis of rare earths in thorium coumpounds prepared by Thorium Purification Pilot Plant at Atomic Energy Institute, Sao Paulo [pt

  16. Dissolution of nickel ferrite and rare earths containing magnetites in citric acid - EDTA - gallic acid (CEG) formulation

    Energy Technology Data Exchange (ETDEWEB)

    Kumbhar, A.G.; Kishore, K.; Venkateswaran, G.; Balaji, V. [Applied Chemistry Div., Bhabha Atomic Research Centre, Mumbai (India)

    2002-07-01

    It has been shown by us earlier that gallic acid can be used as a reductant in dilute chemical decontaminant formulations containing EDTA as chelant. The results on the dissolution of magnetite in such a formulation were quite promising. Moreover, the superior radiation stability of gallic acid vis-a-vis other reductants such as ascorbic acid or oxalic acid is another plus point for this formulation. Besides having an inherent stability against radiation degradation, it is able to protect even EDTA against radiation induced decomposition to a great extent unlike the case of ascorbic acid. In an extension of that work, dissolution experiments have now been carried out on nickel ferrite and magnetites containing rare earths like La, Ce and Zr This is to simulate the presence of fission product oxides in magnetite resulting from a possible phase of operation with leaky fuel. The rate constants have been determined using the inverse cubic rate law. In the case of nickel ferrite, although there is an initial induction period, the rate constants for the dissolution were determined to be at 1.6 x 10{sup -2} and 3.6 x 10{sup -3} min{sup -1} at 353 K and 333 K respectively. Presence of Ce in particular either alone or in combination with Zr/La at a level of 1 at.% equivalent each in magnetite is seen to increase the surface area of the oxide. The rate constants for the dissolution at 353 K in a 11:44:4 mM CEG formulation taken with magnetite and rare earth containing magnetites equivalent to yielding 22 mM Fe upon complete dissolution are as follows: 5.09 x 10{sup -2} min{sup -1} (magnetite), 7.06 x 10{sup -2} min{sup -1} (Ce{sub 2}O{sub 3} containing magnetite), 6.33 x 10{sup -2} min{sup -1} (Ce{sub 2}O{sub 3}, ZrO{sub 2} containing magnetite), 1 x 10{sup -1} min{sup -1} (Ce{sub 2}O{sub 3}, ZrO{sub 2}, La{sub 2}O{sub 3} containing magnetite). The presence of Ce, Zr and La at 1 at.% level each has not resulted in any turbidity in solution at the end of magnetite dissolution

  17. Dissolution of nickel ferrite and rare earths containing magnetites in citric acid - EDTA - gallic acid (CEG) formulation

    International Nuclear Information System (INIS)

    Kumbhar, A.G.; Kishore, K.; Venkateswaran, G.; Balaji, V.

    2002-01-01

    It has been shown by us earlier that gallic acid can be used as a reductant in dilute chemical decontaminant formulations containing EDTA as chelant. The results on the dissolution of magnetite in such a formulation were quite promising. Moreover, the superior radiation stability of gallic acid vis-a-vis other reductants such as ascorbic acid or oxalic acid is another plus point for this formulation. Besides having an inherent stability against radiation degradation, it is able to protect even EDTA against radiation induced decomposition to a great extent unlike the case of ascorbic acid. In an extension of that work, dissolution experiments have now been carried out on nickel ferrite and magnetites containing rare earths like La, Ce and Zr This is to simulate the presence of fission product oxides in magnetite resulting from a possible phase of operation with leaky fuel. The rate constants have been determined using the inverse cubic rate law. In the case of nickel ferrite, although there is an initial induction period, the rate constants for the dissolution were determined to be at 1.6 x 10 -2 and 3.6 x 10 -3 min -1 at 353 K and 333 K respectively. Presence of Ce in particular either alone or in combination with Zr/La at a level of 1 at.% equivalent each in magnetite is seen to increase the surface area of the oxide. The rate constants for the dissolution at 353 K in a 11:44:4 mM CEG formulation taken with magnetite and rare earth containing magnetites equivalent to yielding 22 mM Fe upon complete dissolution are as follows: 5.09 x 10 -2 min -1 (magnetite), 7.06 x 10 -2 min -1 (Ce 2 O 3 containing magnetite), 6.33 x 10 -2 min -1 (Ce 2 O 3 , ZrO 2 containing magnetite), 1 x 10 -1 min -1 (Ce 2 O 3 , ZrO 2 , La 2 O 3 containing magnetite). The presence of Ce, Zr and La at 1 at.% level each has not resulted in any turbidity in solution at the end of magnetite dissolution suggesting chemical dissolution of these rare earth oxides in the formulation. Simple magnetite

  18. Precipitation of the rare earth double sodium and rare earths from the sulfuric liquor and the conversion into rare earth hydroxides through meta ethic reaction

    International Nuclear Information System (INIS)

    Abreu, Renata D.; Oliveira, Ester F.; Brito, Walter de; Morais, Carlos A.

    2007-01-01

    This work presents the purification study of the rare earths through precipitation of rare earth and sodium (Na TR (SO 4 ) 2 . x H 2 O)) double sulfate and his conversion to rare earths hydroxide TR(OH) 3 by meta ethic reaction through the addition of sodium hydroxide solution to the solid double sulfate. The study used the sulfuric liquor as rare earth sample, generated in the chemical processing of the monazite with sulfuric acid by the Industrias Nucleares do Brasil - INB, Brazil, after the thorium and uranium extraction. The work investigated the influence of the main variables involved in the precipitation of Na TR(SO 4 ) 2 .xH 2 O and in the conversion for the TR(OH) 3 , as follows: type and excess of the precipitation agent, temperature and time reaction. The obtained solid composites were characterized by X-ray diffraction, infrared and chemical analysis. The double sulfate diffractogram indicated the Na TR(SO 4 ) 2 mono-hydrated. The characterization of the metatese products has shown that, for obtaining the complete conversion of NaTR(SO 4 ) 2 .H 2 O into TR(OH) 3 , the reaction must be hot processed (∼70 deg C) and with small excess of Na OH (≤ 5 percent). (author)

  19. Global recovery process of thorium and rare earths in a nitrate medium

    International Nuclear Information System (INIS)

    Cailly, F.; Mottot, Y.

    1993-01-01

    The aqueous solution of thorium and rare earth nitrates, obtained by leaching the ore with nitric acid, is extracted by an organic phosphorous compound (phosphate, phosphonate, phosphinate or phosphine oxide) and a cationic extractant chosen among phosphoric acid di-esters. Extraction of thorium and rare earths is possible even in presence of phosphate ions in the aqueous solution. Thorium and rare earths are separated by liquid-liquid extraction of the organic phase

  20. PROCESS FOR SEPARATING AMERICIUM AND CURIUM FROM RARE EARTH ELEMENTS

    Science.gov (United States)

    Baybarz, R.D.; Lloyd, M.H.

    1963-02-26

    This invention relates to methods of separating americium and curium values from rare earth values. In accordance with the invention americium, curium, and rare earth values are sorbed on an anion exchange resin. A major portion of the rare earth values are selectively stripped from the resin with a concentrated aqueous solution of lithium chloride, and americium, curium, and a minor portion of rare earth values are then stripped from the resin with a dilute aqueous solution of lithium chloride. The americium and curium values are further purified by increasing the concentration of lithium chloride in the solution to at least 8 molar and selectively extracting rare earth values from the resulting solution with a monoalkylphosphoric acid. (AEC)

  1. Distribution of rare earths in liver of mice administered with chloride compounds of 12 rare earths

    International Nuclear Information System (INIS)

    Shinohara, A.; Chiba, M.; Inaba, Y.

    1998-01-01

    Full text: Rare earths are used in high technology field, however, the information on their biological effects are not sufficient. The behaviour of rare earths in biology is of interest in connection with their toxicity. In the present study, the distribution of rare earths in liver of mice administered with these elements was investigated. The effects on Ca and other biological essential elements were also determined. Male mice (5 weeks old) were injected with one of 12 kinds of rare earths (chlorides of Y, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Yb) at the dose of 25 mg/KXg body weight. After 20 hours of administration, mice were sacrificed, then liver and other organs were taken out. Liver was homogenized and separated by centrifugation. The concentrations of rare earths administered were measured by microwave-induced plasma-mass spectrometry (MIP-MS) after acid digestion. The concentrations of administered elements in whole liver were about 100μg/g (wet weight), where the difference between elements was few. Distribution amounts of elements administered in four fractions were following order; 700μg precipitate > mitocondrial fraction > microsomal fraction > cytosol. The relative contents in these fractions, however, was different depending on the element administered. Calcium concentrations in liver of administered mice were higher than those of control mice. Increase of Ca concentrations were observed in all four fractions and the increase ratio was also dependent on the elements administered

  2. Extraction of rare earths from iron-rich rare earth deposits

    OpenAIRE

    Bisaka, K.; Thobadi, I.C.; Pawlik, C.

    2017-01-01

    Rare earth metals are classified as critical metals by the United Nations, as they have found wide application in the fabrication of magnets, particularly those used in green energy technologies which mitigate global warming. Processing of ores containing rare earth elements is complex, and differs according to the nature of each ore. In the conventional process, run of mine (ROM) ores are processed in a physical separation plant to produce a concentrate from which rare earth elements are ext...

  3. Spectrofluorimetric characterization and study for the determination of rare earth carbonate complexes

    International Nuclear Information System (INIS)

    Dantas, E.S.K.; Abrao, A.

    1982-01-01

    Some rare earths exhibit fluorescence in acid solution (HC1, H 2 SO 4 or HC10 4 ) when irradiated with ultraviolet radiation; however, analytical application of this property has not been proposed due to the lack of sensitivity resulted from the weakness of the fluorescence transitions. The rare earths are soluble in alkali carbonate solutions, forming anionic carbonate complexes (TR(CO 3 ) sup(n-) sub(x)); some of them have stronger absorption bands than those obtained in acid media. Using this property, the characterization and determination of the six rare earths which fluoresce in carbonate solution has been studied. The excitation and emission wavelengths are (in nm): Sm (406, 596); Eu (280,612); Gd (272,312); Tb (240,542); Dy (350, 576) and Tm (360, 450). Although Ce-III is highly fluorescent in acid media, when in carbonate solution it is easily oxidized to Ce-IV which does not fluoresce neither in acid nor in carbonate solutions. The other rare earths, although soluble in carbonate solution, do not fluoresce in this medium. A comparison is made, between the fluorescence of the fluorescing lanthanides, in acid and carbonate media. The precision and accuracy of this method, the detection limit of all rare earths studied and the mutual interference of some of them is also discussed. The method will be applied to the analytical control of the separation and purification of individual rare earths, now under development. (Author) [pt

  4. Determination of active oxygen content in rare earth peroxides

    International Nuclear Information System (INIS)

    Queiroz, Carlos A.S.; Abrao, Alcidio

    1993-01-01

    The content of active oxygen in rare earth peroxides have been determined after the dissolution of the samples with hydrocloridic acid in the presence of potassium iodide. The free generated iodine is titrated with sodium thiosulfate using starch as indicator. The oxidation of iodide to the free iodine indicates the presence of a higher valence state rare earth oxide, until now specifically recognized for the oxides of cerium (Ce O 2 ), praseodymium (Pr 6 O 1 1) and terbium (TB 4 O 7 ). recently the authors synthesized a new series of rare earth compounds, the peroxides. These new compounds were prepared by precipitating the rare earth elements complexed with carbonate ion by addition of hydrogen peroxide. the authors demonstrated that all rare earth elements, once solubilized by complexing with carbonate ion, are quantitatively precipitated as peroxide by addition of hydrogen peroxide. (author)

  5. Application of liquid-liquid extraction in separation of rare earths [Paper No. : V-6

    International Nuclear Information System (INIS)

    Deshpande, S.M.; Krishnan, N.P.K.; Murthy, T.K.S.; Swaminathan, T.V.

    1979-01-01

    The rare earths consist of fifteen elements which have very similar chemical properties and are difficult to separate from each other. Since they exist together in all naturally occurring minerals their separation is one of the important and difficult aspects of their technology. Liquid-liquid extraction has proved to be an efficient technique for their separation. The two important extraction systems that find practical and large scale application, the nitric acid + tri-n-butyl phosphate, and mineral acid (particularly hydrochloric acid) + organo phosphoric acid (like di-2-ethyl hexyl phosphoric acid), are briefly reviewed. The factors affecting the extraction and separation of rare earths in the two systems are discussed. On an industrial scale the extraction process is very often employed for an initial concentration of the desired rare earths from complex mixtures. The final purification is generally achieved by the ion exchange method. The utility of the solvent extraction process for the upgrading of selected rare earths-europium, samarium and gadolinium-from a mixed rare earth chloride, derived from monazite, is illustrated by the work carried out in this laboratory and pilot plant operation at the Alwaye plant of M/s. Indian Rare Earths Ltd. (author)

  6. China's rare-earth industry

    Science.gov (United States)

    Tse, Pui-Kwan

    2011-01-01

    Introduction China's dominant position as the producer of over 95 percent of the world output of rare-earth minerals and rapid increases in the consumption of rare earths owing to the emergence of new clean-energy and defense-related technologies, combined with China's decisions to restrict exports of rare earths, have resulted in heightened concerns about the future availability of rare earths. As a result, industrial countries such as Japan, the United States, and countries of the European Union face tighter supplies and higher prices for rare earths. This paper briefly reviews China's rare-earth production, consumption, and reserves and the important policies and regulations regarding the production and trade of rare earths, including recently announced export quotas. The 15 lanthanide elements-lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium (atomic numbers 57-71)-were originally known as the rare earths from their occurrence in oxides mixtures. Recently, some researchers have included two other elements-scandium and yttrium-in their discussion of rare earths. Yttrium (atomic number 39), which lies above lanthanum in transition group III of the periodic table and has a similar 3+ ion with a noble gas core, has both atomic and ionic radii similar in size to those of terbium and dysprosium and is generally found in nature with lanthanides. Scandium (atomic number 21) has a smaller ionic radius than yttrium and the lanthanides, and its chemical behavior is intermediate between that of aluminum and the lanthanides. It is found in nature with the lanthanides and yttrium. Rare earths are used widely in high-technology and clean-energy products because they impart special properties of magnetism, luminescence, and strength. Rare earths are also used in weapon systems to obtain the same properties.

  7. Forced-flow chromatography of rare earths using sensitive spectrophometry

    International Nuclear Information System (INIS)

    Matsui, Masakazu; Aoki, Toru; Kumagai, Tetsu.

    1981-01-01

    The sensitive spectrophotometric method for the rare earth elements with xylenol orange in the presence of cetylpyridinium bromide was applied to the continuous detection system of liquid chromatography. Fourteen rare earth elements were completely separated within 130 min cation-exchange chromatography using 2-hydroxy-iso-butylic acid. The eluted ions were determined with absorption maxima of their complexes at around 610 nm. A linear relationship between the peak height and the amounts of rare earth elements was also obtained over the range 0.04 to 0.5 MU g. (author)

  8. Mechanochemical decomposition of monazite to assist the extraction of rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Wantae; Bae, Inkook; Chae, Soochun [Korea Institute of Geoscience and Mineral Resources, 92 Gwahang-no, Yuseong-gu, Daejeon 305-350 (Korea, Republic of); Shin, Heeyoung, E-mail: hyshin@kigam.re.k [Korea Institute of Geoscience and Mineral Resources, 92 Gwahang-no, Yuseong-gu, Daejeon 305-350 (Korea, Republic of)

    2009-11-03

    Mechanochemical decomposition by milling a mixture of monazite and sodium hydroxide powder and subsequent leaching by sulfuric acid for the extraction of rare earth elements at room temperature has been investigated. The milling of the mixture allows the mechanochemical formation of rare earth hydroxides and sodium phosphate as milling progresses. Nearly all the monazite is decomposed within 120 min under the present milling conditions. A 0.05N sulfuric acid solution enables us to improve the yield of each of La, Nd and Sm to around 85% or more in the powder milled for 120 min. Also, respective Ce and Pr yields of about 20% and 70% remain un-dissolved since they are changed into oxide forms during and after the milling operation. These rare earth oxides are mostly dissolved as the acid concentration increases to 5N. The yield of rare earth elements increases with increasing milling time. Thus mechanochemical milling plays a significant role in achieving high yield of rare earth elements from the leaching of the milled powder.

  9. Mechanochemical decomposition of monazite to assist the extraction of rare earth elements

    International Nuclear Information System (INIS)

    Kim, Wantae; Bae, Inkook; Chae, Soochun; Shin, Heeyoung

    2009-01-01

    Mechanochemical decomposition by milling a mixture of monazite and sodium hydroxide powder and subsequent leaching by sulfuric acid for the extraction of rare earth elements at room temperature has been investigated. The milling of the mixture allows the mechanochemical formation of rare earth hydroxides and sodium phosphate as milling progresses. Nearly all the monazite is decomposed within 120 min under the present milling conditions. A 0.05N sulfuric acid solution enables us to improve the yield of each of La, Nd and Sm to around 85% or more in the powder milled for 120 min. Also, respective Ce and Pr yields of about 20% and 70% remain un-dissolved since they are changed into oxide forms during and after the milling operation. These rare earth oxides are mostly dissolved as the acid concentration increases to 5N. The yield of rare earth elements increases with increasing milling time. Thus mechanochemical milling plays a significant role in achieving high yield of rare earth elements from the leaching of the milled powder.

  10. Rapid separation of individual rare-earth elements from fission products

    International Nuclear Information System (INIS)

    Baker, J.D.; Gehrke, R.J.; Greenwood, R.C.; Meikrantz, D.H.

    1980-01-01

    A microprocessor-controlled radiochemical separation system has been developed to rapidly separate rare-earth elements from gross fission products. The system is composed of two high performance liquid chromatography columns coupled in series by a stream-splitting injection valve. The first column separates the rare-earth group by extraction chromatography using dihexyldiethylcarbamylmethylenephosphonate (DHDECMP) adsorbed on Vydac C 8 resin. The second column isolates the individual rare-earth elements by cation exchange using Aminex A-9 resin with α-hydroxyisobutyric acid (α-HIBA) as the eluent. With this system, fission-product rare-earth isotopes with half-lives as short as three minutes have been studied

  11. Enhanced separation of rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, K. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Greenhalgh, M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Herbst, R. S. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Garn, T. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Welty, A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Soderstrom, M. D. [Cytec Solvay Group, Tempe, AZ (United States); Jakovljevic, B. [Cytec Solvay Group, Niagara Falls, ON (Canada)

    2016-09-01

    Industrial rare earth separation processes utilize PC88A, a phosphonic acid ligand, for solvent extraction separations. The separation factors of the individual rare earths, the equipment requirements, and chemical usage for these flowsheets are well characterized. Alternative ligands such as Cyanex® 572 and the associated flowsheets are being investigated at the pilot scale level to determine if significant improvements to the current separation processes can be realized. These improvements are identified as higher separation factors, reduced stage requirements, or reduced chemical consumption. Any of these improvements can significantly affect the costs associated with these challenging separation proccesses. A mid/heavy rare earth element (REE) separations flowsheet was developed and tested for each ligand in a 30 stage mixer-settler circuit to compare the separation performance of PC88A and Cyanex® 572. The ligand-metal complex strength of Cyanex® 572 provides efficient extraction of REE while significantly reducing the strip acid requirements. Reductions in chemical consumption have a significant impact on process economics for REE separations. Partitioning results summarized Table 1 indicate that Cyanex® 572 offers the same separation performance as PC88A while reducing acid consumption by 30% in the strip section for the mid/heavy REE separation. Flowsheet Effluent Compositions PC88A Cyanex® 572 Raffinate Mid REE Heavy REE 99.40% 0.60% 99.40% 0.60% Rich Mid REE Heavy REE 2.20% 97.80% 0.80% 99.20% Liquor Strip Acid Required 3.4 M 2.3 M Table 1 – Flowsheet results comparing separation performance of PC88A and Cyanex® 572 for a mid/heavy REE separation.

  12. Membrane assisted solvent extraction for rare earth element recovery

    Science.gov (United States)

    Bhave, Ramesh R.; Kim, Daejin; Peterson, Eric S.

    2018-05-15

    Systems and methods for the recovery of rare earth elements are provided. The systems and methods generally include membrane assisted solvent extraction using permeable hollow fibers having an immobilized organic phase within the pores of the hollow fibers. The permeable hollow fibers are generally in contact with an acidic aqueous feed on one side thereof and a strip solution on another side thereof. The systems and methods generally include the simultaneous extraction and stripping of rare earth elements as a continuous recovery process that is well suited for post-consumer products, end-of-life products, and other recovery sources of rare earth elements.

  13. Rare earths and rare earth alloys electrolytic preparation process and device for this process

    International Nuclear Information System (INIS)

    Seon, F.; Barthole, G.

    1986-01-01

    Electrolysis of a molten salt of rare earth or rare earth alloy for preparation of the metal or alloy is described. The molten salt bath comprises at least a rare earth chloride, at least an alkaline or alkaline earth chloride and at least an alkaline or alkaline earth fluoride [fr

  14. Rare earths: critical elements for various applications and challenges in their separation

    International Nuclear Information System (INIS)

    Singh, D.K.; Chakravartty, J.K.

    2015-01-01

    High purity rare earths oxides, metal and alloys find wide applications in high tech area such as nuclear energy, permanent magnets, materials for storing hydrogen, phosphors, laser, etc. Rare earths consists a group of 15 elements from La to Lu in the periodic table and it also includes Sc and Y. Due to similar chemical nature owing to common oxidation state of +3, rare earths are very difficult to separate from each other. They have very low separation factors with acidic extractants like D2EHPA and EHEHPA and hence require large number of stages in various cascade of extraction process. Monazite (a source of rare earths, thorium and uranium) is processed at IREL to separate rare earths from thorium and uranium. The rare earths are fractionated into three groups namely light rare earths (LRE), middle rare earths (MRE) and heavy rare earths (HRE) by solvent extraction method employing EHEHPA as extractant

  15. Rare earths as a future resource

    International Nuclear Information System (INIS)

    Cornell, D.H.

    1988-01-01

    The fourteen rare earth or lanthanide elements have recently emerged as an important natural resource because of the rapidly growing demand in the electronic, chemical and metallurgical industries. The Symposium on rare earth elements as a future resource presented a multidisciplinary review of rare earth chemistry, geology, beneficiation, industrial applications and marketing. Papers by experts in many fields were presented on the following topics: chemical properties of the rare earth elements; the analysis of rare earth elements and minerals; beneficiation and extraction of rare earth elements; economic geochemistry and mineralogy of rare earths; present industrial uses of rare earth elements; the role of rare earth elements in high-temperature superconductors; the technical application of high-temperature superconductors; supply and demand for rare earth products - now and in the future, and the geology of rare earth deposits

  16. Equilibrium and non-equilibrium extraction separation of rare earth metals in presence of diethylenetriaminepentaacetic acid in aqueous phase

    International Nuclear Information System (INIS)

    Azis, Abdul; Teramoto, Masaaki; Matsuyama, Hideto.

    1995-01-01

    Equilibrium and non-equilibrium extraction separations of rare earth metals were carried out in the presence of chelating agent in the aqueous phase. The separation systems of the rare earth metal mixtures used were Y/Dy, Y/Ho, Y/Er and Y/Tm, and the chelating agent and the extractant were diethylenetriaminepentaacetic acid (DTPA) and bis (2,4,4-trimethylpentyl) phosphinic acid (CYANEXR 272), respectively. For Y/Dy and Y/Ho systems, higher selectivities were obtained in equilibrium separation compared with those in non-equilibrium separation. On the other hand, the selectivities in non-equilibrium separation were higher for Y/Er and Y/Tm systems. In the separation condition suitable to each system, the addition of DTPA to the aqueous phase was found to be very effective for obtaining higher selectivities. The distribution ratios of the rare earth metals and the selectivities in the equilibrium separations obtained experimentally were thoroughly analyzed by considering various equilibria such as the extraction equilibrium and the complex formation equilibrium between rare earth metals and DTPA in the aqueous phase. Moreover, the extraction rates and the selectivities in the non-equilibrium separations were also analyzed by the extraction model considering the dissociation reactions of the rare earth metal-DTPA complexes in the aqueous stagnant layer. Based on these analyses, we presented an index which is useful for selecting the optimum operation mode. Using this index, we can predict that the selectivities under equilibrium conditions are higher than those under non-equilibrium conditions for Y/Dy and Y/Ho systems, while for Y/Er and Y/Tm systems, higher selectivities are obtained under non-equilibrium conditions. The experimental results were in agreement with predictions by this index. Further, the selectivities in various systems including other chelating agents and extractants were discussed based on this index. (J.P.N.)

  17. Rare earths 1998 market update

    International Nuclear Information System (INIS)

    Tourre, J.M.

    1998-01-01

    The rare earth industry has always been a world of rapid change with the emergence of new markets, new ores and new players, as well as the disappearance of old applications. Rare earth based products are used in a great diversity of applications such as hard disk drives, CD drives, batteries, capacitors, pigments, ceramics, polishing powders, fuel cells, flints, catalyst converter, fluid cracking catalysts, etc. South East Asia holds the largest share of the known reserve of rare earth ores and is one of the major markets for rare earth compounds; in the last ten years, China has become the largest producer of rare earth intermediates as well as an important exporter of separated rare earth elements. Today, China has approximately 150 factories producing rare earth compounds, most of which are experiencing financial difficulties due to the lack of knowledge of true market needs, lack of control of their distribution channels and production over-capacity. Recently the Chinese rare earth producers have recognized the situation and efforts are underway to rationalize rare earth production. Japan has dominated many of the major application markets, and is by far the largest market for metal and alloy products. This will remain the case for the next five years; however, new countries are emerging as significant users of rare earth products such as Korea, Taiwan and Malaysia. During the last ten years rare earth producers adjusted to several radical changes that affected the raw materials, the application mix and the price structure. New producers have emerged, especially from China; some have subsequently stopped their activities while others have focused their efforts in a specific market segment

  18. Rare earths: occurrence, production and applications

    International Nuclear Information System (INIS)

    Murthy, T.K.S.; Mukherjee, T.K.

    2002-01-01

    The mining and processing of rare earth minerals, particularly of monazite, began in a modest way in 1880s for commercialized production of mantle for gas lighting. For all major applications up to mid-twentieth century- production of lighter flints, misch metal as a metallurgical alloying agent, colouring, decolourizing and polishing agents for glass, petroleum cracking catalysts and arc-carbons, unseparated or partially separated rare earths were adequate. These applications continue till today. With the development and industrial application of powerful techniques like ion exchange and solvent extraction for the separation of rare earths, the decades after 1960 saw increasing utilization of the specific properties of the individual rare earths. Some of these advanced technological applications include: special glass for optical systems including camera lenses, phosphors for colour television, cathode ray tubes and fluorescent lighting, X-ray intensification screens, high intensity permanent magnets, electro optical devices, lasers, hydrogen storage materials, hydride rechargeable batteries, photomagnetic data storage systems, autoexhaust catalysts, special ceramics of unusual toughness, artificial diamonds and nonpoisonous plastic colorants. The topics covered in the book include rare earths: their story identity, rare earth resources, processing of ores and recovery of mixed rare earths products, separation and purification of rare earths, nonmetallic applications of rare earths, rare earth metals: production and applications, rare earth alloys and their applications, analysis of rare earth, processing of rare earth resources in India by Indian Rare Earth Ltd. and availability and market conditions

  19. Rare earth germanates

    International Nuclear Information System (INIS)

    Bondar', I.A.; Vinogradova, N.V.; Dem'yanets, L.N.

    1983-01-01

    From the viewpoint of structural chemistry and general regularities controlling formation reactions of compounds and phases in melts, solid and gaseous states, recent achievements in the chemistry of rare earth germanates are generalized. Methods of synthesizing germanates, systems on the base of germanium oxides and rare earths are considered. The data on crystallochemical characteristics are tabulated. Individual compounds of scandium germanate are also characterized. Processes of germanate formation using the data of IR-spectroscopy, X-ray phase analysis are studied. The structure and morphotropic series of rare earth germanates and silicates are determined. Fields of their present and possible future application are considered

  20. Radiological aspects in a monazite based rare earth production facility

    International Nuclear Information System (INIS)

    Harikumar, M.; Sujata, R.; Chinnaesakki, S.; Tripathi, R.M.; Puranik, V.D.; Nair, N.N.G.

    2011-01-01

    One of the largest reserves of monazite in the world is present in the Indian subcontinent. Monazite ore has around 8-9% thorium oxide and nearly 60% Rare earth oxides. Selective acid extraction is used to separate the composite rare earths. The main radiological hazard arises from the presence of thorium and its daughter products. Monitoring of the radiation field and air activity in the rare earths plant is done routinely to reduce the radiation exposure to plant personnel. The separation of uranium and rare earths from Thorium concentrate separated from Monazite is being done as a part of the THRUST (Thorium Retrieval, Recovery of Uranium and Re-storage of Thorium) project from 2004 at Indian Rare Earths Limited, Udyogamandal. The radiological aspect for this extraction of uranium and rare earths was studied. The general radiation field in the rare earth production plant was 0.3-5.0 μGyh -1 and the average short lived air activity was 46 ± 7 mWL. The long lived air activity arising from 232 Th is very insignificant radiologically. The occupational radiation exposure for the rare earths separation plant is only 6 % of the total dose and the estimated average individual dose is 1.6 mSv per year. Studies were also done to estimate the residual radioactivity in the separated rare earth compounds using gamma spectrometry and the results showed significant presence of 227 Ac arising due to the protactinium fraction in the thorium concentrate. This activity is not detectable in a freshly separated rare earth compound but can buildup with time. (author)

  1. The Chinese Society of Rare Earth is Studying The Feasibility of Marketing Rare Earth Futures

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    Lin Donglu,secretary-general of the Chinese Society of Rare Earth recently said,the Chinese Society of Rare Earth undertook the research on subject of the National Social Science Fund Foundation on the reform of Chinese rare earth trading pricing mechanism on promoting RMB globalization,and is focusing on studying the feasibility of marketing rare earth futures variety.

  2. Bench scale studies on separation of rare earths by ion exchange

    International Nuclear Information System (INIS)

    Aroonrung-Areeya, A.

    1976-01-01

    The method of ion exchange was applied to the separation of mixtures of rare earth oxides into the pure components. The method consists of eluting a band of mixed rare earths adsorbed on a cation-exchange resin through a second cation-exchange bed in the copper II state. The eluent consists of an ammonia buffered solution of ethylenediamine tetraacetic acid. The mixed rare earth oxide used as testing material was obtained from the digestion of Thai monazite. The amounts varied from 1, 5 to 50 grams. The purity of the rare earth fractions were analyzed either by neutron activation of X-ray fluorescence. The Cu.EDTA was recovered by the addition of lime. It was found that gram quantities of pure rare earths could be obtained by this method

  3. Synthesis and investigation of some physicochemical properties of rare earth nitrobarbiturates

    International Nuclear Information System (INIS)

    Biryulina, V.N.; Chupakhina, R.A.; Serebrennikov, V.V.

    1984-01-01

    Crystal depositions of L 3 MnH 2 O composition where L is anion of nitrobarbituric acid C 4 H 2 N 3 O 5 - ; M is rare earth ion excluding Ce 3+ and Pm 3+ ; n=12 are extracted under dissolution of freshly prepared hydroxides of rare earth elements (REE) in ethanol aqueous solution of nitrobarbituric acid. The method of IR spectroscopy has been applied to disclose relation of rare earth ion with groups of C=0 acid. The method of derivatography has been used to study thermolysis of REE nitrobarbiturates; dehydration proceeds in two stages with decrease of temperature of the beginning of dehydration by 20 deg C in the La 3+ → Lu 3+ series. The curve of dependence of REE nitrobarbiturate solubility in water at 25 deg C on serial number of REE passes through the minimum accounted for Sm 3+

  4. Rare earths and actinides

    International Nuclear Information System (INIS)

    Coqblin, B.

    1982-01-01

    This paper reviews the different properties of rare-earths and actinides, either as pure metals or as in alloys or compounds. Three different cases are considered: (i) First, in the case of 'normal' rare-earths which are characterized by a valence of 3, we discuss essentially the magnetic ordering, the coexistence between superconductivity and magnetism and the properties of amorphous rare-earth systems. (ii) Second, in the case of 'anomalous' rare-earths, we distinguish between either 'intermediate-valence' systems or 'Kondo' systems. Special emphasis is given to the problems of the 'Kondo lattice' (for compounds such as CeAl 2 ,CeAl 3 or CeB 6 ) or the 'Anderson lattice' (for compounds such as TmSe). The problem of neutron diffraction in these systems is also discussed. (iii) Third, in the case of actinides, we can separate between the d-f hybridized and almost magnetic metals at the beginning of the series and the rare-earth like the metals after americium. (orig.)

  5. Safety aspects in rare earths recovery

    International Nuclear Information System (INIS)

    Bhattacharya, R.

    2014-01-01

    Recovery of rare earths involves mining of beach sands, mineral separation to obtain monazite and its chemical processing to obtain rare earth composites. The composites are then subjected to further chemical treatment to obtain individual rare earths. Although the separated out rare earths are not radioactive, the process for recovery of rare earths involve both radiological as well as conventional hazards. This paper highlights the safety aspects in the mining, mineral separation and chemical processing of monazite to obtain rare earths

  6. Separation of heavier rare earths from neutron irradiated uranium targets

    International Nuclear Information System (INIS)

    Bhargava, V.K.; Rao, V.K.; Marathe, S.G.; Sahakundu, S.M.; Iyer, R.H.

    1978-01-01

    A radiochemical method is described for the separation of heavier rare earths from the fission of uranium. The method is particularly suitable for the separation of low yield (10sup(-5)%-10sup(-7)%), highly asymmetric rare earth fission products viz. sup(179,177)Lu, sup(175)Yb, sup(173)Tm, sup(172,171)Er, sup(167)Ho and sup(161,160)Tb in the neutron induced fission of natural and depleted uranium targets. Additional separation steps have been incorporated for decontamination from sup(239)Np (an activation product) and sup(93-90)Y (a high fission-yield product) which show similar chemical behaviour to rare earths. Separation of individual rare earths is achieved by a cation exchange method performed at 80 deg C by elution with α-hydroxyisobutyric acid (α-HIBA). (author)

  7. Recovery of uranium and of rare earths from Moroccan phosphates

    International Nuclear Information System (INIS)

    Ezahr, I.; El Houari, A.; Smani, S.M.

    1984-01-01

    The contents of uranium and of rare earths in Moroccan phosphates vary from 75 to 250 ppm and from 900 to 1500 ppm, respectively. The phosphates produced in Morocco contain therefore about 2500 t of uranium and 25 000 t of rare earths, compared with annual productions of uranium and of rare earths of 43 000 t and 33 000 t, respectively. During the sulphuric leaching of the phosphate ores, uranium is found to 80-90% in the phosphoric acid. Research into the extraction of uranium has shown that for the phosphoric acids produced at Safi the coefficient of extraction: is not very sensitive to the P 2 O 5 concentration on the 28-30% region; is not affected by the sulphur level up to the concentration of 4%; is very sensitive to the fluorine content beyond 1%. On the level of the first cycle of the process in Depa-Topo, four extraction stages permit a yield of between 92 and 98% to be reached. The addition of an oxidizing agent to the phosphoric acids under examination was not necessary, as their potential level is high. The purity of the yellow-cakes obtained varies from 94 to 99%. The overall recovery efficiency lies between 67 and 71%. In a second part, this paper deals with the recovery of the rare earths [fr

  8. Neutron activation analysis of rare earths in uranium containing rocks

    International Nuclear Information System (INIS)

    May, S.; Pinte, G.

    1984-01-01

    The determination of rare earths by activation analysis in uranium rocks is disturbed either by fission-produced rare earths, or by neptunium-239 originating from uranium-238. In order to eliminate these interferencies, the chemical separation of rare earths from uranium prior to activation should be performed. The chemical process is as follows: the rock sample is fused with sodium borate, then, after addition of hydrochloric acid, the resulting solution is passed through a Dowex 1x8 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 earth radionuclide. Activity measurements are performed in successive steps during one month. The following elements are determined: Pr, La, Sm, Nd, Yb, Lu, Ce, Tb, Eu and Sc. The chemical yield is measured by using scandium as an internal standard. (author)

  9. Intra-group separation of rare earths using new organic phosphorus ligands

    International Nuclear Information System (INIS)

    Hadic, Sanela

    2017-01-01

    Rare earth elements (REE) have unique magnetic, photophysical, and chemical properties and they are therefore used in numerous high-technology applications. However, to this day, the isolation of pure rare earths from primary and secondary raw materials is very challenging. In this work, the hydrometallurgical separation of neighboring rare earths (e.g., praseodymium/ neodymium) was optimized with novel selective extraction agents. The separation of rare earths (yttrium and all lanthanides except promethium) was investigated with fourteen new organophosphorus compounds. Oxygen-bearing phosphinic acids yielded good separation results for heavy rare earths (dysprosium to lutetium). For light rare earths (lanthanum to neodymium), particularly high separation factors were realized with synergistic systems containing an aromatic dithiophosphinic acid and a co-extractant, such as tris (2-ethylhexyl) phosphate (TEHP). Optimization studies of the latter extraction system revealed an extremely high separation factor (SF) of 4.21 between praseodymium and neodymium. Another focus of this work was to understand the extraction mechanism. With the aid of nuclear magnetic resonance spectroscopy ("1H-NMR) and time-resolved laser fluorescence spectroscopy (TRLFS), the complex stoichiometry of promising extraction systems was examined. Studies revealed a dependency between the selectivity for rare earths and the coordination number of the formed complexes. In addition, temperature-dependent extraction experiments were performed and thermodynamic data (ΔG, ΔH, and ΔS) determined. These data provided additional information about the origin of selectivity for neighboring rare earths. With regard to the industrial capability of the investigated extraction systems, the chemical durability of ligands was studied under process-relevant conditions. Qualitative and quantitative analytical methods (e.g., GC-MS) were used in long-term experiments to determine the ligand degradation. After

  10. Origin of middle rare earth element enrichments in acid waters of a Canadian high Arctic lake.

    Science.gov (United States)

    Johannesson, Kevin H.; Zhou, Xiaoping

    1999-01-01

    -Middle rare earth element (MREE) enriched rock-normalized rare earth element (REE) patterns of a dilute acidic lake (Colour Lake) in the Canadian High Arctic, were investigated by quantifying whole-rock REE concentrations of rock samples collected from the catchment basin, as well as determining the acid leachable REE fraction of these rocks. An aliquot of each rock sample was leached with 1 N HNO 3 to examine the readily leachable REE fraction of each rock, and an additional aliquot was leached with a 0.04 M NH 2OH · HCl in 25% (v/v) CH 3COOH solution, designed specifically to reduce Fe-Mn oxides/oxyhydroxides. Rare earth elements associated with the leachates that reacted with clastic sedimentary rock samples containing petrographically identifiable Fe-Mn oxide/oxyhydroxide cements and/or minerals/amorphous phases, exhibited whole-rock-normalized REE patterns similar to the lake waters, whereas whole-rock-normalized leachates from mafic igneous rocks and other clastic sedimentary rocks from the catchment basin differed substantially from the lake waters. The whole-rock, leachates, and lake water REE data support acid leaching or dissolution of MREE enriched Fe-Mn oxides/oxyhydroxides contained and identified within some of the catchment basin sedimentary rocks as the likely source of the unique lake water REE patterns. Solution complexation modelling of the REEs in the inflow streams and lake waters indicate that free metal ions (e.g., Ln 3+, where Ln = any REE) and sulfate complexes (LnSO 4+) are the dominant forms of dissolved REEs. Consequently, solution complexation reactions involving the REEs during weathering, transport to the lake, or within the lake, cannot be invoked to explain the MREE enrichments observed in the lake waters.

  11. Distribution of rare earth elements in an alluvial aquifer affected by acid mine drainage: the Guadiamar aquifer (SW Spain)

    International Nuclear Information System (INIS)

    Olias, M.; Ceron, J.C.; Fernandez, I.; Rosa, J. de la

    2005-01-01

    This work analyses the spatial distribution, the origin, and the shale-normalised fractionation patterns of the rare earth elements (REE) in the alluvial aquifer of the Guadiamar River (south-western Spain). This river received notoriety in April 1998 for a spill that spread a great amount of slurry (mainly pyrites) and acid waters in a narrow strip along the river course. Groundwaters and surface waters were sampled to analyse, among other elements, the REEs. Their spatial distribution shows a peak close to the mining region, in an area with low values of pH and high concentrations of sulphates and other metals such as Zn, Cu, Co, Ni, Pb, and Cd. The patterns of shale-normalised fractionation at the most-contaminated points show an enrichment in the middle rare earth elements (MREE) with respect to the light (LREE) and heavy (HREE) ones, typical of acid waters. The Ce-anomaly becomes more negative as pH increases, due to the preferential fractionation of Ce in oxyhydroxides of Fe. - Pollution of the aquifer with rare earth elements is documented at a site of a major spill from a mining operation

  12. Study of complexing of rare earths with ethylenediaminedisuccinic acid by the method of pH-metric titration

    International Nuclear Information System (INIS)

    Muratova, N.M.; Martynenko, L.I.

    1979-01-01

    The pH-metric titration technique was used to study the possibility of formation of higher complexes between rare earth elements of the whole series and ethylenediaminedisuccinic acid (L). The logarithms of stability constants were determined for LaL - (10.95), PrL - (11.30), NdL - (11.35), ErL 2 5- (4.10), TuL 2 5- (4.00), YbL 2 5- (4.25) and LnL 2 5- (4.8). In the concentrations studied only heavy lanthanides were forming unstable bis-ethylenediaminedisuccinates. Lighter rare earth elements did not form higher complexes even when the ligand was in four-fold excess; however, the complexes did appear in more concentrated solutions

  13. Possibility study of use rare earth deposit from Araxa, Minas Gerais State

    International Nuclear Information System (INIS)

    Fernandes, M.D.

    1975-01-01

    Prospecting work done by Instituto de Pesquisas Radioativas on the Barreiro area (Araxa, M.G.) has shown the existence of a rare earth deposit of about 700.000 ton, averaging 13,5 % rare earth oxide, mainly associated to the mineral monazite. In a first stage, the conventional mineral dressing methods were tried to treat the monazite. This was followed by a study of a chemical process for the production of rare earth compounds of commercial grade. The conventional methods of mineral dressing tested did not lead to satisfactory results. This was assumed to be due to insufficient liberation of the monazite. However, the application of the chemical process to the natural material, using concentrated sulfuric acid in the initial attack, allowed more than 90% rare earth extraction and a subsequent yield of commercial grade rare earth oxide, with over 75% rare earth recovery. (author)

  14. Ion associates of rare earth elements with salicylic acid derivatives and rhodamine B and their analytical application

    Energy Technology Data Exchange (ETDEWEB)

    Tselik, E I; Poluehktov, N S; Mishchenko, V T [AN Ukrainskoj SSR, Odessa. Fiziko-Khimicheskij Inst.

    1979-10-01

    The determination of rare earth elements by extraction photometry (fluorimetric) technique with the use of salicylic acid derivatives and Rhodamine B is reported. The best results in the determination of REE in the form of ionic associates between their acidocomplexes and Rhodamine B are obtained with the use of 3,5-diiodinesalicylic acid. The ratio between components in the compounds formed and the conditions of extraction are determined.

  15. An improved ion-exchange separation of rare-earth elements for spectrographic analysis

    International Nuclear Information System (INIS)

    Jones, E.A.

    1978-01-01

    Rare-earth elements are separated from scandium and base metals by adsorption onto anion resin BIORAD AG1-X8 in the nitrate form from a mixture of 5 per cent 7M nitric acid and 95 per cent methanol. The yttrium subgroup is eluted with a mixture of 45 per cent 7M nitric acid and 55 per cent methanol, followed by elution of the cerium subgroup with 8M nitric acid. This separation facilitates the determination of the traces of the heavier yttrium subgroup of rare-earth elements

  16. Raman scattering of rare earth hexaborides

    International Nuclear Information System (INIS)

    Ogita, Norio; Hasegawa, Takumi; Udagawa, Masayuki; Iga, Fumitoshi; Kunii, Satoru

    2009-01-01

    Raman scattering spectra were measured for the rare-earth hexaborides RB 6 (R = Ce, Gd, or Dy). All Raman-active phonons due to B 6 vibrations were observed in the range 600 - 1400 cm -1 . Anomalous peaks were detected below 200 cm -1 , which correspond to vibrations of rare-earth ion excited by second-order Raman scattering process. The intensity and energy of the rare-earth mode decrease with decreasing temperature. This suggests that the rare-earth ion vibrates in a shallow and anharmonic potential due to the boron cage. Using the reported values of mean square displacement of rare-earth ion, we estimated the anharmonic contribution for the rare-earth vibrations.

  17. Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system

    International Nuclear Information System (INIS)

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

    2013-01-01

    Highlights: • Recycling of rare earth metals from fluorescent lamps was conducted by ionic liquid-mediated extraction. • Acid leaching from a waste phosphor powder was carried out using sulfuric and nitric acids. • An ionic liquid was used as extracting solvent for the rare earth metals. • Selective extraction of rare earth metals from leach solutions was attained. •The extracting ionic liquid phase was recyclable in the recovery process. -- Abstract: The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid–liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system

  18. Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Kamiya, Noriho [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Center for Future Chemistry, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Goto, Masahiro, E-mail: m-goto@mail.cstm.kyushu-u.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Center for Future Chemistry, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan)

    2013-06-15

    Highlights: • Recycling of rare earth metals from fluorescent lamps was conducted by ionic liquid-mediated extraction. • Acid leaching from a waste phosphor powder was carried out using sulfuric and nitric acids. • An ionic liquid was used as extracting solvent for the rare earth metals. • Selective extraction of rare earth metals from leach solutions was attained. •The extracting ionic liquid phase was recyclable in the recovery process. -- Abstract: The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid–liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system.

  19. Some features of transplutonium and rare earth elements extraction by HDEHP from lactic acid solutions

    International Nuclear Information System (INIS)

    Nikolaev, V.M.; Lebedev, V.M.; Lebedeva, L.S.

    1986-01-01

    The mechanisms of transplutonium (TPE) and rare earth elements (REE) extraction by HDEHP from lactic acid solutions are analysed in the literature. On the base of the known expressions and experimental data the model for TPE and REE extraction by HDEHP from lactic acid, accounting lactic acid and metal extraction as MeA 3 x3HA, MeLA 2 x2HA and MeLA 2 complexes, is suggested. The expression, permitting to estimate quantitatively the effect of TPE and REE complexing with lactic acid and the extraction of complex forms on the distribution coefficient of the extracted metal, is obtained. Comparison of calculational data with experimental ones show their good coincidence that confirms the rightness of the model accepted for extraction

  20. Advanced system for separation of rare-earth fission products

    International Nuclear Information System (INIS)

    Baker, J.D.; Gehrke, R.J.; Greenwood, R.C.; Meikrantz, D.H.

    1982-01-01

    A microprocessor-controlled radiochemical separation system has been further advanced to separate individual rare-earth elements from mixed fission products in times of a few minutes. The system was composed of an automated chemistry system fed by two approximately 300 μg 252 Cf sources coupled directly by a He-jet to transport the fission products. Chemical separations were performed using two high performance liquid chromatography columns coupled in series. The first column separated the rare-earth group by extraction chromatography using dihexyldiethylcarbamoylmethylphosphonate (DHDECMP) adsorbed on Vydac C 8 resin. The second column isolated the individual rare-earth elements by cation exchange chromatography using Aminex A-9 resin with α-hydroxyisobutyric acid (α-HIBA) as the eluent. Significant results, which have been obtained to date with this advanced system, are the identification of several new neutron-rich rare-earth isotopes including 155 Pm (T=48+-4 s) and 163 Gd (T=68+-3 s). In addition, a half-life of 41+-4 s is reported for 160 Eu. (author)

  1. Dissolution of the rare-earth mineral bastnaesite by acidic amide ionic liquid for recovery of critical

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Sheng [Chemical Science Division, Oak Ridge, TN (United States); Freiderich, John W. [Chemical Science Division, Oak Ridge, TN (United States); Luo, Huimin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Moyer, Bruce A. [Chemical Science Division, Oak Ridge, TN (United States); Stankovich, Joseph J. [Chemical Science Division, Oak Ridge, TN (United States)

    2015-08-19

    Rare-earth elements provide the cornerstones to clean sustainable energy and modern technologies such as computers, communications, and transportation. As such, the recovery of rare earths (REs) from minerals such as bastnaesite remains important for modern times. As the light lanthanides (La–Nd) constitute the majority (typically > 98.7 %) of the REs in bastnaesite with the heavy REs (Sm–Lu) contributing the remainder (approximately 1.3 %), an enrichment of heavier REs may serve as an effective means of assisting rare-earth recovery. Such an extractive metallurgy process involving ionic liquids (ILs) leads to an enrichment of heavy REs by nearly an order of magnitude. The acidic IL N,N-dimethylacetamidium bis(trifluoromethylsulfonyl)imide (DMAH+NTf2) in the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM+NTf2) dissolves froth flotation bastnaesite, synthetic bastnaesite analogues (RECO3F), RE2O3, and RE2(CO3)3 minerals. Furthermore, an overall reaction for the dissolution of bastnaesite is proposed for this IL system. This IL system may provide the initial stages of a greater RE separation scheme for bastnaesite froth flotation concentrates.

  2. Metallothermic reduction of rare earth oxides

    International Nuclear Information System (INIS)

    Sharma, R.A.

    1986-01-01

    Rare earth oxides can be reduced to rare earth metals by a novel, high yield, metallothermic process. The oxides are dispersed in a suitable, molten, calcium chloride bath along with sodium metal. The sodium reacts with the calcium chloride to produce calcium metal which reduces the rare earth oxides to rare earth metals. The metals are collected in a discrete layer in the reaction vessel

  3. Rare earth industries: Downstream business

    International Nuclear Information System (INIS)

    2011-01-01

    The value chain of the rare earths business involves mining, extraction, processing, refining and the manufacture of an extensive range of downstream products which find wide applications in such industries including aerospace, consumer electronics, medical, military, automotive, renewable wind and solar energy and telecommunications. In fact the entire gamut of the high-tech industries depends on a sustainable supply of rare earths elements. The explosive demand in mobile phones is an excellent illustration of the massive potential that the rare earths business offers. In a matter of less than 20 years, the number of cell phones worldwide has reached a staggering 5 billion. Soon, going by the report of their growth in sales, the world demand for cell phones may even exceed the global population. Admittedly, the rare earths business does pose certain risks. Top among the risks are the health and safety risks. The mining, extraction and refining of rare earths produce residues and wastes which carry health and safety risks. The residues from the extraction and refining are radioactive, while their effluent waste streams do pose pollution risks to the receiving rivers and waterways. But, as clearly elaborated in a recent report by IAEA experts, there are technologies and systems available to efficiently mitigate such risks. The risks are Rare Earth manageable. However, it is crucial that the risk and waste management procedures are strictly followed and adhered to. This is where effective monitoring and surveillance throughout the life of all such rare earths facilities is crucial. Fortunately, Malaysia's regulatory standards on rare earths follow international standards. In some areas, Malaysia's regulatory regime is even more stringent than the international guidelines. (author)

  4. Rare earth industries: Strategies for Malaysia

    International Nuclear Information System (INIS)

    2011-01-01

    Evidently, many reports cite Malaysia as having reasonably substantial amounts of rare earths elements. In fact, based on the rare earths found in the residual tin deposits alone, Malaysia has about 30,000 tonnes. This does not take into account unmapped deposits which experts believe may offer more tonnages of rare earths. Brazil which is reported to have about 48,000 tonnes has announced plans to invest aggressively in the rare earths business. China has on record the largest reserves with about 36 million tonnes. This explains why China has invested heavily in the entire value chain of the rare earths business. Chinas committed investment in rare earths started many years ago when the country's foremost leaders proclaimed the strategic position of rare earths in the world economy. That forecast is now a reality where the rise in the green high-tech economy is seen driving global demand for rare earths in a big way. Malaysia needs to discover and venture into new economic growth areas. This will help fuel the country's drive to achieve a high income status by 2020 as articulated in the New Economic Model (NEM) and the many supporting Economic Transformation Plans that the Government has recently launched. Rare earths may be the new growth area for Malaysia. However, the business opportunities should not just be confined to the mining, extraction and production of rare earths elements alone if Malaysia is to maximise benefits from this industry. The industry's gold mine is in the downstream products. This is also the sector that China wants to expand. Japan which now controls about 50 % of the global market for downstream rare earths-based high-tech components is desperately looking for partners to grow their stake in the business. Malaysia needs to embark on the right strategies in order to build the rare earths industry in the country. What are the strategies? (author)

  5. Hydrochloric acid leaching of uranium, thorium, radium and rare-earth elements, from an Elliot lake radioactive ore

    International Nuclear Information System (INIS)

    Mahdy, M.A.

    1988-01-01

    Extraction of uranium by commercial methods using sulphuric acid developed a lot of environmental problems. To avoid such problems, other uranium extraction techniques have been adopted including fluorination, chlorination, chlorine assisted leaching, hydrochloric acid leaching, etc. This work is oriented towards the study of the factors controlling the hydrochloric acid leaching. The target of the study is to extract the total amount of U, Th, Ra-226 and rare earth elements. By using a suitable combination of the leaching factors, it was possible to achieve the designed target

  6. Fabrication of Superhydrophobic and Luminescent Rare Earth/Polymer complex Films.

    Science.gov (United States)

    Wang, Zefeng; Ye, Weiwei; Luo, Xinran; Wang, Zhonggang

    2016-04-18

    The motivation of this work is to create luminescent rare earth/polymer films with outstanding water-resistance and superhydrophobicity. Specifically, the emulsion polymerization of styrene leads to core particles. Then core-shell-structured polymer nanoparticles are synthesized by copolymerization of styrene and acrylic acid on the core surface. The coordination reaction between carboxylic groups and rare earth ions (Eu(3+) and Tb(3+)) generates uniform spherical rare earth/polymer nanoparticles, which are subsequently complexed with PTFE microparticles to obtain micro-/nano-scaled PTFE/rare earth films with hierarchical rough morphology. The films exhibit large water contact angle up to 161° and sliding angle of about 6°, and can emit strong red and green fluorescence under UV excitation. More surprisingly, it is found that the films maintain high fluorescence intensity after submersed in water and even in aqueous salt solution for two days because of the excellent water repellent ability of surfaces.

  7. Rare earth-iron-boron premanent magnets

    International Nuclear Information System (INIS)

    Ghendehari, M.H.

    1988-01-01

    This patent describes a method for producing rare earth-iron-boron permanent magnets containing added rare earth oxide, comprising the steps of: (a) mixing a particulate alloy containing at least one rare earth metal, iron, and boron with at least one particulate rare earth oxide; (b) aligning magnetic domains of the mixture in a magnetic field; (c) compacting the aligned mixture to form a shape; and (d) sintering the compacted shape

  8. The industry of metallic rare earths (R.E.)

    International Nuclear Information System (INIS)

    Poirier, P.

    1979-01-01

    The following subjects are discussed: rare earths resources (rare earths abondance and world reserves, main ores). Rare earths separation and purification (ionic exchange, solvent extraction). Metallic rare earths and their mixtures, metallothermic reduction of oxides or fluorides (Ca, Mg, Al, Si or rare earth metals), Co-reduction process for intermetallic compounds (SmCo 5 ). Industrial applications of metallic rare earths (traditional applications such as flints, nodular cast iron, steel refining, magnesium industrie, applications under development such as rare earths/cobalt magnets, LaNi 5 for hydrogen storage, special alloys (automotive post combustion), magnetostrictive alloys). Economical problems: rare earth are elements relatively abundant and often at easily accessible prices. However, this group of 15 elements are liable to certain economical restraints. It is difficult to crack ore for only one rare earth. Availability of one given rare earth must be associated with the other corresponding rare earths to absorb all the other rare earths in other applications. Rare-earth industry has a strong expanding rate. 20% per year average for 6 years with Rhone-Poulenc. Thanks to their exceptional, specific characteristics rare earths have a bright future particularly for their metals

  9. Rare earth elements: end use and recyclability

    Science.gov (United States)

    Goonan, Thomas G.

    2011-01-01

    Rare earth elements are used in mature markets (such as catalysts, glassmaking, lighting, and metallurgy), which account for 59 percent of the total worldwide consumption of rare earth elements, and in newer, high-growth markets (such as battery alloys, ceramics, and permanent magnets), which account for 41 percent of the total worldwide consumption of rare earth elements. In mature market segments, lanthanum and cerium constitute about 80 percent of rare earth elements used, and in new market segments, dysprosium, neodymium, and praseodymium account for about 85 percent of rare earth elements used. Regardless of the end use, rare earth elements are not recycled in large quantities, but could be if recycling became mandated or very high prices of rare earth elements made recycling feasible.

  10. Potentiometric study of rare earth complexing with trans-1,2-diaminocyclohexane-N,N'-dimalonic acid

    International Nuclear Information System (INIS)

    Smirnova, T.I.; Gorelov, I.P.

    1980-01-01

    Complexing of rare earths (Ln) and yttrium with trans-1,2-diaminocyclohexane-N, N'-dimalonic acid in aqueous solutions is studied using indirect potentiometric method with an aid of stationary mercury electrode and by the method of pH-potentiometric titration. It is shown that in the investigated solutions the LnL - and LnL 2 5- complexes are formed. At 25 deg C and ion force 0.1 stability constants of the complexes detected are determined [ru

  11. Recovery of rare earth minerals, with emphasis on flotation process

    International Nuclear Information System (INIS)

    Houot, R.; Cuif, J.P.; Mottot, Y.; Samama, J.C.

    1991-01-01

    Bastnasite and monazite are the two major minerals used commercially to supply most of the rare earths. Monazite is often a by-product of the concentration of heavy minerals of zirconium and titanium in beach sands. Thus, the methods of concentration are gravity (spirals, Reichert cones and shaking tables), ending with magnetism, electrostatic and in certain cases, flotation. The two main deposits of bastnasite are Mountain Pass (U.S.A.) and Bayan Obo (China). The rock bastnasite content is within 15% and the recovery of rare earth minerals is made through flotation. The flowsheets are complex enough because the existence of accompanying minerals such as quartz, iron components, barite, fluorite, calcite, etc. The conditioning is done by heating and the frequently employed collector is a fatty acid associated with selective agents, as sodium silicate or fluosilicate, lignin sulphonate, sodium carbonate, aluminium salts, etc. Recent studies tempt to introduce the use of phosphoric esters, dicarboxilic, sulphonic and/or sulphosuccinic acids. Concentrates with 60% REO are then treated with acidic solution to eliminate residual calcite. The possibility of obtaining products enriched with rare earths are also noted: these are ores of uranium (Elliot Lake), pyrochlore, apatite, and other complex ores with euxenite, fergusonite or loparite. (author) 10 figs., 6 tabs., 57 refs

  12. Tetracyanidoborates with triply charged rare earth metal cations and their optical properties

    International Nuclear Information System (INIS)

    Hackbarth, Liisa

    2015-01-01

    The aim of this thesis is the description of the synthesis and characterization of a new group of tetracyanidoborates: tetracyanidoborates with trivalent rare earth metal cations. Their optical properties in the ultraviolet and visible range are also discussed. Common synthetic routes for tetracyanidoborates are adapted and applied to the preparation of the rare earth tetracyanidoborate hydrates. They are accessible with high yields and high purity through a reaction between the tetracyanidoboronic acid and rare earth hydroxides. It is shown that the rare earth tetracyanidoborates form isostructural groups, like the [LRE(H_2O)_5][B(CN)_4]_3.0.5 H_2O, where LRE"3"+ is La, Ce, Pr, Nd, Sm, Eu and Gd, the [HRE(H_2O)_7][B(CN)_4]_3 and the [HRE(H_2O)_8][B(CN)_4]_3.3 H_2O, where HRE"3"+ is Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. Furthermore, the coordination number 9 is noticed to be common among the light rare earth cations, whereas the minor coordination number 8 is prevalent for the heavy rare earth cations in their tetracyanidoborates. This different construction of the coordination spheres between light and heavy rare earth cations leads to different structures depending on the energetic efficiency of the structural arrangement. Generally, the rare earth tetracyanidoborate hydrates are found to crystallize in the monoclinic crystal system. Moreover, other different crystal structures are observed depending on the crystallization temperature and the type of coordinated ligands and co-crystallized solvent molecules. The tetracyanidoborate hydrates with triply charged rare earth cations are characterized comprehensively by X-ray diffraction, vibrational spectroscopy, NMR-spectroscopy as well as by thermal analysis. Furthermore, the optical properties of some dehydrated rare earth tetracyanidoborates are investigated by UV-spectroscopy and luminescence measurements. The results of the optical measurements indicate that the tetracyanidoborates with rare earth metal cations

  13. Recovering heavy rare earth metals from magnet scrap

    Science.gov (United States)

    Ott, Ryan T.; McCallum, Ralph W.; Jones, Lawrence L.

    2017-08-08

    A method of treating rare earth metal-bearing permanent magnet scrap, waste or other material in a manner to recover the heavy rare earth metal content separately from the light rare earth metal content. The heavy rare earth metal content can be recovered either as a heavy rare earth metal-enriched iron based alloy or as a heavy rare earth metal based alloy.

  14. Optimization of leaching process for sum of rare earth and calcium oxides

    International Nuclear Information System (INIS)

    Troyanier, L.S.; Elunkina, Z.A.; Nikonov, V.N.; Lobov, V.I.

    1978-01-01

    Presented are the results of investigation of leaching process for rare earth and calcium oxides by sulfuric acid. The method of planning experiment has been used for this investigation. Mixtures of cerium, yttrium and neodyum oxides, taken in the relation of 1:1:0.5, have been used as rare earth elements. Received are adequate models characterizing dependence of solubility of rare earth and calcium oxides on some factors (H 2 SO 4 concentration, CaO:R 2 O 3 relation, liquid to solid ratio, solution temperature, mixing time). Dependences of solubility of rare earth elements and calcium on the process parameters are received and presented in a form of regression equations. Dependences received can be used for choice of optimum regime of the process as well as for its control

  15. Procedure for the separation of cerium from rare earth phosphate mixtures

    International Nuclear Information System (INIS)

    Richter, H.; Grauss, H.; Schmitt, A.; Schade, H.; Lindeholz, M.; Lorenz, E.; Weickart, J.

    1986-01-01

    The invention is concerned with a procedure for the separation of cerium from rare earth concentrates originating from the partial neutralization of nitric crude phosphate decomposition solutions without preceding elimination of impurities from the raw material. The rare earth phosphates are treated with an excess of concentrated nitric acid through which the Ce 3+ , contained in the solution, is oxidized to Ce 4+ and precipitated as cerium(IV) phosphate by neutralization with alkalis

  16. Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system.

    Science.gov (United States)

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

    2013-06-15

    The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid-liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Trace recovery of uranium and rare earth contained in phosphates by liquid-liquid extraction in sulfuric attack liquor

    International Nuclear Information System (INIS)

    Bousquet, F.; Foraison, D.; Leveque, A.; Sabot, J.L.

    1980-06-01

    Uranium and rare earths can be recovered in sedimentary phosphates during the wet processing of the ore by sulfuric acid giving raw phosphoric acid at 30 per cent of P 2 O 5 . Practically all the uranium contained and only part of rare earths are put into solution in this treatment. Separation of these elements in the phosphoric solution is obtained by liquid-liquid extraction with alkylphosphoric acids and especially with their mono and di esters. Partition isotherms are determined and counter-current tests are effected. Uranium and rare earths reextraction from these solvents can be simultaneous or separate with aqueous solutions alkaline or containing HF or by antisynergism. Pros and cons of each reextraction process are discussed. In conclusion HDEHP or OPPA are recommended because of availability, stability and hydrodynamic, OPPA less selective with rare earths allows the recovery with uranium of ceric earths, yttrium and yttric earths [fr

  18. Multielement determination of rare earth elements by liquid chromatography/inductively coupled plasma atomic emission spectrometry

    International Nuclear Information System (INIS)

    Sawatari, Hideyuki; Asano, Takaaki; Hu, Xincheng; Saizuka, Tomoo; Itoh, Akihide; Hirose, Akio; Haraguchi, Hiroki

    1995-01-01

    The rapid determination of rare earth elements (REEs) has been investigated by an on-line system of high performance liquid chromatography/multichannel inductively coupled plasma atomic emission spectrometry. In the present system, all REEs could be detected simultaneously in a single chromatographic measurement without spectral interferences. Utilizing a cation exchange column and 2-hydroxy-2-methylpropanoic acid aqueous solution as the mobile phase, the detection limits of 0.4-30 ng ml -1 for all REEs were obtained. The system was applied to the determination of REEs in geological standard rock samples and rare earth impurities in high purity rare earth oxides. The REEs in standard rocks could be determined by the present HPLC/ICP-AES system without pretreatment after acid digestion, although the detection limits were not sufficient for the analysis of rare earth oxides. (author)

  19. Sintered cobalt-rare earth intermetallic product

    International Nuclear Information System (INIS)

    Benz, M.C.

    1975-01-01

    A process is described for preparing novel sintered cobalt--rare earth intermetallic products which can be magnetized to form permanent magnets having stable improved magnetic properties. A cobalt--rare earth metal alloy is formed having a composition which at sintering temperature falls outside the composition covered by the single Co 5 R intermetallic phase on the rare earth richer side. The alloy contains a major amount of the Co 5 R intermetallic phase and a second solid CoR phase which is richer in rare earth metal content than the Co 5 R phase. The specific cobalt and rare earth metal content of the alloy is substantially the same as that desired in the sintered product. The alloy, in particulate form, is pressed into compacts and sintered to the desired density. The sintered product is comprised of a major amount of the Co 5 R solid intermetallic phase and up to about 35 percent of the product of the second solid CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase

  20. A new hydrometallurgical process for extracting rare earths from apatite using solvent extraction with P35

    International Nuclear Information System (INIS)

    Li Hongfei; Guo Fuqiang; Zhang Zhifeng; Li Deqian; Wang Zhonghuai

    2006-01-01

    In this paper, a new process is proposed to recover rare earths from nitric acid leaching of apatite without interfering with the normal route for fertilizer production using solvent extraction with dimethyl heptyl methyl phosphonate CH 3 P(O)(OC 8 H 17 ) 2 (P 35 , B). In the present work, the leaching conditions are studied. In selected condition, apatite was dissolved in 20% (v/v) nitric acid solution at 60-70 deg. C while agitating. The most suitable acidity for extraction is 0.4 M HNO 3 . More than 98% of rare earths in apatite can be recovered using countercurrent extraction process with six stages when phase ratio = 0.5, and defluorination is unnecessary. The influences of phase ratio, stage number, acidity and salting-out agent on extractabilities of P 35 are studied. The results show that rare earths can be separated with P 35 from Ca, P, Fe and other impurities. Mixed rare earth oxides (REO) of which purity is more than 95% with yield over 98% can be obtained

  1. HfO2 - rare earth oxide systems in the region with high content of rare earth oxide

    International Nuclear Information System (INIS)

    Shevchenko, A.V.; Lopato, L.M.

    1982-01-01

    Using the methods of annealing and hardenings (10 2 -10 4 deg/s cooling rate) and differential thermal analysis elements of state diagrams of HfO 2 - rare earth oxide (rare earths-La, Pr, Nd, Sm, Gd, Tb, Dy, Y, Er, Yb, Lu, Sc) systems from 1800 deg C up to melting in the range of 60-100 mol% rare earth oxide concentration were constructed. Regularities of HfQ 2 addition effect on high-temperature polymorphic transformations of rare earth oxides were studied. Results of investigation were discussed from viewpoint of crystal chemistry

  2. Concentration of rare earths ore from Pocos de Caldas - MG, Brazil

    International Nuclear Information System (INIS)

    Sampaio, J.A.; Lins, F.F.; Porphirio, N.H.

    1990-01-01

    The objective of this research was to concentrate, mainly by flotation, a rare-earth ore body. The valuable mineral is bastnaesite which occurs intimately associated with iron oxides and other gangue minerals, making difficult to get a concentrate of commercial grade. The use of oleic acid at a pulp temperature of -80 sup(0)C gave a concentrate of 23% rare-earth oxides at 72% overall recovery. The magnetic separation could enhance the grade of the flotation feed. (author)

  3. Production of rare earth-silicon-iron alloys

    International Nuclear Information System (INIS)

    Mehra, O.K.; Bose, D.K.; Gupta, C.K.

    1987-01-01

    At Metallurgy Division, BARC, improved procedures for producing rare earth-silicon alloys have been investigated. In these methods, reduction of mixed rare earth oxide by a ferro-silicon and aluminium mixture in combination with CaO-MgO flux/CaO-CaF 2 flux have been tried to prepare an alloy product with a higher rare earth recovery at a higher rare earth content than the present commercial production method. The rare earth recovery using CaO-CaF 2 was 85 per cent while in the case of CaO-MgO flux it was 76 per cent. The corresponding rare earth contents in the alloy correspond to 40 per cent and 55 per cent by weight respectively. (author)

  4. Labelling of TTHA coupled IgG and MCAb with rare earth radionuclides

    International Nuclear Information System (INIS)

    Wu Younghui; Zhang Yulei; Wu Chuanchu; Wang Xiangyun; Liu Yuanfang

    1988-07-01

    This article expands a process of labelling G-immunoglobulin (IgG) and monoclonal antibody (MCAb) with rare earth radionuclides. In this labelling process, cycloanhydride (CTTHAA) of Tri-ethyl Tetra-amine Hexa-acetic Acid (TTHA) is employed as a bifunctional chelating conjugate, the metal chelation takes place after CTTHAA has first been linked to IgG, followed by chemical reaction with rare earth radionuclides. Detailed investigations have been carried out to examine the influencing parameters of labelling globulins with rare earth, such as metal to CTTHAA mole-ratio, pH value and labelling time. The immunoreactivity of the labelled compound (RE-TTHA-IgG) has been retained throughout the whole labelling process

  5. Column extraction chromatography with HEH (EHP) for separating rare earth elements from coexistent elements and its application

    International Nuclear Information System (INIS)

    Peng Chunlin; Sun Baocheng; Zhao Junwu; Liu Xuan

    1985-01-01

    For separating rare earths from large amount of coexistent elements a new method of column extraction chromatography with HEH (EHP) as a stationary phase and sulphosalicylic acid, gluconic acid, ascorbic acid respectively as a mobile phase has been developed. It has been applied to the determination of trace rare earth elements in nickel-base alloys and iron-nickel-base alloys with satisfactory results

  6. Bio- and mineral acid leaching of rare earth elements from synthetic phosphogypsum

    Science.gov (United States)

    Hu, Z.; Antonick, P.; Fujita, Y.; Reed, D. W.; Riman, R.; Eslamimanesh, A.; Das, G.; Anderko, A.; Wu, L.; Shivaramaiah, R.; Navrotsky, A.

    2017-12-01

    Rare earth elements (REE) are critical to many clean energy technologies. However, the lack of U.S. domestic production and the reliance on imported REE put U.S. energy security at risk. Consequently development of new sources is of strategic interest. Global phosphate deposits contain 27 million tons of REE and 38% of these REE end up in phosphogypsum (PG) waste during phosphate fertilizer production. Recovering REE from PG is a first step toward a trash-to-treasure transformation. We studied the leaching of REE from synthetic PG samples containing Y, Nd, or Eu using a suite of lixiviants including spent medium from the growth of the bacterium Gluconobacter oxydans ("biolixiviant"), gluconic acid, common mineral acids (phosphoric and sulfuric), and water. Synthetic PG was used to facilitate the comparison of the different lixiviants; real PG waste is extremely heterogeneous. Gluconic acid was the predominant identified organic acid in the biolixiviant. The leaching efficiency of the acidic lixiviants at the same pH (2.1) or molar concentration as gluconic acid in the biolixiviant (220 mM) were compared and rationalized by thermodynamic simulation using the mixed-solvent electrolyte model. Initial results indicate that the biolixiviant was more effective at leaching the REE than the mineral acids at pH 2.1. At 220 mM acid concentrations, sulfuric acid was the most effective, followed by the biolixiviant. Interestingly, for a given lixiviant, the leaching behavior of the REE differed. This study provides insight into the definition of an efficient lixiviant for leaching REE from phosphate fertilizer production waste.

  7. Rare earth mobility in hydrothermal ore-forming systems

    International Nuclear Information System (INIS)

    Cornell, D.H.; Schade, J.; Scheepers, R.; Watkeys, M.K.

    1988-01-01

    Rocks and ores which form by magmatic processes display a range of chondrite-normalised rare earth profiles. One REE (rare earth elements) profile feature which seems unrelated to magmatic processes is the birdwing profile, in which both heavy and light rare earths are enriched relative to the middle rare earths. Birdwing rare earth profiles are an easily identified geochemical anomaly. It is proposed that rare earth geochemistry could be applied in geochemical prospecting for ore formed by hydrothermal processes. 5 figs

  8. Tetracyanidoborates with triply charged rare earth metal cations and their optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Hackbarth, Liisa

    2015-11-24

    The aim of this thesis is the description of the synthesis and characterization of a new group of tetracyanidoborates: tetracyanidoborates with trivalent rare earth metal cations. Their optical properties in the ultraviolet and visible range are also discussed. Common synthetic routes for tetracyanidoborates are adapted and applied to the preparation of the rare earth tetracyanidoborate hydrates. They are accessible with high yields and high purity through a reaction between the tetracyanidoboronic acid and rare earth hydroxides. It is shown that the rare earth tetracyanidoborates form isostructural groups, like the [LRE(H{sub 2}O){sub 5}][B(CN){sub 4}]{sub 3}.0.5 H{sub 2}O, where LRE{sup 3+} is La, Ce, Pr, Nd, Sm, Eu and Gd, the [HRE(H{sub 2}O){sub 7}][B(CN){sub 4}]{sub 3} and the [HRE(H{sub 2}O){sub 8}][B(CN){sub 4}]{sub 3}.3 H{sub 2}O, where HRE{sup 3+} is Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. Furthermore, the coordination number 9 is noticed to be common among the light rare earth cations, whereas the minor coordination number 8 is prevalent for the heavy rare earth cations in their tetracyanidoborates. This different construction of the coordination spheres between light and heavy rare earth cations leads to different structures depending on the energetic efficiency of the structural arrangement. Generally, the rare earth tetracyanidoborate hydrates are found to crystallize in the monoclinic crystal system. Moreover, other different crystal structures are observed depending on the crystallization temperature and the type of coordinated ligands and co-crystallized solvent molecules. The tetracyanidoborate hydrates with triply charged rare earth cations are characterized comprehensively by X-ray diffraction, vibrational spectroscopy, NMR-spectroscopy as well as by thermal analysis. Furthermore, the optical properties of some dehydrated rare earth tetracyanidoborates are investigated by UV-spectroscopy and luminescence measurements. The results of the optical

  9. Processing of Pakistani carbonatites for separation of cerium from adjacent rare earths

    International Nuclear Information System (INIS)

    Akram, M.; Qazi, N.K.; Khan, M.F.; Hasan, G.H.; Ahmed, N.; Chughtai, N.A.

    2003-01-01

    Carbonatite rock of Loe-Shilman area in North Western Frontier Province (NWFP) of Pakistan contains rare earth elements. This rock was upgraded in terms of its rare earths content from 2,000 ppm to 10,000 ppm rare earths oxide (REO) by crushing, calcination at 1000 deg. C for 3 hrs and cold leaching with 2% HCl for 1 hr. 80% to 95% of rare earths present in carbonatite powder were digested in nitric acid at 60 deg. C after 2 hrs stirring. Tributyl phosphate (TBP), diluted with dodecane, was used as extractant for extraction of rare earths. Since extraction is dependent on pH of the aqueous feed solution, the role of nitrate ions concentration in the solvent extraction of rare earth elements (REEs) was studied. It was observed that extraction of REEs was maximum at pH 1.1. The solvent had been unable to extract REEs from high acidic feed solutions. Solvents of different molarities were also tried against aqueous phase of pH 1.1. Studies showed a poor gain at 0 M and 0.5 M of organic phase while no gain observed beyond 2 molar solvent. 1 M organic phase gave maximum yield of rare earths salt, Ln(OH)/sub 3/, when stripped solution precipitated with ammonium hydroxide solution. It was also observed that if aqueous solution of 3.0 N was treated with blank solvent (i.e. Molarity = 0), it gave almost the same result. It was further established that optimum quantity of caging agent, Al(NO/sub 3/)/sub 3/-9H/sub 2/O added to aqueous solution prior to pH adjustment (i.e. 10 gm/100 gm powder dissolved) suppressed fluoride ions (F') which were hindering the extraction of rare earths. This improved the extraction efficiency of desired elements. To optimise the process parameters like solvent dilution, aqueous to organic ratio and extraction/stripping times, a' series of experiments were performed. Recovery for the desired elements had been between 78% to 86%. The optimum extraction parameters were found to be TBP concentration 40% (v/v) for aqueous to organic ratio 1:5 and 50

  10. The Rare Earth Magnet Industry and Rare Earth Price in China

    Directory of Open Access Journals (Sweden)

    Ding Kaihong

    2014-07-01

    Full Text Available In the past four years, the price of rare earth metal fluctuates sharply for many reasons. Currently, it has become more stable and more reasonable. This presentation is focused on the effect about the rare earth metal price. Some motor manufacturers have shifted from rare earth permanent magnet to ferrite magnet. Many motor manufacturers changed the design for the motor cooling system to make the motor function at a lower temperature. Thus the consumption of Dy can be markedly reduced. As for manufacturer of NdFeB magnet, we are also trying to optimize our process to reduce to dependence of HREE such as Dy and Tb. HS process have been introduced to solve the problem. With more and more people focusing and engaging on the REE industry, the price of REE will be more transparent without too many fluctuations. China is considering the problems of balancing the environment, energy sources, and labor sources. The application field about NdFeB such as wind turbine generator, HEV/EV, FA /OA is flourishing.

  11. The Rare Earth Magnet Industry and Rare Earth Price in China

    Science.gov (United States)

    Ding, Kaihong

    2014-07-01

    In the past four years, the price of rare earth metal fluctuates sharply for many reasons. Currently, it has become more stable and more reasonable. This presentation is focused on the effect about the rare earth metal price. Some motor manufacturers have shifted from rare earth permanent magnet to ferrite magnet. Many motor manufacturers changed the design for the motor cooling system to make the motor function at a lower temperature. Thus the consumption of Dy can be markedly reduced. As for manufacturer of NdFeB magnet, we are also trying to optimize our process to reduce to dependence of HREE such as Dy and Tb. HS process have been introduced to solve the problem. With more and more people focusing and engaging on the REE industry, the price of REE will be more transparent without too many fluctuations. China is considering the problems of balancing the environment, energy sources, and labor sources. The application field about NdFeB such as wind turbine generator, HEV/EV, FA /OA is flourishing.

  12. Rare earth elements behavior in Peruibe black mud

    International Nuclear Information System (INIS)

    Torrecilha, Jefferson K.; Carvalho, Leandro P.; Gouvea, Paulo F.M.; Silva, Paulo S.C. da

    2015-01-01

    Rare earth elements in sediments have been used as powerful tools for environmental studies because of their behavior during geochemical processes and are also widely accepted as reliable provenance tracers because they are largely water-immobile and thus behave conservatively during sedimentary processes. The Peruibe Black Mud (PBM) is a sedimentary deposit originated from the interactions of marine sediments and organic matter in an estuarine environment that originates a peloid currently used for medicinal purposes. The objective of this study was to examine rare earth elements pattern distribution in the Peruibe black mud sedimentary deposit as a proxy for its geochemical development. Elemental ratios such as LaN/YbN, Th/U and La/Th were determined and a normalization of the mean rare earth elements concentrations in the samples related to NASC indicates that the light (La to Eu) rare earth elements present values close to the unity while the heavy (Tb to Lu) rare earth elements are depleted related to NASC. It can be observed that the light rare earth elements present enrichment values slightly enriched over the unity while the heavy rare earth elements present values generally below the unity reflecting the enrichment of the light rare earth elements over the heavy rare earth. Rare earth elements concentrations determined in Peruibe black mud samples showed a distribution similar to that found in the NASC for the light rare earth elements and depleted for the heavy rare earth elements. (author)

  13. Rare earth elements behavior in Peruibe black mud

    Energy Technology Data Exchange (ETDEWEB)

    Torrecilha, Jefferson K.; Carvalho, Leandro P.; Gouvea, Paulo F.M.; Silva, Paulo S.C. da, E-mail: jeffkoy@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Rare earth elements in sediments have been used as powerful tools for environmental studies because of their behavior during geochemical processes and are also widely accepted as reliable provenance tracers because they are largely water-immobile and thus behave conservatively during sedimentary processes. The Peruibe Black Mud (PBM) is a sedimentary deposit originated from the interactions of marine sediments and organic matter in an estuarine environment that originates a peloid currently used for medicinal purposes. The objective of this study was to examine rare earth elements pattern distribution in the Peruibe black mud sedimentary deposit as a proxy for its geochemical development. Elemental ratios such as LaN/YbN, Th/U and La/Th were determined and a normalization of the mean rare earth elements concentrations in the samples related to NASC indicates that the light (La to Eu) rare earth elements present values close to the unity while the heavy (Tb to Lu) rare earth elements are depleted related to NASC. It can be observed that the light rare earth elements present enrichment values slightly enriched over the unity while the heavy rare earth elements present values generally below the unity reflecting the enrichment of the light rare earth elements over the heavy rare earth. Rare earth elements concentrations determined in Peruibe black mud samples showed a distribution similar to that found in the NASC for the light rare earth elements and depleted for the heavy rare earth elements. (author)

  14. Sc, Y, La-Lu - Rare Earth Elements

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    At present extensive efforts are being made in completing work on system number Rare Earth Elements. Part A is devoted to the occurrence of these elements on the earth and in the universe. Part B deals with the pure metals; the 7 volumes published cover the description of the separation from the raw materials, the preparation of pure metals,their uses and toxicology, the physical properties of nuclei, atoms, molecules, and isotopes; in addition the behavior of ions in solution and the electrochemical behavior of rare earth elements are described. The compounds are described in Part C. Part D with 6 volumes has been devoted to the description of coordination compounds and is completed. The volume ''Rare Earth Elements C 10'' deals with the rare earth tellurides, oxide tellurides, tellurates, telluride halides, tellurate halides, sulfide tellurides, selenide tellurides, and alkali rare earth tellurates. Another topic of this volume are the compounds of the rare earth elements with polonium. So far as meaningful and in accordance with all earlier volumes of ''Rare Earth Elements'' Series C, comparative data are presented in sections preceding treatment of the individual compounds and systems

  15. Rare Earth Metals: Resourcefulness and Recovery

    Science.gov (United States)

    Wang, Shijie

    2013-10-01

    When we appreciate the digital revolution carried over from the twentieth century with mobile communication and the Internet, and when we enjoy our high-tech lifestyle filled with iDevices, hybrid cars, wind turbines, and solar cells in this new century, we should also appreciate that all of these advanced products depend on rare earth metals to function. Although there are only 136,000 tons of annual worldwide demand, (Cho, Rare Earth Metals, Will We Have Enough?)1 rare earth metals are becoming such hot commodities on international markets, due to not only to their increasing uses, including in most critical military hardware, but also to Chinese growth, which accounts for 95% of global rare earth metal production. Hence, the 2013 technical calendar topic, planned by the TMS/Hydrometallurgy and Electrometallurgy Committee, is particularly relevant, with four articles (including this commentary) contributed to the JOM October Issue discussing rare earth metals' resourcefulness and recovery.

  16. Separation method for rare-earths using high-voltage electrophoresis on paper strip

    International Nuclear Information System (INIS)

    Clarence, J.

    1966-01-01

    The equipment includes an electrophoresis set running at 3 000 V and 20 mA. Two cooling plates are used as heat exchanger, and a pneumatic pressure device to insure an uniform pressure on the paper strip laid flat. The mobilities and the separations of the rare earths in lactic, and, α hydroxy-isobutyric acid solutions are investigated on cellulose acetate strip. Better results are obtained with α hydroxy-isobutyric acid. The method is rapid and allows a fine fractionation of rare earth elements within less than an hour. A complete separation of a Ce - Pr - Nd - Pm - Eu mixture, and a Y - Tb mixture is obtained. (author) [fr

  17. Preparation and luminescent properties of the novel polymer-rare earth complexes composed of Poly(ethylene-co-acrylic acid) and Europium ions

    Science.gov (United States)

    Wu, Yuewen; Hao, Haixia; Wu, Qingyao; Gao, Zihan; Xie, Hongde

    2018-06-01

    A series of novel polymer-rare earth complexes with Eu3+ ions have been synthesized and investigated successfully, including the binary complexes containing the single ligand poly(ethylene-co-acrylic acid) (EAA) and the ternary complexes using 1,10-phenanthroline (phen), dibenzoylmethane (DBM) or thenoyltrifluoroacetone (TTA) as the second ligand. Their structures have been characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis and X-ray diffraction (XRD), which confirm that both EAA and small molecules participate in the coordination reaction with rare earth ions, and they can disperse homogeneously in the polymer matrixes. Both ultraviolet-visible (UV-vis) absorption and photoluminescence tests for the complexes have been recorded. The relationship between fluorescence intensity of polymer-rare earth complexes and the quantity of ligand EAA has been studied and discussed. The films casted from the complexes solution can emit strong characteristic red light under UV light excitation. All these results suggest that the complexes possess potential application as luminescent materials.

  18. Processes for the production of rare earths from monazite (Paper No. 36)

    International Nuclear Information System (INIS)

    Murthy, T.K.S.

    1979-01-01

    A few typical cases are briefly described to illustrate different methods available for rare earth concentration and separation from mixed rare earths chloride obtained for monazite. In the case of cerium, rare earths chloride mixture is treated with sodium sulphate to precipitate rare earths as double sulphates from which hydroxide cake is prepared. The cake is dried to oxidise cerium. Trivalent rare earths are selectively leached and the product is treated with HNO 3 . The resulting ceric nitrate solution is purified by liquid-liquid extraction using TBP. The scrubbed extract is reduced with H 2 O 2 and cerous nitrate is recovered by evaporation. Lanthanum is first concentrated by selective precipitation of hydroxides from rare earths chloride using air-ammonia mixture. The hydroxyde cake is dissolved in HNO 3 and NH 4 NO 3 to get the double nitrate which is subjected to counter current crystallisation for purification. Europium is present at a concentration of 0.01% in the rare earths chloride. It is concentrated in several steps by liquid-liquid extraction using di-2-ethyl hexyl phosphoric acid. The product is purified by selective reduction and europium is obtained as europium sulphate. In the same solvent extraction process samarium and gadolinium are also concentrated to about 25%. They are further upgraded to above 90% purity by repetion of liquid-liquid extraction technique. Cerium, lanthanum and europium obtained by the above processes analyse > 99% as oxides. (M.G.B.)

  19. Thermochemistry of rare-earth trifluorides

    International Nuclear Information System (INIS)

    Kim, K.Y.; Johnson, C.E.

    1981-01-01

    Using the most recent crystallographic data, the Born-Lande equation was employed to calculate lattice energies of the rare-earth trifluorides. The excellent agreement ( 0 sub(f)(MX 3 ,c,298.15K) can be estimated. The magnitude of the monotonic change of ΔH 0 sub(f)(MX 3 ) for the rare-earth trihalides series (14 4f electrons) is comparable to the energy change between Sc and Ti in which only one 3d electron is added. This energy change is consistent with the chemical evidence that the electrons in the f-orbitals of rare earths contribute negligibly to the bonding. (author)

  20. Thermodynamics of rare earths in steelmaking

    International Nuclear Information System (INIS)

    Vahed, A.; Kay, D.A.R.

    1976-01-01

    The standard free energies of formation of the oxides, sulfides and oxysulfides of cerium and lanthanum under steelmaking conditions have been calculated and used to predict the behavior of rare earths in steelmaking. Deoxidation and desulfurization constants, expressed in terms of Henrian activities, have been used to construct a precipitation diagram which indicates the sequence of rare earth inclusion formation. An enrichment of lanthanum in (RE)-oxysulfide and cerium in (RE)-sulfide is predicted. It is also predicted that rare earths should be able to reduce the soluble oxygen and sulfur contents of liquid steel well below the contents presently found in most industrial and laboratory practices. A simple method of calculating steelmaking additions for complete rare earth control of inclusion composition is presented

  1. Theory of Rare-Earth Alloys

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1977-01-01

    A mean-field random alloy theory combined with a simple calculation of the exchange interaction J(c,Q) is shown to quantitatively account for the phase diagrams for alloys of rare-earth metals with Y, Lu, Sc, and other rare-earth metals. A concentration-dependent J(c,Q) explains the empirical 2...

  2. Procedure for the separation of cerium from crude phosphates and rare earth concentrates

    International Nuclear Information System (INIS)

    Richter, H.; Koenig, O.; Schmitt, A.; Grauss, H.; Freitag, S.

    1986-01-01

    The invention has to do with a procedure for the separation of cerium from crude phosphates and rare earth phosphate concentrates originating from the partial neutralization of nitric crude phosphate decomposition solutions. It is aimed at the cerium separation from the raw material at an early stage of reprocessing without preceding elimination of other components and impurities. The rare earth phosphate concentrates or crude phosphates are dissolved in nitric acid, the Ce 3+ is oxidized with potassium permanganate or magnanese(IV) hydroxide, and cerium(IV) phosphate is precipitated as pure substance by decreasing the acidity of the solution

  3. Synthesis and study of rare earth complexes with ortho-hydroxyphenyliminodiacetic acid containing lactone ring

    International Nuclear Information System (INIS)

    Martynenko, L.I.; Mitrofanova, N.D.; Muratova, N.M.; Kurbatova, S.V.

    1978-01-01

    Solid complex compounds of o-oxyphenyliminodiacetic acid with rare earth elements of the composition of LnA 2 Clx6H 2 O and LnA 3 x5H 2 O (where Ln=La, Pr, Nd, Eu, Dy, Er, and Y) not described earlier, have been synthesized. The thermographic analysis of the compounds has been performed. It is shown by infrared spectroscopy that a lactone ring is retained in the dicomplex structure. The presence of the absorption bands of non-ionized COOH-groups in the infrared spectra of tricomplexonates of heavy r.e.e. points to opening of the lactone ring in the ligand part

  4. The production of rare earth elements group via tributyl phosphate extraction and precipitation stripping using oxalic acid

    OpenAIRE

    Jorjani, Esmaeil; Shahbazi, Malek

    2016-01-01

    In this study, solvent extraction and precipitation stripping were used to produce rare earth elements (REEs). Tributyl phosphate (TBP) was used to extract yttrium, lanthanum, cerium, and neodymium from an aqueous solution produced by nitric acid leaching of apatite concentrate. In the extraction stage, the effects of TBP concentration, pH, contact time, temperature, and phase ratio were investigated. The results show that about 95%, 90%, 87% and 80% of neodymium, cerium, lanthanum, and yttri...

  5. Enhanced pinning in mixed rare earth-123 films

    Science.gov (United States)

    Driscoll, Judith L [Los Alamos, NM; Foltyn, Stephen R [Los Alamos, NM

    2009-06-16

    An superconductive article and method of forming such an article is disclosed, the article including a substrate and a layer of a rare earth barium cuprate film upon the substrate, the rare earth barium cuprate film including two or more rare earth metals capable of yielding a superconductive composition where ion size variance between the two or more rare earth metals is characterized as greater than zero and less than about 10.times.10.sup.-4, and the rare earth barium cuprate film including two or more rare earth metals is further characterized as having an enhanced critical current density in comparison to a standard YBa.sub.2Cu.sub.3O.sub.y composition under identical testing conditions.

  6. Solvent extraction of rare earth elements by γ-ray spectrometry

    International Nuclear Information System (INIS)

    Sudha Vani, T.J.; Krishna Rao, K.S.V.; Krishna Reddy, L.; Jaya Rami Reddy, M.; Lee, Yong III

    2010-01-01

    Rare earth element (REE) is a mine of new material and has very wide uses in industry. India has second largest abundant resources of rare earths and with its products and exports playing an important part in the world. REEs are important in nuclear energy programs, hence the separation and purification of rare earths is demanded. As well known, the separation between trivalent REEs is one of the most difficult tasks in separation chemistry due to their similar chemical properties. A large number of acidic and neutral organo-phosphorus and sulphur extractants have been widely employed industrially for the solvent extraction separation of REEs. However, these reagents display various shortcomings, such as poor selectivity, third phase formation, etc. In view of the ever increasing demand for high purity REEs as a group or from one another, there is a growing interest in the development of new and more selective solvent extraction reagents

  7. Rare earths production and marketing opportunities

    International Nuclear Information System (INIS)

    Falconnet, P.G.

    1988-01-01

    The rare earths (RE) market is relatively small. The total production during 1968 was only 10000 tons (REO) which rose to 27000 tons (REO) during 1985. The three major areas of application, which are volume market for ceric rare earths are catalysts, glass ceramics and metallurgy. Among the other uses of rare earths, the permanent magnets, lamp phosphors and fine ceramics have registered significant growth in RE consumption. Monazite and bastnasite are the main natural source for rare earths and processing of these for one of the rare earths in high demand leads to over production of some others not in demand, thus creating a balance problem. The growth in RE market has always been influenced by the technology shifts and product substitution. For example, the RE consumption during 1974/76 for desulfurization of steel had substantially decreased due to the usage of calcium. Similarly, 1985 had witnessed a drastic cut in the use of REs in fluid cracking due to the introduction of stabilized zeolites which contain less REO. Thus, the overall compound growth rate of demand was only 3.9 % per year during the period 1970-1985. At present, 37 % of the rare earths production goes to the glass/ceramics industry, 33 % for catalyst and 25 % to metallurgy. The price of REs constantly shows a downward trend. This trend coupled with the rapid changes taking place in the various technological fields, demands greater flexibility and high marketing skills from the RE producers. The key factor for future expansion of RE market will be the development of 'high volume' application of ceric rare earths. (author) 2 figs., 8 tabs

  8. Hydrothermal synthesis, characterization and up/down-conversion luminescence of barium rare earth fluoride nanocrystals

    International Nuclear Information System (INIS)

    Jia, Li-Ping; Zhang, Qiang; Yan, Bing

    2014-01-01

    Graphical abstract: Lanthanide ions doped bare earth rare earth fluoride nanocrystals are synthesized by hydrothermal technology and characterized. The down/up-conversion luminescence of them are discussed. - Highlights: • Mixed hydrothermal system H 2 O–OA (EDA)–O-A(LO-A) is used for synthesis. • Barium rare earth fluoride nanocrystals are synthesized comprehensively. • Luminescence for down-conversion and up-conversion are obtained for these systems. - Abstract: Mixed hydrothermal system H 2 O–OA (EDA)–O-A(LO-A) is developed to synthesize barium rare earth fluorides nanocrystals (OA = oleylamine, EDA = ethylenediamine, O-A = oleic acid and LO-A = linoleic acid). They are presented as BaREF 5 (RE = Ce, Pr, Nd, Eu, Gd, Tb, Dy, Y, Tm, Lu) and Ba 2 REF 7 (RE = La, Sm, Ho, Er, Yb). The influence of reaction parameters (rare earth species, hydrothermal system and temperature) is checked on the phase and shape evolution of the fluoride nanocrystals. It is found that reaction time and temperature of these nanocrystals using EDA (180 °C, 6 h) is lower than those of them using OA (220 °C, 10 h). The photoluminescence properties of these fluorides activated by some rare earth ions (Nd 3+ , Eu 3+ , Tb 3+ ) are studied, and especially up-conversion luminescence of the four fluoride nanocrystal systems (Ba 2 LaF 7 :Yb, Tm(Er), Ba 2 REF 7 :Yb, Tm(Er) (RE = Gd, Y, Lu)) is observed

  9. Afganistan and rare earths

    Directory of Open Access Journals (Sweden)

    Emilian M. Dobrescu

    2013-05-01

    Full Text Available On our planet, over a quarter of new technologies for the economic production of industrial goods, are using rare earths, which are also called critical minerals and industries that rely on these precious items being worth of an estimated nearly five trillion dollars, or 5 percent of world gross domestic product. In the near future, competition will increase for the control of rare earth minerals embedded in high-tech products. Rare minerals are in the twenty-first century what oil accounted for in the twentieth century and coal in the nineteenth century: the engine of a new industrial revolution. Future energy will be produced increasingly by more sophisticated technological equipment based not just on steel and concrete, but incorporating significant quantities of metals and rare earths. Widespread application of these technologies will result in an exponential increase in demand for such minerals, and what is worrying is that minerals of this type are almost nowhere to be found in Europe and in other industrialized countries in the world, such as U.S. and Japan, but only in some Asian countries, like China and Afghanistan.

  10. Preparing rare earth-silicon-iron-aluminum alloys

    International Nuclear Information System (INIS)

    Marchant, J.D.; Morrice, E.; Herve, B.P.; Wong, M.M.

    1980-01-01

    As part of its mission to assure the maximum recovery and use of the Nation's mineral resources, the Bureau of Mines, investigated an improved procedure for producing rare earth-silicon alloys. For example, a charge consisting of 681 grams of mixed rare-earth oxides, 309 grams of ferrosilicon (75 wt-pct Si), and 182 grams of aluminum metal along with a flux consisting of 681 grams of CaO and 45 grams of MgO was reacted at 1500 0 C in an induction furnace. Good slag-metal separation was achieved. The alloy product contained, in weight-percent, 53 RE, 28 Si, 11 Fe, and 4 Al with a rare earth recovery of 80 pct. In current industrial practice rare earth recoveries are usually about 60 pct in alloy products that contain approximately 30 wt-pct each of rare earths and silicon. Metallurgical evaluations showed the alloys prepared in this investigation to be as effective in controlling the detrimental effect of sulfur in steel and cast iron as the commercial rare earth-silicon-iron alloys presently used in the steel industry

  11. High purity neodymium acetate from mixed rare earth carbonates

    International Nuclear Information System (INIS)

    Queiroz, Carlos A. da Silva; Rocha, Soraya M. Rizzo da; Vasconcellos, Mari E. de; Lobo, Raquel M.; Seneda, Jose A.; Pedreira, Walter dos R.

    2011-01-01

    A simple and economical chemical process for obtaining high purity neodymium acetate is discussed. The raw material in the form rare earth carbonate is produced industrially from the chemical treatment of Brazilian monazite. Ion exchange chromatography technique with a strong cationic resin, proper to water treatment, and without the use of retention ions was used for the fractionating of the rare earth elements (REE). In this way, it was possible to obtain 99.9% pure Nd 2 O 3 in yields greater than or equal 80%, with the elution of the REE using ammonium salt of ethylenediaminetetraacetic acid (EDTA) solution in pH controlled. The complex of EDTA-neodymium was transformed into neodymium oxide, which was subsequently dissolved in acetic acid to obtain the neodymium acetates. Molecular absorption spectrophotometry was used to monitor the neodymium content during the process and sector field inductively coupled plasma mass spectrometry was used to certify the purity of the neodymium acetates. The typical neodymium acetates obtained contain the followings contaminants in μg g -1 : Sc(5.1); Y (0.9); La (1.0); Ce (6.1); Pr (34,4); Sm (12.8); Eu (1.1); Gd (15.4); Tb (29.3); Dy (5.2), Ho(7.4); Er (14.6); Tm (0.3); Yb (2.5); Lu (1.0). The high purity neodymium acetates obtained from this procedure have been applied, replacing the imported product, in research and development area on rare earth catalysts. (author)

  12. Rare Earth Garnet Selective Emitter

    Science.gov (United States)

    Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

    1994-01-01

    Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional

  13. Investigation of rare earth natural radionuclide in Gannan region, Jiangxi province

    International Nuclear Information System (INIS)

    Liu Huiping; Zhong Minglong; Hu Yongmei

    2014-01-01

    In order to identify the types, level and migration law of natural radionuclide in ionic rare earth during its development and utilization process, the natural radionuclide in raw ore, waste residues and wastewater of south ionic rare of Gannan region, Jiangxi province were investigated. The results showed that: the natural radionuclide in rare earth raw ore in An'yuan and Longnan is with high content, in which the specific activities of natural U, 226 Ra and 232 Th are 3.69 × l0 4 , 8.33 × l0 3 and 3,40 × l0 3 Bq/ kg respectively; And the specific activities of the acid-soluble slag are 2.58 × l0 4 , 2.81 × l0 4 and 2.75 × l0 4 Bq/kg respectively; The radioactive level of natural U and 232 Th in some rare earth tailings, and the specific activity of natural U in the neutralizing slag of some individual enterprises is higher than national standards' exemption level (1000 Bq/kg). Also, the total content of Th and U in the efflux wastewater of some rare earth enterprises efflux wastewater are higher than the national emission standards limit (0.1 mg/L). (authors)

  14. Production of Rare Earth Elements from Malaysian Monazite by Selective Precipitation

    International Nuclear Information System (INIS)

    Che Nor Aniza Che Zainul Bahri; Al- Areqi, W.M.; Amran Abdul Majid; Mohd Izzat Fahmi Mohd Ruf

    2016-01-01

    Rare earth elements (REEs) are very valuable and have high demands for advanced technology nowadays. REEs can be classified to light rare earth elements (LREEs) and heavy rare earth elements (HREEs). Malaysian rare earth ore especially monazite, is rich with LREEs compared to HREEs. Therefore a study was carried out to extract the REE from Malaysian monazite. The objectives of this study are to determine the content of REEs in Malaysian monazite leach solution, as well as to produce high grade of REEs. Concentrated sulphuric acid was used in digestion process and the filtrate containing the REEs was determined using Inductively Coupled Plasma- Mass Spectrometry (ICP-MS). Ammonia solution was used for REEs precipitation from monazite leach solution. The result indicated that REEs was successfully separated from monazite leach solution through selective precipitation using ammonia at pH 2.34 and the percentage of REEs that successfully separated was 70.03 - 81.85 %. The percentage of REEs which successfully separated from final solution was 96.05 - 99.10 %. Therefore, to have high purification of individual REEs, solvent extraction process should be carried out. (author)

  15. Alaska's rare earth deposits and resource potential

    Science.gov (United States)

    Barker, James C.; Van Gosen, Bradley S.

    2012-01-01

    Alaska’s known mineral endowment includes some of the largest and highest grade deposits of various metals, including gold, copper and zinc. Recently, Alaska has also been active in the worldwide search for sources of rare earth elements (REE) to replace exports now being limitedby China. Driven by limited supply of the rare earths, combined with their increasing use in new ‘green’ energy, lighting, transportation, and many other technological applications, the rare earth metals neodymium, europium and, in particular, the heavy rare earth elements terbium, dysprosium and yttrium are forecast to soon be in critical short supply (U.S. Department of Energy, 2010).

  16. Rare earth metal alloy magnets

    International Nuclear Information System (INIS)

    Harris, I.R.; Evans, J.M.; Nyholm, P.S.

    1979-01-01

    This invention relates to rare earth metal alloy magnets and to methods for their production. The technique is based on the fact that rare earth metal alloys (for e.g. cerium or yttrium) which have been crumbled to form a powder by hydride formation and decomposition can be used for the fabrication of magnets without the disadvantages inherent in alloy particle size reduction by mechanical milling. (UK)

  17. Binding of rare earths to serum proteins and DNA

    International Nuclear Information System (INIS)

    Rosoff, B.; Spencer, H.

    1979-01-01

    In order to investigate further the physiological behavior of rare earths and rare earth chelates, studies of the binding of 46 Sc, 91 Y, and 140 La to serum proteins and to nucleic acids were performed using the methods of equilibrium dialysis and ultrafiltration. The binding of lanthanum and yttrium as the chlorides to α-globulin increased as the free rare earth concentration increased. When scandium and lanthanum were chelated in nitrilotriacetate (NTA) the binding to α-globulin was considerably less and there was no binding to albumin. The binding of 46 Sc chelated to ethylenediamine di(O-hydroxyphenylacetate) (EDDHA) was five times greater than of 46 Sc chloride. When the free scandium concentration was increased, the moles bound per mole of protein increased proportionally and the binding was reversible. Scandium was 100% filterable from a mixture of human serum and from the scandium chelates with high stability constants scandium diethylenetriaminepentaacetate (ScDTPA), scandium ethylenediaminetetraacetate (ScEDTA) and scandium cyclohexane trans-1,2-diaminetetraacetate (ScCDTA) respectively. In contrast, only 2% of the scandium was filterable when scandium nitrilotriacetate, a scandium chelate of low stability constant, was used. (Auth.)

  18. Rare earth impurities in high purity lanthanum oxide determined by neutron activation analysis

    International Nuclear Information System (INIS)

    Nguyen Van Suc; Desai, H.B.; Parthasarathy, R.; Gangadharan, S.

    1992-01-01

    Individual rare earth impurities in high purity La 2 O 3 (≥99.9%) have been determined by NAA after pre-separation of the matrix (La). The separation is carried out on an anion exchanger (Dowex 1x8) using different mixtures of methanol/nitric acid as eluants. The rare earth elements from Dy to Lu are eluted quantitatively using a 10% 1M HNO 3 - 90% methanol mixture, while the light rare earths from Ce to Gd are eluted quantitatively using a 10% 0.05M HNO 3 - 90% methanol mixture. La, which is retained on the column, is eluted using 0.1M HNO 3 . The recoveries of the various rare earth elements have been checked using radiotracers and also by spiking the sample with known amount of elements, and the recoveries are found to be quantitative. Results obtained on a typical high purity lanthanum oxide are reported here. (author) 5 refs.; 1 fig

  19. From NdFeB magnets towards the rare-earth oxides: a recycling process consuming only oxalic acid

    OpenAIRE

    Vander Hoogerstraete, Tom; Blanpain, Bart; Van Gerven, Tom; Binnemans, Koen

    2014-01-01

    A chemical process which consumes a minimum amount of chemicals to recover rare-earth metals from NdFeB magnets was developed. The recovery of rare-earth elements from end-of-life consumer products has gained increasing interest during the last few years. Examples of valuable rare earths are neodymium and dysprosium because they are important constituents of strong permanent magnets used in several large or growing application fields (e.g. hard disk drives, wind turbines, electric vehicles, m...

  20. Rare earth metals for automotive exhaust catalysts

    International Nuclear Information System (INIS)

    Shinjoh, Hirohumi

    2006-01-01

    The usage of rare earth metals for automotive exhaust catalysts is demonstrated in this paper. Rare earth metals have been widely used in automotive catalysts. In particular, three-way catalysts require the use of ceria compounds as oxygen storage materials, and lanthana as both a stabilizer of alumina and a promoter. The application for diesel catalysts is also illustrated. Effects of inclusion of rare earth metals in automotive catalysts are discussed

  1. Rare earth elements leaching from Tin slag using Acid Chloride after Alkaline fusion process

    International Nuclear Information System (INIS)

    Kurnia Trinopiawan; Budi Yuli Ani; June Mellawati; Mohammad Zaki Mubarok

    2016-01-01

    Tin slag, a waste product from tin smelting process, has a potency to be utilized further by extracting the valuable metals inside, such as rare earth elements(REE). The objective of this study is to determine the optimum leaching condition of REE from tin slag after alkali fusion. Silica structure in slag is causing the direct leaching uneffectively. Therefore, pre-treatment step using alkali fusion is required to break the structure of silica and to increase the porosity of slag. Fusion is conducted in 2 hours at 700°C, with ratio of natrium hydroxide (NaOH) : slag = 2 : 1. Later, frit which is leached by water then leached by chloride acid to dissolve REE. As much as 87,5% of REE is dissolved at 2 M on chloride acid (HCl) concentration, in 40°C temperature, -325 mesh particle size, 15 g/100 ml of S/L, 150 rpm of agitation speed, and 5 minutes of leaching time. (author)

  2. Rare earth impact on glass structure and alteration kinetics

    International Nuclear Information System (INIS)

    Molieres, E.

    2012-01-01

    This work is related to the question of the geological deep repository of high-level waste glass. These wastes include fission products and minor actinides, elements which can be simulated by rare earths. As new glass compositions could enable increased rare earth concentrations, it is crucial to know and understand rare earth impact on glass structure on the one hand, and on glass alteration kinetics or their incorporation into an altered layer. This work studied simplified borosilicate glasses in order to limit synergetic effects between rare earths and other elements. Various complementary techniques were used to characterize pristine and altered glasses (solid-high resolution NMR, Raman spectroscopy, fluorescence, SIMS, SAXS). Firstly, the structural role of a rare earth is discussed and is compared to a calcium cation. The local environment of rare earths is also probed. Secondly, rare earth (nature and concentration) impact on several alteration regimes was studied (initial rate, rate drop). Then, after alteration, rare earth elements being retained within the altered layer, the structural impact of rare earth elements (and their local environment) in this alteration layer was also investigated. (author) [fr

  3. Sintered cobalt-rare earth intermetallic product

    International Nuclear Information System (INIS)

    Benz, M.G.

    1975-01-01

    This patent describes a sintered product having substantially stable permanent magnet properties in air at room temperature. It comprises compacted particulate cobalt--rare earth alloy consisting essentially of a Co 5 R intermetallic phase and a CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase, where R is a rare earth metal. The Co 5 R intermetallic phase is present in an amount of at least 65 percent by weight of the sintered product and the CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase is present in a positive amount having a value ranging up to about 35 percent by weight of the product. The sintered product has a density of at least 87 percent and has pores which are substantially noninterconnecting and wherein the component grains have an average size less than 30 microns

  4. Red-emitting alkaline-earth rare-earth pentaoxometallates powders ...

    Indian Academy of Sciences (India)

    Moisture-insensitive metal carboxylates that are mostly liquids at room temperature have been first applied to ... alkaline-earth ion, or possibly even a rare-earth ion and alkali metal ... sion spectra of the powders were recorded on a fluorescent.

  5. Rare metal and rare earth pegmatites of Western India

    International Nuclear Information System (INIS)

    Maithani, P.B.; Nagar, R.K.

    1999-01-01

    Rajasthan Mica Belt in western India is one of the three major mica-producing Proterozoic pegmatite belts of India, the others being in Bihar and Andhra Pradesh. The pegmatites of these mica belts, in general, are associated with the rare metal (RM) and rare earth element (REE)-bearing minerals like columbite-tantalite, beryl, lepidolite and other multiple oxides. RM-REE pegmatites of Gujarat are devoid of commercially workable mica. These pegmatites are geologically characterised in this paper, based on their association with granite plutons geochemistry, and RM and REE potential. In addition to RM and RE-bearing pegmatites, granites of the Umedpur area, Gujarat also show anomalous concentration (0.97 wt%) of rare metals (6431 ppm Nb, 1266 ppm Ta, 454 ppm Sn, 173 ppm W), (1098 ppm Ce 1.36% Y 2 O 3 ) rare earths, and uranium (0.40% eU 3 O 8 ). Eluvial concentrations in the soil and panned concentrate (0.04-0.28 wt%) analysed up to 7.4%Nb 2 O 5 , 836 ppm Ta, and 1.31% Y. Discrete columbite-tantalite and betafite have been identified in these concentrates in addition to other minerals like zircon, rutile, sphene and xenotime. This area with discrete RM R EE mineral phases could be significant as a non-pegmatite source for rare metal and rare earths. (author)

  6. Rare earth industries: Upstream business

    International Nuclear Information System (INIS)

    2011-01-01

    Evidently, many factors contribute to the rush to invest in the unprecedented revival of rare earths. One major reason has to do with the rapidly growing world demand. The other reason relates to the attractive price of rare earths which is projected to stay strong in the coming years. This is because supply is predicted to have difficulty keeping pace with demand. Experts believe a major driver of global rare earths demand is the forecasted expansion in the green economy. Climate change is a major driver of the green economy. With climate change, there is concern that the uncontrolled emission of the greenhouse gases, especially carbon dioxide, can lead to catastrophic consequences for the world. This has been documented in countless studies and reports. Another important driver of the green economy is the growing shortfall in many resources. The world is now experiencing declines in key resources to meet a growing global demand. With more than 6 billion people now in the world and growing, the pressure exerted on global resources including energy, water and food is a major concern. Recent demand surge in China and India has dented the supply position of major world resources. The much quoted Stern Report from the UK has warned that, unless immediate steps are taken to reduce greenhouse gas emissions, it may be a costly exercise to undertake the corrections later. Since energy use, especially fossil fuels, is a major contributor to climate change, greener options are being sought. Add to that the fact that the fossil energy resources of the world are declining, the need to seek alternatives becomes even more urgent. One option is to change to renewable energy sources. These include such potentials as solar, wind and biomass. Rare earths have somehow become a critical feature of the technologies in such renewable. Another option is to improve the efficient use of energy in transport, buildings and all the other energy intensive industries. Again the technologies in

  7. Rare earth - no case for government intervention

    OpenAIRE

    Georg Zachmann

    2010-01-01

    China has officially restricted exports of rare earth for several years and announced this year it will further tighten exports. Rare earth is a group of 17 different metals, usually found clustered together. These metals have hundreds of different industry applications. For example, they are used in certain high capacity magnets, batteries and lasers. As the rare earth elements are used in sectors that are assumed to have an over-proportionate growth potential (eg. green-technology), policy ...

  8. Light Rare Earth Elements enrichment in an acidic mine lake (Lusatia, Germany)

    International Nuclear Information System (INIS)

    Bozau, Elke; Leblanc, Marc; Seidel, Jean Luc; Staerk, Hans-Joachim

    2004-01-01

    The distribution of Rare Earth Elements (REE) was investigated in the acidic waters (lake and groundwater) of a lignite mining district (Germany). The Fe- and SO 4 -rich lake water (pH 2.7) displays high REE contents (e.g. La∼70 μg/l, Ce∼160 μg/l) and an enrichment of light REE (LREE) in the NASC normalised pattern. Considering the hydrodynamic model and geochemical data, the lake water composition may be calculated as a mixture of inflowing Quaternary and mining dump groundwaters. The groundwater of the dump aquifer is LREE enriched. Nevertheless, the leachates of dump sediments generally have low REE contents and display flat NASC normalised patterns. However, geochemical differences and REE pattern in undisturbed lignite (LREE enriched pattern and low water soluble REE contents) and the weathered lignite of the dumps (flat REE pattern and high water soluble REE contents) suggest that lignite is probably the main REE source rock for the lake water

  9. Advances in the hydrometallurgical separation techniques of high purity rare earth elements

    International Nuclear Information System (INIS)

    Vijayalakshmi, R.; Kain, V.

    2017-01-01

    (phosphoric acid, fly ash, end-of-life products) while focusing on challenges faced in developing the processes for separation of heavy rare earth elements at BARC. (author)

  10. Effects of rare earth and acid rain pollution on plant chloroplast ATP synthase and element contents at different growth stages.

    Science.gov (United States)

    Zhang, Fan; Hu, Huiqing; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

    2018-03-01

    Combined rare earth and acid rain pollution has become a new environmental problem, seriously affecting plant survival. The effects of these two kinds of pollutants on plant photosynthesis have been reported, but the micro mechanisms are not very clear. In this research, we studied the effects of lanthanum [La(III), 0.08, 1.20 and 2.40 mM] and acid rain (pH value = 2.5, 3.5 and 4.5) on the ATPase activity and gene transcription level and the functional element contents in rice leaf chloroplasts. The results showed that the combined 0.08 mM La(III) and pH 4.5 acid rain increased the ATPase activity and gene transcription level as well as contents of some functional elements. But other combined treatments of acid rain and La(III) reduced the ATPase activity and gene transcription level as well as functional element contents. The change magnitude of the above indexes at rice booting stage was greater than that in seedling stage or grain filling stage. These results reveal that effects of La(III) and acid rain on ATPase activity and functional element contents in rice leaf chloroplasts are related to the combination of La(III) dose and acid rain intensity and the plant growth stage. In addition, the changes in the ATPase activity were related to ATPase gene transcription level. This study would provide a reference for understanding the microcosmic mechanism of rare earth and acid rain pollution on plant photosynthesis and contribute to evaluate the possible environmental risks associated with combined La(III) and acid rain pollution. The effects of La(III) and acid rain on activity and gene transcription level of rice chloroplast ATPase and contents of functional elements were different at different growth stages. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. A study on dehydration of rare earth chloride hydrate

    International Nuclear Information System (INIS)

    Cho, Yong Zun; Eun, Hee Chul; Son, Sung Mo; Lee, Tae Kyo; Hwang, Taek Sung

    2012-01-01

    The dehydration schemes of rare earth (La, Ce, Nd, Pr, Sm. Eu, Gd, Y) chloride hydrates was investigated by using a dehydration apparatus. To prevent the formation of the rare earth oxychlorides, the operation temperature was changed step by step (80→150→230 degree C) based on the TGA (thermo-gravimetric analysis) results of the rare earth chloride hydrates. A vacuum pump and preheated Ar gas were used to effectively remove the evaporated moisture and maintain an inert condition in the dehydration apparatus. The dehydration temperature of the rare earth chloride hydrate was increased when the atomic number of the rare earth nuclide was increased. The content of the moisture in the rare earth chloride hydrate was decreased below 10% in the dehydration apparatus.

  12. Rare (Earth Elements [score

    Directory of Open Access Journals (Sweden)

    Camilo Méndez

    2014-12-01

    Full Text Available Rare (Earth Elements is a cycle of works for solo piano. The cycle was inspired by James Dillon’s Book of Elements (Vol. I-V. The complete cycle will consist of 14 pieces; one for each selected rare (earth element. The chosen elements are Neodymium, Erbium, Tellurium, Hafnium, Tantalum, Technetium, Indium, Dysprosium, Lanthanium, Cerium, Europium, Terbium, Yttrium and Darmstadtium. These elements were selected due to their special atomic properties that in many cases make them extremely valuable for the development of new technologies, and also because of their scarcity. To date, only 4 works have been completed Yttrium, Technetium, Indium and Tellurium.

  13. Extraction of rare earth elements from a contaminated cropland soil using nitric acid, citric acid, and EDTA.

    Science.gov (United States)

    Tang, Hailong; Shuai, Weitao; Wang, Xiaojing; Liu, Yangsheng

    2017-08-01

    Rare earth elements (REEs) contamination to the surrounding soil has increased the concerns of health risk to the local residents. Soil washing was first attempted in our study to remediate REEs-contaminated cropland soil using nitric acid, citric acid, and ethylene diamine tetraacetic acid (EDTA) for soil decontamination and possible recovery of REEs. The extraction time, washing agent concentration, and pH value of the washing solution were optimized. The sequential extraction analysis proposed by Tessier was adopted to study the speciation changes of the REEs before and after soil washing. The extract containing citric acid was dried to obtain solid for the X-ray fluorescence (XRF) analysis. The results revealed that the optimal extraction time was 72 h, and the REEs extraction efficiency increased as the agent concentration increased from 0.01 to 0.1 mol/L. EDTA was efficient to extract REEs over a wide range of pH values, while citric acid was around pH 6.0. Under optimized conditions, the average extraction efficiencies of the major REEs in the contaminated soil were 70.96%, 64.38%, and 62.12% by EDTA, nitric acid, and citric acid, respectively. The sequential extraction analyses revealed that most soil-bounded REEs were mobilized or extracted except for those in the residual fraction. Under a comprehensive consideration of the extraction efficiency and the environmental impact, citric acid was recommended as the most suitable agent for extraction of the REEs from the contaminated cropland soils. The XRF analysis revealed that Mn, Al, Si, Pb, Fe, and REEs were the major elements in the extract indicating a possibile recovery of the REEs.

  14. An Overview of Rare Earth Science and Technology

    Science.gov (United States)

    Gschneidner, Karl, Jr.

    2012-02-01

    Currently rare earth science and technology is robust: this includes all the major branches of science -- biochemistry, chemistry, materials and physics. There are, however, currently some anomalies and distortions especially in the technology and applications sector of the rare earth field, which is caused by the dominance of China on the sales of rare earths and rare earth containing products. For the past 5 to 10 years ˜95% of rare earths utilized in commerce came from China. Although Chinese actions have lead to sudden and large price spikes and export embargoes, the rare earths are still available but at a higher cost. The start up of production in 2011 at mines in the USA and Australia will alleviate this situation in about two years. Basic and applied research on the condensed matter physics/materials science has hardly been impacted by these events, but new research opportunities are opening up especially with regard to the USA's military and energy security. Magnets seems to be the hottest topic, but research on battery materials, phosphors and catalysts are also (or should be) strongly considered.

  15. Rare Earth Elements: Overview of Mining, Mineralogy, Uses, Sustainability and Environmental Impact

    Directory of Open Access Journals (Sweden)

    Nawshad Haque

    2014-10-01

    Full Text Available Rare earths are used in the renewable energy technologies such as wind turbines, batteries, catalysts and electric cars. Current mining, processing and sustainability aspects have been described in this paper. Rare earth availability is undergoing a temporary decline due mainly to quotas being imposed by the Chinese government on export and action taken against illegal mining operations. The reduction in availability coupled with increasing demand has led to increased prices for rare earths. Although the prices have come down recently, this situation is likely to be volatile until material becomes available from new sources or formerly closed mines are reopened. Although the number of identified deposits in the world is close to a thousand, there are only a handful of actual operating mines. Prominent currently operating mines are Bayan Obo in China, Mountain Pass in the US and recently opened Mount Weld in Australia. The major contributor to the total greenhouse gas (GHG footprint of rare earth processing is hydrochloric acid (ca. 38%, followed by steam use (32% and electricity (12%. Life cycle based water and energy consumption is significantly higher compared with other metals.

  16. State of rare earth impurities in gallium and indium antimonides

    International Nuclear Information System (INIS)

    Evgen'ev, S.B.; Kuz'micheva, G.M.

    1990-01-01

    State of rare earth impurities in indium and gallium antimonides was studied. Results of measuring density and lattice parameter of samples in GaSb-rare earth and InSb-rare earth systems are presented. It is shown that during rare earth dissolution in indium and gallium antimonides rare earth atoms occupy interstitial positions or, at least, are displaced from lattice points

  17. Monazite upgradation and production of high pure rare earths

    International Nuclear Information System (INIS)

    Asnani, C.K.; Mohanty, D.; Kumar, S.S.

    2014-01-01

    Rare earth extraction from monazite and further processing of mixed rare earth chlorides for producing individual high pure rare earths involves a complex flowsheet based on solvent extraction process. Apart from involving multiple extractions, scrubbing and stripping operations, the flowsheet requires optimization of critical parameters such as solvent molarity, solvent saponification level and recycling of product solutions as reflux to ensure preferential upload of required rare earths to generate high purity product. This paper tracks monazite flow from the raw sand feed through to the monazite product and its processing to generate rare earths of internationally acceptable quality

  18. Synthesis and physicochemical investigation of 3-nitro-5-aminobenzoates of rare earths

    International Nuclear Information System (INIS)

    Makushova, G.N.; Zakharova, T.V.; Shilova, L.I.

    1994-01-01

    The compounds of cerium subgroup rare earth with 3-nitro-5-aminobenzoic acid of composition Ln(C 7 H 5 N 2 O 4 ) 3 ·nH 2 O, where Ln-La, Ce, Pr, Nd, Sm, Eu; n=4-14 not yet described in literature were obtained. Rare earth 3-nitro-5-aminobenzoates were individual crystal substances, as shown by X-ray diffraction; their interplanar distances were calculated. Thermal stability of the derived compounds was studied by means of thermography and thermal gravimetry. The interval of dehydration and start of decomposition of anhydrous salts was determined

  19. Rare earth oxyhydrides and preparation process

    International Nuclear Information System (INIS)

    Diaz, H.

    1986-01-01

    Rare earth oxyhydrides of formula RE 1-q Th q Ni 5-p M p O x H y are claimed. RE is a rare earth, Th can be replaced by Yt, M is Cu, Mn, Al, Fe, Cr or Co, o O C and the hydrides are oxidized. They are catalysts for various chemical reactions [fr

  20. Rare Earth Elements Distribution in Beryl

    International Nuclear Information System (INIS)

    El Gawish, H.K.; Nada, N.; Ghaly, W.A.; Helal, A.I.

    2012-01-01

    Laser ablation method is applied to a double focusing inductively coupled plasma mass spectrometer to determine the rare earth element distribution in some selected beryl samples. White, green and blue beryl samples are selected from the Egyptian eastern desert. Distributions of chondrite- normalized plot for the rare earth element in the selected beryl samples are investigated

  1. Rare Earth-Activated Silica-Based Nanocomposites

    Directory of Open Access Journals (Sweden)

    C. Armellini

    2007-01-01

    Full Text Available Two different kinds of rare earth-activated glass-based nanocomposite photonic materials, which allow to tailor the spectroscopic properties of rare-earth ions: (i Er3+-activated SiO2-HfO2 waveguide glass ceramic, and (ii core-shell-like structures of Er3+-activated silica spheres obtained by a seed growth method, are presented.

  2. Rare earth mineralogy of the Olympic Dam Cu-U-Au-Ag deposit, South Australia

    International Nuclear Information System (INIS)

    Lottermoser, B.G.; Day, A.

    1993-01-01

    Rare earth elements (REE) and yttrium accompany uranium and copper mineralisation within the polymetallic Olympic Dam deposit. The light and heavy rare earths tend to occur in different host minerals. Most of the light rare earths (LREE) are present as the essential structural constituents of LREE fluorocarbonates such bastnaesite and synchysite, or in phosphates such as florencite and monazite. Yttrium and the heavy rare earths (HREE) occur mostly as minor concentrations in the form of cation substitutions within uranium minerals such as uraninite and coffinite, as well as brannerite to a lesser extent. Selective dissolution of uraninite and coffinite during acid leaching leads to the liberation of yttrium and HREE from their host minerals, resulting in higher percentage extractions of HREE than LREE in uranium bearing leach liquors. LREE liberation is more restricted because only the synchysite dissolves to any significant extent, while bastnaesite is more difficult to dissolve. 9 refs., 2 figs

  3. Rare earth intermetallic compounds produced by a reduction-diffusion process

    International Nuclear Information System (INIS)

    Cech, R.E.

    1975-01-01

    A reduction-diffusion process is given for producing novel rare earth intermetallic compounds, such as cobalt--rare earth intermetallic compounds, especially compounds useful in preparing permanent magnets. A particulate mixture of rare earth metal halide, cobalt and calcium hydride is heated to effect reduction of the rare earth metal halide and to diffuse the resulting rare earth metal into the cobalt to form the intermetallic compound

  4. Recovery of rare earths from spent NdFeB magnets of wind turbine: Leaching and kinetic aspects.

    Science.gov (United States)

    Kumari, Aarti; Sinha, Manish Kumar; Pramanik, Swati; Sahu, Sushanta Kumar

    2018-05-01

    Increasing demands of rare earth (RE) metals for advanced technological applications coupled with the scarcity of primary resources have led to the development of processes to treat secondary resources like scraps or end of life products that are often rich in such metals. Spent NdFeB magnet may serve as a potential source of rare earths containing around ∼30% of neodymium and other rare earths. In the present investigation, a pyro-hydrometallurgical process has been developed to recover rare earth elements (Nd, Pr and Dy) from the spent wind turbine magnet. The spent magnet is demagnetized and roasted at 1123 K to convert rare earths and iron to their respective oxides. Roasting of the magnet not only provides selectivity, but enhances the leaching efficiency also. The leaching of the roasted sample with 0.5 M hydrochloric acid at 368 K, 100 g/L pulp density and 500 rpm for 300 min selectively recovers the rare earth elements almost quantitatively leaving iron oxide in the residue. Leaching of rare earth elements with hydrochloric acid follows the mixed controlled kinetic model with activation energy (E a ) of 30.1 kJ/mol in the temperature range 348-368 K. The leaching mechanism is further established by characterizing the leach residues obtained at different time intervals by scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD). Individual rare earth elements from the leach solution containing 16.8 g/L of Nd, 3.8 g/L Pr, 0.28 g/L of Dy and other minor impurity elements could be separated by solvent extraction. However, mixed rare earth oxide of 99% purity was produced by oxalate precipitation followed by roasting. The leach residue comprising of pure hematite has a potential to be used as pigment or can find other applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Carbon footprint assessment of recycling technologies for rare earth elements: A case study of recycling yttrium and europium from phosphor.

    Science.gov (United States)

    Hu, Allen H; Kuo, Chien-Hung; Huang, Lance H; Su, Chao-Chin

    2017-02-01

    Rare earth elements are key raw materials in high-technology industries. Mining activities and manufacturing processes of such industries have caused considerable environmental impacts, such as soil erosion, vegetation destruction, and various forms of pollution. Sustaining the long-term supply of rare earth elements is difficult because of the global shortage of rare earth resources. The diminishing supply of rare earth elements has attracted considerable concern because many industrialized countries regarded such elements as important strategic resources for economic growth. This study aims to explore the carbon footprints of yttrium and europium recovery techniques from phosphor. Two extraction recovery methods, namely, acid extraction and solvent extraction, were selected for the analysis and comparison of carbon footprints. The two following functional units were used: (1) the same phosphor amounts for specific Y and Eu recovery concentrations, and (2) the same phosphor amounts for extraction. For acid extraction method, two acidic solutions (H 2 SO 4 and HCl) were used at two different temperatures (60 and 90°C). For solvent extraction method, acid leaching was performed followed by ionic liquid extraction. Carbon footprints from acid and solvent extraction methods were estimated to be 10.1 and 10.6kgCO 2 eq, respectively. Comparison of the carbon emissions of the two extraction methods shows that the solvent extraction method has significantly higher extraction efficiency, even though acid extraction method has a lower carbon footprint. These results may be used to develop strategies for life cycle management of rare earth resources to realize sustainable usage. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Rare earth industries; Moving Malaysia's Green Economy Forward

    International Nuclear Information System (INIS)

    2011-08-01

    There is a famous saying, Where there is risk, there is opportunity. Rare earths present both health and environmental risks as well as potential economic opportunities. However, the risks are manageable thanks to improved technologies and a better understanding of the implications on health and the environment. This explains why there is a rush by many countries to reopen old mines and increase investment in the production of rare earths concentrate and their high value downstream products. Why is there such a scramble to risk money on rare earths? What have ignited global demand? Where are the opportunities? How are the risks associated with rare earths managed? Can Malaysia benefit from this new growth industry? What should be our strategies? This report, produced by the joint Working Group of the Academy of Sciences Malaysia (ASM) and the Majlis Professor Negara (MPN), discusses the science of rare earths and their business prospects; and proposes some strategic directions for Malaysia. The analysis is based on information culled from various secondary sources as well as the groups engagement with experts from the Rare Earths Society of China. (author)

  7. Enzymatic determination of rare earth elements using pyrophosphatases

    International Nuclear Information System (INIS)

    Shekhovtsova, T.N.; Pirogova, S.V.; Fedorova, O.M.; Dolmanova, I.F.; Bajkov, A.A.

    1993-01-01

    A highly sensitive(determination limit 8x10 -6 -4x10 -4 μ g/m) and selective enzymatic method for determination of rare earth elements has been developed. The method is based on inhibition action of rare earths on the catalytic activity of pyrophosphates isolated from bakery geast and E.Coli. The mechanism of the rare earth element action, corresponding to competitive inhibition, has been established

  8. Study on rare earths complexes separation by means of different type of ion exchangers

    International Nuclear Information System (INIS)

    Hubicka, H.

    1990-01-01

    The applicability of different types of ion exchangers for purification and separation of rare earths complexes has been examined. The experimental work has been carried out on 14 chelating ion exchangers. The investigation results proved the great usefulness chelating ion exchangers especially of amino acid and phosphorus-type. Application of that type ion exchangers in column chromatographic process gave the excellent rare earths separation as well as enabled to obtain their preparates of high purity. 218 refs, 21 figs, 27 tabs

  9. SEPARATION OF TRANSURANIC ELEMENTS FROM RARE EARTH COMPOUNDS

    Science.gov (United States)

    Kohman, T.P.

    1961-11-21

    A process of separating neptunium and plutonium values from rare earths and alkaline earth fission products present on a solid mixed actinide carrier (Th or U(IV) oxalate or fluoride) --fission product carrier (LaF/sub 3/, CeF/sub 3/, SrF/sub 2/, CaF/sub 2/, YF/sub 3/, La oxalate, cerous oxalate, Sr oxalate, Ca oxalate or Y oxalate) by extraction of the actinides at elevated temperature with a solution of ammonium fluoride and/or ammonium oxalate is described. Separation of the fission-product-containing carriers from the actinide solution formed and precipitation of the neptunium and plutonium from the solution with mineral acid are also accomplished. (AEC)

  10. Extraction of rare earth elements from low-grade Bauxite via precipitation reaction

    Science.gov (United States)

    Kusrini, E.; Nurani, Y.; Bahari, ZJ

    2018-03-01

    The aim of this research was to determine the optimum hydrometallurgical parameters to extract the rare earth elements (REE) from low-grade bauxite through acid leaching and precipitation reaction. REE or lanthanide recovery by a precipitation method with sodium sulphate and sodium phosphate as precipitation agents is reported where the effect of pH and recovery of REE are described. The metal composition of REE in low-grade bauxite after treatment were analyzed by ICP-OES. The total recovery values of REE elements at the first precipitation reaction using sodium sulphate as the precipitation agent at pH 3.5 showed ~68.2% of lanthanum, ~18.9% cerium, and ~7.8% yttrium. Lanthanum was the rare-earth element present at the highest concentration in the low-grade bauxite after the series treatments. An optimum pH of 3.5 for precipitation of rare-earth elements using sodium sulphate was demonstrated where this method is recommended for the extraction of REE elements from low-grade bauxite.

  11. Hydrometallurgical separation of rare earth elements, cobalt and nickel from spent nickel-metal-hydride batteries

    Science.gov (United States)

    Rodrigues, Luiz Eduardo Oliveira Carmo; Mansur, Marcelo Borges

    The separation of rare earth elements, cobalt and nickel from NiMH battery residues is evaluated in this paper. Analysis of the internal content of the NiMH batteries shows that nickel is the main metal present in the residue (around 50% in weight), as well as potassium (2.2-10.9%), cobalt (5.1-5.5%), rare earth elements (15.3-29.0%) and cadmium (2.8%). The presence of cadmium reveals that some Ni-Cd batteries are possibly labeled as NiMH ones. The leaching of nickel and cobalt from the NiMH battery powder with sulfuric acid is efficient; operating variables temperature and concentration of H 2O 2 has no significant effect for the conditions studied. A mixture of rare earth elements is separated by precipitation with NaOH. Finally, solvent extraction with D2EHPA (di-2-ethylhexyl phosphoric acid) followed by Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) can separate cadmium, cobalt and nickel from the leach liquor. The effect of the main operating variables of both leaching and solvent extraction steps are discussed aiming to maximize metal separation for recycling purposes.

  12. 12 Ministries Control Rare Earth Exports

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>"It is very natural to reserve rare earth as a strategic resource.Many countries do this,including China."On April 8,Sun Lihui,Vice Director of Metal Section of Chemicals Import & Export Commerce Chamber of China Minmetals Corporation told a reporter that as early as 2006,China has launched a strategic plan for rare earth,"but it was interrupted by the subsequent financial crisis."

  13. Preparation and characterization of PT-rare earth/C electrocatalysts for PEM fuel cells

    International Nuclear Information System (INIS)

    Santoro, Thais Aranha de Barros

    2009-01-01

    Pt-rare earth/C electrocatalysts (rare earth = La, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Tm, and Lu) were prepared (20 wt.% and Pt-to-RE atomic ratio of 50:50) by an alcohol reduction process using H 2 PtCl 6 .6H 2 O (Aldrich) and rare earth (III) chlorides (Aldrich) as metal sources, ethylene glycol as solvent and reducing agent, and Vulcan XC72 as support. The electrocatalysts were characterized by Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffractometry (XRD) and Transmission Electron Microscopy (TEM). The energy dispersive x-ray spectroscopy analysis showed that the Pt-Rare Earth atomic ratios obtained for all electrocatalysts were similar to those used in the preparations. In all diffractograms, it was observed a broad peak at about 25 degree which was associated to the Vulcan XC72 support material and four peaks at approximately 28=40 degree, 47 degree, 67 degree and 82 degree, which were associated to the (111), (200), (220), (311), and (222) planes, respectively, of the face-centered cubic (fcc) structure characteristic of platinum and platinum alloys. For the Pt-Rare Earth/C electrocatalysts, it was also observed peaks related to the rare earth oxides on the X ray diffractograms. PtLa/C electrocatalysts were prepared at different atomic ratio. Transmission electronic microscopy micrographs of electrocatalysts showed a reasonable distribution of the Pt particles on the carbon support with some agglomerations, which is in agreement with x-ray diffractometry result. The performance for CO, methanol and ethanol oxidation was investigated by cyclic voltammetry, chronoamperometry and Fourier transform infrared spectroscopy spectroscopy. The electrocatalytic activity of the Pt-Rare Earth/C electro catalyst, specially PtLa/C, were higher than that of the Pt/C electrocatalyst. Fourier transform infrared spectroscopy studies for ethanol oxidation on Pt-Rare Earth/C electrocatalyst showed that acetaldehyde and acetic acid were the main products. The PtLa/C (30

  14. Emerging industrial processes for low grade rare earth mineral concentrates

    International Nuclear Information System (INIS)

    Soldenhoff, Karin; Ho, Elizabeth

    2015-01-01

    Historically rare earth recovery has mainly been derived from the processing of monazite, bastnasite and xenotime containing ores amenable to beneficiation, yielding high grade mineral concentrates. A notable exception is the recovery of heavy rare earths from ionic clays in Southern China. Recently, projects are being proposed to treat a range of mineral concentrates which tend to be lower grade with wide ranging modal mineralogy for rare earths and associated gangue minerals. This has a significant impact on processing routes. This paper discusses processes proposed for emerging rare earth producers and how different projects have responded to particular challenges including: Control of phosphorous due to the presence of xenotime or monazite type minerals; Control of phosphorous due to the presence of rare earth containing apatite; Rare earth recovery from polymetallic ores; Control of radionuclides in rare earth processing, etc.

  15. Thermogravimetric study of rare earth concentrates

    International Nuclear Information System (INIS)

    Delyagejd, V.V.; Anisimova, V.N.; Eremenko, Z.V.; Kutsev, V.S.

    1974-01-01

    Methods of thermogravimetric, chemical and phase analysis were used in measuring the concentration of rare-earth elements of different origins. At temperatures 400-800 deg C a gradual decomposition of fluorocarbonates takes place leading to the formation of derivatives of corresponding oxides and oxyfluorides. For concentrates containing siderite the process takes place at 550-600 deg C followed by oxidation of bivalent iron into trivalent state. Reaction of rare-earth elements with sodium carbonate and the increase in the concentration of the latter results in a narrowing down of the interval of temperatures at which decomposition takes place. Under these conditions an intense reaction and a fusion take place leading to the formation of eutectic at 500-600 deg C and further synthesis of sodium fluoride and oxyfluoride derivatives of calcium and rare-earth elements

  16. Recovery of lead-208 radiogenic of residues of thorium with rare earth

    International Nuclear Information System (INIS)

    Ferreira, J.C.; Freitas, A.A. de; Seneda, J.A.F.; Carvalho, M.S. de; Abrao, A.

    2008-01-01

    In the middle of the years 1970 in IPEN, considerable work for the purification and conversion of uranium and thorium project, the production of thorium nitrate, a pilot scale from different compounds of Thorium was accomplished; This installation of thorium nitrate produced for national marketing, given the industry of incandescent lighting gas mangles.. The method used by this installation was the purification by solvent extraction with pulsed columns. The thorium was in the organic phase, which was reversed as of thorium nitrate with a high degree of purity. The aqueous phase of this chemical process, containing impurities, some not extracted thorium and virtually all rare earths was precipitated in the form of a hydroxide. This was called RETOTER hydroxide (residue of Thorium and Rare Earth). This residue containing thorium, rare earth and some impurities such as lead-208 product of the decay of thorium-232 were stored in the shed of safeguarding IPEN for further recovery of thorium and rare earth. In this work was studied the recovery of lead-208, nuclear material of interest, separating it by the technique of cementation , where it adds zinc metallic to an acid solution of RETOTER, holding up the lead on the surface of the metallic zinc. (author)

  17. Cermets based on rhenium and rare earth element oxides

    International Nuclear Information System (INIS)

    Varfolomeev, M.B.; Velichko, A.V.; Zajtseva, L.L.; Shishkov, N.V.

    1977-01-01

    The reduction of perrhenates of rare earth elements and of yttrium by hydrogen and the subsequent sintering have yielded cermets based on rhenium and rare earth element oxides inherent in which are more disperse and homogeneous structures than those of the ''molecular'' rare earth element-Tc cermets. The dispersity of cermets increases in the rare earth elements series from La to Lu. The microhardness of the Re phase in cermets is 490 kgf/mm 2 ; the total microhardness of a cermet is substantially higher

  18. Micromagnetics of rare-earth efficient permanent magnets

    Science.gov (United States)

    Fischbacher, Johann; Kovacs, Alexander; Gusenbauer, Markus; Oezelt, Harald; Exl, Lukas; Bance, Simon; Schrefl, Thomas

    2018-05-01

    The development of permanent magnets containing less or no rare-earth elements is linked to profound knowledge of the coercivity mechanism. Prerequisites for a promising permanent magnet material are a high spontaneous magnetization and a sufficiently high magnetic anisotropy. In addition to the intrinsic magnetic properties the microstructure of the magnet plays a significant role in establishing coercivity. The influence of the microstructure on coercivity, remanence, and energy density product can be understood by using micromagnetic simulations. With advances in computer hardware and numerical methods, hysteresis curves of magnets can be computed quickly so that the simulations can readily provide guidance for the development of permanent magnets. The potential of rare-earth reduced and rare-earth free permanent magnets is investigated using micromagnetic simulations. The results show excellent hard magnetic properties can be achieved in grain boundary engineered NdFeB, rare-earth magnets with a ThMn12 structure, Co-based nano-wires, and L10-FeNi provided that the magnet’s microstructure is optimized.

  19. Radiochemical studies in chemical separation and spectrographic determination of rare earths in thorium oxide matrix (Preprint No. RA.06)

    International Nuclear Information System (INIS)

    Adya, V.C.; Dhawale, B.A.; Rajeshwari, B.; Bangia, T.R.; Sastry, M.D.

    1989-01-01

    A chemical separation procedure was standardised for the separation of traces of rare earths from ThO 2 matrix using HDEHP (Di 2-ethyl hexyl phosphoric acid). The studies were carried out using both nitric acid and hydrochloric acid medium in different concentrations. The extraction studies were also carried out using radioactive isotopes of rare earths viz. 141 Ce, 152-154 Eu, 153 Gd, 170 Tm etc. The extraction was effective in both media. In 0.1 M HDEHP/xylene and 3 M HNO 3 , Ce was partially extracted into organic phase. So HCl/xylene medium was chosen for extraction purposes. The recovery was confirmed by both gamma counting and emission spectropgraphic method. It was found to be quantitative within experimental error. The separation procedure development here was used for determination of rare earths in thorium oxide matrix by emission spectrographic method. (author)

  20. Complexing in aqueous solutions of rare earth n-aminobenzoates

    International Nuclear Information System (INIS)

    Efremova, G.I.; Buchkova, R.T.; Lapitskaya, A.V.; Pirkes, S.B.

    1977-01-01

    Complexing in the system ''ion of a rare-earth metal - n-aminobenzoic acid'' has been investigated by the pH-metric method in the pH range of 3.5-5.5. In the La-Eu series, the stability of n-aminobenzoate complexes increases and attains the maximum value in the complex Eu (lg Ksub(st)=2.66). In the Gd-Lu series the stability of the complex particles decreases monotonically

  1. Spectrophotometric method for the analysis of rare earths by first and second order derivatives

    International Nuclear Information System (INIS)

    Deshpande, S.M.; Singh, H.

    1997-01-01

    Spectrophotometric methods are widely used for the analysis of rare earth elements as they are simple, fast, precise and accurate. Many of the rare earth ions in acidic solutions absorb in ultraviolet and visible region of the electromagnetic spectrum. Because of the restricted transition of the 4f electrons the absorption peaks are very sharp and these peaks are used for the qualitative and quantitative analysis of rare elements. When analysis of one or two minor constituents in the mixture of rare earths is involved, it is a straightforward and simple matter, but the analysis of multiple elements from a complex mixture is very difficult because of the mutual interference of the absorption bands. Simultaneous equations of the type: (OD) 1 = C A X Φ A1 + C B X Φ B1 and (OD) 2 = C A X Φ A2 + C B X Φ B2 are also employed to overcome the mutual interference. In this paper first order and second order derivative spectra are used for the analysis of rare earths. It is a simple and effective technique for accurate analysis of rare earths from a complex mixture. Absorption data in the first derivative mode is also presented. Analysis of Nd-Pr-Sm from their synthetic mixtures is reported. (author). 4 refs., 1 tab., 1 ill

  2. Research On Technology Of Making Rare Earth Alloy Having Rare Earth Content ≽30% From Ore (≽40% REO) Using Aluminum Thermal Technology In Arc Furnace

    International Nuclear Information System (INIS)

    Ngo Xuan Hung; Ngo Trong Hiep; Tran Duy Hai; Nguyen Huu Phuc

    2014-01-01

    Arc furnace was used to smelt materials consisting of rare earth ore having rare earth content of ≽40% REO, aluminum as the reducing agent and additives. Rare earth alloy was obtained with rare earth metal content of more than 30%. (author)

  3. Rare earth industry in India

    International Nuclear Information System (INIS)

    Singh, D.S.

    2016-01-01

    Rare Earths (RE) comprises of 17 elements i.e. elements from atomic No. 57-71 (lanthanide series) along with yttrium (atomic No. 39) and scandium (atomic No. 21). They exhibit special electronic, magnetic, optical and catalytic properties. The first 7 elements in the lanthanide series from atomic Nos. 57 to 63 (La to Eu) are called Light Rare Earths (LRE), while the remaining elements from atomic Nos. 64 to 71 (Gd to Lu) are grouped as Heavy Rare Earths (HRE). Scandium and Yttrium have properties similar to HRE. The concentration of the REs in the earth's crust is as high as some other elements including that of copper. The only difference is that REs do not occur as separate minerals amenable for easy exploration and mining and are widely distributed across the earth's surface, hence they are called as REs. Resources In India, monazite has been the principal source of RE. It occurs in association with other heavy minerals, such as ilmenite, rutile, zircon etc. in the beach sands and inland placer deposits. The monazite content in this assemblage varies from negligible quantity to as high as 5%. As per AMD resource estimation, the reported resource of monazite in India is about 11.93 million tons which corresponds with about 6.9 million tons of RE oxides. Although India possesses large deposits of monazite, the heavier RE are not present in sufficient quantities in this mineral. (author)

  4. Intra-group separation of rare earths using new organic phosphorus ligands; Intragruppentrennung Seltener Erden mittels neuer phosphororganischer Liganden

    Energy Technology Data Exchange (ETDEWEB)

    Hadic, Sanela

    2017-10-01

    Rare earth elements (REE) have unique magnetic, photophysical, and chemical properties and they are therefore used in numerous high-technology applications. However, to this day, the isolation of pure rare earths from primary and secondary raw materials is very challenging. In this work, the hydrometallurgical separation of neighboring rare earths (e.g., praseodymium/ neodymium) was optimized with novel selective extraction agents. The separation of rare earths (yttrium and all lanthanides except promethium) was investigated with fourteen new organophosphorus compounds. Oxygen-bearing phosphinic acids yielded good separation results for heavy rare earths (dysprosium to lutetium). For light rare earths (lanthanum to neodymium), particularly high separation factors were realized with synergistic systems containing an aromatic dithiophosphinic acid and a co-extractant, such as tris (2-ethylhexyl) phosphate (TEHP). Optimization studies of the latter extraction system revealed an extremely high separation factor (SF) of 4.21 between praseodymium and neodymium. Another focus of this work was to understand the extraction mechanism. With the aid of nuclear magnetic resonance spectroscopy ({sup 1}H-NMR) and time-resolved laser fluorescence spectroscopy (TRLFS), the complex stoichiometry of promising extraction systems was examined. Studies revealed a dependency between the selectivity for rare earths and the coordination number of the formed complexes. In addition, temperature-dependent extraction experiments were performed and thermodynamic data (ΔG, ΔH, and ΔS) determined. These data provided additional information about the origin of selectivity for neighboring rare earths. With regard to the industrial capability of the investigated extraction systems, the chemical durability of ligands was studied under process-relevant conditions. Qualitative and quantitative analytical methods (e.g., GC-MS) were used in long-term experiments to determine the ligand degradation

  5. Recovery of rare earths from red mud

    International Nuclear Information System (INIS)

    Bautista, R.G.

    1992-01-01

    The prospect for the recovery of rare earths from red mud, the bauxite tailings from the production of alumina is examined. The Jamaican red mud by far has the higher trace concentrations of lanthanum, cerium, neodymium, and yttrium. Scandium is also present. The dissolution of the rare earth is a major extraction problem because of the large volume of other materials. The recovery processes that have been proposed include the production of co-products such as iron, alumina, and titanium concentrates, with the rare earths going with the titanium. In this paper a critical examination of the possible processes are presented with the recommended research projects to be carried out

  6. Studies on Three Liquid Phase Extraction (TLPE) system for separation of rare earths

    International Nuclear Information System (INIS)

    Yadav, Kartikey K.; Singh, D.K.; Anitha, M.; Singh, H.

    2014-01-01

    Three-liquid-phase extraction (TLPE) is relatively a new separation technique, which takes the advantage of the differences in physicochemical properties of three coexisted phases to achieve multi-phase liquid separation of two or more components in one-step extraction. TLPE system consists of three liquid layers namely an organic solvent phase (organophosphorous type) and two aqueous phases one rich in polymer phase (poly alkylene glycol) and other a salt solution. To study the feasibility of using such system for separation of rare earths, it is important to optimize the preparatory conditions by selective suitable polymer and salt solutions at an appropriate pH to obtain a stable three phase layers to effect the separation. D2EHPA (di-2-ethyl hexyl phosphoric acid) is a well- established extractant in the rare earth industry and has been chosen in the present work to form a TLPE with polymer and salt solution. In the present investigation after preparing the stable three phase, the feasibility of using TLPE has been examined to separate rare earths from a multicomponent solutions. This study has demonstrated the ability of TLPE having D2EHPA as organic phase to separate rare earths from a multicomponent system. Effect of pH, concentration and types of polymer, complexing agent and D2EHPA concentration has been studied. Variation in pH study indicated that 4.0 leads to extraction of rare earths in the polymer phase. PEG 600 was found to be best amongst the polymer investigated. Presence of DTPA as complexing agent in the salt solution having pH >4.0 resulted in enhanced extraction of rare earths in PEG phase

  7. On solubility of rare earth chlorides in water at different temperatures

    International Nuclear Information System (INIS)

    Nikolaev, A.V.; Sorokina, A.A.; Sokolova, N.P.; Kotlyar-Shapirov, G.S.; Bagryantseva, L.I.

    1978-01-01

    Solubility of rare earth chlorides at -5, -10 and -15 deg C is studied. Rare earth chloride solubility dependences on the temperature in the interval from -15 to 50 deg C are presented. Decrease of solubility temperature coefficient to a zero is observed at temperature drop almost for all rare earth chlorides. Solubility temperature coefficient at the same temperature but for different rare earth chlorides reduces appreciably with the growth of rare earth chloride serial number. This testifies to the corresponding decrease of integral solution heat of rare earth chloride crystallohydrates

  8. Rare earth elements and permanent magnets (invited)

    Science.gov (United States)

    Dent, Peter C.

    2012-04-01

    Rare earth (RE) magnets have become virtually indispensible in a wide variety of industries such as aerospace, automotive, electronics, medical, and military. RE elements are essential ingredients in these high performance magnets based on intermetallic compounds RECo5, RE2TM17 (TM: transition metal), and RE2TM14B. Rare earth magnets are known for their superior magnetic properties—high induction, and coercive force. These properties arise due to the extremely high magnetocrystalline anisotropy made possible by unique 3d-4f interactions between transition metals and rare earths. For more than 40 years, these magnets remain the number one choice in applications that require high magnetic fields in extreme operating conditions—high demagnetization forces and high temperature. EEC produces and specializes in RECo5 and RE2TM17 type sintered magnets. Samarium and gadolinium are key RE ingredients in the powder metallurgical magnet production processes which include melting, crushing, jet milling, pressing, sintering, and heat treating. The magnetic properties and applications of these magnets will be discussed. We will also briefly discuss the past, current, and future of the permanent magnet business. Currently, over 95% of all pure rare earth oxides are sourced from China, which currently controls the market. We will provide insights regarding current and potential new magnet technologies and designer choices, which may mitigate rare earth supply chain issues now and into the future.

  9. Isopiestic determination of the activity coefficients of some aqueous rare earth electrolyte solutions at 250C. I. The rare earth chlorides

    International Nuclear Information System (INIS)

    Spedding, F.H.; Weber, H.O.; Saeger, V.W.; Petheram, H.H.; Rard, J.A.; Habenschuss, A.

    1976-01-01

    The osmotic coefficients of the aqueous trichlorides of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y were determined from 0.1 M to saturation at 25 0 C. Semiempirical least-squares equations were obtained for the osmotic coefficients as a function of molality and these equations were used to calculate water activities and mean molal activity coefficients. The water activities of the light rare earth chlorides at constant molalities are higher than for the heavy rare earths, while the mean molal activity coefficients are larger for the heavy rare earths than for the light ones. The above effects are discussed in terms of changes in the cationic radii and hydration of the rare earth ions

  10. China’s Rare Earths Production Forecasting and Sustainable Development Policy Implications

    Directory of Open Access Journals (Sweden)

    Xibo Wang

    2017-06-01

    Full Text Available Because of their unique physical and chemical properties, Rare earth elements (REEs perform important functions in our everyday lives, with use in a range of products. Recently, the study of China’s rare earth elements production has become a hot topic of worldwide interest, because of its dominant position in global rare earth elements supply, and an increasing demand for rare earth elements due to the constant use of rare earth elements in high-tech manufacturing industries. At the same time, as an exhaustible resource, the sustainable development of rare earth elements has received extensive attention. However, most of the study results are based on a qualitative analysis of rare earth elements distribution and production capacity, with few studies using quantitative modeling. To achieve reliable results with more factors being taken into consideration, this paper applies the generic multivariant system dynamics model to forecast China’s rare earth elements production trend and Hubbert peak, using Vensim software based on the Hubbert model. The results show that the peak of China’s rare earth elements production will appear by 2040, and that production will slowly decline afterwards. Based on the results, the paper proposes some policy recommendations for the sustainable development of China’s—and the world’s—rare earth elements market and rare earth-related industries.

  11. Evaluation of Rare Earth Element Extraction from North Dakota Coal-Related Feed Stocks

    Science.gov (United States)

    Laudal, Daniel A.

    identified that the predominant modes of rare earths occurrence in the lignite coals are associations with the organic matter, primarily as coordination complexes and a lesser amount as ion-exchangeable cations on oxygen functional groups. Overall it appears that about 80-95% of rare earths content in North Dakota lignite is organically associated, and not present in mineral forms, which due to the weak organic bonding, presented a unique opportunity for extraction. The process developed for extraction of rare earths was applied to the raw lignite coals instead of fly ash or other byproducts being investigated extensively in the literature. Rather, the process uses a dilute acid leaching process to strip the organically associated rare earths from the lignite with very high efficiency of about 70-90% at equilibrium contact times. Although the extraction kinetics are quite fast given commercial leaching operations, there is some tradeoff between extraction efficiency and contact time. (Abstract shortened by ProQuest.).

  12. Distribution characteristics of rare earth elements in plants from a rare earth ore area

    International Nuclear Information System (INIS)

    Zhang, Z.Y.; Wang, Y.Q.; Li, F.L.; Xiao, H.Q.; Chai, Z.F.

    2002-01-01

    The contents of eight rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in various plant species taken from a rare earth ore area were determined by instrumental neutron activation analysis. For a given plant, the REE patterns in root, leaf and host soil are different from each other. The REE distribution characteristics in roots of various species are very similar and resemble those in the surface water. The results of this study suggest that there is no significant fractionation between the REEs during their uptake by the plant roots from soil solution. However, the variation of the relative abundance of individual REE occurs in the process of transportation and deposition of REEs in plants. (author)

  13. Mammography with rare earth intensifying screens

    International Nuclear Information System (INIS)

    Maurer, H.J.; Goos, F.

    1987-01-01

    Screens basing on rare earth phosphors with suitable films green or blue sensitive may be used in mammography with grids without diagnostic losses. Highest definition will be obtained with medium densities on film. High-speed screens may reduce dose, but definition is poor. Best compromise between speed and high definition may be reached with relative low thickness of phosphor layers. A system of high definition films (Medichrome) and special rare earth screens give best results. (orig.) [de

  14. Replacing critical rare earth materials in high energy density magnets

    Science.gov (United States)

    McCallum, R. William

    2012-02-01

    High energy density permanent magnets are crucial to the design of internal permanent magnet motors (IPM) for hybride and electric vehicles and direct drive wind generators. Current motor designs use rare earth permanent magnets which easily meet the performance goals, however, the rising concerns over cost and foreign control of the current supply of rare earth resources has motivated a search for non-rare earth based permanent magnets alloys with performance metrics which allow the design of permanent magnet motors and generators without rare earth magnets. This talk will discuss the state of non-rare-earth permanent magnets and efforts to both improve the current materials and find new materials. These efforts combine first principles calculations and meso-scale magnetic modeling with advance characterization and synthesis techniques in order to advance the state of the art in non rare earth permanent magnets. The use of genetic algorithms in first principle structural calculations, combinatorial synthesis in the experimental search for materials, atom probe microscopy to characterize grain boundaries on the atomic level, and other state of the art techniques will be discussed. In addition the possibility of replacing critical rare earth elements with the most abundant rare earth Ce will be discussed.

  15. On fluorozirconates and fluorohafnates of rare earths

    International Nuclear Information System (INIS)

    Korenev, Yu.M.; Antipov, P.I.; Novoselova, A.V.

    1980-01-01

    It has been shown by the method of X-ray phase analysis that on interaction between rare-earth fluorides and zirconium and hafnium tetrafluorides, compounds with 1:1, 1:2, 1:3 molar ratios of components are formed. Compounds of the LnHfF 4 type are prepared for all rare-earths. Fluoro-metals of the LnHf 2 F 11 composition are typical only of light lanthanides from lanthanum to neodymium, while pentafluorated salts Ln(EF 5 ) 3 are formed in the reaction between EF 4 with fluorides of heavy rare-earth elements from samarium to lutecium, as well as with yttrium trifluoride. Parameters of unit cells of heptafluohafnates and pentafluometallates are determined

  16. Spectral determination of individual rare earths in different classes of inorganic compounds

    International Nuclear Information System (INIS)

    Karpenko, L.I.; Fadeeva, L.A.; Shevchenko, L.D.

    1979-01-01

    The conditions are found allowing to analyze various inorganic compounds for rare-earth elements without separation from non-rare-earth components. The influence of the plasma composition on the intensity of spectral lines of rare-earth elements is studied. The relative intensity of homologous spectral lines of various rare-earth elements remains constant regardless of the plasma composition. The conditions are found for the determination of individual rare-earth elements acting as both alloying additives (Csub(n) -- n x 10 -1 -n x 10 -3 %), and basic components (up to tens of per cent) in different classes of inorganic compounds of 1-7 elements. The general method is developed for the determination of individual rare-earth elements in mixtures of oxides of rare-earth elements, complex fluorides of rare-earth elements and elements of group 2, gallates, borates, germanates, vanadates of rare-earth elements and aluminium; zirconates-titanates of lead and barium, containing modifying additives of rare-earth elements, complex chalcogenides of rare-earth elements and elements of group 5

  17. Investigation of ionic associates of rare earths with 3,5-diiodosalicylic acid and rhodamine B as an analytical form

    Energy Technology Data Exchange (ETDEWEB)

    Tselik, E I; Kushch, V P; Poluehktov, N S; Mishchenko, V T [AN Ukrainskoj SSR, Kiev. Inst. Fizicheskoj Khimii

    1979-11-01

    It is established that three-charge ions of rare earth elements form ionic associates with 3,5-diiodosalicylic acid (DISA) and rhodamine B (RB) with the ratio of components Me:DISA:RB = 1:4:1. For the associates toluene is the most suitable solvent. Certain correlation dependencies of properties in the natural series of these elements are found. Extraction-photometric method of Nd and Er determination with sensitivity of 0.026 and 0.033 ..mu..g/ml respectively (l = 0.3 cm) and relative standard deviation of <= 0.043 is developed. The use of DISA permits to increase the method sensitivity as compared with the method in which salicylic acid is used.

  18. On optimal length of hydrocarbon chain of fatty-acid collectors of rare earth ions

    International Nuclear Information System (INIS)

    Skrylev, L.D.; Sazonova, V.F.; Markina, Eh.L.

    1978-01-01

    The mechanism of the effect of the length of alkyl chain in fatty-acid collectors on the efficiency of flotation separation of the ions of rare earth elements (REE) collected by them has been investigated. REE flotation separation was studied on gadolinium chloride. Aqueous solutions of potassium caprinata, indecanate, laurate, tridecanate, myristate, pentadecanate and palmitate were used as collectors of Gd ions. The interaction of Gd ions with these compounds proceeds rapidly and is accompanied by stable colloidal solutions of Gd soaps being formed. Infrared spectra and radiograms of the sublates have been studied. It has been found that, with the number of carbon atoms in the collector molecule increasing from 10 to 16, the rate of flotation separation of Gd ions from solutions with pH 6 and 8 at first practically does not change (for potassium caprinate, undecanate and laurate), then drops sharply (potassium tridecanate and myristate), after which is again increases sharply (potassium pentadecanata and palmitate). The separation rate of Gd ions does not rise in solutions with pH 10. The nature of the sublate is shown to be determined by the solubility of the corresponing fatty acids and gadolinium soaps

  19. Heavy rare earths, permanent magnets, and renewable energies: An imminent crisis

    International Nuclear Information System (INIS)

    Smith Stegen, Karen

    2015-01-01

    This article sounds the alarm that a significant build-out of efficient lighting and renewable energy technologies may be endangered by shortages of rare earths and rare earth permanent magnets. At the moment, China is the predominant supplier of both and its recent rare earth industrial policies combined with its own growing demand for rare earths have caused widespread concern. To diversify supplies, new mining—outside of China—is needed. But what many observers of the “rare earth problem” overlook is that China also dominates in (1) the processing of rare earths, particularly the less abundant heavy rare earths, and (2) the supply chains for permanent magnets. Heavy rare earths and permanent magnets are critical for many renewable energy technologies, and it will require decades to develop new non-Chinese deposits, processing capacity, and supply chains. This article clarifies several misconceptions, evaluates frequently proposed solutions, and urges policy makers outside of China to undertake measures to avert a crisis, such as greater support for research and development and for the cultivation of intellectual capital. - Highlights: • Rare earths are needed for many efficient lighting and renewable energy technologies. • The industries for rare earths and permanent magnets are dominated by China. • China's reliability is compromised, necessitating non-Chinese mining and processing. • Recycling, substitution and reducing rare earth content are long-term solutions only. • Policy makers should support development of supply chains and intellectual capital

  20. Handbook on the physics and chemistry of rare earths

    International Nuclear Information System (INIS)

    Gschneidner, K.A. Jr.; Eyring, L.

    1982-01-01

    This handbook is a six-volume work which covers the entire rare earth field in an integrated manner. Each chapter is a comprehensive, up-to-date, critical review of a particular segment of the field. The first volume is devoted to the rare earth metals, the second to rare earth alloys and intermetallics, and the third and fourth volumes to the non-metallic rare earth materials, including solutions, complexes and bioinorganic substances, in addition to solid inorganic compounds. The electronic structure of these unique elements is the primary basis of understanding their physical, metallurgical and chemical natures. The interrelationship of the 4f and valence electrons and the observed optical, electrical, magnetic, crystallographic, elastic, thermal, mechanical, chemical, geochemical and biological behaviors is brought forth time and again throughout the chapters. Also discussed are the preparative, separation and solution chemistry of the elements and their compounds and the various chemical and physical analytical methods for determining the rare earths in various materials and impurities in a rare earth matrix. Vol. 5 is a update complement of the previous volumes. Volume 6 is concerned with ternary and higher order materials. (Auth.)

  1. Geochemistry of rare earths in main media of clay formation and sedimentation

    International Nuclear Information System (INIS)

    Bonnot-Courtois, C.

    1981-01-01

    This work aims i) at a better knowledge of rare earth behavior in surface conditions and ii) possible use of rare earth as a marker for argilaceous mineral genesis. Chemical properties of rare earths and geochemistry of these elements in main rocks are recalled. Rare earth behaviour during continental alteration process, experimental hydrolysis of various magmatic materials and rare earth geochemistry in argilaceous minerals in continental shelf are examined. Then some aspects of rare earth behaviour in oceans are studied: alteration of sea bed and hydrothermalism rare earth distribution in pelagic sediments red clays of deep seas and manganese nodules. In conclusion rare earth behaviour in sedimentary processes of the exogenous cycle is summarized [fr

  2. Studies on the separation of rare earth elements and the nuclear decay properties of short lived rare-earth nuclides in U-235 fission products

    International Nuclear Information System (INIS)

    Ohyoshi, Akira; Ohyoshi, Emiko.

    1980-01-01

    The effect of a complex-forming agent, with which rare earths consecutively form the complexes, on the separation of a pair of adjacent rare earths by electromigration has been investigated. The relation between the separation factor for two complexes and the ligand-ion concentration was examined in the separation of La-Ce and Ce-Pr pairs with nitrilotriacetic acid. Rare earths were able to be isolated rapidly at the optimum ligand-ion concentration in lower one, and this method was applied to study the nuclear decay properties of the short lived isotopes of La, Ce, Pr, Nd and Yt formed in the fission of U-235. This method permits the direct measurement of the decay of La-144 without the interference from the radiation of other fission products. The gamma-ray spectrum of La-144 was measured with a high resolution Ge(Li) detector, and the gamma-transition was observed. From the decay plots of two strong photopeaks, the half-life of La-144 was determined. In the case of Ce fraction, the photopeaks assigned to respective isotopes were observed. In the studies on the decay properties of Pr-148 and Pr-149, the decay plot of the strong photopeak showed good linearity, and the accurate half-life of Pr-148 was determined. Similarly, the half-life of Pr-149 was longer than the previously reported value. (Kako, I.)

  3. Rare earths in iron and steelmaking and gaseous desulphurisation

    International Nuclear Information System (INIS)

    Kay, D.A.R.; Subramanian, S.V.; Meng, V.; Kumar, R.V.

    1985-01-01

    Rare earth (RE) additions, either as mischmetal or rare earth silicide, are used in many ladle treatment processes in modern ferrous metallurgy. In ironmaking they provide the basis for the control of graphite morphology in cast irons and in steelmaking additions are made to aluminum-killed steels for desulphurisation and the control of inclusion composition and morphology. Rare earth oxides may also be used in the desulphurisation of medium calorific value gaseous fuels and stack gases. In this paper, Ce-S-O and La-S-O phase stability diagrams are used to determine the role of the rare earths in the external processing of iron and steel, and gaseous desulphurisation

  4. Double Solvent for Extracting Rare Earth Concentrate

    International Nuclear Information System (INIS)

    Bintarti, AN; Bambang EHB

    2007-01-01

    An extraction process to rare earth concentrate which contain elements were yttrium (Y), lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm), gadolinium (Gd) and dysprosium (Dy) which were dissolved in to nitric acid has been done. The experiment of the extraction by double solvent in batch to mix 10 ml of the feed with 10 ml solvent contained the pair of solvent was TBP and TOA, D2EHPA and TOA, TBP and D2EHPA in cyclohexane as tinner. It was selected a right pairs of solvent for doing variation such as the acidity of the feed from 2 - 6 M and the time of stirring from 5 - 25 minutes gave the good relatively extraction condition to Dy element such as using 10 % volume of TOA in D2EHPA and cyclohexane, the acidity of the feed 3 M and the time stirring 15 minutes produced coefficient distribution to dysprosium = 0.586 and separation factor Dy-Ce = ∼ (unlimited); Dy-Nd = 4.651. (author)

  5. Recycling of Rare Earth Elements

    Science.gov (United States)

    Lorenz, Tom; Bertau, Martin

    2017-01-01

    Any development of an effective process for rare earth (RE) recycling has become more and more challenging, especially in recent years. Since 2011, when commodity prices of REs had met their all-time maximum, prices have dropped rapidly by more than 90 %. An economic process able to offset these fluctuations has to take unconventional methods into account beside well-known strategies like acid/basic leaching or solvent extraction. The solid-state chlorination provides such an unconventional method for mobilizing RE elements from waste streams. Instead of hydrochloric acid this kind of chlorination decomposes NH4Cl thermally to release up to 400 °C hot HCl gas. After cooling the resulting solid metal chlorides may be easily dissolved in pH-adjusted water. Without producing strongly acidic wastes and with NH4Cl as cheap source for hydrogen chloride, solid-state chlorination provides various advantages in terms of costs and disposal. In the course of the SepSELSA project this method was examined, adjusted and optimized for RE recycling from fluorescent lamp scraps as well as Fe14Nd2B magnets. Thereby many surprising influences and trends required various analytic methods to examine the reasons and special mechanisms behind them.

  6. Deep-sea mud in the Pacific Ocean as a potential resource for rare-earth elements

    Science.gov (United States)

    Kato, Yasuhiro; Fujinaga, Koichiro; Nakamura, Kentaro; Takaya, Yutaro; Kitamura, Kenichi; Ohta, Junichiro; Toda, Ryuichi; Nakashima, Takuya; Iwamori, Hikaru

    2011-08-01

    World demand for rare-earth elements and the metal yttrium--which are crucial for novel electronic equipment and green-energy technologies--is increasing rapidly. Several types of seafloor sediment harbour high concentrations of these elements. However, seafloor sediments have not been regarded as a rare-earth element and yttrium resource, because data on the spatial distribution of these deposits are insufficient. Here, we report measurements of the elemental composition of over 2,000 seafloor sediments, sampled at depth intervals of around one metre, at 78 sites that cover a large part of the Pacific Ocean. We show that deep-sea mud contains high concentrations of rare-earth elements and yttrium at numerous sites throughout the eastern South and central North Pacific. We estimate that an area of just one square kilometre, surrounding one of the sampling sites, could provide one-fifth of the current annual world consumption of these elements. Uptake of rare-earth elements and yttrium by mineral phases such as hydrothermal iron-oxyhydroxides and phillipsite seems to be responsible for their high concentration. We show that rare-earth elements and yttrium are readily recovered from the mud by simple acid leaching, and suggest that deep-sea mud constitutes a highly promising huge resource for these elements.

  7. Quantitative analysis of thorium in the presence of rare earth by X-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Jesus, Camila S. de; Taam, Isabel; Vianna, Claudio A.

    2013-01-01

    The occurrence of Thorium in ores is normally associated to other elements such as Uranium and Cerium, as well as some Rare-Earths (RE). The separation of these elements by traditional analytic chemistry techniques is both time and reagent consuming, thus increasing the analysis cost. The hereby proposed method consists in the direct determination of Thorium in rare earths ores and compounds by X-ray fluorescence spectroscopy without any prior chemical separation from other matrix elements. This non-destructive technique is used to determine which elements are present in solid and liquid samples, as well as their concentrations. The studied matrix contains Lanthanum, Cerium, Praseodymium, Neodymium, Samarium, Gadolinium and Yttrium. This study evaluated the analytical lines of radiation emission for each rare earth contained in the matrix, comparing it to the Thorium main analytical line. The Thorium quantification was measured through the Th L line, where there is no influence or interference from the rare earths analytical lines. The studied samples are certified standards and the obtained results have been compared to Ethylenediaminetetraacetic acid (EDTA) titration results, an already well-established and widely trusted method. We also measured the matrix effect thus using complex rare earths liquor. This liquor contains also elements commonly found in monazites sands: phosphates, aluminum, iron. Obtained results state the efficiency of X-ray Fluorescence to determine Thorium in the presence of rare earths without any prior chemical separation. (author)

  8. Squeezing clathrate cages to host trivalent rare-earth guests

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian [Iowa State Univ., Ames, IA (United States). Department of Chemistry; Ames Lab., Ames, IA (United States); He, Yuping [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Mordvinova, Natalia E. [Laboratoire CRISMAT, ENSICAEN, CNRS UMR (France); Lebedev, Oleg [Laboratoire CRISMAT, ENSICAEN, CNRS UMR (France); Kovnir, Kirill [Iowa State Univ., Ames, IA (United States). Department of Chemistry; Ames Lab., Ames, IA (United States)

    2017-11-01

    Strike difference of the trivalent rare-earth cations from their alkali and alkaline-earth peers is in the presence of localized 4f-electrons and strong spin-orbit coupling. Placing trivalent rare-earth cations inside the fullerene molecules or in between the blocks of itinerant magnetic intermetallics gave rise to plethora of fascinating properties and materials. A long-time missing but hardly desired piece is the semiconducting or metallic compound where rare-earth cations are situated inside the oversized polyhedral cages of three-dimensional framework. In this work we present a synthesis of such compounds, rare-earth containing clathrates Ba8-xRxCu16P30. The unambiguous proofs of their composition and crystal structure were achieved by a combination of synchrotron powder diffraction, time-of-flight neutron powder diffraction, scanning-transmission electron microscopy, and electron energy-loss spectroscopy. Our quantum-mechanical calculations and experimental characterizations show that the incorporation of the rare-earth cations significantly enhances the hole mobility and concentration which results in the drastic increase in the thermoelectric performance.

  9. Rare earths: harvesting basic research for technology

    International Nuclear Information System (INIS)

    Jagatap, B.N.

    2014-01-01

    In recent years, rare earths are increasingly becoming a versatile platform for basic research that presents enormous technological potentials. A variety of nano-sized inorganic matrices varying from oxides, phosphates, gallates and aluminates, tungstates, stannates, vanadates to fluorides doped with different lanthanide ions have been synthesized and their optical properties have been investigated in the Chemistry Group, BARC. Another interesting application is laser cooling of solids using rare earth doped glasses with potential applications in remote cooling of electronic devices. Combining the luminescence properties of rare earths with photonic crystals is yet another potent area with wide ranging applications. In this presentation we provide an overview of these developments with examples from the R and D programs of the Chemistry Group, BARC

  10. A rare earth-based metal-organic framework for moisture removal and control in confined spaces

    KAUST Repository

    Eddaoudi, Mohamed

    2017-04-13

    A method for preparing a metal-organic framework (MOF) comprising contacting one or more of a rare earth metal ion component with one or more of a tetratopic ligand component, sufficient to form a rare earth-based MOF for controlling moisture in an environment. A method of moisture control in an environment comprising adsorbing and/or desorbing water vapor in an environment using a MOF, the MOF including one or more of a rare earth metal ion component and one or more of a tetratopic ligand component. A method of controlling moisture in an environment comprising sensing the relative humidity in the environment comprising a MOF; and adsorbing water vapor on the MOF if the relative humidity is above a first level, sufficient to control moisture in an environment. The examples relate to a MOF created from 1,2,4,5-Tetrakis(4-carboxyphenyl )benzene (BTEB) as tetratopic ligand, 2-fluorobenzoic acid and Y(NO3)3, Tb(NO3)3 and Yb(NO3)3 as rare earth metals.

  11. Contributions to the rare earths to science and technology

    International Nuclear Information System (INIS)

    Spedding, F.H.

    1975-01-01

    This is a brief summary of some areas of science where the rare earths have already played an important role and of other areas where they are almost certain to be helpful. The discovery, abundance, separation, and properties of rare earths are discussed. It is pointed out that the rare earths comprise almost one-fourth of the known metals, and their alloys a third of the possible alloys

  12. Separation of rare earths by liquid-liquid extraction

    International Nuclear Information System (INIS)

    Helgorsky, M.; Leveque, M.

    1978-01-01

    The elements of the rare earth family are characterised by very similar chemical properties connected with their special electronic structure. The purification of the rare earths sold by RHONE-POULENC is now done by the liquid-liquid extraction technique. The development of different extracting agents and also counter-current techniques have led to solvent extraction replacing the other fractionation techniques because of its efficiency and low cost. There are usually several possible solutions to the main problem of choosing the extracting agent and its mode of use. The difficulty is to find the most economical one taking account of the thermodynamic and hydrodynamic constraints of the solvent. It is shown how ideas about the separation have changed over the course of the development of the uses of the rare earths, ending finally in an integrated scheme that makes RHONE-POULENC a world leader of manufacturers of separated rare earths [fr

  13. Rare-earth metal prices in the USA ca. 1960 to 1994

    Science.gov (United States)

    Hedrick, James B.

    1997-01-01

    Rare-earth metal prices were compiled from the late 1950s and early 1960s through 1994. Although commercial demand for rare-earth metals began in 1908, as the alloy mischmetal, commercial quantities of a wide range of individual rare-earth metals were not available until the late 1950s. The discovery of a large, high-grade rare-earth deposit at Mountain Pass. CA, USA, in 1949, was significant because it led to the production of commercial quantities or rare-earth elements that reduced prices and encouraged wider application of the materials. The availability of ore from Mountain Pass, and other large rare-earth deposits, especially those in Australia and China, has provided the world with abundant resources for rare-earth metal production. This availability, coupled with improved technology from Government and private-sector metallurgical research, has resulted in substantial decreases in rare-earth metal prices since the late 1950s and early 1960s. Price series for the individual rare-earth metals (except promethium) are quoted on a kilogram basis from the late 1950s and early 1960s through 1994. Prices are given in US dollars on an actual and constant dollar basis. Industrial and economic factors affecting prices during this time period are examined.

  14. Complexometric determination of trivalent rare earths and actinides with diethylene-triaminepentaacetic acid

    International Nuclear Information System (INIS)

    Timofeev, G.A.; Simakin, G.A.; Baklanova, P.F.; Kuznetsov, G.F.; Ivanov, V.I.

    1976-01-01

    Optimal conditions have been found for the separate quantitative determination of 200 to 500 mcg of trivalent Eu, La, Nd, Pr, Am and Cm by complexometric titration with diethylenetriaminepentaacetic acid. The final titration point (FTP) has been determined by using one of the following three methods, namely by visual inspection with the aid of xylene orange as an indicator, spectrophotometrically at pH 4.5-4.7 with xylene orange and potentiometrically at pH 4.0-5.5 through the backward titration of the excess complexone with the solution of Fe(3) in HNO 3 . The relative standard errors Ssub(r)=0.004 (Eu), 0.011 Cm with the visual indication of FTP; Ssub(r)=0.005 (Am) with the spectrophotometric indication of FTP; Ssub(r)=0.0O9 (Eu), 0.011 (Pr) and 0.02 (Am) with the potentiometric indication of FTP. Determination of trivalent lanthanides and actinoids is adversely affected by tetravalent actinoids, Zr, U(6), Hg(2) and Fe(3). Titration conditions chosen have been checked in the analysis of the mixture containing the sum of trivalent rare earths, Am and Cm [ru

  15. Study on Yen Phu rare earth ore concentrate treatment technology and separation of major heavy rare earth elements by solvent extraction method

    International Nuclear Information System (INIS)

    Le Ba Thuan; Pham Quang Trung; Vu Lap Lai

    2003-01-01

    PC88A and Aliquat 336 systems have been optimized using the computer simulation program. The solution containing > 80% pure Y 2 O 3 after upgrading by PC88A (18 extraction, 18 scrubbing and 10 stripping stages) is purified further by another cycle of SX (24 extraction, 10 scrubbing and 10 stripping stages) with 25% Aliquat 336 in kerosene in presence of 1.0 M NH 4 SCN and 2.0 M NH 4 Cl. The impurities of Ho, Er, and another heavy elements are extracted leaving >99.9% pure Y 2 O 3 in the aqueous phase. The yield of the process is > 85%. 4. Separation and purification of europium: The isolation and purification of europium consists of following steps: isolation of Eu by reduction on zinc column and precipitation in the form EuSO 4 by H 2 SO 4 under CO 2 atmosphere; first purification by conversion of EuSO 4 to EuCl 3 , reduction and precipitation in the form EuSO 4 ; and second purification by reduction on zinc column and precipitation of other rare earth elements in the form RE(OH) 3 by NH 4 Cl-NH 4 OH buffer of pH = 10 under atmosphere N 2 . Eu 2 O 3 of 99.9% purity has been recovered with overall yield. 5. Separation and purification of gadolinium: The middle subgroup after Eu removing is subject to Gd recovery by SX with PC88A. The SX parameters for Gd separation had been optimized by computer program. The separation process consists of 12 extraction, 12 scrubbing and 6 stripping stages. The acidity of scrubbing solution is 1.0.M HCl. The purity and yield of the Gd separation process were > 98% and >85% respectively. The obtained Gd 2 O 3 was purified by Eu removing using zinc column and H 2 SO 4 . The final purity of the Gd 2 O 3 was reached value 99%. 6. Overall schema for individual separation of some rare earth elements of high purity from Yenphu rare earth ore concentrate: Based on the above obtained results, overall schema for individual separation of some rare earth elements (Y, Gd, Eu and Sm) of high purity from Yenphu rare earth ore concentrate has been

  16. Investigations for chromatographic separation and determination of the rare earths and auxiliary group elements

    International Nuclear Information System (INIS)

    Post, K.

    1981-01-01

    Different method have been developed to quantitatively determine rare earth elements after their column chromatographic separation. The influence of the active solvents in the running systems diethyl ether/tetra hydrofuran (THF)/nitric acid (HNO 3 ) and diethyl ether/bis-(2-ethyl hexyl) phosphate (HDEHP)/HNO 3 was investigated on the column chromatographic separation of all rare earth elements is possible by the synergistic combination of the active running components THF and HDEHP. Further from product isotopes could also be separated using the running agents described here in investigations to separate fission product mixtures of irradiated uranium. (orig./HBR) [de

  17. Restoration of rare earth mine areas: organic amendments and phytoremediation.

    Science.gov (United States)

    Zhou, Lingyan; Li, Zhaolong; Liu, Wen; Liu, Shenghong; Zhang, Limin; Zhong, Liyan; Luo, Ximei; Liang, Hong

    2015-11-01

    Overexploitation of rare earth mine has caused serious desertification and various environmental issues, and ecological restoration of a mining area is an important concern in China. In this study, experiments involving dry grass landfilling, chicken manure broadcasting, and plant cultivation were carried out to reclaim a rare earth mine area located in Heping County, Guangdong Province, China. The prime focus was to improve soil quality in terms of nutrients, microbial community, enzyme activity, and physicochemical properties so as to reclaim the land. After 2 years of restoration, an increase of organic matter (OM), available potassium (K), available phosphorus (P) levels, and acid phosphatase (ACP) activity and a reduction of the available nitrogen (N) level and urease (URE) activity in soil were achieved compared to the original mined land. The nutrients and enzyme activities in soil with 5 years of restoration were close to or surpass those in the unexploited land as control. The bulk density, total porosity, water holding capacity, pH, and electrical conductivity (EC) of soil were improved, and the number of cultivable microorganisms and the bacterial diversity in soil were greatly increased with time during ecological restoration, especially for surface soil. Furthermore, the artificial vegetation stably grew at the restored mining sites. The results indicated that organic amendments and phytoremediation could ecologically restore the rare earth mining sites and the mined land could finally be planted as farmland.

  18. Rare earth niobate coordination polymers

    Science.gov (United States)

    Muniz, Collin N.; Patel, Hiral; Fast, Dylan B.; Rohwer, Lauren E. S.; Reinheimer, Eric W.; Dolgos, Michelle; Graham, Matt W.; Nyman, May

    2018-03-01

    Rare-earth (RE) coordination polymers are infinitely tailorable to yield luminescent materials for various applications. Here we described the synthesis of a heterometallic rare-earth coordination compound ((CH3)2SO)3(RE)NbO(C2O4)3((CH3)2SO) = dimethylsulfoxide, DMSO, (C2O2= oxalate), (RE=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb). The structure was obtained from single crystal X-ray diffraction of the La analogue. The Nb˭O and DMSO terminal-bonding character guides assembly of an open framework structure with noncentrosymmetric RE-coordination geometry, and large spacing between the RE centers. A second structure was observed by PXRD for the smaller rare earths (Dy, Ho, Er, Yb); this structure has not yet been determined. The materials were further characterized using FTIR, and photoluminescence measurements. Characteristic excitation and emission transitions were observed for RE = Nd, Sm, Eu, and Tb. Quantum yield (QY) measurements were performed by exciting Eu and Tb analoges at 394 nm (QY 66%) and 464 nm (QY 71%) for Eu; and 370 nm (QY=40%) for Tb. We attribute the high QY and bright luminescence to two main structure-function properties of the system; namely the absence of water in the structure, and absence of concentration quenching.

  19. Preparation of polymer-rare earth complex using salicylic acid-containing polystyrene and its fluorescence emission property

    Energy Technology Data Exchange (ETDEWEB)

    Gao Baojiao, E-mail: gaobaojiao@126.com [Department of Chemical Engineering, North University of China, Taiyuan 030051 (China); Zhang Wei; Zhang Zhengguo; Lei Qingjuan [Department of Chemical Engineering, North University of China, Taiyuan 030051 (China)

    2012-08-15

    Salicylic acid (SA) was first bonded onto the side chains of polystyrene (PS), obtaining functional macromolecule SAPS. Using the salicylic acid-containing polystyrene as a macromolecular ligand, a polymer-rare earth complex, SAPS-Eu(III), was prepared. The structure of SAPS-Eu(III) was characterized, and the fluorescence properties of SAPS-Eu(III) were mainly investigated. The experimental results show that the complex SAPS-Eu(III) has fine chemical stability because of the bidentate chelating effect of salicylic acid ligand. More important, the ligand SA on the side chains of PS can strongly sensitize the fluorescence emission of the center ion, Eu{sup 3+} ion, and it enables the complex SAPS-Eu(III) to produce the apparent 'Antenna Effect'. In the diluted solution of the functional macromolecule SAPS, the formed complex SAPS-Eu(III) belongs to an intramolecular complex, or an intrachain complex. For the binary intramolecular complex SAPS-Eu(III), the apparent saturated coordination number of SA of SAPS towards Eu{sup 3+} ion is equal to 10, and here the binary intrachain complex SAPS-Eu(III) has the strongest fluorescence emission. On this basis, small-molecule 1,10-phenanthroline (Phen) acting as a co-ligand is added and the ternary complex SAPS-Eu(III)-Phen will be formed. As long as a small amount of Phen is added (in the molar ratio 1:1 (n(Phen):n(Eu))), the coordination of the two kinds of ligands, SA of SAPS and Phen, to Eu{sup 3+} ion will reach complete saturation, and here the fluorescence emission of the ternary complex will be further enhanced via the complementary coordination effect in comparison with that of the binary complex SAPS-Eu(III). - Highlights: Black-Right-Pointing-Pointer We prepared the functional polystyrene, SAPS, on whose side chain salicylic acid ligand was bonded. Black-Right-Pointing-Pointer The polymer-rare earth complex, SAPS-Eu(III), was prepared and a stronger 'antenna effect' was produced. Black

  20. Preparation of polymer–rare earth complex using salicylic acid-containing polystyrene and its fluorescence emission property

    International Nuclear Information System (INIS)

    Gao Baojiao; Zhang Wei; Zhang Zhengguo; Lei Qingjuan

    2012-01-01

    Salicylic acid (SA) was first bonded onto the side chains of polystyrene (PS), obtaining functional macromolecule SAPS. Using the salicylic acid-containing polystyrene as a macromolecular ligand, a polymer–rare earth complex, SAPS–Eu(III), was prepared. The structure of SAPS–Eu(III) was characterized, and the fluorescence properties of SAPS–Eu(III) were mainly investigated. The experimental results show that the complex SAPS–Eu(III) has fine chemical stability because of the bidentate chelating effect of salicylic acid ligand. More important, the ligand SA on the side chains of PS can strongly sensitize the fluorescence emission of the center ion, Eu 3+ ion, and it enables the complex SAPS–Eu(III) to produce the apparent “Antenna Effect”. In the diluted solution of the functional macromolecule SAPS, the formed complex SAPS–Eu(III) belongs to an intramolecular complex, or an intrachain complex. For the binary intramolecular complex SAPS–Eu(III), the apparent saturated coordination number of SA of SAPS towards Eu 3+ ion is equal to 10, and here the binary intrachain complex SAPS–Eu(III) has the strongest fluorescence emission. On this basis, small-molecule 1,10-phenanthroline (Phen) acting as a co-ligand is added and the ternary complex SAPS–Eu(III)–Phen will be formed. As long as a small amount of Phen is added (in the molar ratio 1:1 (n(Phen):n(Eu))), the coordination of the two kinds of ligands, SA of SAPS and Phen, to Eu 3+ ion will reach complete saturation, and here the fluorescence emission of the ternary complex will be further enhanced via the complementary coordination effect in comparison with that of the binary complex SAPS–Eu(III). - Highlights: ► We prepared the functional polystyrene, SAPS, on whose side chain salicylic acid ligand was bonded. ► The polymer-rare earth complex, SAPS–Eu(III), was prepared and a stronger “antenna effect” was produced. ► For the intramolecular complex SAPS–Eu(III), the apparent

  1. Coprecipitation of rare earth elements with hydroxyapatite

    International Nuclear Information System (INIS)

    Fujino, Osamu

    1979-01-01

    The distribution behavior of trace rare earth elements between an aqueous phase and hydroxyapatite crystals was investigated. The apatite prepared by adding phosphate ion extremely slowly to an aqueous solution containing calcium, rare earth elements, ethylenediamine and nitrilotriacetate ion at 80 0 C. Apparently the coprecipitation reaction seems to be anomalous, because the apparent distribution coefficient did not have a constant value through the reaction. But when the true distribution coefficient was calculated by using the thermodynamic data at 80 0 C, it was revealed that rare earth ions were coprecipitated obeying logarithmic distribution law. The true distribution coefficient values of trivalent yttrium, scandium, europium and cerium ions were about 10sup(7.3), 10sup(9.8), 10sup(7.4) and 10sup(6.5) respectively. (author)

  2. Iron corrosion inhibition by phosphonate complexes of rare earth metals

    International Nuclear Information System (INIS)

    Kuznetsov, Yu.I.; Raskol'nikov, A.F.; Starobinskaya, I.V.; Alekseev, V.N.

    1993-01-01

    Capability is shown of trivalent rare earth nitrilotrimethylphosphonates (R= Ce, Pr, Nd, Eu, Lu, Y) to retard steel corrosion in soft water due to the formation of slightly soluble hydroxides on steel surface. The protective film is produced as a result of electrophilic substitution of nascent iron cations for rare earth ions in near the surface layer. The introduction of rare earth cations into the protective film is ascertained by Auger spectroscopy in combination with the argon spraying. A quantitative interrelation between the protective effectiveness and solubility product of rare earth hydroxides is revealed

  3. Rare earth ion controlled crystallization of mica glass-ceramics

    International Nuclear Information System (INIS)

    Garai, Mrinmoy; Karmakar, Basudeb

    2016-01-01

    In understanding the effects of rare earth ions to control the crystallization and microstructure of alkaline boroaluminosilicate system, the CeO_2, Nd_2O_3, Sm_2O_3 and Gd_2O_3 doped K_2O−MgO−B_2O_3−Al_2O_3−SiO_2−F glasses were synthesized by melt-quenching at 1550 °C. Higher density (2.82–3.06 g cm"−"3) and thermal stability (glass phase) is experiential on addition of rare earth content, which also affects in increasing the glass transition temperature (T_g) and crystallization temperature (T_c). Decrease of thermal expansion in glasses with rare earth ion content is maintained by the stabilization of glass matrix owing to their large cationic field strength. A significant change in the non-isothermal DSC thermogram observed at 750–1050 °C is attributed to fluorophlogopite crystallization. Opaque glass-ceramics were prepared from such glasses by single step heat-treatment at 1050 °C; and the predominant crystalline phases are identified as fluorophlogopite mica, KMg_3(AlSi_3O_1_0)F_2 by XRD and EDX analysis. The compact glass-ceramic microstructure by the agglomeration of fluorophlogopite mica crystallites (crystal size ∼ 100–500 nm, FESEM) is achieved in attendance of rare earth ion; and such microstructure controlled the variation of density, thermal expansion and microhardness value. Higher thermal expansion (11.11–14.08 × 10"−"6/K at 50–800 °C and 50–900 °C) of such glass-ceramics approve that these rare earth containing glasses can be useful for high temperature vacuum sealing application with metal or solid electrolyte. The increase of Vickers microhardness (5.27–5.61 GPa) in attendance of rare earth ions is attributed to the compact crystallinity of fluorophlogopite mica glass-ceramic microstructure. - Highlights: • Synthesis of rare earth oxide doped alkaline boroaluminosilicate glasses. • Development of opaque fluorophlogopite mica glass-ceramics by single-step heat treatment. • Nanocrystalline glass

  4. Rare earths refining by vacuum sublimation method

    International Nuclear Information System (INIS)

    Rytus, N.N.

    1983-01-01

    The process of rare earths refining by the sUblimation; method in high and superhigh oil-free vacuum, is investigated. The method is effective for rare earths obtaining and permits to prepare metal samples with a high value of electric resistance ratio γ=RsUb(298 K)/Rsub(4.2 K). The estimation of general purity is performed for Sm, Eu, Yb, Tm, Dy, Ho, Er and Se

  5. Immobilization of Radioactive Rare Earth oxide Waste by Solid Phase Sintering

    International Nuclear Information System (INIS)

    Ahn, Byung Gil; Park, Hwan Seo; Kim, Hwan Young; Lee, Han Soo; Kim, In Tae

    2010-01-01

    In the pyroprocessing of spent nuclear fuels, LiCl-KCl waste salt containing radioactive rare earth chlorides are generated. The radioactive rare earth oxides are recovered by co-oxidative precipitation of rare earth elements. The powder phase of rare earth oxide waste must be immobilized to produce a monolithic wasteform suitable for storage and ultimate disposal. The immobilization of these waste developed in this study involves a solid state sintering of the waste with host borosilicate glass and zinc titanate based ceramic matrix (ZIT). And the rare-earth monazite which synthesised by reaction of ammonium di-hydrogen phosphate with the rare earth oxides waste, were immobilized with the borosilicate glass. It is shown that the developed ZIT ceramic wasteform is highly resistant the leaching process, high density and thermal conductivity.

  6. Crystalline and amorphous rare-earth metallic compounds

    International Nuclear Information System (INIS)

    Burzo, E.

    1975-01-01

    During the last years the study of magnetic behaviour of rare-earth (or yttrium) compounds with cobalt and iron has growth of interest. This interest of justified by a large area of experimental and theoretical problems coming into being in the study of some rare-earth materials as well as in their technical applications. In the last three years a great number of new rare earth materials were studied and also new models explaining the magnetic behaviour of these systems have been used. In this paper we refer especially to some typical systems in order to analyse the magnetic behaviour of iron and cobalt and also the part played by the magnetic interactions in the values of the cobalt or iron moments. The model used will be generally the molecular field model. In the second chapter we present comparatively the structure of crystalline and amorphous compounds for further correlation with the magnetic properties. In chapter III we analyse the magnetic interactions in some crystalline and amorphous rare-earth alloys. Finally, we exemplify the ways in which we ensure better requried characteristics by the technical utilizations of these materials. These have in view the modifications of the magnetic interactions and are closely related with the analysis made in chapter III

  7. Rare earth point defects in GaN

    Energy Technology Data Exchange (ETDEWEB)

    Sanna, S.

    2007-12-14

    In this work we investigate rare earth doped GaN, by means of theoretical simulations. The huge unit cells necessary to model the experimental system, where dilute amount of rare earth ions are used, are handled with the charge self consistent density-functional based-tight binding (SCC-DFTB) calculational scheme. The method has been extended to include LDA+U and simplified self interaction corrected (SIC)-like potentials for the simulation of systems with localised and strongly correlated electrons. A set of tight-binding parameters has been created to model the interaction of GaN with some dopants, including a selection of lanthanide ions interesting due to their optical or magnetic properties (Pr, Eu, Gd, Er and Tm). The f-electrons were treated as valence electrons. A qualitatively correct description of the band gap is crucial for the simulation of rare earth doped GaN, because the luminescence intensity of the implanted samples depends on the size of the host band gap and because the rare earths could introduce charge transition levels near the conduction band. In this work these levels are calculated with the Slater-Janak (SJ) transition state model, which allows an approximate calculation of the charge transition levels by analysing the Kohn-Sham eigenvalues of the DFT. (orig.)

  8. Rare earth element abundances and distribution patterns in plant materials

    International Nuclear Information System (INIS)

    Aidid, S.B.

    1994-01-01

    Eight out of the fourteen rare earth elements were estimated from the leaves of Pelthophorum pterocarpum, the leaves and roots of Impatiens balsamina, and the soils from four sampling sites by instrumental neutron activation analysis. The chondrite normalized rare earth element abundances and distribution patterns in the plant materials were found to be significantly correlated to the abundances of the rare earth elements occurring in the soils. The extent of accumulation of the rare earth elements in some plant materials was also governed by the age of the plants and the plant organs. (author) 16 refs.; 4 figs.; 3 tabs

  9. Magnetic rare earth superlattices

    DEFF Research Database (Denmark)

    Majkrzak, C.F.; Kwo, J.; Hong, M.

    1991-01-01

    Advances in molecular beam epitaxy deposition techniques have recently made it possible to grow, an atomic plane at a time, single crystalline superlattices composed of alternating layers of a magnetic rare earth, such as Gd, Dy, Ho, or Er, and metallic Y, which has an identical chemical structure...

  10. Solvent extraction of rare earths from thiocyanate medium using N,N,N',N'-tetra-2-ethylhexyl diglycolamide

    International Nuclear Information System (INIS)

    Anitha, M.; Kotekar, M.K.; Singh, D.K.; Sharma, J.N.; Singh, H.

    2014-01-01

    TEHDGA (N,N,N',N'-tetra-2-ethylhexyl diglycolamide), a neutral extractant, has been explored for separation of Yttrium from other heavy rare earths (Er) from thiocyanate medium. Presence of 5%(v/v) isodecyl alcohol was found to be optimum to prevent third phase formation. Experimental variables such as TEHDGA concentration (0.05M-0.2M), thiocyanate concentration (0.01M-0.04M), aqueous pH, rare earth concentration (0.25g/L-5g/L), temperature (35℃-65℃), stripping reagents on extraction of rare earths were investigated. The extraction of rare earths increased with increase in TEHDGA concentration and the dependency of distribution ratio of rare earth on TEHDGA concentrations is shown. The slopes were analysed to be approximately 3 for all the rare earths. The effect of thiocyanate concentration on distribution ratio is depicted. Based on slope analysis technique, the extracted species was found to be RE(SCN) 3 .3TEHDGA. The distribution ratio values decreased, may possibly be due to decrease in free extractant concentration in the organic phase, from 8.4 to 0.1 for Y with increase in yttrium concentration in the range of 0.25g/L to 5g/L. The extraction of rare earth decreased with increase in temperature indicating exothermic in nature and the enthalpy change (ΔH) obtained for Y(III) was -14.27KJ/mol. Among stripping reagents studied, oxalic acid was efficient in quantitative stripping of rare earths from TEHDGA. The extraction efficiency for rare earths by TEHDGA increased with increase in atomic number: La< Ce< Pr< Nd< Sm< Y< Eu< Gd< Tb< Dy< Ho< Er< Tm< Lu irrespective of thiocyanate concentration. Separation factors between these metal ions were also evaluated. High separation factor of 6.4 for Er/Y pair at 0.03M thiocyanate has indicated the feasibility of using TEHDGA as extractant to separate Y from Er and other rare earths as an alternative for Aliquat 336-thiocyanate system developed in our laboratory

  11. Extraction-differential-photometric method to determine rare earths of cerium subgroup

    International Nuclear Information System (INIS)

    Askerov, D.N.; Gusejnov, I.K.; Melikov, A.A.

    1985-01-01

    The extraction - photometric method to determine great quantities of rare earths of the cerium subgroup as a complex with antipyrine A and diphenylguanidine is developed. Isobutyl and n-butyl alcohols are used as extractants. It is established that proportional dependence between relative optical density and concentration of rare earths of the cerium subgroup in the solution takes place in the concentration interval of 10.3-14.7 μg of rare earths in 1 ml of the solution. Determination error is+-1.12%. The technique is used to determine rare earths of the cerium subgroup in rare earth oxides of a mixed composition, as well as in monozite and loparite

  12. 2004 Top 10 Chinese Rare Earth Events

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    1. Management to the Investment in Rare Earth IndustryConfirmedIn July 2004, "Decision on the Reform in Investment System" was formally publicized by the State Council of the People's Republic of China. The fifth item in the Decision stipulates that ore exploitation, smelting & separation and rare earth deep-processed projects with total investment over RMB¥100 million should be approved by the investment governing department of the State Council, and that other

  13. Automatic collection of the rare-earths with post chromatography column detection

    International Nuclear Information System (INIS)

    David, P.; Metzger, G.; Repellin, M.

    1987-01-01

    The complete separation of rare-earths (in the aim of radio-isotopes measurement) requires High Performance Liquid Chromatography with ternary elution gradient. To automatize their collection with satisfying conditions, we have realized a non polluting, reliable and easy to operate detection method. This one is based on a derivation colorimetric system with arsenazo I (3 -(2 arsophenylazo 4.5) - dihydroxy - 2.7 naphtalene disulfonic acid)

  14. Rare Earths and Clean Energy: analyzing China's upper hand

    International Nuclear Information System (INIS)

    Seaman, J.

    2010-01-01

    An ominous but avoidable resource crunch in the so-called 'rare earth elements' is now threatening the development of a number of key industries from energy to defense to consumer electronics. As key components in the latest generation of technologies, including specialized magnets for windmills and hybrid cars, lasers for range finders and 'smart' munitions, and phosphors for LCD screens, demand for these rare metals is expected to grow rapidly in the years to come. But decades of under-investment in the mining and separation of these elements across the globe has left the industry ill-prepared to meet thi s growing demand. Over the years, only China has recognized the strategic significance of these resources and has succeeded in gaining a near monopoly on production, currently churning out 97% of the world' s rare earth oxides. Faced with problems of its own, and eager to use its resource advantage to master higher levels of value-added production of rare earth-dependent products, China has increasingly limited the rest of the world's access to these raw materials. This only complicates what was already projected to be a problematic resource shortage. This issue demands a higher quality of public debate. Rare earth consuming countries outside of China have only recently become aware of their dependence and started to take stock of the risks. Time is of the essence. Bringing new supplies online to meet growing demand is a long, complicated and risky process but is nevertheless necessary to ensure the development of high tech industries, notably clean energy. Accessible reserves of rare earths do exist outside of China and mitigating the effects of the looming shortage requires opening up these reserves to production. Yet, as the Chinese experience attests, there are substantial risks to the environment associated with mining and separating rare earths. Care must be taken to ensure responsible mining practices across the globe. Longer-term solutions, such as

  15. Determination of rare earth elements in red mud by ICP-MS

    International Nuclear Information System (INIS)

    Kumar, Sanjukta A.; Suvarna, S.; Kiran Kumar, G.

    2017-01-01

    Red mud or red sludge is a highly alkaline waste product composed mainly of iron oxide that is generated in the industrial production of aluminum from bauxite. With about 77 million tons of this hazardous material being produced annually, red mud poses a serious disposal problem in the mining industry. Discharge of red mud is hazardous environmentally because of its alkalinity. Many studies have been conducted to develop uses of red mud. An estimated 2 to 3 million tones are used annually in the production of cement, road construction and as a source for iron. Potential applications include the production of low cost concrete, application to sandy soils to improve phosphorus cycling, amelioration of soil acidity, landfill capping and carbon sequestration. Red mud contains a large amount of iron along with appreciable concentrations of many strategic elements such as rare earth elements and therefore can be a source of valuable secondary raw material. This necessitates the elemental characterization of red mud. This paper presents an effective dissolution procedure using a mixture of phosphoric acid and nitric acid for red mud followed by determination of rare earth elements by ICP-MS. The method was validated by spike recovery experiments. The recoveries were found within 98 to 102 %. The relative standard deviation (RSD) of the method was found to be within 5 %

  16. Assessment of Bioavailable Concentrations of Germanium and Rare Earth Elements in the Rhizosphere of White Lupin (Lupinus albus L.)

    Science.gov (United States)

    Wiche, Oliver; Fischer, Ronny; Moschner, Christin; Székely, Balázs

    2015-04-01

    Concentrations of Germanium (Ge) and Rare Earth Elements in soils are estimated at 1.5 mg kg -1 (Ge), 25 mg kg -1 (La) and 20 mg kg -1 (Nd), which are only roughly smaller than concentrations of Pb and Zn. Germanium and rare earth elements are thus not rare but widely dispersed in soils and therefore up to date, only a few minable deposits are available. An environmental friendly and cost-effective way for Ge and rare earth element production could be phytomining. However, the most challenging part of a phytomining of these elements is to increase bioavailable concentrations of the elements in soils. Recent studies show, that mixed cultures with white lupine or other species with a high potential to mobilize trace metals in their rhizosphere due to an acidification of the soil and release of organic acids in the root zone could be a promising tool for phytomining. Complexation of Ge and rare earth elements by organic acids might play a key role in controlling bioavailability to plants as re-adsorption on soil particles and precipitation is prevented and thus, concentrations in the root zone of white lupine increase. This may also allow the complexes to diffuse along a concentration gradient to the roots of mixed culture growing species leading to enhanced plant uptake. However, to optimize mixed cultures it would be interesting to know to which extend mobilization of trace metals is dependent from chemical speciation of elements in soil due to the interspecific interaction of roots. A method for the identification of complexes of germanium and rare earth elements with organic acids, predominantly citric acid in the rhizosphere of white lupine was developed and successfully tested. The method is based on coupling of liquid chromatography with ICP-MS using a zic-philic column (SeQuant). As a preliminary result, we were able to show that complexes of germanium with citric acid exist in the rhizosphere of white lupin, what may contribute to the bioavailability of this

  17. Preparation and characteristics of various rare earth nitrides

    International Nuclear Information System (INIS)

    Imamura, H.; Imahashi, T.; Zaimi, M.; Sakata, Y.

    2008-01-01

    Active nanocrystalline nitrides of EuN and YbN with high surface areas were successfully prepared by the thermal decomposition of the rare earth amides (Eu(NH 2 ) 2 , Yb(NH 2 ) 2 and Yb(NH 2 ) 3 ). For the preparation of CeN, PrN and NdN, the direct reaction of the rare earth metals with ammonia was extensively studied to determine optimal conditions. In the reaction of rare earth metals with ammonia, hydrides besides the nitrides were competitively formed. The reaction conditions such as temperatures and ratios of ammonia to rare earth metal were crucial in preferential formation of nitride. The nanocrystalline YbN and EuN readily absorbed large amounts of ammonia even at room temperature upon contact with ammonia (13.3 kPa). The absorbed ammonia existed in at least two forms on/in the nitride; the one was surface-adsorbed ammonia and the other ammonia absorbed in the nitride in a decomposed state. The properties of ammonia absorbed by the nitride were further evaluated by temperature-programmed desorption (TPD), FT-IR and XRD techniques

  18. Redox reactions in rare earth chloride molten electrolytes

    International Nuclear Information System (INIS)

    Khokhlov, V.A.; Novoselova, A.V.; Nikolaeva, E.V.; Tkacheva, O.Yu.; Salyulev, A.B.

    2007-01-01

    Rare earth (REM, Ln) solutions in chloride melts including MCI+LnCl 3 mixtures, where M - alkali metals, were investigated by potentiometry, voltammetry, conductometry in wide concentration and temperature intervals. Findings present complete and trusty information on the valent state of rare earths, structure and composition of complex ions affecting essentially on properties of electrolytes. It is demonstrated that the coexistence of rare earth ions with different oxidation level formed as a result of possible redox reactions: 2Ln 3+ + Ln ↔3Ln 2+ , Ln 2+ + Ln↔2Ln + and nM + + Ln↔nM + Ln n+ appears sharply in thermodynamic and transport properties of molten Ln-LnCl 3 and Ln-LnCl 3 -MCl systems [ru

  19. Rare earth ion controlled crystallization of mica glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Garai, Mrinmoy; Karmakar, Basudeb, E-mail: basudebk@cgcri.res.in

    2016-09-05

    In understanding the effects of rare earth ions to control the crystallization and microstructure of alkaline boroaluminosilicate system, the CeO{sub 2}, Nd{sub 2}O{sub 3}, Sm{sub 2}O{sub 3} and Gd{sub 2}O{sub 3} doped K{sub 2}O−MgO−B{sub 2}O{sub 3}−Al{sub 2}O{sub 3}−SiO{sub 2}−F glasses were synthesized by melt-quenching at 1550 °C. Higher density (2.82–3.06 g cm{sup −3}) and thermal stability (glass phase) is experiential on addition of rare earth content, which also affects in increasing the glass transition temperature (T{sub g}) and crystallization temperature (T{sub c}). Decrease of thermal expansion in glasses with rare earth ion content is maintained by the stabilization of glass matrix owing to their large cationic field strength. A significant change in the non-isothermal DSC thermogram observed at 750–1050 °C is attributed to fluorophlogopite crystallization. Opaque glass-ceramics were prepared from such glasses by single step heat-treatment at 1050 °C; and the predominant crystalline phases are identified as fluorophlogopite mica, KMg{sub 3}(AlSi{sub 3}O{sub 10})F{sub 2} by XRD and EDX analysis. The compact glass-ceramic microstructure by the agglomeration of fluorophlogopite mica crystallites (crystal size ∼ 100–500 nm, FESEM) is achieved in attendance of rare earth ion; and such microstructure controlled the variation of density, thermal expansion and microhardness value. Higher thermal expansion (11.11–14.08 × 10{sup −6}/K at 50–800 °C and 50–900 °C) of such glass-ceramics approve that these rare earth containing glasses can be useful for high temperature vacuum sealing application with metal or solid electrolyte. The increase of Vickers microhardness (5.27–5.61 GPa) in attendance of rare earth ions is attributed to the compact crystallinity of fluorophlogopite mica glass-ceramic microstructure. - Highlights: • Synthesis of rare earth oxide doped alkaline boroaluminosilicate glasses. • Development of opaque

  20. Determination of rare earth elements in water ore and grass sample around monazite dressing plant by high performance liquid chromatography

    International Nuclear Information System (INIS)

    Laoharojanaphand, S.

    1993-01-01

    High performance liquid chromatography technique for the analysis of rare earth elements; yttrium, cerium and lanthanum, was developed. A comparison of two mobile phases between α-hydroxy isobutyric acid and mandelic acid was carried out using C 1 8 column for separation and the amount of the rare earth elements were detected by post column complex formation with Arsenazo III. It was found that α-hydroxy isobutyric acid had higher efficiency in separation of the rare earth elements than mandelic acid when 1-octanesulfonic acid was used as an organic modifier. The optimum conditions of the mobile phase were comprised of the p H of 3.65, a flow rate of 1 ml/min which resulted in the values of resolution to be 13.62 between yttrium and cerium and 3.49 between cerium and lanthanum. Standard curves of yttrium and lanthanum yielded linear range of 0.1-45 and 1-60 ppm whereas the cerium curve was in the range of 1-100 ppm. The analyses of water, ore and grass samples collected around the monazite dressing plants from Prachuap Khiri Khan and Phuket showed that none of the rare earth elements was detected in all samples from Prachuap Khiri Khan. But 0.5 ppm of yttrium and 1.5 ppm of lanthanum were found in the water samples from Phuket while in the grass samples contained yttrium and cerium in the amounts of 2 ppm and 14 ppm whereas none was detected in the ore samples by this technique under the previous conditions

  1. Current extraction and separation of uranium, thorium and rare earths elements from monazite leach solution using organophosphorous extractants

    International Nuclear Information System (INIS)

    Biswas, Sujoy; Rupawate, V.H.; Hareendran, K.N.; Roy, S.B.

    2014-01-01

    A new process based on solvent extraction has been developed for separation of uranium, thorium and rare earths from monazite leach solution using organophosphorous extractants. The Thorium cake coming from monazite source was dissolved in HNO 3 medium in presence of trace amount of HF for feed preparation. The separation of U(VI) was carried out by liquid-liquid extraction using tris-2-ethyl hexyl phosphoric acid (TEHP) in dodecane leaving thorium and rare earths elements in the raffinate. The thorium from raffinate was selectively extracted using 1M tri iso amyl phosphate (TiAP) in dodecane in organic phase leaving all rare earths elements in aqueous solution. The uranium and thorium from organic medium was quantitatively stripped using 0.05 M HNO 3 counter current mode. Results indicate the quantitative separation of uranium, thorium and rare earths from thorium cake (monazite source) using organophosphorous extractant in counter current mode

  2. Reversed-phase thin-layer chromatography of the rare earth elements

    International Nuclear Information System (INIS)

    Kuroda, R.; Adachi, M.; Oguma, K.

    1988-01-01

    Partition chromatographic behaviour of the rare earth elements on C 18 bonded silica reversed-phase material has been investigated by thin-layer chromatography in methanol - lactate media. The rare earth lactato complexes are distributed and fractionated on bonded silica layers without ion-interaction reagents. The concentration and pH of lactate solution, methanol concentration and temperature have effects on the migration and resolution of the rare earth elements. The partition system is particularly suited to separate adjacent rare earths of middle atomic weight groups, allowing the separation of gadolinium, terbium, dysprosium, holmium, erbium and thulium to be achieved by development to 18 cm distance. (orig.)

  3. Enzymatic determination of rare earth elements by use of pyrophosphotases

    International Nuclear Information System (INIS)

    Shekhovtseva, T.N.; Pirogova, S.V.; Fedorova, O.M.; Dolmanova, I.F.; Bajkov, A.A.

    1993-01-01

    A highly sensitive (determination limit 8 x 10 -6 - 4 x 10 -4 μg/ml) and selective enzymatic method for determination of rare earth elements has been developed. The method is based on inhibition action of rare earths on the catalytic activity of pyrophosphates isolated from bakery geast and E. Coli. The mechanism of the rare earth element action, corresponding to competitive inhibition, has been established

  4. Thermochemistry of certain rare earth and ammonium double chlorides

    International Nuclear Information System (INIS)

    Usubaliev, D.U.; Abramtsev, V.A.; Kydynov, M.K.; Vilyaev, A.N.

    1987-01-01

    In a calorimeter with isothermal casing at 25 deg C dissolution enthalpies of double chlorides of rare earths and ammonium LnCl 3 x2NH 4 Cl (Ln=La, Sm) and LnCl 3 x3NH 4 Cl (Ln=Gd, Tb, Ho) in water, as well as dissolution enthalpy of rare earth chlorides in solution of ammonium chloride and NH 4 Cl in solution of rare earth chloride, have been measured. Formation enthalpies, standard formation enthalpies, dissociation enthalpies of the above-mentioned double chlorides are calculated

  5. Precipitation of the rare earth double sodium and rare earths from the sulfuric liquor and the conversion into rare earth hydroxides through meta ethic reaction; Precipitacao do sulfato duplo de terras raras e sodio a partir de licor sulfurico e sua conversao em hidroxido de terras raras mediante reacao metatetica

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, Renata D.; Oliveira, Ester F.; Brito, Walter de; Morais, Carlos A. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)]. E-mails: rda@cdtn.br; esterfo@cdtn.br; britow@cdtn.br; cmorais@cdtn.br

    2007-07-01

    This work presents the purification study of the rare earths through precipitation of rare earth and sodium (Na TR (SO{sub 4}){sub 2}. x H{sub 2}O)) double sulfate and his conversion to rare earths hydroxide TR(OH){sub 3} by meta ethic reaction through the addition of sodium hydroxide solution to the solid double sulfate. The study used the sulfuric liquor as rare earth sample, generated in the chemical processing of the monazite with sulfuric acid by the Industrias Nucleares do Brasil - INB, Brazil, after the thorium and uranium extraction. The work investigated the influence of the main variables involved in the precipitation of Na TR(SO{sub 4}){sub 2}.xH{sub 2}O and in the conversion for the TR(OH){sub 3}, as follows: type and excess of the precipitation agent, temperature and time reaction. The obtained solid composites were characterized by X-ray diffraction, infrared and chemical analysis. The double sulfate diffractogram indicated the Na TR(SO{sub 4}){sub 2} mono-hydrated. The characterization of the metatese products has shown that, for obtaining the complete conversion of NaTR(SO{sub 4}){sub 2}.H{sub 2}O into TR(OH){sub 3}, the reaction must be hot processed ({approx}70 deg C) and with small excess of Na OH ({<=} 5 percent). (author)

  6. The transfer of rare earth elements through liquid extraction membranes

    International Nuclear Information System (INIS)

    Kapranchik, V.P.; Proyaev, V.V.; Kopyrin, A.A.

    1988-01-01

    The transfer of rare earth elements through liquid extraction membranes, presenting Dacron nuclear filters, impregnated by extractants of different types (tributylphosphine oxide; di-2-ethylhexylphosphoric acid, HDEHP; trioctylamine, TOA) is investigated. It is ascertained that in systems with extractant-carriers TOA and HDEHP inversion of dependences of flow values and distribution coefficients on the element atomic number is observed. Mathematical model of transfer, permitting to establish relation between extractional and transport characteristics of the membrane, is suggested

  7. Preparation and characterization of Pt Sn / C-rare earth and PtRu / C-rare earth using an alcohol reduction process for ethanol electron-oxidation

    International Nuclear Information System (INIS)

    Rodrigues, Rita Maria de Sousa

    2011-01-01

    The electro catalyst PtRu / C-rare earth and PtSn/C-rare earth (20 wt%) were prepared by alcohol reduction method using H 2 PtCl 6 .6H 2 O Ru Cl xH 2 O, SnCl 2 .2H 2 O as a source of metals 85 % Vulcan - 15 % rare earth as a support and, finally, ethylene glycol as reducing agent. The electrocatalysts were characterized physically by X-ray diffraction (XRD), energy dispersive X-ray (EDX), and transmission electron microscopy (TEM). Analyses by EDX showed that the atomic ratios of different electrocatalysts, prepared by alcohol reduction method are similar to the nominal starting compositions indicating that this methodology is promising for the preparation of electrocatalysts. In all the XRD patterns for the prepared electrocatalysts there is a broad peak at about 2θ = 25 o , which is associated with the carbon support and four additional diffraction peaks at approximately 2θ = 40 o , 47 o , 67 o e 82 o , which in turn are associated with the plans (111), (200), (220) e (311), respectively, of face-centered cubic structure (FCC) platinum. The results of X-ray diffraction also showed average crystallite sizes between 2.0 and 4.0 nm for PtSn e 2,0 a 3,0 para PtRu. The studies for the electrochemical oxidation of ethanol in acid medium were carried out using the technique of chronoamperometry in a solution 0,5 mol.L-1 H 2 SO 4 , + 1,0 mol.L-1 de C 2 H 5 OH. The polarization curves obtained in the fuel cell unit, powered directly by ethanol, are in agreement with the results of voltammetry and chronoamperometry noting the beneficial effect of rare earths in the preparation of electrocatalysts and attesting that the electrocatalysts PtSn/C are more effective than PtRu/C for the oxidation of ethanol.

  8. Rare-earth-free high energy product manganese-based magnetic materials.

    Science.gov (United States)

    Patel, Ketan; Zhang, Jingming; Ren, Shenqiang

    2018-06-14

    The constant drive to replace rare-earth metal magnets has initiated great interest in an alternative. Manganese (Mn) has emerged to be a potential candidate as a key element in rare-earth-free magnets. Its five unpaired valence electrons give it a large magnetocrystalline energy and the ability to form several intermetallic compounds. These factors have led Mn-based magnets to be a potential replacement for rare-earth permanent magnets for several applications, such as efficient power electronics, energy generators, magnetic recording and tunneling applications, and spintronics. For past few decades, Mn-based magnets have been explored in many different forms, such as bulk magnets, thin films, and nanoparticles. Here, we review the recent progress in the synthesis and structure-magnetic property relationships of Mn-based rare-earth-free magnets (MnBi, MnAl and MnGa). Furthermore, we discuss their potential to replace rare-earth magnetic materials through the control of their structure and composition to achieve the theoretically predicted magnetic properties.

  9. Influence of rare-earth ions on fluorogallate glass formation and properties

    International Nuclear Information System (INIS)

    Zhang Guoyin; Poulain, M.J.

    1998-01-01

    Various rare earths have been incorporated in a lead fluorogallate glass with the following chemical composition: 30PbF 2 -20GaF 3 -15InF 3 -20CdF 2 -15ZnF 2 (PGICZ). Selected rare earths are La, Ce, Pr, Nd, Gd, Er, Yb and Lu, and the doping level varies between 1 and 10 mol%. The influence of rare earth fluorides on glass forming ability and on physical properties is investigated. At low concentration ( 3 in a modified PGCIZ glass have been cast. Experimental results suggest that rare earths act as modifiers rather than vitrifies in this fluorogallate system. The effect of rare earths on the values of glass transition temperature, refractive index, density and thermal expansion is reported. (orig.)

  10. Resistivity and magnetoresistivity of amorphous rare-earth alloys

    Science.gov (United States)

    Borchi, E.; Poli, M.; De Gennaro, S.

    1982-05-01

    The resistivity and magnetoresistivity of amorphous rare-earth alloys are studied starting from the general approach of Van Peski-Tinbergen and Dekker. The random axial crystal-field and the magnetic correlations between the rare-earth ions are consistently taken into account. The characteristic features of the available experimental data are explained both of the case of random ferromagnetic and antiferromagnetic order.

  11. Radiological issues in monazite processing for rare earth extraction: regulatory approach

    International Nuclear Information System (INIS)

    Mohandas, P.V.; Sinha, Soumen; Bhattacharya, R.

    2014-01-01

    Rare earth minerals quite often contain Naturally Occurring Radioactive Materials (NORM) in varying concentrations resulting in occupational and environmental radiation exposures during their mining, milling and chemical processing for the extraction of rare earth elements and their compounds. NORMs such as Uranium, Thorium and their decay products in the mineral result in enhanced natural background radiation fields in their areas of occurrence. The mining of the mineral ores and further processing results in concentration/redistribution of the NORM in the process streams, product intermediaries, products and effluents. Monazite which is available in plenty in India is one of the most important resources for Rare Earths (RE). Monazite is chemically processed by subjecting it to alkali digestion and selective extraction with hydrochloric acid. During the above process radium ( 228 Ra) and lead present in the monazite appear in the RE composite chloride (RECl3) fraction. These are removed from the product by a process known as 'deactivation' and 'lead elimination' to obtain deactivated and lead free composite RE chloride. The solid waste obtained from the deactivation and lead elimination, referred to as 'mixed cake' is suitably contained and disposed off as radioactive waste. Radioactive wastes/effluents generated during the processing of monazite is another source of concern with respect to occupational and public exposure. This requires adequate attention from the waste management considerations

  12. Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets.

    Science.gov (United States)

    Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun

    2016-02-01

    Scanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium-iron-boron (NdFeB) and samarium-cobalt (Sm-Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm-Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

  13. Separation of some rare earths with the aid of extraction chromatography Pt. 1

    International Nuclear Information System (INIS)

    Baranyai, R.

    1982-01-01

    Some model systems built up by some rare earths have been separated by extraction chromatography. As shown experimentally, by changing the concentration of the acids used as eluents, tri-n-butyl-phosphate can successfully be applied as the stationary phase fixed on a proper support. The separation process is rapid and efficient. (author)

  14. Spectral and thermal behaviours of rare earth element complexes with 3,5-dimethoxybenzoic acid

    Directory of Open Access Journals (Sweden)

    JANUSZ CHRUŚCIEL

    2003-10-01

    Full Text Available The conditions for the formation of rare earth element 3,5-dimethytoxybenzoates were studied and their quantitative composition and solubilities in water at 293 K were determined. The complexes are anhydrous or hydrated salts and their solubilities are of the orders of 10-5 – 10-4 mol dm-3. Their FTIR, FIR and X-ray spectra were recorded. The compounds were also characterized by thermogravimetric studies in air and nitrogen atmospheres and by magnetic measurements. All complexes are crystalline compounds. The carboxylate group in these complexes is a bidentate, chelating ligand. On heating in air to 1173 K, the 3,5-dimethoxybenzoates of rare earth elements decompose in various ways. The hydrated complexes first dehydrate to form anhydrous salts which then decompose in air to the oxides of the respective metals while in nitrogen to mixtures of carbon and oxides of the respective metals. The complexes are more stable in air than in nitrogen.

  15. Environmental Defects And Economic Impact On Global Market Of Rare Earth Metals

    Science.gov (United States)

    Charalampides, G.; Vatalis, K.; Karayannis, V.; Baklavaridis, A.

    2016-11-01

    Rare earth elements include the 14 lanthanides as well as lanthanium and often yttrium. Actually, most of them are not very rare and occur widely dispersed in a variety of rocks. Rare earth metals are vital to some of the world's faster growing industries: catalysts, Nd-magnets, ceramics, glass, metallurgy, battery alloys, electronics and phosphors. Worldwide, the main countries for distribution of rare earths deposits include China, USA, Russia, Brasil, India, Australia, Greenland and Malaysia. The mining and processing of rare earth metals usually result in significant environmental defects. Many deposits are associated with high concentrations of radioactive elements such as uranium and thorium, which requires separate treatment and disposal. The accumulation of rare earth elements in soils has occurred due to pollution caused by the exploitation of rare earth resources and the wide use of rare earths as fertilizers in agriculture. This accumulation has a toxic effect on the soil microfauna community. However, there are large differences in market prices due to the degree of purity determined by the specifications in the applications. The main focus of this article is to overview Rare Earth Metals’ overall impact on global economy and their environmental defects on soils during processing techniques and as they are used as fertilizers.

  16. The production of rare earth elements group via tributyl phosphate extraction and precipitation stripping using oxalic acid

    Directory of Open Access Journals (Sweden)

    Esmaeil Jorjani

    2016-11-01

    Full Text Available In this study, solvent extraction and precipitation stripping were used to produce rare earth elements (REEs. Tributyl phosphate (TBP was used to extract yttrium, lanthanum, cerium, and neodymium from an aqueous solution produced by nitric acid leaching of apatite concentrate. In the extraction stage, the effects of TBP concentration, pH, contact time, temperature, and phase ratio were investigated. The results show that about 95%, 90%, 87% and 80% of neodymium, cerium, lanthanum, and yttrium, respectively, can be extracted in optimum conditions of extraction. Hot, deionized water was used to scrub the impurities from the loaded organic phase. The results showed that three stages of scrubbing with a phase ratio (Va/Vo of five removed about 80%, 30%, 27%, and 15% of Ca, Mg, Fe, and P, respectively, from loaded TBP, while less than 9% of total REEs was lost. The effects on precipitation stripping of oxalic acid concentration, contact time, and phase ratio were investigated. The results showed that precipitation stripping is a viable alternative to traditional acid stripping in the REEs production process. Mixed REEs oxide with an assay of about 90% can be achieved as a final product.

  17. Thermal Oxidation Resistance of Rare Earth-Containing Composite Elastomer

    Institute of Scientific and Technical Information of China (English)

    邱关明; 张明; 周兰香; 中北里志; 井上真一; 冈本弘

    2001-01-01

    The rare earth-containing composite elastomer was obtained by the reaction of vinyl pyridine-SBR (PSBR) latex with rare earth alkoxides, and its thermal oxidation resistance was studied. After aging test, it is found that its retention rate of mechanical properties is far higher than that of the control sample. The results of thermogravimetric analysis show that its thermal-decomposing temperature rises largely. The analysis of oxidation mechanisms indicates that the main reasons for thermal oxidation resistance are that rare earth elements are of the utility to discontinue autoxidation chain reaction and that the formed complex structure has steric hindrance effect on oxidation.

  18. Thermodynamics and kinetics of the formation of rare earth intermetallics

    International Nuclear Information System (INIS)

    Deodhar, S.S.

    1975-01-01

    Heats of reaction of rare earth intermetallics with iron, cobalt and nickel were determined using Differential Thermal Analysis technique. The intermetallic compounds studied were of MgCu 2 type Laves phases and the rare earth elements studied were praseodymium, gadolinium, dyprosium and erbium. The reactions were exothermic and the heats of reaction were generally high. They varied from the low of -2.5 kcal/g mole for Fe 2 Gd to the high of -35.3 kcal/g mole for Ni 2 Er. The magnitudes of heats of reaction were always greater for the intermetallics of heavy rare earth elements. The rare earth intermetallics studied were either ferromagnetic or antiferromagnetic. The variations in the magnetic moments and the heats of reaction with respect to the atomic number of the rare earth elements followed certain trends. The similarities were observed in the trends of two properties. Electronic configuration for the MgCu 2 type rare earth intermetallics is proposed using Engel--Brewer correlation for metallic structures and the structural features of the Laves phase compounds. Kinetics of the reactions between the rare earth elements and iron, cobalt, and nickel was studied. The rate of reaction was diffusion controlled in each case. The Valensi--Carter equation for the diffusion mechanism satisfactorily described the kinetic behavior. The magnitudes of activation energies and frequency factors were determined. The reactions can be characterized by their reaction temperatures since they always begin at definite temperatures. It was observed that the reaction began at a higher temperature if the activation energy for the reaction was high

  19. Computational search for rare-earth free hard-magnetic materials

    Science.gov (United States)

    Flores Livas, José A.; Sharma, Sangeeta; Dewhurst, John Kay; Gross, Eberhard; MagMat Team

    2015-03-01

    It is difficult to over state the importance of hard magnets for human life in modern times; they enter every walk of our life from medical equipments (NMR) to transport (trains, planes, cars, etc) to electronic appliances (for house hold use to computers). All the known hard magnets in use today contain rare-earth elements, extraction of which is expensive and environmentally harmful. Rare-earths are also instrumental in tipping the balance of world economy as most of them are mined in limited specific parts of the world. Hence it would be ideal to have similar characteristics as a hard magnet but without or at least with reduced amount of rare-earths. This is the main goal of our work: search for rare-earth-free magnets. To do so we employ a combination of density functional theory and crystal prediction methods. The quantities which define a hard magnet are magnetic anisotropy energy (MAE) and saturation magnetization (Ms), which are the quantities we maximize in search for an ideal magnet. In my talk I will present details of the computation search algorithm together with some potential newly discovered rare-earth free hard magnet. J.A.F.L. acknowledge financial support from EU's 7th Framework Marie-Curie scholarship program within the ``ExMaMa'' Project (329386).

  20. Determination of rare earth elements by photometric microtitration using xylenol orange

    International Nuclear Information System (INIS)

    Kuban, V.; Jancarova, I.; Sommer, L.

    1989-01-01

    Stock solutions were prepared of rare earth elements in approx 0.1M nitric acid, xylenol orange and EDTA. All measurements were made using a double-beam digital recording spectrophotometer (Superscan 3) with a titration measuring cell with a volume of approx. 30 ml and optical length of 20 mm. Titration agents were pipetted using an automatic piston microburette. Measured were absorbance pH curves of solutions of several lanthanides with xylenol orange, the absorption spectra of solutions of xylenol orange with lanthanides with increasing addition of titration agents EDTA, and the titration curves of the dependence of absorbance of lanthanide solutions with xylenol orange during titration with the EDTA solution. It was found that photometric microtitration allowed accurate and correct determination of all rare earth elements within the concentration range 0.04 - 0.5 mmol/l by titration with standard EDTA solution of a concentration of xylenol orange of 20 μmol/l. (E.S.). 4 figs., 3 tabs., 7 refs

  1. Chromates (3) and chromates (5) of rare earths

    International Nuclear Information System (INIS)

    Suponitskij, Yu.L.

    1986-01-01

    Data on preparation methods, structure and properties of chromates (3, 5) and mixed chromates (3) of rare earths, scandium and yttrium are generalized. Phase diagrams of systems Ln 2 O 3 -Cr 2 O 3 (Ln - rare earths, Sc, Y), chemical and thermodynamic properties of chromates (3, 5), their crystal structure and character of thermal decomposition are considered. Application fields of the compounds mentioned are suggested

  2. Study on lowering the specific radioactivity of rare earth chlorides

    International Nuclear Information System (INIS)

    Shinhuor, Y.; Jyuung, J.; Shyuerjung, T.; Xiangping, L.

    1985-01-01

    In this paper, the source of radioactivity in rare earth chlorides and the chemical behaviour of its main radionuclides in metallurgy processing are investigated. It is pointed out that the radioactivity in rare earths comes from the long-life radionuclides in three natural radioactive series. Nine of them (/sup 238/U, /sup 234/U, /sup 230/Th, /sup 226/Ra, /sup 210/Po, /sup 232/Th, /sup 228/Th, /sup 235/U, /sup 231/Pa) are alpha-emitters, three of them (/sup 228/Ra, /sup 227/Ac, /sup 210/Pb) are beta-emitters. Among them alpha-emitters contribute the total specific activity of rare earths directly. The rare earths are easily purified in preferential dissolution, radium elimination, and other processes

  3. Rare earths: Market disruption, innovation, and global supply chains

    Science.gov (United States)

    Eggert, Roderick; Wadia, Cyrus; Anderson, Corby; Bauer, Diana; Fields, Fletcher; Meinert, Lawrence D.; Taylor, Patrick

    2016-01-01

    Rare earths, sometimes called the vitamins of modern materials, captured public attention when their prices increased more than ten-fold in 2010 and 2011. As prices fell between 2011 and 2016, rare earths receded from public view—but less visibly they became a major focus of innovative activity in companies, government laboratories and universities. Geoscientists worked to better understand the resource base and improve our knowledge about mineral deposits that will be mines in the future. Process engineers carried out research that is making primary production and recycling more efficient. Materials scientists and engineers searched for substitutes that will require fewer or no rare earths while providing properties comparable or superior to those of existing materials. As a result, even though global supply chains are not significantly different now than they were before the market disruption, the innovative activity motivated by the disruption likely will have far-reaching, if unpredictable, consequences for supply chains of rare earths in the future.

  4. Fatigue Resistance of Filled NR with PMMA-Wrapped and Rare Earth-Doped Alumina-Siloxane Gel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Poly (methyl methacrylate) (PMMA) was used to wrap alumina-siloxane sol which was produced by water glass, aluminum nitrate and α-methacrylic acid, and as a result, alumina-siloxane gel wrapped by PMMA was obtained. Meanwhile, rare earth ions were employed to dope in the course of reaction, and the formed rare earth doped PMMA microcapsule powder was filled into natural rubber (NR). It is found through the analysis of mechanical properties that Young′s modulus universally improves and a remarkable resistance to fatigue is displayed. Retention rate of tensile strength is twice that of the controlled sample after ten thousand times of extension fatigue.

  5. Rare earth permanent magnets in China: production and raw materials

    International Nuclear Information System (INIS)

    Luo, Y.

    1998-01-01

    With the development of computer, electronics, communication and modern information industries, NdFeB magnet industry is growing rapidly as a booming business worldwide. Based on the abundance of rare earth and manpower, supporting by the technical teams and the huge domestic market, China NdFeB magnet industry made big jump during the last decade. Its growth rate is the highest one among all other countries. Now China occupies number one place in the world not only due to its richest rare earth reserves, but also due to its output of rare earth, especially, its sales to the international market. China is the only country, who is able to meet the market needs of rare earth worldwide. The current situation of NdFeB magnet industry can be concluded as ''five highs'', i.e. ''high volume growth'', ''high grade development'', ''high expansion of capacity'', ''high value added product'' and ''high variation speed''. The connotations of these ''five highs'' and a brief review on Chinese rare earth industry will be given in this paper. (orig.)

  6. Studies on up-gradation of Erbium from a heavy fraction of rare earths with EHEHPA

    International Nuclear Information System (INIS)

    Singh, D.K.; Anitha, M.; Yadav, K.K.; Kotekar, M.K.; Vijayalakshmi, R.; Singh, H.

    2014-01-01

    Erbium is an important heavy rare earth element, which finds wide applications. Recently, use of Erbium oxide as structural coating material in fusion reactor has stimulated the interest in obtaining Erbium in pure form. The separation of Erbium from other rare earths such as Dy, Ho, Y, Yb, Tm etc is very difficult due to low separation factor owing to their similar chemical properties. Additionally due to very low concentration ( 2 O 3 : 1.09, Dy 2 O 3 : 58.07, Er 2 O 3 : 22.0, Ho 2 O 3 : 13.33, Yb 2 O 3 : 4.74, Tm 2 O 3 :0.67 is obtained during purification of Y by Aliquat 336 from thiocyanate medium. In the present investigation this HRE fraction is taken as the feed material for up-gradation of Er by an acidic extractant namely 2 ethyl hexyl - 2 ethyl hexyl phosphonic acid (EHEHPA)

  7. Raw materials for advanced ceramics: rare earths separation processes

    International Nuclear Information System (INIS)

    Ricci, D.R.; Nobre, J.S.M.; Paschoal, J.O.A.

    1990-01-01

    The importance of obtaining purified rare earths oxidesis related, mainly to the increasing use of these compounds as raw materials for advanced ceramics. Processes of rare earths separation and purification are almost always based on the solvent extraction, fractional precipitation and ion exchange chromatography techniques, whose association depends on the initial concentrate and on the desired purity. This paper describes some steps of fractionation of didymium carbonate by using the solvent extraction and fractional precipitation techniques. The experimental conditions presented here have enable the production of lantanium, neodimium - praseodimium, samarium - gadolinium and ytrium concentrates, which constitute the intermediate fractions of the overall process to obtain high purity rare earths. (author) [pt

  8. Coercive Levers in Chinese Economic Statecraft: Attributed Across Earth, Rarely Apparent

    Science.gov (United States)

    2012-06-01

    Singapore, Malaysia, Indonesia, Thailand, the Philippines and Brunei) and the CLMV (Cambodia, Laos , Myanmar, Vietnam) economies by skewing development...Earths Industry and its Role in the International Market,” 2–3. 186 Tse Pui-Kwan, “China’s rare-earth industry,” U.S. Geological Survey Open-File Report...Assessment of China’s Rare Earth Policy,” The Jamestown Foundation, China Brief 10:22 (2010): 2–5. 190 Ibid., 3. 191 Tse , “China’s rare-earth

  9. Anthropogenic Cycles of Rare Earth Elements

    Science.gov (United States)

    Du, X.; Graedel, T. E.

    2009-12-01

    This research will develop quantitatively resolved anthropogenic cycles and in-use stocks for the rare earth metals specifically cerium, lanthanum and dysprosium in Japan, China, and the U.S. for the year of 2007. Rare earth elements (REE) is a group of 17 scare metals widely used in a growing number of emerging technologies and have been in high demand for emerging technologies as raw materials during past the three decades. New market participants from newly industrializing countries, primarily China, have had strong impacts on the demand of share. Consequently, the importance to sustain a reliable, steady, uninterrupted supply on global market triggered comprehensive research to recognize and understand the life cycles of rare earths. Moreover, because China plays a dominant role in mining production since 1990, it requires the assessment for the countries, which are almost completely dependent on imports from China with respect to rare earth resources. The study aims to analyze the flows and stocks of rare earth elements individually as elemental form in spite of their natural geological co-occurrence and mixed composition in applications. By applying the method of Material Flow Analysis (MFA) work has been done on evaluating current and historical flows of specific technologically significant materials, for example, copper, zinc, nickel, etc., determining the stocks available in different types of reservoirs (e.g., lithosphere, in-use) and the flows among the reservoirs, developing scenarios of possible futures of metal use, and assessing the environmental and policy implications of the results. Therefore, REE as a new target deserves inclusion because of its potential demand-supply conflict and importance to secure the competitive advantage of technical innovation in future. This work will generate a quantitatively resolved anthropogenic life cycle and in-use stocks for REE for the main target countries for a chosen year, 2007, providing flows and stocks from

  10. Rare-earth doping of high T/sub c/ superconducting perovskites

    International Nuclear Information System (INIS)

    Mc Kinnon, W.R.; Tarascon, J.M.; Greene, L.H.; Hull, G.W.

    1987-01-01

    In most superconductors, the magnetic moments of rare-earth (Re) ions interact with the conduction electrons and break the Cooper pairs, supressing or destroying superconductivity. But in the perovskite-based superconductors discovered recently, the rare-earth ions are separated from the copper and oxygen where the superconducting electrons are believed to be located. The authors study the effects of rare-earth doping in both the 40K La/sub 2-x/Sr/sub x/CuO/sub 4-y/ system and 90K YBa/sub 2/Cu/sub 3/O/sub 7-x/ system. In these materials, the RE ions only weakly affect superconductivity, and the effects we do see are more strongly correlated with changes in the volume of the crystal than with the magnetism of the rare earths

  11. Creating a multi-national development platform: Thorium energy and rare earth value chain

    International Nuclear Information System (INIS)

    Kennedy, J.; Kutsch, J.

    2014-01-01

    Rare earths and thorium are linked at the mineralogical level. Changes in thorium regulations and liabilities resulted in the development of excessive market concentrations in the rare earth value chain. High value monazite rare earth resources, a by-product of heavy mineral sands mining, constituted a significant portion of global rare earth supply (and nearly 100% of heavy rare earths) until legislative changes, interpretation and enforcement regarding “source materials” in the early 1980s eliminated these materials from the supply chain.

  12. A divalent rare earth oxide semiconductor: Yttrium monoxide

    Science.gov (United States)

    Kaminaga, Kenichi; Sei, Ryosuke; Hayashi, Kouichi; Happo, Naohisa; Tajiri, Hiroo; Oka, Daichi; Fukumura, Tomoteru; Hasegawa, Tetsuya

    Rare earth sesquioxides like Y2O3 are known as widegap insulators with the highly stable closed shell trivalent rare earth ions. On the other hand, rare earth monoxides such as YO have been recognized as gaseous phase, and only EuO and YbO were thermodynamically stable solid-phase rock salt monoxides. In this study, solid-phase rock salt yttrium monoxide, YO, was synthesized in a form of epitaxial thin film by pulsed laser deposition method. YO possesses unusual valence of Y2+ ([Kr] 4d1) . In contrast with Y2O3, YO was narrow gap semiconductor with dark-brown color. The electrical conductivity was tunable from 10-1 to 103 Ω-1 cm-1 by introducing oxygen vacancies as electron donor. Weak antilocalization behavior was observed indicating significant spin-orbit coupling owing to 4 d electron carrier. The absorption spectral shape implies the Mott-Hubbard insulator character of YO. Rare earth monoixdes will be new platform of functional oxides. This work was supported by JST-CREST, the Japan Society for the Promotion of Science (JSPS) with Grant-in-Aid for Scientific Research on Innovative Areas (Nos. 26105002 and 26105006), and Nanotechnology Platform (Project No.12024046) of MEXT, Japan.

  13. Non-rare earth magnetic nanoparticles

    Science.gov (United States)

    Carpenter, Everett E.; Huba, Zachary J.; Carroll, Kyler J.; Farghaly, Ahmed; Khanna, Shiv N.; Qian, Meichun; Bertino, Massimo

    2017-09-26

    Continuous flow synthetic methods are used to make single phase magnetic metal alloy nanoparticles that do not contain rare earth metals. Soft and hard magnets made from the magnetic nanoparticles are used for a variety of purposes, e.g. in electric motors, communication devices, etc.

  14. Radiological safety in extraction of rare earths in India: regulatory control

    International Nuclear Information System (INIS)

    Sinha, S.; Bhattacharya, R.

    2011-01-01

    The term 'rare earths' refers to a group of f-block elements in the periodic table including those with atomic numbers 57 (Lanthanum) to 71 (Lutetium), as well as the transition metals Yttrium (39) and Scandium (21). Economically extractable concentrations of rare earths are found in minerals such as monazite, bastnaesite, cerites, xenotime etc. Of these, monazite forms the main source for rare earths in India, which along with other heavy minerals is found abundantly in the coastal beach sands. However, in addition to rare earths, monazite also contains 0.35% U 3 O 8 and 8-9% ThO 2 . Hence, extraction of rare earths involves chemical separation of the rare earths from thorium and uranium which are radioactive. The processing and extraction of rare earths from monazite therefore invariably results in occupational radiation exposure to the workers involved in these operations. In addition, in the process of removal of radioactivity from rare earths, radioactive solid waste gets generated which has 2 2 8Ra concentration in the range 2000-5000 Bq/g. Unregulated disposal of such high active waste would not only result in contamination of the soil but the radionuclides would eventually enter the food chain and lead to internal exposure of the general public. Therefore such facilities involved in recovery of rare earths from monazite attract the provisions of radiological safety regulations. Atomic Energy Regulatory Board of India has been enforcing the provisions of The Atomic Energy (Radiation Protection) Rules, 2004 and The Atomic Energy (Safe Disposal of Radioactive Waste) Rules, 1987 in these facilities. This paper shall discuss the associated radiological hazard involved in recovery of rare earths from monazite. It shall also highlight the regulatory requirements for controlling the occupational exposure of workers during design stage such as requirements on lay out of the building, ventilation, containment of radioactivity, etc and also the during operational

  15. Carbonatite and alkaline intrusion-related rare earth element deposits–A deposit model

    Science.gov (United States)

    Verplanck, Philip L.; Van Gosen, Bradley S.

    2011-01-01

    The rare earth elements are not as rare in nature as their name implies, but economic deposits with these elements are not common and few deposits have been large producers. In the past 25 years, demand for rare earth elements has increased dramatically because of their wide and diverse use in high-technology applications. Yet, presently the global production and supply of rare earth elements come from only a few sources. China produces more than 95 percent of the world's supply of rare earth elements. Because of China's decision to restrict exports of these elements, the price of rare earth elements has increased and industrial countries are concerned about supply shortages. As a result, understanding the distribution and origin of rare earth elements deposits, and identifying and quantifying our nation's rare earth elements resources have become priorities. Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare earth elements. The general mineral deposit model summarized here is part of an effort by the U.S. Geological Survey's Mineral Resources Program to update existing models and develop new descriptive mineral deposit models to supplement previously published models for use in mineral-resource and mineral-environmental assessments. Carbonatite and alkaline intrusion-related REE deposits are discussed together because of their spatial association, common enrichment in incompatible elements, and similarities in genesis. A wide variety of commodities have been exploited from carbonatites and alkaline igneous rocks, such as rare earth elements, niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other enrichments include manganese, strontium, tantalum, thorium, vanadium, and uranium.

  16. Spectroscopic properties of rare earths in optical materials

    CERN Document Server

    Parisi, Jürgen; Osgood, R; Warlimont, Hans; Liu, Guokui; Jacquier, Bernard

    2005-01-01

    Aimed at researchers and graduate students, this book provides up-to-date information for understanding electronic interactions that impact the optical properties of rare earth ions in solids. Its goal is to establish a connection between fundamental principles and the materials properties of rare-earth activated luminescent and laser optical materials. The theoretical survey and introduction to spectroscopic properties include electronic energy level structure, intensities of optical transitions, ion-phonon interactions, line broadening, and energy transfer and up-conversion. An important aspect of the book lies in its deep and detailed discussions on materials properties and the potential of new applications such as optical storage, information processing, nanophotonics, and molecular probes that have been identified in recent experimental studies. This volume will be a valuable reference book on advanced topics of rare earth spectroscopy and materials science.

  17. Mechanical Properties of Magnesium-Rare Earth Alloy Systems: A Review

    Directory of Open Access Journals (Sweden)

    Sravya Tekumalla

    2014-12-01

    Full Text Available Magnesium-rare earth based alloys are increasingly being investigated due to the formation of highly stable strengthening phases, activation of additional deformation modes and improvement in mechanical properties. Several investigations have been done to study the effect of rare earths when they are alloyed to pure magnesium and other Mg alloys. In this review, the mechanical properties of the previously investigated different magnesium-rare earth based binary alloys, ternary alloys and other higher alloys with more than three alloying elements are presented.

  18. Study on Preparation and Property of Poly-Aminosilicone-Rare Earth Composite

    Institute of Scientific and Technical Information of China (English)

    Zhang Ming(张明); Qiu Guanming(邱关明); Chen Haiyan(陈海燕); Zhou Lanxiang(周兰香); Inoue Shinich; Okamoto Hiroshi

    2003-01-01

    The poly-aminosilicone-rare earth composite was prepared by poly-aminosilicone cross-linked with rare earth and active silanol. The thermal stability of the composites was studied by thermogravimetric analysis (TG). Force condition of the composites in electric field was analyzed and relative polarizability was derived. It is found that the composites containing different rare earth ions have different relative polarizability. The experiment results reveal that organosilicon materials with different electrical performance can be obtained by this way. Meanwhile, the absorption and flourescene spectrum of composites were also investigated. Compared to rare earth chloride, the spectrum properties of the composite are changed obviously. The possible reasons for these phenomena were discussed.

  19. Study On Beneficiation Technology Of Dong Pao Rare-Earth-Barite-Fluorite With Two Product Plans About Content And Recovery Of Rare-Earth Fine Ores

    International Nuclear Information System (INIS)

    Duong Van Su; Truong Thi Ai; Bui Ba Duy; Bui Thi Bay; Nguyen Hong Ha; Le Thi Hong Ha; Doan Thi Mo; Doan Dac Ban; Nguyen Hoang Son

    2014-01-01

    The ore sample used in the research was taken from the F3 ore bodies and the sample of the F7, F9 and F16 ore bodies which contain the average of 5.98% TR 2 O 3 ; they are multi-metals ore which is difficult to enrich, highly weather with very complex ingredients. The process of the experiment is the ore is crushed, ground, screened and classified reasonably to -0.1 mm and divided into 3 particle size with the following technique: (1) -0.020 mm is primary sludge and the rare-earth fine ore; (2) 0.075-1 mm is gotten through the sludge concentrating table with the output is the 2 parts: the heavy part which is dried magnetic separator with high magnetism to get the rare-earth fine ore and the light one; (3) Light minerals, non-magnetic and ferromagnetic minerals group are ground together to 85% of them get size within -0.075 mm then mix it with 0.020-0.075 mm group. Using flotation separator, get barite-rare earth mixture and fluorite. After that, we separate this mixture by secondary flotation and get refined rare earth, barite and fluorite mineral. The result of the theme: (1) product plan A-rare-earth fine ore has TR 2 O 3 content archive 42.07% with recovery is 69.70%; (2) product plan B-rare-earth fine ore has TR 2 O 3 content archive 29.64% with recovery is 80.01%. (author)

  20. Direct current electroluminescence in rare-earth-doped zinc sulphide

    International Nuclear Information System (INIS)

    Bryant, F.J.; Krier, A.

    1984-01-01

    Some of the properties and characteristics of rare-earth-doped zinc sulphide DCEL devices are reported. Two types of devices are discussed, co-evaporated ZnS:RE thin films and ion implanted ZnS:RE single crystal diodes. The thin film devices exhibit bright DCEL of various colours at low applied voltages (typically approximately 12 V). A study of the spectral intensities and lifetimes of the Er 3+ ion in ZnS:Er 3+ thin films is consistent with a Boltzmann energy distribution amongst the conduction electrons present in these devices. The ZnS:RE single crystal diodes fabricated in this laboratory by ion implantation are also capable of various colour DCEL. By comparing the EL emission obtained from the different rare earth dopants, erbium and neodymium are identified as the most efficient luminescence centres. Further consideration of the EL emission spectra gives evidence for the presence of inter-conduction band hot electron transitions in those devices containing rare earth dopants which are inefficent electroluminescence centres. These findings can be explained in terms of Auger processes occurring in rare earth complexes. (author)

  1. Nuclear orientation on rare earth nickel alloys

    International Nuclear Information System (INIS)

    Nishimura, K.

    1998-01-01

    A hyperfine interaction study of the light rare earth elements, Ce, Pr, Nd and Pm, in the rare earth nickel and CeNi 2 Al 5 compounds by means of the low temperature nuclear orientation is summarised. The magnitudes and directions of the magnetic hyperfine fields obtained through measurements of γ-ray anisotropy and angular distributions reveal the magnetic structures of the ions. The experiments extracted peculiar results for the magnetic properties of the ions, and show certain novel features of the technique to the study of solid-state magnetism. Copyright (1998) Australian Journal of Physics

  2. Features of rare earth element (3) complexing

    International Nuclear Information System (INIS)

    Martynenko, L.I.

    1991-01-01

    Reasons for nonobeyance to the regularity of tetrad ''W'' effect of rare earth chelate complex compounds are discussed in the review. The concept of metal-ligand ionic bond in rare earth complexes is put in the basis of the consideration. From this viewpoint mutual influence of ligands in lower, higher, polynuclear and different-ligand complexes, formed by the ligands of low, medium and high denticity, is discussed. Problems of intermolecular interaction of complexes with different structure are considered in relation to problems of variation of chelate volatility and selectivity in the processes of sublimation and precipitation

  3. Magnetostriction of rare earth-Fe2 Laves phase compounds

    International Nuclear Information System (INIS)

    Clark, A.E.; Abbundi, R.; Savage, H.T.

    1977-01-01

    Single crystal magnetostriction measurements were made as a function of temperature on TbFe 2 and DyFe 2 . From these, the intrinsic magnetoelastic coupling coefficients were determined for the rare earth-Fe 2 compounds. Employing X-ray techniques, certain multicomponent rare earth-Fe 2 compounds were identified to maximize the magnetostriction to anisotropy ratio. (Auth.)

  4. Separation method for rare-earths using high-voltage electrophoresis on paper strip; Methode de separation des terres rares par electrophorese a haute tension sur papier - support

    Energy Technology Data Exchange (ETDEWEB)

    Clarence, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-07-01

    The equipment includes an electrophoresis set running at 3 000 V and 20 mA. Two cooling plates are used as heat exchanger, and a pneumatic pressure device to insure an uniform pressure on the paper strip laid flat. The mobilities and the separations of the rare earths in lactic, and, {alpha} hydroxy-isobutyric acid solutions are investigated on cellulose acetate strip. Better results are obtained with {alpha} hydroxy-isobutyric acid. The method is rapid and allows a fine fractionation of rare earth elements within less than an hour. A complete separation of a Ce - Pr - Nd - Pm - Eu mixture, and a Y - Tb mixture is obtained. (author) [French] L'equipement comporte un appareil d'electrophorese fonctionnant sous 3000 V a 20 mA. Deux plaques refrigerantes absorbent la chaleur dissipee, et un coussin pneumatique assure une pression uniforme sur le papier support. Les mobilites et les separations des terres rares sont etudiees en milieux lactiques et {alpha} hydroxyisobutyriques sur papier d'acetate de cellulose. De meilleurs resultats sont obtenus avec l'acide {alpha} hydroxyisobutyrique. La methode est tres rapide et permet de separer un melange de terres rares radioactives en moins d'une heure. Des separations fines d'un melange Ce, Pr, Nd, Pm, Eu, et d'un melange Y, Tb sont egalement obtenues. (auteur)

  5. Separation of Rare Earths from Uranium and Thorium

    International Nuclear Information System (INIS)

    Krebs, Damien

    2014-01-01

    Greenland Minerals and Energy - Key Highlights – A unique world class mining project: 1. World-class, large scale development project: • Economically robust, proven technology, large-scale, long life production of rare earths concentrate and uranium; • Large JORC resource base to produce ~7kt HREO, 37kt LREO & 3Mlbs U_3O_8 per annum over 30 year mine life; • Ideally located near international airport, existing towns and potential hydro-electric power source. 2. Very attractive commodity portfolio: • Heavy rare earths and uranium are both recognised as strategically important commodities for the future; • Rare earths market characterised by limited capacity and increasing demand (particularly Dy, Nd, Tb, Eu and Y). 3. Strong management and technical team: • Experienced management team with proven track record; • Well-respected and knowledgeable technical/project team in place with exceptional local expertise. 4. Highly advantageous ore-type, makes for simple cost-effective processing, highly scalable production: • High upgrade through beneficiation brings optionality to Kvanefjeld project; • Leaching can be done in Greenland, or owing to the high-grade concentrate, can be shipped to other locations; • Allows to single concentrator in Greenland, multiple refineries/partners globally. 5. Globally significant, long life, low cost, multi-commodity asset: • Company to become one of the largest producers of rare earths globally and a significant U_3O_8 mine; • Potential to supply >20% of global critical (including heavy) rare earth element demand; • Company has low cost of production due to multiple by-product opportunities. 6. Low political risk: • Stable, low-risk operating environment with government looking to develop new industries and employment; • GME fully permitted to evaluate the project, exploration licence now includes radioactive elements; • Management and board have a solid working relationship with the government and are

  6. Rare earth element lithogeochemistry of granitoid mineral deposits

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, R.P.; Fryer, B.J. (Memorial Univ. of Newfoundland, St. John' s (Canada). Dept. of Earth Sciences)

    1983-12-01

    As a monitor of the processes involved in the formation of granitoid mineral deposits the coherent group behaviour of the rare earth elements (REE) actively reflects changing fluid characteristics. For example, in the porphyry environment, magmatic-hydrothermal fluids produce potassic alteration with strong enrichment in the light rare earth elements, reflecting their high pH, low fluid/rock ratios, and the dominant role of Cl/sup -/ complexing in metal (i.e. Cu, Au) transport. With increasing fluid/rock ratios and decreasing pH accompanying the progressive involvement of meteoric fluids (and the production of propylitic, argillic, and phyllic alteration) anionic species such as F/sup -/ and CO/sub 3//sup 2 -/ become important in metal (e.g. Mo, W) transport through complexing, and their activity in the hydrothermal fluids is illustrated by mobilization of the heavy rare earth elements. The relative involvement of Cl/sup -/ versus F/sup -/ versus CO/sub 3//sup 2 -/ in metal transport in other granite-related systems can also be monitored through REE behaviour. Hence granitoid tin-tungsten mineralization and associated greisenization typically exhibit heavy rare earth enrichment and evidence the importance of F/sup -/ and CO/sub 3//sup 2 -/ in metal transport. Similarly, heavy rare earth element enrichment in hydrothermal uranium deposits can be related to the transport of uranium as carbonate complexes. REE are widely accepted as powerful tools in the study of rock petrogenesis, but their use has been neglected in the investigation of mineral deposits. The recognition of the systematic variation of REE distributions in granitoid mineral deposits suggests that the application of REE geochemistry, particularly when integrated with fluid inclusion and isotope studies, can provide l) an effective method for identifying the physiochemical controls of metal transport and 2) a useful criterion of elucidating metal distribution.

  7. Rare earth element lithogeochemistry of granitoid mineral deposits

    International Nuclear Information System (INIS)

    Taylor, R.P.; Fryer, B.J.

    1983-01-01

    As a monitor of the processes involved in the formation of granitoid mineral deposits the coherent group behaviour of the rare earth elements (REE) actively reflects changing fluid characteristics. For example, in the porphyry environment, magmatic-hydrothermal fluids produce potassic alteration with strong enrichment in the light rare earth elements, reflecting their high pH, low fluid/rock ratios, and the dominant role of Cl - complexing in metal (i.e. Cu, Au) transport. With increasing fluid/rock ratios and decreasing pH accompanying the progressive involvement of meteoric fluids (and the production of propylitic, argillic, and phyllic alteration) anionic species such as F - and CO 3 2- become important in metal (e.g. Mo, W) transport through complexing, and their activity in the hydrothermal fluids is illustrated by mobilization of the heavy rare earth elements. The relative involvement of Cl - versus F - versus CO 3 2- in metal transport in other granite-related systems can also be monitored through REE behaviour. Hence granitoid tin-tungsten mineralization and associated greisenization typically exhibit heavy rare earth enrichment and evidence the importance of F - and CO 3 2- in metal transport. Similarly, heavy rare earth element enrichment in hydrothermal uranium deposits can be related to the transport of uranium as carbonate complexes. REE are widely accepted as powerful tools in the study of rock petrogenesis, but their use has been neglected in the investigation of mineral deposits. The recognition of the systematic variation of REE distributions in granitoid mineral deposits suggests that the application of REE geochemistry, particularly when integrated with fluid inclusion and isotope studies, can provide l) an effective method for identifying the physiochemical controls of metal transport and 2) a useful criterion of elucidating metal distribution

  8. Role of americium interference in analysis of samples containing rare earths

    International Nuclear Information System (INIS)

    Mohapatra, P.K.; Adya, V.C.; Thulasidas, S.K.; Bhattacharyya, A.; Kumar, Mithlesh; Godbole, S.V.; Manchanda, V.K.

    2007-01-01

    Quality control of nuclear fuel samples requires precise estimation of rare earths which have high neutron absorption cross sections and act as neutron poisons. Am is generated by nuclear decay where as lanthanides may be present as impurities picked up during reprocessing/fuel fabrication. Precise estimation of the rare earths by ICP-AES method in presence of 241 Am is a challenging task due to the likelihood of spectral interference of the latter. Rare earths impurities in the purified Am sample were estimated by ICP-AES method. Known amounts of the rare earths viz. Sm, Eu, Dy and Gd were used as synthetic sample and the interference due to Am was investigated. (author)

  9. Spectra of fluorinated rare earth β-diketonates with added ligands

    International Nuclear Information System (INIS)

    Khomenko, V.S.; Lozinskij, M.O.; Fialkov, Yu.A.; Rasshinina, T.A.; Krasovskaya, L.I.; AN Ukrainskoj SSR, Kiev. Inst. Organicheskoj Khimii)

    1984-01-01

    Different-ligand rare earth complexes are synthesized. Fluorated β-diketones, triethylphosphine oxide and trifluoracetic acid are used as active ligands. Mass-spectra of low and high resolution are taken at the energy of ionizing electrons of 70 eV, as well as luminescence spectra of complexes. Fragmentation ways of complexes decomposition under electron shock are studied. A series of changing the bound strength of additional ligands with europium in mixed complexes is determined. It is shown that the introduction of additional ligands can purposefully change physical and chemical properties of complexes

  10. Spectra of fluorinated rare earth. beta. -diketonates with added ligands

    Energy Technology Data Exchange (ETDEWEB)

    Khomenko, V.S.; Lozinskij, M.O.; Fialkov, Yu.A.; Rasshinina, T.A.; Krasovskaya, L.I. (AN Belorusskoj SSR, Minsk. Inst. Fiziki; AN Ukrainskoj SSR, Kiev. Inst. Organicheskoj Khimii)

    1984-01-01

    Different-ligand rare earth complexes are synthesized. Fluorated ..beta..-diketones, triethylphosphine oxide and trifluoracetic acid are used as active ligands. Mass-spectra of low and high resolution are taken at the energy of ionizing electrons of 70 eV, as well as luminescence spectra of complexes. Fragmentation ways of complexes decomposition under electron shock are studied. A series of changing the bound strength of additional ligands with europium in mixed complexes is determined. It is shown that the introduction of additional ligands can purposefully change physical and chemical properties of complexes.

  11. Neutron activation analysis of the rare earth elements in Nasu hot springs

    International Nuclear Information System (INIS)

    Ikeda, Nagao; Takahashi, Naruto.

    1978-01-01

    Eleven rare earth elements (lanthanum, cerium, neodymium, samarium, europium, gadolinium, terbium, holmium, thulium, ytterbium and lutetium) in hot spring waters and sinter deposits in the Nasu area were determined by the neutron activation method. The rare earth elements in hot spring water were preconcentrated in ferric hydroxide precipitate and neutron-irradiated. The rare earth elements were chemically separated into lighter and heavier groups and the activity of each group was measured with a Ge(Li) detector. Distribution of the rare earth elements between the hot spring water and the sinter deposit was also discussed. (auth.)

  12. Prospects for trivalent rare earth molecular vapor lasers for fusion

    International Nuclear Information System (INIS)

    Krupke, W.F.

    1976-01-01

    The dynamical properties of three types of RE 3+ molecular vapors were considered: (1) rare earth trihalogens, (2) rare earth trihalogens complexed with transition metal trihalogens, and (3) rare earth chelates. Radiative and nonradiative (unimolecular and bimolecular) transition probabilities have been calculated using phenomenological models predicted on the unique electronic structure of the triply ionized RE ion (well shielded ground electronic configuration of equivalent of electrons). Although all the lanthanide ions have been treated in some detail, specific results are presented for the Nd 3+ and Tb 3+ ions to illustrate the systematics of these vapors as a class of new laser media. Once verified, these phenomenological models will provide a powerful tool for the directed experimental exploration of these systems. Because of the structural similarity to the triply ionized actinides, comments offered here for the lanthanide rare earth series generally apply to gaseous actinide lasers which are also under consideration

  13. Separation of cerium from other lanthanides by leaching with nitric acid rare earth(III) hydroxide-cerium(IV) oxide mixtures

    International Nuclear Information System (INIS)

    Mioduski, T.; Dong Anh Hao; Hoang Hong Luan

    1989-01-01

    The objective of the present work is a method for separating Ce from other Ln in the raw natural mixtures of rare earth hydroxides obtained from Vietnamese and Mongolian fluorocarbonate ores. The method, a simple acid digestion, should combine a maximum Ln(III) concentration of the effluent solution with a nitrate counter-ion environment and high selectivity vs. leaching yield parameters. Under optimum conditions Ce (and Th, if present) virtually does not pass into solution while the yield of leaching and the sum of REE oxides concentration in the after-leach solution reach the maximum values of 97% (mass) and 0.18 kg x dm -3 , respectively. (author) 9 refs.; 8 tabs

  14. Rare earth taggants in-printing ink - its potential in forensic applications

    International Nuclear Information System (INIS)

    Joseph, Daisy; Chodhury, R.K.; Maind, Sandip

    2011-01-01

    Proton Induced X-ray Emission (PIXE) and Energy Dispersive X-ray Fluorescence (EDXRF) techniques were used for elemental characterization of offset printing ink tagged with rare-earth taggants. The offset printing ink was tagged with rare-earth (La, Pr, Nd, Sm, Eu and Gd) thenoyltrifluoroacetonate chelates at about 1000-ppm level for each element separately. Small aliquots (approximately 20 mg) of tagged inks were coated on paper supports in the form of small circles having diameter 10-15 mm each and then analyzed. In the case of PIXE, a proton beam of energy 4 MeV and in the case of EDXRF a radioisotope source of 241 Am (100 mCi) was used to excite the samples. The PIXE analysis showed well-resolved rare-earth LX-rays and EDXRF analysis showed the K X-rays of rare earths. The aim of this study is to see the efficacy of homogeneous mixing of inorganic taggants in offset printing ink with the objective to establish linear relation of intensity (signal) against concentrations/ amounts of taggant(s) and to derive the minimum detection limit, by EDXRF and PIXE. The feasibility study of determination of rare-earth elements in offset printing ink tagged with rare-earth thenoyltrifluoroacetonates was examined. In the present study, we have used the facility of Proton Induced X-ray Emission (PIXE) and Energy Dispersive X-ray Fluorescence (EDXRF) technique for identification of rare earths in tagged printing ink on paper support. Satisfactory results to identify and quantify the taggants were achieved. (author)

  15. Geological research on rare earth elements, results and outlook

    International Nuclear Information System (INIS)

    Fortin, H

    1999-01-01

    This is a report of the geological investigation of rare earth elements carried out by CCHEN and ENAMI (Empresa Nacional de Mineria) over 70,000 square kilometers in Chile's northern coastal mountain range. Twenty areas were identified with sphena, davidite, ilmenite, pyroxene, anatase and magnetite minerals containing 0.3 kg/t to 6.0 kg/t of rare earth elements. Additional research on Cerro Carmen Prospect, located near Diego de Almagro, define it as a metasomatic deposit, hosted in metamorphic contact rocks, between andesites (Pliensbachian to early Jurassic) and intrusive monzonitic rocks. This information increases knowledge about the metallogenesis of Chile's copper - iron - rare earth - uranium deposits and the application of this geological model of ore deposits as defined in Australia's Olympic Dam

  16. Quantum Theory of Rare-Earth Magnets

    Science.gov (United States)

    Miyake, Takashi; Akai, Hisazumi

    2018-04-01

    Strong permanent magnets mainly consist of rare earths (R) and transition metals (T). The main phase of the neodymium magnet, which is the strongest magnet, is Nd2Fe14B. Sm2Fe17N3 is another magnet compound having excellent magnetic properties comparable to those of Nd2Fe14B. Their large saturation magnetization, strong magnetocrystalline anisotropy, and high Curie temperature originate from the interaction between the T-3d electrons and R-4f electrons. This article discusses the magnetism of rare-earth magnet compounds. The basic theory and first-principles calculation approaches for quantitative description of the magnetic properties are presented, together with applications to typical compounds such as Nd2Fe14B, Sm2Fe17N3, and the recently synthesized NdFe12N.

  17. Separation of uranium from rare earths in chloride medium using Alamine 336

    International Nuclear Information System (INIS)

    Mondal, S.; Giriyalkar, A.B.; Singh, A.K.; Hubli, R.C.

    2014-01-01

    Present work was carried out to optimize a process to separate uranium from rare earths using Alamine-336 (tri-n-octyl amine). This paper describes the process of extraction of uranium from chloride liquor generated after dissolution of impure SDU cake in hydrochloric acid. The solvent used in this study is Alamine-336 which was procured from M/s. Chemical Centre, Mumbai. Dodecane was used as diluent and isodecanol as phase modifier. The extraction and stripping experiments were carried out in separating funnels shaken manually at room temperature. The contact time was fixed at five minutes for all the experiments. Following contact, the aqueous phase and the organic phase were separated and the aqueous phase was taken up for analysis. Analysis of uranium and rare earths were done by ICP-AES. Metal extraction by amines depends on the capacity of the metallic ions to form anionic/neutral species in the aqueous media; these species are then extracted by anion exchange mechanism or by adduct formation respectively

  18. Alkali roasting of bomar ilmenite: rare earths recovery and physico-chemical changes

    Directory of Open Access Journals (Sweden)

    Sanchez-Segado Sergio

    2014-11-01

    (FeTiO3 is presented as a process route for integrated beneficiation of the mineral for rutile-rich phase and rare earth oxides; the latter is released as a consequence of physical changes in the ilmenite matrix, during the water leaching after roasting. The oxidative alkali roasting transforms ilmenite mineral into water-insoluble alkali titanate and water-soluble ferrite. After roasting the insoluble alkali titanate is separated from rare-earth oxide mixture in colloidal form and water-soluble ferrite. Further leaching of alkali titanate is carried out with oxalic (0.3M and ascorbic (0.01M acid solution which removes the remaining Fe2+ ions into the leachate and allows precipitation of high-purity synthetic rutile containing more than 95% TiO2. Iron is removed as iron oxalate. The physico-chemical changes occurred during the roasting and leaching processes are reported by comparing the role of alkali on the roasting process and product morphologies formed.

  19. Magnetism in rare-earth metals and rare-earth intermetallic compounds

    International Nuclear Information System (INIS)

    Johansson, B.; Nordstroem, L.; Eriksson, O.; Brooks, M.S.S.

    1991-01-01

    Some of out recent local spin density electronic structure calculations for a number of ferromagnetic rare-earth systems are reviewed. A simplified model of the level densities for rare-earth (R) transition metal (M) intermetallic compounds, R m M n , is used to describe in a simple way the main features of their basic electronic structure. Explicit calculations for LuFe 2 and RFe 2 (R=Gd-Yb) systems are presented, where a method to treat simultaneously the localized 4f and the conduction electron spin magnetism is introduced. Thereby it becomes possible to calculate the K RM exchange coupling constant. This method is also used to study theoretically the permanent magnet material Nd 2 Fe 14 B. The electronic structure of the anomalous ferromagnets CeFe 2 and CeCo 5 is discussed and an induced 4f itinerant magnetism is predicted. The γ-α transition in cerium metal is considered, and results from calculations including orbital polarization are presented, where a volume collapse of 10% is obtained. On one side of the transition the 4f electrons are calculated to be essentially non-bonding (localized) and on the other side they are found to contribute to the metallic bonding and this difference in behaviour gives rise to the volume collapse. Recent calculations by Wills, Eriksson and Boring for the crystal structure changes in cerium metal under high pressure are discussed. Their successful results imply an itinerant picture for the 4f electrons in α-cerium. Consequently this strongly supports the view that the γ-α phase transformation is caused by a Mott transition of the 4f electrons. (orig.)

  20. Investigation of recovery and recycling of rare earth elements from waste fluorescent lamp phosphors

    Science.gov (United States)

    Eduafo, Patrick Max

    Characterization techniques and experimental measurements were used to evaluate a process for recycling rare earth elements (REEs) from spent fluorescent lamp phosphors. QEMSCAN analysis revealed that over 60% of the rare earth bearing minerals was less than 10 microm. A representative sample of the as-received feed contained 14.59 wt% total rare earth elements (TREE) and upon sieving to below 75 microm, the grade increased to 19.60 wt% REE with 98.75% recovery. Based on experimental work, a new process for extracting the chief REEs from end of life fluorescent lamps has been developed. The proposed flowsheet employs a three-stage leaching and precipitation process for selective extraction and recovery of the REEs. Hydrochloric acid was used as lixiviant in batch leach experiments on the phosphor powder. The maximum extraction obtained was 100% for both yttrium and europium under the following leaching conditions: 2.5 M HCl, 70°C, 1 hour, 180 g/L and 600 rpm. However, the solubility of cerium, lanthanum and terbium remained low at these conditions. Kinetic data of the leaching of yttrium and europium showed best fit to the logarithmic rate expression of the empirical model of leaching. Activation energy was calculated to be 77.49 kJ/mol for Y and 72.75 kJ/mol for Eu in the temperature range of 298 to 343 K. Precipitation tests demonstrate that at least 50% excess the stoichiometric amount of oxalic acid is needed to recover yttrium and europium efficiently to produce a pure (Y, Eu) mixed oxide. Total recovery of the REEs was achieved even at very low pH or without any base added. Over 99% pure mixed rare earth oxide at 99% recovery has been attained. An economic assessment of the developed process using operating and capital cost have be undertaken and based on the analysis of the three economic scenarios, two are economic and one is non-economic.

  1. Quantitative analysis or rare earths by X-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Taam, Isabel; Mantovano, J.L.; Gante, Valdir; Jesus, Camila S.

    2013-01-01

    Rare earths ores and compounds are of growing importance to the worldwide industry. Its applications range from raw material to catalysts, manufacturing of electronics and even super magnets. Therefore, the demand for quick and accurate quantitative analysis methods is continuously growing. Current quantification methods of rare earths involve the separation of these elements by ion exchange and liquid-liquid extraction prior to the analysis itself, processes both time and reagent consuming. In the present work, we propose a method that directly quantifies by XRF technique the following rare earths: La, Pr, Nd, Sm and Gd in a concentrated liquor whose matrix also contains Ca, Y, PO4, U and Th. We evaluated the analytical interference of each element present on the sample on X-rays spectrum. The studied samples are certified standards and the obtained results have been compared to EDTA titration results, an already well-established and widely trusted method.We also measured the matrix effect thus using a complex rare earths standard. Results show that quantification by XRF technique is as accurate as the results in dose titration with EDTA for the same elements, with the advantage of exempting the previous separation step from each rare earth and from other elements present in the matrix (such as U and Th). (author)

  2. Mineral characterisation of Don Pao rare earth deposit in Vietnam

    International Nuclear Information System (INIS)

    XuanBen, T.

    1998-01-01

    Full text: The Don Pao Rare Earth Deposit was discovered in 1959 in Phon Tho district, about 450km North-West of Hanoi capital. Geological work was conducted between 1959-95, resulting in 60 ore bodies of various sizes being identified. The ore bodies are irregularly shaped nests, lenses and veins hosted in the shear zone, at the margin of a Paeleogene aged syenite massif. The mineral composition of Don Pao Deposit is very complex, consisting of more than 50 minerals. Among them, basnaesite, parisite, fluorite and barite are the main constituent minerals of the ore. All the minerals were identified by the modern methods of mineralogical studies. Based on the constituent mineral ratios, four ore types have been distinguished in the deposit: 1. Rare earth ore containing over 5 percent of RE 2 O 3 . 2. Rare Earth-Barite ore containing 0.5 to 30 percent of RE 2 O 3 . 3. Rare Earth-Barite-Fluorite ore containing 1 to 5 percent of RE 2 O 3 . 4. Rare Earth bearing Fluorite ore containing 1 to 5 percent of RE 2 O 3 . According to the benefication test, the ores in Don Pao can be enriched to a concentrate of 60 percent of RE 2 O 3 with a recover of 75 percent

  3. MICROBIALLY MEDIATED LEACHING OF RARE EARTH ELEMENTS FROM RECYCLABLE MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Reed, D. W.; Fujita, Y.; Daubaras, D. L.; Bruhn, D. F.; Reiss, J. H.; Thompson, V. S.; Jiao, Y.

    2016-09-01

    Bioleaching offers a potential approach for recovery of rare earth elements (REE) from recyclable materials, such as fluorescent lamp phosphors or degraded industrial catalysts. Microorganisms were enriched from REE-containing ores and recyclable materials with the goal of identifying strains capable of extracting REE from solid materials. Over 100 heterotrophic microorganisms were isolated and screened for their ability to produce organic acids capable of leaching REE. The ten most promising isolates were most closely related to Pseudomonas, Acinetobacter and Talaromyces. Of the acids produced, gluconic acid appeared to be the most effective at leaching REE (yttrium, lanthanum, cerium, europium, and terbium) from retorted phosphor powders (RPP), fluidized cracking catalyst (FCC), and europium-doped yttrium oxide (YOEu). We found that an Acinetobacter isolates, BH1, was the most capable strain and able to leach 33% of the total REE content from the FCC material. These results support the continuing evaluation of gluconic acid-producing microbes for large-scale REE recovery from recyclable materials.

  4. Correlations in rare-earth transition-metal permanent magnets

    International Nuclear Information System (INIS)

    Skomski, R.; Manchanda, P.; Kashyap, A.

    2015-01-01

    It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition-metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo 5 . On an independent-electron level, the use of a single Slater determinant with broken spin symmetry introduces Hund's rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDA + U approximations to DFT. By contrast, rare-earth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. Analyzing DFT as a Legendre transformation and using Bethe's crystal-field theory, we show that the corresponding density functionals are very different from familiar LSDA-type expressions and outline the effect of spin-charge separation on the magnetocrystalline anisotropy

  5. Correlations in rare-earth transition-metal permanent magnets

    Science.gov (United States)

    Skomski, R.; Manchanda, P.; Kashyap, A.

    2015-05-01

    It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition-metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo5. On an independent-electron level, the use of a single Slater determinant with broken spin symmetry introduces Hund's rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDA + U approximations to DFT. By contrast, rare-earth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. Analyzing DFT as a Legendre transformation and using Bethe's crystal-field theory, we show that the corresponding density functionals are very different from familiar LSDA-type expressions and outline the effect of spin-charge separation on the magnetocrystalline anisotropy.

  6. Determination of rare-earth elements content in granitic rocks by argon plasma emission spectrometry

    International Nuclear Information System (INIS)

    Merodio, J.C.; Martinez, J.M.

    1990-01-01

    A method has been developed that enables the rare-earth elements in granitic rocks to be measured sequentially, using an inductively coupled plasma (ICP) source spectrometer with medium spectral resolution (0,02nm). The rocks were dissolved in an open system with a mixture of nitric-hydrofluoric-perchloric acids. Any residues remaining at this stage were removed by filtration and digested using a mini-fusion method with lithium tetraborate. Prior to the excitation in the spectrometer the rare-earth group was separated from other constituents using cation-exchange chromatography. A detailed study of spectral interferences and the evaluation of the detection limits have been performed. Five geochemical reference sample (granitic rocks) were analyzed and the obtained results agree favourably with recommended values and with reported determinations, using high spectral resolution ICP spectrometry. (Author) [es

  7. Complex formation constant and hydration number change of aqua-rare earth ions

    International Nuclear Information System (INIS)

    Kanno, H.

    1998-01-01

    Full text: It is now well established that the inner-sphere hydration number of aqua-rare earth ions changes from nine to eight in the middle of the rare earth series. This hydration number change greatly affects the complex formation of rare earth ions as we observe irregular variations in most series behaviours of the complex formation constant (K) in aqueous solution systems when K being plotted against 1/r or r (r is ionic radius of rare earth ion). Furthermore, it shows very anomalous concentration dependence in the sense that nona-aqua Ln 3+ ion increases in number with increase in salt concentration in aqueous rare earth salt solution (salt chloride, perchlorate). In this report, a theoretical derivation of the formation constant (K) for the inner-sphere complex formation of rare earth ions with a monodentate ligand was made by taking account of both the hydration number change in the middle of the series and its anomalous salt concentration dependence. The series behaviour of the formation constant against 1/r (or r) is successfully explained with using the empirical finding that K varies almost linearly with 1/r (or r) in the region where only one hydration number dominates. This success is also taken as evidence that the anomalous salt concentration dependence of the hydration number change is caused by the outer-sphere complex formation of rare earth ions with the condition that nona-aqua rare earth ions form outer-sphere complexes more easily than octa-aqua ions

  8. Proceedings of the international conference on science, technology and applications of rare earths

    International Nuclear Information System (INIS)

    2015-01-01

    Rare Earth Elements (REEs) are extensively used in clean energy applications like wind turbines, hybrid car batteries/electric motors, solar energy collectors, permanent magnets, phosphors, multifunctional pigments, thin film technologies, defence - related systems, etc. The use of rare earth elements in modern technology has increased several folds over the past few years in both domestic and international sectors due to the growing economy. The current global demand for rare earths is expected to provide a myriad of business opportunities for rare earth industries across the world including India for the utilization of rare earths in green energy, technology and industry. Papers relevant to INIS are indexed separately

  9. Geochemistry of rare earth elements in a passive treatment system built for acid mine drainage remediation.

    Science.gov (United States)

    Prudêncio, Maria Isabel; Valente, Teresa; Marques, Rosa; Sequeira Braga, Maria Amália; Pamplona, Jorge

    2015-11-01

    Rare earth elements (REE) were used to assess attenuation processes in a passive system for acid mine drainage treatment (Jales, Portugal). Hydrochemical parameters and REE contents in water, soils and sediments were obtained along the treatment system, after summer and winter. A decrease of REE contents in the water resulting from the interaction with limestone after summer occurs; in the wetlands REE are significantly released by the soil particles to the water. After winter, a higher water dynamics favors the AMD treatment effectiveness and performance since REE contents decrease along the system; La and Ce are preferentially sequestered by ochre sludge but released to the water in the wetlands, influencing the REE pattern of the creek water. Thus, REE fractionation occurs in the passive treatment systems and can be used as tracer to follow up and understand the geochemical processes that promote the remediation of AMD. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Advances in chromatography of the rare earth elements (review)

    International Nuclear Information System (INIS)

    Oguma, Koichi; Kuroda, Rokuro; Shimizu, Tsuneo.

    1995-01-01

    A review is presented which covers liquid chromatography, gas chromatography, and related techniques. This article intends to describe the chromatographic methods playing an important role in the separation of the rare earth elements. Special attention is paid to the usefulness of various types of liquid chromatography which enable the complete mutual separation of the rare earth elements. Applications are also discussed. (author) 161 refs

  11. Yttrium and rare earths separation by ion exchange resin

    International Nuclear Information System (INIS)

    Pinatti, D.G.; Ayres, M.J.G.; Ribeiro, S.; Silva, G.L.J.P.; Silva, M.L.C.P.; Martins, A.H.

    1988-01-01

    The experimental results of yttrium and rare earths separation from Brazilian xenotime are presented. The research consist in five stage: 1) Preparation of yttrium, erbium and lutetium standard solutions, from solubilization of pure oxides 2) yttrium and rare earths separation by ion exchange chromatrography 3) Separation and recovery of EDTA 4) Precipitation and calcination and 4) Analytical control of process. (C.G.C.) [pt

  12. Crystal field symmetry and magnetic interactions in rare earth-silver amorphous alloys

    International Nuclear Information System (INIS)

    Pappa, Catherine.

    1979-01-01

    A study has been made of the following rare earth based amorphous alloys: Ndsub(x)Agsub(100-x), Prsub(x)Agsub(100-x), Gdsub(x)Agsub(100-x), Tlsub(x)Agsub(100-x). In rare earth based amorphous alloys, the symmetrical distribution of the crystal field is very wide and hence not very sensitive to the content of the alloys. The existence of preponderant negative magnetic interactions leads to an upset magnetic order, the magnetization of a small volume not being nil. The magnetic behaviour of alloys with a small concentration of rare earths is governed by the existence of clusters of statistical origin, within which a rare earth ion has at least one other rare earth ion in the position of first neighbour. The presence of a high anisotropy at low temperatures make the magnetic interactions between clusters inoperative [fr

  13. Rare Earth Elements - A New Challenge for the World Economy

    Directory of Open Access Journals (Sweden)

    Cristina Bumbac

    2013-01-01

    Full Text Available Rare Earth Elements or Rare Earth Metals (REM are a collection of seventeen chemical elements in the periodic table, namely scandium, yttrium and fifteen lanthanides. The term "rare earth" arises from the rare earth minerals from which they were first isolated. They are uncommon oxide-type minerals (earths found in Gandolinite extracted from one mine in Sweden. The first discovery was made in 1794, but it was only in 1940 that the scientist Frank Spedding developed an ion exchange procedure for separating and purifying the REM. For the next decades, they were hardly used in some "minor" industrial fields. Only after 2000 their importance grew, once the multitude of possibilities to use them was discovered due to technological progress. Now REM are incorporated into almost all modern technological devices: superconductors, magnets, electronic polishers, refining catalysts hybrid car components and military techniques. They are used in small quantities, but due to their extraordinary properties the prices are very high. The main problem is that China dominates this market, with 97% of total global supply. The highest concentration of rare earth metals are in Inner Mongolia in China, Mountain Pass in California U.S.A. and in Mount Weld in Australia. The developed countries are far behind China regarding production and are indeed depending on Chinese exports. Hence, there is a difficult situation on this particular market, with an uncertain future.

  14. International strategic minerals inventory summary report; rare-earth oxides

    Science.gov (United States)

    Jackson, W.D.; Christiansen, Grey

    1993-01-01

    Bastnaesite, monazite, and xenotime are currently the most important rare-earth minerals. Bastnaesite occurs as a primary mineral in carbonatites. Monazite and xenotime also can be found in primary deposits but are recovered principally from heavy-mineral placers that are mined for titanium or tin. Each of these minerals has a different composition of the 15 rare-earth elements. World resources of economically exploitable rare-earth oxides (REO) are estimated at 93.4 million metric tons in place, composed of 93 percent in primary deposits and 7 percent in placers. The average mineral composition is 83 percent bastnaesite, 13 percent monazite, and 4 percent of 10 other minerals. Annual global production is about 67,000 metric tons of which 41 percent is from placers and 59 percent is from primary deposits; mining methods consist of open pits (94 percent) and dredging (6 percent). This output could be doubled if the operations that do not currently recover rare earths would do so. Resources are more than sufficient to meet the demand for the predictable future. About 52 percent of the world's REO resources are located in China. Ranking of other countries is as follows: Namibia (22 percent), the United States (15 percent), Australia (6 percent), and India (3 percent); the remainder is in several other countries. Conversely, 38 percent of the production is in China, 33 percent in the United States, 12 percent in Australia, and 5 percent each in Malaysia and India. Several other countries, including Brazil, Canada, South Africa, Sri Lanka, and Thailand, make up the remainder. Markets for rare earths are mainly in the metallurgical, magnet, ceramic, electronic, chemical, and optical industries. Rare earths improve the physical and rolling properties of iron and steel and add corrosion resistance and strength to structural members at high temperatures. Samarium and neodymium are used in lightweight, powerful magnets for electric motors. Cerium and yttrium increase the

  15. Microstructure-property relationships of rare-earth--zinc-oxide varistors

    International Nuclear Information System (INIS)

    Williams, P.; Krivanek, O.L.; Thomas, G.; Yodogawa, M.

    1980-01-01

    The microstructure and properties of ZnO varistors containing Ba, Co, and rare-earth--metal oxides, which give values of α [α=d(log I)/d(log V)] as high as 29, are examined. Mean ZnO grain size is 11 μm, and the grains are uniformly doped with Co. The barium and rare earth metals concentrate into 1.5-μm-wide particles embedded in a matrix of ZnO grains. Within the grains and at grain boundaries, the barium and rare-earth--metal concentration is below the detection limit of the energy-dispersive spectrometer technique (about 0.5%). No intergranular films, amorphous or crystalline, are detected, to within 10 A resolution. These results are shown to be consistent with the grain boundary charge depletion model for the voltage barrier formation and breakdown

  16. Fascinating world of rare earth research

    International Nuclear Information System (INIS)

    Gschneidner, K.A. Jr.

    1977-01-01

    The first part of this paper concerns some of the notable events which occurred early in the author's career as a rare earther and some of the major events which took place in the two decades 1950 to 1970. The notable changes and advances in the rare earth research world since the 1971 Durham Conference are described in the second and largest part of the paper. The final portion is concerned with actinide developments since 1971

  17. Determination of rare earth impurities in thorium by spectrographic methods

    Energy Technology Data Exchange (ETDEWEB)

    Wray, L W

    1957-08-15

    A method for determining rare earth impurities in thorium in the fractional ppm range is described. Before spectrographic examination is possible, the impurities must be freed from the thorium matrix. This is accomplished by removing the bulk of the thorium by extraction with TBP-CCl{sub 4} and the remainder by extraction with TTA-C{sub 6}H{sub 6}. This results in a consistent recovery of rare earths of about 85% with an average sensitivity of 0.2 ppm. The experimental error is within 10%. Details of the procedure are given together with working curves for the major neutron absorbing rare earths; i.e. dysprosium, europium, gadolinium and samarium. (author)

  18. A study on artificial rare earth (RE2O3) based neutron absorber

    International Nuclear Information System (INIS)

    KIM, Kyung-O; Kyung KIM, Jong

    2015-01-01

    A new concept of a neutron absorption material (i.e., an artificial rare earth compound) was introduced for criticality control in a spent fuel storage system. In particular, spent nuclear fuels were considered as a potential source of rare earth elements because the nuclear fission of uranium produces a full range of nuclides. It was also found that an artificial rare earth compound (RE 2 O 3 ) as a High-Level Waste (HLW) was naturally extracted from pyroprocessing technology developed for recovering uranium and transuranic elements (TRU) from spent fuels. In this study, various characteristics (e.g., activity, neutron absorption cross-section) were analyzed for validating the application possibility of this waste compound as a neutron absorption material. As a result, the artificial rare earth compound had a higher neutron absorption probability in the entire energy range, and it can be used for maintaining sub-criticality for more than 40 years on the basis of the neutron absorption capability of Boral™. Therefore, this approach is expected to vastly improve the efficiency of radioactive waste management by simultaneously keeping HLW and spent nuclear fuel in a restricted space. - Highlights: • Quantitative analysis of rare earth elements in PWR spent fuels. • Extraction of artificial rare earth compound using pyroprocessing technology. • Characteristic analysis of artificial rare earth elements. • Performance evaluation of artificial rare earth for criticality control.

  19. X-ray dichroism of rare earth materials

    International Nuclear Information System (INIS)

    Goedkoop, J.B.

    1989-01-01

    The theme of this thesis is the investigation of the strong polarization dependende, or dichroism, that occur in the X-ray absorption spectra of rare earth materials. The rare earth elements distinguish themselves from the other elements through the behaviour of the 4f electrons which form the valence shell. This shell lies deep inside the atom, with the result that influences from the surrounding solid are well screened off by the outer electrons, so that even in the solid the 4f shell behaves very much like a in free atom or ion, and is almost completely spherically symmetric. Perturbations from the solid environment however always disturb this symmetry to some extend, with the result that the absorption spectrum becomes dependent on the mutual orientation of the polarization vector of the radiation and the ion. Earlier the existence of a strong magnetic X-ray dichroism (MXD) in the 3d→4f transitions of rare earths. In this thesis this work is extended, to a small degree theoretically but mainly experimentally. MXD is used in experiments on bulk sample, terbium iron garnet, and on rare earth overlayers on a ferromagnetic surface, Ni(110). The results of the latter study show unequivocally the potential of the MXD technique. The second theme of the thesis concerns experimental developments in soft X-ray spectroscopy. A description is given of a double crystal monochromator beamline that was constructed by our group at LURE, France. Results of the use of an organic crystal - multilayer comination in such a monochromator is described. Also a method is described for the characterization of the resolution of soft X-ray monochromators. Finally a contribution to the characterization of the electron yield technique in the soft X-ray range is given. (author). 296 refs.; 64 figs.; 59 schemes; 9 tabs

  20. Contribution for the studies of rare earth dithionates

    International Nuclear Information System (INIS)

    Schmitz, L.C.

    1988-01-01

    The main objective of this work is the synthesis and investigation of some properties of rare earth dithionates. The rare earth dithionates were prepared from the respective sulphates, by the reaction of the latter with BaS sub(2) O sub(6) in aqueous solutions. The lanthanide ion content was estimated by complexometric titration with EDTA; analysis for H were carried out by microanalysis and the water content was determinated by Karl Fischer titration. This experimental results in addition to thermogravimetric (TG) data gave the stoichiometry of the compounds. (author)

  1. Activation analysis of rare-earth elements in opium and cannabis samples

    International Nuclear Information System (INIS)

    Henke, G.

    1977-01-01

    Rare-earth concentrations in 65 Opium, Cannabis and Cannabis resin samples seized from various parts of the world were determined by destructive NAA. Because of the greater concentrations of Ca, P, K, Fe, Na and Si in plant materials, rare-earth elements were isolated after neutron irradiation and determined by gamma-spectrometry. The main steps of the method are: Preashing of 1 g Cannabis resin, 2.5 g Cannabis or 7.5 g Opium, respectively, in quartz ampoules (5 h, 500 deg C). Neutron irradiation, 24 h at 5x10 13 n cm -2 sec -1 . Cooling period 2-3 days. After addition of 0.1 μCi 139 Ce and rare-earth carriers wet ashing of irradiated samples with H 2 SO 4 /HNO 3 , followed by alternate addition of HNO 3 and H 2 O 2 (30%). Precipitation and removal of silicates, precipitation of fluorides, precipitation of hydroxides. Dissolution of hydroxides in HCl. Extraction with di-(2-ethylhexyl)phosphate (DEHP)/toluene and twice back-extraction of rare earths, gamma-spectrometry of HCl phase. Due to sample activity and half-life of nuclides, three measurements were made on each sample: 2 days (for La, Sm, Gd, Ho, Er, Yb); 14 days (for Nd, Lu) and 30 days after irradiation (for Ce, Eu, Tb). Great variations in absolute element concentrations, but only small significant differences of rare earth concentration ratios were found, indicating inconsiderable biogeochemical fractionation. The mean values of these ratios correspond to the relative abundances of the rare earths in the upper continental earth's crust. (T.G.)

  2. Lifetime measurements of the rare earths

    International Nuclear Information System (INIS)

    Stahnke, H.J.

    1981-01-01

    The lifetime of excited energy levels of Praseodymium, Neodymium, Gadolinium, Holmium and Erbium are measured. The measurements were done on atomic beams excited by laser radiation. The experimental results allow an interpretation of the electronic structure of the rare earths. (BEF)

  3. Determination of individual rare earth elements in Vietnamese monazite by radiochemical neutron activation analysis

    International Nuclear Information System (INIS)

    Nguyen Van Suc; Nguyen Mong Sinh

    1993-01-01

    Radiochemical neutron activation analysis (RNAA) has been applied for determination of rare earth elements (REE) in Vietnamese monazite. The chemical separation procedure used is based on the chromatographic elution of rare earth groups, after the separation of 233 Pa(Th) in irradiated monazite samples by coprecipitation with MnO 2 , the rare earth elements were retained by Biorad AG1 x 8 resin column in 10% 15.4M HNO 3 -90% methanol solution. The elution of heavy rare earth (HREE) and middle rare earth (MREE) groups was carried out with 10% 1M HNO 3 - 90% methanol and 10% 0.05M HNO 3 -90% methanol solution, respectively; while the light rare earths (LREE) were eluted from the column by 0.1M HNO 3 solution. The accuracy of the method was checked by the analysis of granodiorite GSP-I and the rare earth values were in good agreement. (author) 7 refs.; 3 tabs

  4. Determination Of Rare Earth And Other Elements In YEN-PHU Rare Earth Ore And Other Intermediate Products From The Floatation And Hydrometallurgical Process On Portable XRF Si-PIN Detector

    International Nuclear Information System (INIS)

    Doan Thanh Son; Phung Vu Phong; Nguyen Hanh Phuc

    2014-01-01

    The concentration of rare earths elements such as La, Ce, Pr, Nd, Gd and other elements as Ca, Fe, U, Th in Yen Phu rare earth ore and other intermediate products from the flotation and hydrometallurgical process was determined by using Si-PIN detector fluorescence spectrometry. The precision and accuracy of quantitative analysis was tested by standard reference materials and comparative analysis with different analytical methods. The analytical procedures were set-up and applied for the determination of rare earth and other elements in Yen Phu rare earth ore and other intermediate products from the flotation and hydrometallurgical process with high precision and accuracy. (author)

  5. Addressing Rare-Earth Element Criticality: An Example from the Aviation Industry

    Science.gov (United States)

    Ku, Anthony Y.; Dosch, Christopher; Grossman, Theodore R.; Herzog, Joseph L.; Maricocchi, Antonio F.; Polli, Drew; Lipkin, Don M.

    2014-11-01

    Rare-earth (RE) elements are enablers for a wide range of technologies, including high-strength permanent magnets, energy-efficient lighting, high-temperature thermal barrier coatings, and catalysts. While direct material substitution is difficult in many of these applications because of the specific electronic, optical, or electrochemical properties imparted by the individual rare-earth elements, we describe an example from the aviation industry where supply chain optimization may be an option. Ceramic matrix composite engine components require environmental barrier coatings (EBCs) to protect them from extreme temperatures and adverse reactions with water vapor in the hot gas path. EBC systems based on rare-earth silicates offer a unique combination of environmental resistance, thermal expansion matching, thermal conductivity, and thermal stability across the service temperature window. Several pure rare-earth silicates and solid solutions have been demonstrated in EBC applications. However, all rely on heavy rare-earth elements (HREEs) for phase stability. This article considers the possibility of using separation tailings containing a mixture of HREEs as a source material in lieu of using the high-purity HREE oxides. This option arises because the desired properties of RE-silicate EBCs derive from the average cation size rather than the electronic properties of the individual rare-earth cations. Because separation tailings have not incurred the costs associated with the final stages of separation, they offer an economical alternative to high-purity oxides for this emerging application.

  6. Rare earth element and rare metal inventory of central Asia

    Science.gov (United States)

    Mihalasky, Mark J.; Tucker, Robert D.; Renaud, Karine; Verstraeten, Ingrid M.

    2018-03-06

    Rare earth elements (REE), with their unique physical and chemical properties, are an essential part of modern living. REE have enabled development and manufacture of high-performance materials, processes, and electronic technologies commonly used today in computing and communications, clean energy and transportation, medical treatment and health care, glass and ceramics, aerospace and defense, and metallurgy and chemical refining. Central Asia is an emerging REE and rare metals (RM) producing region. A newly compiled inventory of REE-RM-bearing mineral occurrences and delineation of areas-of-interest indicate this region may have considerable undiscovered resources.

  7. An introduction to the economics of rare earths

    NARCIS (Netherlands)

    Bartekova, E.

    2014-01-01

    The aim of this paper is to examine the supply risk of rare earths and its impact on low carbon technologies deployment. Bringing together seemingly disconnected strands of scientific literature, this multidisciplinary approach allows to provide an overarching overview of the economics of rare

  8. High purity samarium oxide from mixed rare earth carbonates

    International Nuclear Information System (INIS)

    Queiroz, Carlos A. da S.; Seneda, Jose A.; Vasconcellos, Mari E. de; Pedreira Filho, Walter dos R.

    2013-01-01

    A simple and economical chemical process for the production of highly pure samarium oxides is discussed. The raw material, which was used in the form of rare earth carbonates was produced industrially from the chemical treatment of Brazilian monazite. Ion exchange chromatography was performed using a strong cationic resin that is typically employed in water treatment processes to fractionate rare earth elements (REE) without the use of retention ions. Under these conditions, 99.9% pure Sm 2 O 3 was eluted using the ammonium salt of ethylenediaminetetraacetic acid (EDTA) at a controlled pH. The EDTA-samarium complex was separated from EDTA and then precipitated as oxalate and fired to samarium oxide. Molecular absorption spectrophotometry was used to monitor the samarium content during the proposed process, and sector field inductively coupled plasma mass spectrometry was used to certify the purity of the samarium oxide. Typical samarium oxide obtained from the proposed procedure contained the following contaminants in micrograms per gram: Sc (20.90); Y (11.80); La (8.4); Ce (4.3); Pr (2.5); Nd (5.1); Eu (94); Gd (114); Tb (3.6); Dy (2.5), Ho (2.3); Er (3.0); Tm (2.3); Yb (38,2); Lu (25.6). The high-purity samarium oxides produced in the present study can be used as an alternative to imported products in research and development applications. (author)

  9. Extraction and separation of Am and rare earth elements in HNO3 solution with P507-sulphonating kerosene

    International Nuclear Information System (INIS)

    Li Zhenhu; Jiao Rongzhou; Zhu Yongjun

    1994-01-01

    A study has been made of the extraction equilibrium of Am(III) and rare earth elements (III) in HNO 3 solution with P507-sulphonating kerosene. It has been found that this equilibrium depends on saponification ratio of P507, feed acidity, metal concentration as well as phase ratio. The extraction ability in order is La< Ce< Am< Pr< Nd< Sm. The model of distribution ratio has been founded. The agreement for calculated and experimental values of distribution ratio is fairly good. These values can be used to design the extraction and separation process of Am and rare earth elements

  10. Rare earths from uranium mineralization occurrences in the Permian of the Gemericum, the Western Carpathians

    International Nuclear Information System (INIS)

    Rojkovic, I.; Medved, J.; Walzel, E.; Posta, S.; Sulovsky, P.

    1989-01-01

    Uranium mineralization in the Permian of the Gemericium is accompanied by apatite, monazite and xenotime. The study of rare earth elements distribution is based on the results of instrumental neutron activation analysis and optical emission spectroscopy analysis of rocks and energy-dispersive X-ray microanalyses of minerals. The main light rare earth elements bearing mineral is monazite; for heavy rare earth elements it is xenotime. The rocks accompanying uranium mineralization have increased rare earth elements contents. The mobilization and concentration of uranium mineralization took place during the Alpine metallogenic processes. These processes were also associated with rare earth elements mobilization is which total and selective enrichment in light rare earth elements and heavy rare earth elements was observed. (author). 12 figs., 6 tabs., 5 refs

  11. Magnetic Partitioning Nanofluid for Rare Earth Extraction from Geothermal Fluids

    Energy Technology Data Exchange (ETDEWEB)

    McGrail, Bernard P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Thallapally, Praveen K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Liu, Jian [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nune, Satish K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-08-21

    Rare earth metals are critical materials in a wide variety of applications in generating and storing renewable energy and in designing more energy efficient devices. Extracting rare earth metals from geothermal brines is a very challenging problem due to the low concentrations of these elements and engineering challenges with traditional chemical separations methods involving packed sorbent beds or membranes that would impede large volumetric flow rates of geothermal fluids transitioning through the plant. We are demonstrating a simple and highly cost-effective nanofluid-based method for extracting rare earth metals from geothermal brines. Core-shell composite nanoparticles are produced that contain a magnetic iron oxide core surrounded by a shell made of silica or metal-organic framework (MOF) sorbent functionalized with chelating ligands selective for the rare earth elements. By introducing the nanoparticles at low concentration (≈0.05 wt%) into the geothermal brine after it passes through the plant heat exchanger, the brine is exposed to a very high concentration of chelating sites on the nanoparticles without need to pass through a large and costly traditional packed bed or membrane system where pressure drop and parasitic pumping power losses are significant issues. Instead, after a short residence time flowing with the brine, the particles are effectively separated out with an electromagnet and standard extraction methods are then applied to strip the rare earth metals from the nanoparticles, which are then recycled back to the geothermal plant. Recovery efficiency for the rare earths at ppm level has now been measured for both silica and MOF sorbents functionalized with a variety of chelating ligands. A detailed preliminary techno-economic performance analysis of extraction systems using both sorbents showed potential to generate a promising internal rate of return (IRR) up to 20%.

  12. Cation exchange separation of 16 rare earth metals by microscale high-performance liquid chromatography

    International Nuclear Information System (INIS)

    Ishii, D.; Hirose, A.; Iwasaki, Y.

    1978-01-01

    The separation of rare earth metals has been studied with a microcolumn of 0.5 mm i.d. and 75 mm length, packed with TSK LS-212 high-performance cation exchange resin. A micro-feeder (Model MF-2, from Azumadenki Kogyo) was used to drive carrier and sample solutions through the ion exchange column and detection cell. By combining a 250 μl syringe and a 0.5 mm i.d. sampling tube the micro-feeder, 0.1-1.0 μl rare earth metals were separated within 38 min, using only 304 μl of 0.4M α-hydroxy-isobutyric acid solution adjusted to pH 3.1-6.0 with ammonia solution as gradient carrier solution. The gradient elution was successfully performed by applying a new technique developed for microscale liquid chromatography. (author)

  13. Ultrasonic attenuation in rare-earth monoarsenides

    Indian Academy of Sciences (India)

    2015-11-27

    Home; Journals; Pramana – Journal of Physics; Volume 86; Issue 6. Ultrasonic attenuation in rare-earth monoarsenides .... Proceedings of the International Workshop/Conference on Computational Condensed Matter Physics and Materials Science (IWCCMP-2015). Posted on November 27, 2015. Guest Editors: Anurag ...

  14. Heavy mineral survey for rare earths in the Northern part of Palawan

    International Nuclear Information System (INIS)

    Reyes, R.Y.; Santos, G.P.; Magsambol, W.N.; Ramos, A.F.; Petrache, C.A.; Tabora, E.U.

    1992-01-01

    A reconnaissance geochemical survey for rare earths was carried out over the northern half of Palawan with considerable success. The survey represents the first systematic geochemical exploration effort to look for indigenous rare earth resources in the Philippines. Total area covered was about 5,000 sq km. The survey entailed the systematic collection of 740 heavy mineral panned concentrate and stream sediment samples along streams and rivers. The average sampling density was about one set of sample per 2-15 sq km. A total of 218 heavy mineral samples were analyzed for lathanum, cerium, praseodymium, neodymium and yttrium. Analysis of stream sediments for rare earths was discontinued due to the high detection limit of the X-ray fluorescence spectrometer. Results of the survey clearly indicated the effectiveness of heavy mineral sampling for rare earths at the reconnaissance level of exploration. Six anomalous and well-defined areas of interest were delineated for possible rare earth mineralization. Three priority zones were further outlined from the six prospective areas for possible follow-up surveys. Mineralogical examination of heavy minerals revealed the presence of major allanite and minor monazite as the potential hosts of rare earths in the priority zone number one. Gray monazite was identified in the priority zone number two as the rare earth mineral. Minute specks and grains of gold were visibly present in some of the heavy mineral samples taken in this area. A combined mineralization of rare earths and gold in this area is a possibility. The discovery of the first gray nodular monazite in Palawan may extend the age of the oldest rocks in the Philippines to Lower Paleozoic. A separate study to establish the age of the oldest rocks in the country is likewise necessary. (auth.). 27 refs.; 6 figs.; 8 tabs

  15. Novel precursors for the deposition of rare earth oxides

    International Nuclear Information System (INIS)

    Ahlers, Mareike

    2010-01-01

    During this work rare earth solvates with nitrate and perchlorate anions have been investigated. All compounds have been structurally characterized and analyzed using thermal gravimetric analysis. The decomposition residues were analyzed using powder diffraction methods. Almost all compounds showed a characteristically intense exothermic decomposition step during the thermal decomposition, most likely caused by an intramolecular redox reaction between the nitrate or perchlorate anion respectively and the organic solvent molecules. The nitrates RE(NO 3 ) 3 (CH(OCH 3 ) 3 ) 2 (RE = Sm, Eu) were isolated and characterized for the first time as the intermediate of the dehydration reaction with trimethyl orthoformate. The known compound group of dimethoxyethane solvates was then expanded with RE(NO 3 ) 3 (O 2 C 4 H 10 ) (RE = La, Sm, Eu). Considering the possible use as precursor material the already described neodymium compound is also discussed. The thermal decomposition of these compounds yields the respective cubic rare earth oxide and shows the typical intense exothermic decomposition reaction. A variety of different precursor system based on nitrate solvates for the deposition of rare earth oxide layers on a silicon surface was developed and investigated in collaboration with the group of Prof. Dr. Al-Shamery (Univ. Oldenburg). Ultra thin films on a H-Si(111) surface were obtained via the deposition of the precursor, which was dissolved in organic solvents. An oxide layer was detected after the heating of the sample. The film thickness was measured as < 10 nm, whereas the thickness of the film was controlled by the concentration of the precursor solution. Sm(ClO 4 ) 3 (CH(OCH 3 ) 3 ) 3 was isolated and characterized for the first time as the intermediate of the dehydration reaction with trimethyl orthoformate. Eu(ClO 4 ) 3 (CH(OCH 3 ) 3 ) 2 (MeOH) 2 was obtained without recrystallization. The methanol molecules, formed during the hydrolysis of the trimethyl

  16. Synthesis and characterization of rare-earth-doped calcium tungstate nanocrystals

    Science.gov (United States)

    Suneeta, P.; Rajesh, Ch.; Ramana, M. V.

    2018-02-01

    In this paper, we report synthesis and characterization of rare-earth-ion-doped calcium tungstate (CaWO4) nanocrystals (NCs). Rare-earth ions, such as gadolinium (Gd), neodymium (Nd), praseodymium (Pr), samarium (Sm) and holmium (Ho), were successfully doped in the CaWO4 NCs by changing the synthesis conditions. The adopted synthesis route was found to be fast and eco-friendly. Structural characterizations, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and compositional analysis, were performed using energy dispersive analysis of X-rays (EDAX) on as-synthesized NCs. The results indicate the size of the NCs ranging between 47 to 68nm and incorporation of rare-earth ions in CaWO4 NCs.

  17. Determination of the heavy rare earth radionuclides in melted rock

    International Nuclear Information System (INIS)

    Li Yinming; Wang Yalong; Zhang Quanshi

    1995-01-01

    There are some heavy rare earth radionuclides in the melted rocks, such as 160 Tb, 168,170 Tm, 88,91 Y, 174,177 Lu, 169 Yb, etc.. Because their contents are very low in the melted rocks and the light rare earth fission products are interfered with their determination, it is very complicated to measure them quantitatively. So a new method has been studied in which P507 resin is used to separate and purify the rare earths. Radioactive sources are prepared by the pieces of filter paper for determining chemical yield with X-fluorescence analysis, and radioactive activity is determined with the γ-spectra analysis. It is proved that this method has satisfied the demands of experiments

  18. Thermal shock behavior of rare earth modified alumina ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Junlong; Liu, Changxia [Ludong Univ., Yantai (China). School of Transportation

    2017-05-15

    Alumina matrix ceramic composites toughened by AlTiC master alloys, diopside and rare earths were fabricated by hot-pressing and their thermal shock behavior was investigated and compared with that of monolithic alumina. Results showed that the critical thermal shock temperature (ΔT) of monolithic alumina was 400 C. However, it decreased to 300 C for alumina incorporating only AlTiC master alloys, and increased with further addition of diopside and rare earths. Improvement of thermal shock resistance was obtained for alumina ceramic composites containing 9.5 wt.% AlTiC master alloys and 0.5 wt.% rare earth additions, which was mainly attributed to the formation of elongated grains in the composites.

  19. Life cycle inventory of the production of rare earths and the subsequent production of NdFeB rare earth permanent magnets.

    Science.gov (United States)

    Sprecher, Benjamin; Xiao, Yanping; Walton, Allan; Speight, John; Harris, Rex; Kleijn, Rene; Visser, Geert; Kramer, Gert Jan

    2014-04-01

    Neodymium is one of the more critical rare earth elements with respect to current availability and is most often used in high performance magnets. In this paper, we compare the virgin production route of these magnets with two hypothetical recycling processes in terms of environmental impact. The first recycling process looks at manual dismantling of computer hard disk drives (HDDs) combined with a novel hydrogen based recycling process. The second process assumes HDDs are shredded. Our life cycle assessment is based both on up to date literature and on our own experimental data. Because the production process of neodymium oxide is generic to all rare earths, we also report the life cycle inventory data for the production of rare earth oxides separately. We conclude that recycling of neodymium, especially via manual dismantling, is preferable to primary production, with some environmental indicators showing an order of magnitude improvement. The choice of recycling technology is also important with respect to resource recovery. While manual disassembly allows in principle for all magnetic material to be recovered, shredding leads to very low recovery rates (<10%).

  20. Purification process for aqueous solutions of rare earths by liquid-liquid extraction

    International Nuclear Information System (INIS)

    Rollat, A.; Sabot, J.L.; Burgard, M.; Delloye, T.

    1986-01-01

    Alkaline earth metals are removed by liquid-liquid extraction between on aqueous nitric phase of impure rare earth compounds and an organic phase of polyether (crown ether). This process is particularly suited to removal of Ca, Ba and Ra contained in nitric solutions of rare earths [fr

  1. The Influence of Lactic Acid Concentration on the Separation of Light Rare Earth Elements by Continuous Liquid-Liquid Extraction with 2-Ethylhexyl Phosphonic Acid Mono-2-ethylhexyl Ester

    Science.gov (United States)

    de Carvalho Gomes, Rafael; Seruff, Luciana Amaral; Scal, Maira Labanca Waineraich; Vera, Ysrael Marrero

    2018-02-01

    The separation of rare earth elements (REEs) using solvent extraction adding complexing agents appears to be an alternative to saponification of the extractant. We evaluated the effect of lactic acid concentration on didymium (praseodymium and neodymium) and lanthanum extraction with 2-ethylhexyl phosphonic acid mono-2-ethyl hexyl ester [HEH(EHP)] as extractant. First, we investigated in batch experiments the separation of lanthanum (La) and didymium (Pr and Nd) using McCabe-Thiele diagrams to estimate the number of extraction stages when the feed solution was or was not conditioned with lactic acid. Additionally, we conducted continuous liquid-liquid extraction experiments and evaluated the influence of lactic acid concentration on the REE extraction and separation. The tests showed that the extraction percentage of REEs and the separation factor Pr/La increased when the lactic acid concentration increased, but the didymium purity decreased. Lanthanum, praseodymium, and neodymium extraction rate were 23.0, 89.7, and 99.2 pct, respectively, with 1:1 aqueous/organic volume flow rate and feed solution doped with 0.52 mol L-1 lactic acid. The highest didymium purity reached was 92.0 pct with 0.26 mol L-1 lactic acid concentration.

  2. Interactions of rare earth elements with bacteria and organic ligands

    International Nuclear Information System (INIS)

    Ozaki, Takuo; Suzuki, Yoshinori; Nankawa, Takuya; Yoshida, Takahiro; Ohnuki, Toshihiko; Kimura, Takaumi; Francis, Arokiasamy J.

    2006-01-01

    We investigated the interactions of rare earth elements (REEs) Eu(III) and/or Ce(III, IV) with the common soil bacterium Pseudomonas fluorescens and organic ligands, such as malic acid, citric acid, a siderophore (DFO), cellulose, chitin, and chitosan. Malic acid formed complexes with Eu(III), but degradation of malic acid was observed when the ratio of malic acid to Eu(III) was higher than 100. Citric acid formed a stoichiometric complex with Eu(III) that was not degraded by P. fluorescens. Adsorption of Eu(III) from the DFO complex occurred as a free ion dissociated from DFO and not as the Eu(III)-DFO complex. Cerium(III) was oxidized to Ce(IV) during complexation with DFO to form the Ce(IV)-DFO complex. Time-resolved laser-induced fluorescence spectroscopy (TRLFS) analysis showed that cellulose, chitin, and chitosan, respectively, formed a weak complex, an inner-spherical complex, and an outer-spherical complex with Eu(III). This method also demonstrated that the coordination environment of Eu(III) adsorbed on P. fluorescens possessed similar characteristics to that of chitin, and revealed that adsorption of Eu(III) on P. fluorescens was through a multidentate and predominantly inner-spherical coordination

  3. Spectrofluorimetric determination of rare earth elements using solidmatrix

    International Nuclear Information System (INIS)

    Suh, I.S.; Chi, K.Y.

    1982-01-01

    In this experiment, rare earth elements are separated from uranium by using the alumina column, anion exchange resin column, and 20% TOA in xylene and fluorescence characteristics were found in the solid matrix to analyze these elements without preseparation from each other. It becomes clear that the YVO 4 matrix is more sensitive than the Y 2 O 3 matrix when the red filter is used to minimized the second order peak intensity. And micro quantity of the rare earth elements in the yellow cake are analyzed by the using of the YVO 4 soid matrix. (Author)

  4. Process to remove rare earth from IFR electrolyte

    International Nuclear Information System (INIS)

    Ackerman, J.P.; Johnson, T.R.

    1994-01-01

    The invention is a process for the removal of rare earths from molten chloride electrolyte salts used in the reprocessing of integrated fast reactor fuel (IFR). The process can be used either continuously during normal operation of the electrorefiner or as a batch process. The process consists of first separating the actinide values from the salt before purification by removal of the rare earths. After replacement of the actinides removed in the first step, the now-purified salt electrolyte has the same uranium and plutonium concentration and ratio as when the salt was removed from the electrorefiner. 1 fig

  5. Proceedings of the national conference on rare earth processing and utilization - 2014: abstracts

    International Nuclear Information System (INIS)

    Anitha, M.; Dasgupta, Kinshuk; Singh, D.K.

    2014-01-01

    The rare earth elements (REEs) are becoming increasingly important in the transition to a low-carbon, circular economy, considering their essential role in permanent magnets, lamp phosphors, rechargeable nickel metal hydride batteries and catalysts and other green applications. The increasing popularity of hybrid and electric cars, wind turbines and compact fluorescent lamps is causing an increase in the demand and price of REEs. The European Commission considers the REEs as the most critical raw materials group, with the highest supply risk. According to the medium-term criticality matrix of the U.S. Department of Energy (DOE), the five most critical REEs are neodymium (Nd), europium (Eu), terbium (Tb), dysprosium (Dy) and yttrium (Y). China is presently producing more than 90% of all rare earths, although they possess less than 40% of the proven reserves. Due to large and increasing domestic demands, China tightened its REE export quota from 2012 onwards. These export quotas caused serious problems for REE users outside of China. To tackle the REE supply challenge, several approaches have been proposed. Fortunately India is blessed with large resources of rare earths in the form of monazite found in the beach sands of Kerala, Tamil Nadu and Odisha. Indian Rare Earths Limited at Aluva near Kochi used to produce mainly mixed rare earths chloride and export to USA, UK, France, Japan, etc. During the 1990s and early 2000s this plant exported pure oxides of samarium, neodymium, etc. to developed countries. This national conference has expanded its canvas by including newer emerging areas in rare earths recycling, environmental issues, recent advances in rare earth material science, rare earth research and development initiatives around the world which provide a platform for the growth of rare earth Industry. Papers relevant to INIS are indexed separately

  6. Some aspects of ICP-AES analysis of high purity rare earths

    International Nuclear Information System (INIS)

    Murty, P.S.; Biswas, S.S.

    1991-01-01

    Inductively coupled plasma atomic emission spectrometry (ICP-AES) is a technique capable of giving high sensitivity in trace elemental analysis. While the technique possesses high sensitivity, it lacks high selectivity. Selectivity is important where substances emitting complex spectra are to be analysed for trace elements. Rare earths emit highly complex spectra in a plasma source and the determination of adjacent rare earths in a high purity rare earth matrix, with high sensitivity, is not possible due to the inadequate selectivity of ICP-AES. One approach that has yielded reasonably good spectral selectivity in the high purity rare earth analysis by ICP-AES is by employing a combination of wavelength modulation techniques and high resolution echelle grating. However, it was found that by using a high resolution monochromator senstitivities either comparable to or better than those reported by the wavelength modulation technique could be obtained. (author). 2 refs., 2 figs., 2 tabs

  7. Thermodynamic studies on the interaction between some amino acids with some rare earth metal ions in aqueous solutions

    International Nuclear Information System (INIS)

    Mohamed, AbdAllah A.; Bakr, Moustafa F.; Abd El-Fattah, Khaled A.

    2003-01-01

    The interactions between the amino acids (glycine and L-threonine) with some rare earth metal ions (Pr 3+ , Nd 3+ , Eu 3+ , Gd 3+ , Dy 3+ , Ho 3+ and Yb 3+ ) were studied at a wide range from ionic strengths (0.07-0.32 M KNO 3 ) and temperatures (25-45 deg. C) in aqueous solutions by using Bjerrum potentiometric method. The stoichiometric and thermodynamic stability constants were calculated as well as the standard thermodynamic parameters (ΔG deg., ΔH deg. and ΔS deg. ) for all possible reactions that occur. The degree of formation (n-bar) for all studied systems was determined and discussed. The thermodynamic parameters differences (ΔΔG deg., ΔΔH deg. and ΔΔS deg. ) were calculated and discussed to determine the factors which control these complexation processes from the thermodynamic point of view

  8. Determination of preferential rare earth adatom adsorption geometries on Si(001)

    International Nuclear Information System (INIS)

    Shinde, Aniketa; Cao Juexian; Ouyang Wenjie; Wu Ruqian; Ragan, Regina

    2009-01-01

    The adsorption patterns of rare earth atoms on Si(001) were investigated using scanning tunneling microscopy measurements and density functional calculations. Stable configurations were systematically determined via calculation of binding energies of various adatom coverage and adsorption geometry. Competition between inter-adatom hybridization and Coulomb repulsion is the mechanism contributing to binding energy minima associated with commonly observed rare earth adsorption geometries. Comparison of stable configurations with experimental scanning tunneling microscopy images demonstrated accuracy of the theoretical models. This paves a way for the understanding of self-assembly of rare earth disilicide nanowires on vicinal Si(001) substrates.

  9. Guided mode cutoff in rare-earth doped rod-type PCFs

    DEFF Research Database (Denmark)

    Poli, F.; Cucinotta, A.; Passaro, D.

    2008-01-01

    Guided mode properties of rare-earth doped photonic crystal fibers are investigated as a function of the core refractive index, showing the possibility to obtain cutoff at low normalized wavelength.......Guided mode properties of rare-earth doped photonic crystal fibers are investigated as a function of the core refractive index, showing the possibility to obtain cutoff at low normalized wavelength....

  10. Coated air-stable cobalt--rare earth alloy particles and method

    International Nuclear Information System (INIS)

    Smeggil, J.C.; Charles, R.J.

    1975-01-01

    A process is described for producing novel air-stable coated particles of a magnetic transition metal-rare earth alloys. An organometallic compound which decomposes at a temperature below 500 0 C is heated to produce a metal vapor which is contacted with particles of a transition metal-rare earth alloy to deposit a metal coating on the particles. (U.S.)

  11. Preparation, thermogravimetric study and infrared spectra of rare earth acetates

    International Nuclear Information System (INIS)

    Graehlert, X.; Starke, M.

    1992-01-01

    The anhydrous and the hydrated acetates of Ho, Er, Tm, Yb and Lu have been prepared. The compounds obtained have been investigated by thermogravimetric analysis and infrared spectroscopy. The thermal decomposition of the rare earth acetates may proceed via various steps. It depends on both the number of crystal water molecules in the acetates and the rare earth element's behaviour. (orig.)

  12. Electro-kinetic separation of rare earth elements using a redox-active ligand

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Huayi; Cole, Bren E.; Qiao, Yusen; Bogart, Justin A.; Cheisson, Thibault; Manor, Brian C.; Carroll, Patrick J.; Schelter, Eric J. [Department of Chemistry, University of Pennsylvania, Philadelphia, PA (United States)

    2017-10-16

    Purification of rare earth elements is challenging due to their chemical similarities. All of the deployed separation methods rely on thermodynamic properties, such as distribution equilibria in solvent extraction. Rare-earth-metal separations based on kinetic differences have not been examined. Herein, we demonstrate a new approach for rare-earth-element separations by exploiting differences in the oxidation rates within a series of rare earth compounds containing the redox-active ligand [{2-(tBuN(O))C_6H_4CH_2}{sub 3}N]{sup 3-}. Using this method, a single-step separation factor up to 261 was obtained for the separation of a 50:50 yttrium-lutetium mixture. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Uncovering the end uses of the rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Du, Xiaoyue, E-mail: xiaoyue.du@empa.ch [Swiss Federal Laboratories for Materials Science and Technology (EMPA), Lerchenfeldstrasse 5, 9014 St. Gallen (Switzerland); Yale University, 195 Prospect Street, New Haven CT 06511 (United States); Graedel, T.E. [Yale University, 195 Prospect Street, New Haven CT 06511 (United States)

    2013-09-01

    The rare earth elements (REE) are a group of fifteen elements with unique properties that make them indispensable for a wide variety of emerging and conventional established technologies. However, quantitative knowledge of REE remains sparse, despite the current heightened interest in future availability of the resources. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports render primary supply vulnerable to short term disruption. We have drawn upon the published literature and unpublished materials in different languages to derive the first quantitative annual domestic production by end use of individual rare earth elements from 1995 to 2007. The information is illustrated in Sankey diagrams for the years 1995 and 2007. Other years are available in the supporting information. Comparing 1995 and 2007, the production of the rare earth elements in China, Japan, and the US changed dramatically in quantities and structure. The information can provide a solid foundation for industries, academic institutions and governments to make decisions and develop strategies. - Highlights: • We have derived the first quantitative end use information of the rare earths (REE). • The results are for individual REE from 1995 to 2007. • The end uses of REE in China, Japan, and the US changed dramatically in quantities and structure. • This information can provide solid foundation for decision and strategy making.

  14. Thin-film method-XRF determination of the composition of rare earth oxides

    International Nuclear Information System (INIS)

    Xiao Deming

    1992-01-01

    The author describes the thin-film sample preparation by precipitation-pumping filtering method and the composition of rare earth oxide materials by XRF determination. The determination limits are 0.01% to 0.17%. The coefficients of variation are in the range of 0.85% to 14.9%. The analytical results of several kinds of rare earth oxide materials show that this method can be applied to the determination of the composition of rare earth oxide mixtures

  15. Preconcentration of rare earth elements from rocks by thin-layer chromatography and their neutron-activation determination

    International Nuclear Information System (INIS)

    Ryabukhin, V.A.; Volynets, M.P.; Myasoedov, B.F.

    1990-01-01

    Conditions were studied for separation of rare earths and accompanying elements in rocks on Fixion 50x8 thin-layer plates using solutions of oxalic acid and ammonium chloride in ammonia medium. A simple technique was developed for TLC proconcentration of rare earths followed by gamma spectrometric analysis of the irradiated fractions that enabled to determine 8-10 elements in samples with a mass of up to 30 mg. The limits of detection (μg/g) were 0.05 (Eu), 0.1 (Sm), 0.2 (Tb), 0.3 (Yb), 0.4 (La), 1.0 (Tu), 2.0 (Ce), 10 (Nd). The relative standard deviation was 0.05-0.20 at element levels 5-10 times as high as the detection limits

  16. Leaching of complex ores with radioactive impurities, e.g. monazite, followed by rare earth solvent extraction

    International Nuclear Information System (INIS)

    Ballhorn, R.; Brodt, P.

    1987-01-01

    Pre-crushing plays a decisive role in the chemical development of monazite, the orthophosphate of the rare earth elements. Various mineralogical investigation methods - mineral-optical investigations, diffractometric surveys, thermoluminescence investigations - were applied in accordance with various grinding methods, with the aim of studying the possible effect of physically produced grid flows on the effectiveness of leaching. To obtain 95% of the rare earth elements, individual parameters such as grinding intensity, HNO 3 concentration, acid-concentrate ratio, temperature, duration of leaching and foreign ion admixture were varied, and the whole process was optimized. The recently developed method is compared with older methods with regard to profitability, the extraction of marketable uranium and thorium, etc., with a low accumulation of radioactive residues. (RB) [de

  17. Development of reduction technology for oxide fuel. Behaviour of rare-earth in lithium reduction process

    International Nuclear Information System (INIS)

    Kato, Tetsuya; Usami, Tsuyoshi; Yuda, Ryoichi; Kurata, Masateru; Moriyama, Hirotake

    2000-01-01

    Solubility measurements of rare-earth oxides in molten LiCl-Li 2 O salt and reduction tests of UO 2 doped with rare-earth oxides were carried out to determine the behavior of rare-earths in lithium reduction process. The solubility of rare-earth oxides increases in the order of Gd 2 O concentration. In multi-element systems including 6 rare-earth oxides, the solubility of each element is smaller than that in the individual systems. In the reduction tests, more than 90% of UO 2 was reduced within 1 hour after starting reduction and about 7% of rare-earths eluded into the LiCl molten salt bath containing Li 2 O which is formed by the reduction of UO 2 . The rare-earth concentrations in the bath were evaluated using the solubility data, assuming that rare-earth oxides in multi-element systems form solid solution as the equilibrium solid phase and that the activity coefficients in the solid phase are independent of the compositions. The calculated concentrations are consistent with the experimental ones obtained in the reduction tests. (author)

  18. Spectrophotometric determination of rare earths in binary mixtures

    International Nuclear Information System (INIS)

    Krasnova, A.V.; Shvarev, V.S.

    1978-01-01

    The possibility was investigated of using the reaction with brompyrogallol red (BPR) (dibrompyrogallosulfophthalein) for analyzing binary mixtures of rare earth metals close in ordinal numbers (La-Y, La-Eu, La-Sm, La-Nd, Nd-Y, Nd-Eu). Heavy REM are masked by nitrile-acetic acid (NAA). The experimental design method was used to determine optimum conditions. The optimizing parameters were the optical density measured with respect to water and the amount of the component bound into the complex. It was found that optimum conditions for the analysis of investigated mixtures differ only in the amount of NAA necessary to mask the heavy element [NAA]/[Sm 3+ ]=4; [NAA]/[Eu 3+ ]=5; [NAA]/Nb 3+ ]=10; [NAA]/[Y 3+ ]=2.5. The optimum acidity and the amount of BPR are always the same: pH 6.5; [BPR]/[La 3+ ]=[BPR]/[Nd 3+ ]=4. The given method for analyzing binary mixtures of lanthanoids surpasses considerably in sensitivity the methods based on intrinsic absorption spectra, while retaining the same reproducibility

  19. Radiological Impacts and Regulation of Rare Earth Elements in Non-Nuclear Energy Production

    Directory of Open Access Journals (Sweden)

    Timothy Ault

    2015-03-01

    Full Text Available Energy industries account for a significant portion of total rare earth usage, both in the US and worldwide. Rare earth minerals are frequently collocated with naturally occurring radioactive material, imparting an occupational radiological dose during recovery. This paper explores the extent to which rare earths are used by various non-nuclear energy industries and estimates the radiological dose which can be attributed to these industries on absolute and normalized scales. It was determined that typical rare earth mining results in an occupational collective dose of approximately 0.0061 person-mSv/t rare earth elements, amounting to a total of 330 person-mSv/year across all non-nuclear energy industries (about 60% of the annual collective dose from one pressurized water reactor operated in the US, although for rare earth mining the impact is spread out over many more workers. About half of the collective dose from non-nuclear energy production results from use of fuel cracking catalysts for oil refining, although given the extent of the oil industry, it is a small dose when normalized to the energy equivalent of the oil that is used annually. Another factor in energy industries’ reliance on rare earths is the complicated state of the regulation of naturally occurring radiological materials; correspondingly, this paper also explores regulatory and management implications.

  20. Rare-earth elements in granites: concentration and distribution pattern

    International Nuclear Information System (INIS)

    Galindo, A.C.

    1983-01-01

    The geochemistry of rare earth elements in granites is studied. The rare earth element (REE) distribution pattern in granites is characterized by a smooth curve with decreasing concentrations from La to Lu, and frequently a marked Eu negative anomaly. It seems to exist relationship between granite genesis and its REE pattern, in that bodies of primary (magmatic differentiation) origin always show this negative Eu anomaly, while those bodies generated by crustal anatexis do not show this anomaly. (E.G.) [pt

  1. Development of polysulfonic composite beads for extraction and separation of rare earths

    International Nuclear Information System (INIS)

    Yadav, K.K.; Singh, D.K.; Singh, H.; Varshney, L.

    2012-01-01

    Solvent extraction technology has been extensively applied to the practical separation of rare earth metals. Among the extractants commonly employed at present, di(2-ethylhexyl) hydrogen phosphate (D2EHPA) and 2-ethylhexyl hydrogen 2-ethylhexylphosphonate (PC-88A) are known to have advantages of high separation efficiency for rate earth metals and of low solubility in water. However, separation via solvent extraction requires multistage cycles of extraction and back extraction in order to attain favorable separation. Novel adsorbents such as solvent impregnated resins (SIRS), metal-imprinted polymers and microcapsules containing extractants might have wide applicability due to their characteristics having respective advantages of solvent extraction and the ion-exchange technique. In the present work, polymeric composite material impregnating extractants such as D2EHPA, PC88A and DNPPA were prepared and tested for rare earths recovery from chloride medium. Exploratory tests were conducted with Yttrium (taking as representative of rare earths) to evaluate the suitability of the composite beads having D2EHPA, PC88A and DNPPA. Preparation of beads comprises of following steps. Initially, a polymer solutions containing suitable amount of polymer (5 to 15% with 1% water soluble additive) in N-methyl pyrrolidone (NMP) was prepared. The above prepared solutions were then mixed with organophosphorus type of extractant namely D2EHPA, PC88A and di nonyl phenyl phosphoric acid (DNPPA). This polymer solution was gradually dropped drop wise into the water bath through a syringe needle. In the preparation, the temperature of the water was kept constant using a thermostatic unit. As as polymeric drop comes in contact with water due to phase inversion, polysulfonic microcapsules impregnated with the extractant were obtained, these microcapsules were immersed and stabilized in the water bath for 24 h

  2. Defect structure of cubic solid solutions of alkaline earth and rare earth fluorides

    NARCIS (Netherlands)

    DenHartog, HW

    1996-01-01

    In this paper we will consider the disorder in some cubic solid solutions consisting of one of the alkaline earth fluorides and one of the rare earth fluorides. This is an attractive group of model materials, because these materials have a rather simple overall cubic structure. We will discuss the

  3. Production of rare earth polishing powders in Russia

    International Nuclear Information System (INIS)

    Kosynkin, V.D.; Ivanov, E.N.; Kotrekhov, V.A.; Shtutza, M.G.; Grabko, A.I.

    1998-01-01

    Full text: Russia is a potent producer of polishing powders made of rare earth material presented as an extensive and well developed base. Considering the reserves, the facilities predisposition and the polishing agent (cerium dioxide) content the chief mineral source is loparite, apatite and monazite. The production of rare earth polishing powders is based on specially developed continuous technological processes, corrosion-proof equipment, ensuring a high and stable production quality. A special attention is paid to the radiation safety of the powders. The initial material for the rare earth polishing powders based on loparite is the fusion cake of rare earth chlorides obtained at that mineral chlorination. The technology of the polishing powder production from the REE fusion cake includes the following stages: dissolution of the REE fusion cake chlorides; - thorough cleaning of the REE fusion cake chlorides from radioactive and non-rare-earth impurities; chemical precipitation of REE carbonates, obtaining middlings with proper material and granulometric composition, thermal treatment of precipitated carbonates followed with the operations of drying and roasting; classification of roasted oxides, obtaining end products - polishing powders. The production of fluorine-containing powders includes the stage of their fluorination after the stage of carbonate precipitation. The stabilizing doping can be introduced both into the middlings during one of the technological process of powders manufacturing and into the end product. Rare earth polishing powders are manufactured in Russia by the Share Holding Company 'Chepetz Mechanical Plant' (ChMP Co.), the city of Glasov. The plant produces a number of polishing materials, such as; polishing powder Optinol, containing at least 50% by mass of cerium dioxide, used in the mass production of optical and other articles; polishing powder Optinol-10 with doping to improve the sedimentary and aggregate stability of the solid phase

  4. Recovery of rare earths from used polishes by chemical vapor transport process

    International Nuclear Information System (INIS)

    Ozaki, T.; Machida, K.; Adachi, G.

    1998-01-01

    Full text: Rare earth oxide polishes are widely used in the glass industry because of its mechanical and chemical polishing action. The Japanese glass industry use 2000 tons per year of the polishes, and a large portion of them are thrown away after their polishing lifetime. A dry recovery processes for rare earths from the used polishes have been investigated by using a chemical vapor transport method via the formation of vapor complexes RAl n Cl 3+3n (R = rare earths). A flow type reactor with various temperature gradients was employed for the process. The used polishes were mixed with active carbon, and chlorinated with N 2 + Cl 2 mixture at 1273 K. Aluminium oxide were also chlorinated at lower temperature and the resulting AlCl 3 were introduced to the reactor. The rare earth chlorides and AlCl 3 were converted to the vapor complexes. These were driven along the temperature gradient, decomposed according to the reverse reaction, and regenerated RCl 3 . About 90 % of the used polish were chlorinated after 2 hours. Rare earth chlorides, AlCl 3 , and FeCl 3 were fully transported after 82 hours. The rare earth chlorides were mainly condensed over the temperature range 1263-903 K. On the other hand, AlCl 3 and FeCl 3 were deposited at the temperature range below 413 K. CaCl 2 and SrCl 2 were hardly transported and remained in the residue. When the temperature gradient with the smaller slope was used, mutual separation efficiencies among the rare earths was improved. The highest CeCl 3 purity of 80% was obtained in the process

  5. China’s Rare Earths Supply Forecast in 2025: A Dynamic Computable General Equilibrium Analysis

    Directory of Open Access Journals (Sweden)

    Jianping Ge

    2016-09-01

    Full Text Available The supply of rare earths in China has been the focus of significant attention in recent years. Due to changes in regulatory policies and the development of strategic emerging industries, it is critical to investigate the scenario of rare earth supplies in 2025. To address this question, this paper constructed a dynamic computable equilibrium (DCGE model to forecast the production, domestic supply, and export of China’s rare earths in 2025. Based on our analysis, production will increase by 10.8%–12.6% and achieve 116,335–118,260 tons of rare-earth oxide (REO in 2025, based on recent extraction control during 2011–2016. Moreover, domestic supply and export will be 75,081–76,800 tons REO and 38,797–39,400 tons REO, respectively. The technological improvements on substitution and recycling will significantly decrease the supply and mining activities of rare earths. From a policy perspective, we found that the elimination of export regulations, including export quotas and export taxes, does have a negative impact on China’s future domestic supply of rare earths. The policy conflicts between the increase in investment in strategic emerging industries, and the increase in resource and environmental taxes on rare earths will also affect China’s rare earths supply in the future.

  6. Investigation and modelling of rare-earth activated waveguide structures

    International Nuclear Information System (INIS)

    Wolinski, W.; Malinowski, M.; Mossakowska-Wyszynska, A.; Piramidowicz, R.; Szczepanski, P.

    2005-01-01

    In this paper the overview of the recent study on the rare-earth activated waveguides performed in the Optoelectronic Department of IMiO is presented. We reported on the development of rare earth-doped fluorozirconate (ZBLAN) glass fibers that allow a construction of a new family of visible and ultraviolet fiber lasers pumped by upconversion. Especially the performance of holmium devices is presented. The properties of laser planar waveguides obtained by the LPE process and the growth conditions of rare earths doped YAG layers are presented. In this paper we present also the theoretical study of the nonlinear operation of planar waveguide laser, as an example the microdisk Nd:YAG structure is discussed. We derived an approximate formula which relates the small signal gain in the Nd:YAG active medium and the laser characteristics, obtained for whispering-gallery modes and radial modes, to the output power and real parameters of the laser structure (authors)

  7. A problem in gravimetric method for the determination of rare earth elements as oxide after the fluoride separation

    International Nuclear Information System (INIS)

    Takada, Kunio

    1979-01-01

    For the gravimetric determination of lanthanum, it was precipitated as fluoride and converted to oxide by igniting (ca. 930 0 C) in a town gas flame. However, the oxidation of lanthanum fluoride by ignition was incomplete, the major part of the precipitate being converted to oxyfluoride (LaOF) and a mixture of oxide and oxyfluoride resulted. Therefore, analytical results were generally (5 -- 7)% higher than theoretically expected. The lanthanum fluoride became converted into the oxide by repeating ignition (ca. 1070 0 C) three times, each for (30 -- 40)min. However, the weight was lower than that of the corresponding sesquioxide, La 2 O 3 . Except for ytterbium and lutetium, gravimetric results as oxides for the other rare earth elements (Y, Pr, Nd, Sm, Eu and Gd) were higher than theoretical values. Therefore, the precipitation of the rare earth elements as fluoride and the subsequent determination as oxide by ignition of the fluoride could not be recommended as the gravimetric method for the rare earths. In order to obtain accurate results for major to minor amounts of the rare earth elements, an EDTA titration at pH 6 should be used after the dissolution of fluoride in acid, if the fluoride precipitation separation is involved. (author)

  8. The fascination of the rare earths - then, now and in the future

    International Nuclear Information System (INIS)

    Wybourne, Brian G.

    2004-01-01

    The rare earths have long been a subject of fascination to chemists and physicists. Herein, I comment on some of the prehistory leading up to the advent of the Judd-Ofelt theory of the intensities of their remarkable spectra, the origins of the Judd-Ofelt theory and its early applications. I then consider subsequent developments and extensions of the theory, its current status and its relevance to current problems of interest in rare earth spectroscopy and the future of rare earth studies

  9. Study on recovering directly the commercial cerium oxide and total of residue rare earths from Dongpao bastnasite concentrate

    International Nuclear Information System (INIS)

    Nguyen Trong Hung; Nguyen Thanh Chung; Luu Xuan Dinh

    2003-01-01

    A technology for decomposition roasting and sequential leaching processes of Dong Pao bastnasite concentrate to recover directly commercial cerium oxide and total of residue rare earth elements from the leaching solution of the roasted product have been investigated. The bastnasite concentrate is initially roasted at temperature range of 600 - 650 degC and for time of 4 hrs in order to decompose and convert the hardly soluble carbonate forms of ore into easily soluble oxide. The roasted solid is then leached with sulfuric acid solution of 6N at 60 degC for 4 hrs to convert rare earths in oxide and fluoride form into rare earth sulfate. The recovery yield of rare earths of these stages is more than 95%. The attention has especially been paid on recovering directly the commercial cerium oxide and total of residue rare earth element from the above leaching solution. Complex ions of CeSO 4 2+ , Ce(SO 4 ) 2 , Ce(SO 4 ) 3 2- and Ce(SO 4 ) 4 4- exist in aqueous solution of cerium (IV) sulfate. Based on the property, the method of ion - sieve with DOWEX cation resin column has been applied to estimating separation of the ceric complex anions from Ln(III). The survey showed that most of the ceric complex anions are separated from total of residue rare earths. The latter which are absorbed in the cation column are recovered by elution of HCl of 4N. The recovery yield of cerium can only be reached 20% but the purity of that is very high, can be reached 99.6%. About 5 kg of CeO 2 of high grade and 5 kg of TREO of commercial specification have been produced. (author)

  10. Determination of rare earth elements in high purity rare earth oxides by liquid chromatography, thermionic mass spectrometry and combined liquid chromatography/thermionic mass spectrometry

    International Nuclear Information System (INIS)

    Stijfhoorn, D.E.; Stray, H.; Hjelmseth, H.

    1993-01-01

    A high-performance liquid chromatographic (HPLC) method for the determination of rare earth elements in rocks has been modified and used for the determination of rare earth elements (REE) in high purity rare earth oxides. The detection limit was 1-1.5 ng or 2-3 mg/kg when a solution corresponding to 0.5 mg of the rare earth oxide was injected. The REE determination was also carried out by adding a mixture of selected REE isotopes to the sample and analysing the collected HPLC-fractions by mass spectrometry (MS) using a thermionic source. Since the matrix element was not collected, interference from this element during the mass spectrometric analysis was avoided. Detection limits as low as 0.5 mg/kg could then be obtained. Detection limits as low as 0.05 mg/kg were possible by MS without HPLC-pre-separation, but this approach could only be used for those elements that were not affected by the matrix. Commercial samples of high purity Nd 2 O 3 , Gd 2 O 3 and Dy 2 O 3 were analysed in this study, and a comparison of results obtained by HPLC, combined HPLC/MS and direct MS is presented. (Author)

  11. Processing of Phosphorus Slag with Recovery of Rare Earth Metals and Obtaining Silicon Containing Cake

    Science.gov (United States)

    Karshigina, Zaure; Abisheva, Zinesh; Bochevskaya, Yelena; Akcil, Ata; Sharipova, Aynash; Sargelova, Elmira

    2016-10-01

    The present research is devoted to the processing of slag generating during the yellow phosphorus production. In this paper are presented studies on leaching of phosphorus production slag by nitric acid with recovery of rare earth metals (REMs) into solution. REMs recovery into the solution achieved 98 % during the leaching process with using 7.5 mol/L of HNO3, liquid-to-solid ratio is 2.6:1, temperature is 60°C, process duration is 1 hour and stirrer speed is 500 rpm. Behaviour during the leaching of associated components such as calcium, aluminium, and iron was studied. After the leaching cake contains ∼⃒75-85 % of SiO2 and it might be useful for obtaining of precipitated silicon dioxide. With the purpose of separation from the impurities, recovery and concentrating of REMs, the obtained solution after leaching was subjected to extraction processing methods. The influence of ratio of organic and aqueous phases (O: A) on the extraction of rare earth metals by tributyl phosphate (TBP) with concentrations from 20 up to 100 % was studied. The REMs extraction with increasing TBP concentration under changes O:A ratio from 1:20 down to 1:1 into the organic phase from the solutions after nitric acid leaching increased from 22.2 up to 99.3%. The duration effect of REMs extraction process was studied by tributyl phosphate. It is revealed that with increasing of duration of the extraction process from 10 to 30 minutes REMs recovery into the organic phase almost did not changed. The behaviour of iron in the extraction process by TBP was studied. It was found that such accompanying components as calcium and aluminium by tributyl phosphate didn't extracted. To construct isotherm of REMs extraction of by tributyl phosphate was used variable volume method. It was calculated three-step extraction is needed for REMs recovery from the solutions after nitric acid leaching of phosphorus production slag. The process of the three-steps counter current extraction of rare earth

  12. Influence of rare earth additions on the oxidation resistance of chromia forming alloys

    International Nuclear Information System (INIS)

    Pillis, Marina Fuser

    1995-01-01

    The addition of rare earths to alloys, either in elemental form or as surface coatings reduces the oxidation rate of chromia forming alloys. The rare earths either act as nucleation sites for surface oxides or get incorporates into the surface oxide and diffuse to oxide grain boundaries. If the latter occurs, a change in the defect structure close to the grain boundaries, probably takes place. In this manner, the rare earths inhibits the movement of chromium ions to the oxide/gas interface. The influence of rare earth additions to AISI 316, AISI 316L and Ni-20 Cr on their oxidation behavior has been studied., AISI 316+Ce, AISI 316+Y, Ni-20 Cr and Ni-20 Cr-2 Al-1 Ce were prepared by melting and AISI 316L, AISI 316L+Ce O 2 and AISI 316L+Y 2 O 3 by powder compaction. The effect of superficial deposits of rare earth oxides was also studied. The alloys were coated with rare earth oxides by high temperature conversion of the respective rare earth nitrates. Isothermal oxidation tests were carried out at 900-1100 deg C and the cyclic oxidation tests consisted of 6 cycles of 2 hours each at 900 deg C, followed by cooling to room temperature. All the tests were carried out in air. Oxidation behavior was evaluated gravimetrically. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis and X-ray diffraction techniques were used to identify oxide constituents. Overall, it has been observed that with the addition of rare earths, oxidation resistance increases by decreasing oxidation rates and increasing oxide adhesion. Addition of rare earths to AISI 316 prepared by melting resulted in rapid formation of a chromium rich oxide layered near the metal/oxide interface which reduced overall oxidation rate. The addition of Ce O 2 to AISI 316L was found to improve oxidation behavior after 10 hours at 1100 deg C and also inhibit the formation of volatile Cr O 3 . The isothermal oxidation behavior of rare earth oxide covered Ni-20 Cr at 900 deg C

  13. Neural Network Modeling for the Extraction of Rare Earth Elements from Eudialyte Concentrate by Dry Digestion and Leaching

    OpenAIRE

    Yiqian Ma; Srecko Stopic; Lars Gronen; Milovan Milivojevic; Srdjan Obradovic; Bernd Friedrich

    2018-01-01

    Eudialyte is a promising mineral for rare earth elements (REE) extraction due to its good solubility in acid, low radioactive, and relatively high content of REE. In this paper, a two stage hydrometallurgical treatment of eudialyte concentrate was studied: dry digestion with hydrochloric acid and leaching with water. The hydrochloric acid for dry digestion to eudialyte concentrate ratio, mass of water for leaching to mass of eudialyte concentrate ratio, leaching temperature and leaching time ...

  14. Calculation of binary phase diagrams between the actinide elements, rare earth elements, and transition metal elements

    International Nuclear Information System (INIS)

    Selle, J.E.

    1992-01-01

    Attempts were made to apply the Kaufman method of calculating binary phase diagrams to the calculation of binary phase diagrams between the rare earths, actinides, and the refractory transition metals. Difficulties were encountered in applying the method to the rare earths and actinides, and modifications were necessary to provide accurate representation of known diagrams. To calculate the interaction parameters for rare earth-rare earth diagrams, it was necessary to use the atomic volumes for each of the phases: liquid, body-centered cubic, hexagonal close-packed, and face-centered cubic. Determination of the atomic volumes of each of these phases for each element is discussed in detail. In some cases, empirical means were necessary. Results are presented on the calculation of rare earth-rare earth, rare earth-actinide, and actinide-actinide diagrams. For rare earth-refractory transition metal diagrams and actinide-refractory transition metal diagrams, empirical means were required to develop values for the enthalpy of vaporization for rare earth elements and values for the constant (C) required when intermediate phases are present. Results of using the values determined for each element are presented

  15. Method of forming magnetostrictive rods from rare earth-iron alloys

    Science.gov (United States)

    McMasters, O. Dale

    1986-09-02

    Rods of magnetrostructive alloys of iron with rare earth elements are formed by flowing a body of rare earth-iron alloy in a crucible enclosed in a chamber maintained under an inert gas atmosphere, forcing such molten rare-earth-iron alloy into a hollow mold tube of refractory material positioned with its lower end portion within the molten body by means of a pressure differential between the chamber and mold tube and maintaining a portion of the molten alloy in the crucible extending to a level above the lower end of the mold tube so that solid particles of higher melting impurities present in the alloy collect at the surface of the molten body and remain within the crucible as the rod is formed in the mold tube.

  16. Rare earth materials research in European Community R and D programmes

    International Nuclear Information System (INIS)

    Gavigan, J.P.

    1992-01-01

    The level of involvement of EC research programmes in rare earth materials research is quite high. A total of 65 projects have been identified representing an involvement of 283 partners from all over Europe. This corresponds to a budget a 63.3 MECU (76MDollars) of which the EC contributes 40.7 MECU (49MDollars). In this paper, the various research activities will be discussed under the main themes of rare earth permanent magnets, high Tc superconductors, optical and other materials, with specific reference to the three main programmes involved, BRITE/EURAM, SCIENCE and ESPRIT. Two other programmes currently involved in rare earth research are RAW MATERIALS and JOULE. (orig.)

  17. Recovery and purification of rare earth elements and thorium

    International Nuclear Information System (INIS)

    Sungur, A.; Saygi, Z.; Yildiz, H.

    1985-01-01

    Rare earth elements and thorium found in the low-grade Eskisehir-Beylikahir ore have been recovered by HCl leaching, Lanthanides and thorium were separated and purified from the leach solutions through the precipitation sequence as double sulphate, hydroxide and oxalate. The Ln 2 O 3 and Th(OH) 4 products, finally obtained contained 36% Ce and 65% Th. The analysis of rare earth elements, thorium and other present ingredients were carried out by instrumental neutron activation analysis, atomic absorption spectroscopy, vis-spectroscopy and gravimetry. (author)

  18. Rare earth oxyhalogenide base thermoluminescent material

    International Nuclear Information System (INIS)

    Rabatin, J.G.

    1976-01-01

    A process is described that consists to expose a thermoluminescent material to ionizing radiations, the material being a rare earth oxyhalogenide with terbium additions, to heat this material up to the emission of visible radiations and to measure the emitted radiations which are proportional to the ionizing radiation dose [fr

  19. Photostability of solutions of rare earth chelates in organic solvents and polymers

    International Nuclear Information System (INIS)

    Karasev, V.E.; Mirochnik, A.G.; Lysun, T.V.; Vovna, V.I.

    1990-01-01

    Consideration is given to results of comparative study of photochemical properties of rare erath chelate complexes (adducts of rare earth β-diketonates with triphenylphosphine oxide, hexamethylphosphotriamide, phenanthroline) in organic solvents and polymers. Effect of excitation conditions, composition, solvent, nature of ligand and rare earth ion on photolysis rate was investigated. 9 refs.; 2 figs.; 4 tabs

  20. Research and development of tungsten electrodes added with rare earth oxides

    International Nuclear Information System (INIS)

    Zuoren Nie; Ying Chen; Meiling Zhou; Tieyong Zuo

    2001-01-01

    The recent research and development of tungsten electrodes used in TIG and Plasma technologies are introduced, and the tungsten materials as well as the effects of rare earth oxides are specially discussed. in W-La 2 O 3 , W-CeO 2 , W-Y 2 O 3 and W-ThO 2 electrode materials, the W-2.2mass%La 2 O 3 electrode exhibited the best properties when the current is of little or middle volume, and when the electrodes are used in large current, the W-Y 2 O 3 electrode is the best. By a comparative study between the tungsten electrodes activated with single metal oxides, as above-mentioned, and those containing two or three rare earth oxides, namely La 2 O 3 , CeO 2 and Y 2 O 3 , it was indicated that the welding arc properties of the tungsten electrodes activated with combined rare earth oxides additions is superior than that of the electrodes containing single oxides as above mentioned. It was also shown that the operating properties of tungsten electrodes depend intensively on the rare earth oxides contained in the electrodes, and the actions of rare earth oxides during arcing are the most important factors to the electrodes' operating properties, temperature, work function as well as the arc stability. (author)

  1. Isomerization of butene-1 on rare earth oxides. [Rare earths: La, Nd, Dy

    Energy Technology Data Exchange (ETDEWEB)

    Khodakov, Yu S; Nesterov, V K; Minachev, Kh M [AN SSSR, Moscow. Inst. Organicheskoj Khimii

    1975-09-01

    A study has been made into the isomerization of butene-1 on oxides of rare-earth elements. The dependence of the reaction rate at 20/sup 0/C on the baking temperature of La and Nd oxides have the maximum at 700/sup 0/C. A decrease in the activity of these oxides after bakinq at 800/sup 0/C is observed, as well as during experiments at -30 deq C. In the case of Dy/sub 2/O/sub 3/, the activity at 20/sup 0/C increases gradually with Tsub(bak)=500 to 800/sup 0/C Zeolite 0.57LaNaY exhibits maximum activity at Tsub(bak)=500/sup 0/C Similar data as to the effect of the baking temperature on the catalyst activity were obtained earlier for hydrogenation of ethylene. According to their maximum activity, oxides of rare-earth elements, in the isomerization as well as hydrogenation reactions, can be arranged as follows: La/sub 2/O/sub 3/>Nd/sub 2/O/sub 3/

  2. Mother Lode: The Untapped Rare Earth Mineral Resources of Vietnam

    Science.gov (United States)

    2013-11-01

    to exert their monopolistic control of the market by artificially restricting supply in the interest of higher commodity prices, but were rather...linked. World markets for rare earth elements are at present a near-monopoly controlled by China, and it is becoming ever clearer that alternative... markets for rare earth elements are at present a near- monopoly controlled by China, and it is becoming ever clearer that alternative sources for these

  3. Effect of rare earth oxide additives on the performance of NiMH batteries

    International Nuclear Information System (INIS)

    Tanaka, Toshiki; Kuzuhara, Minoru; Watada, Masaharu; Oshitani, Masahiko

    2006-01-01

    To date, we have performed research on nickel-metal hydride (NiMH) batteries used in many applications and have found that addition of rare earth oxides to the nickel electrode and the hydrogen-storage alloy (MH) electrode improves battery performance significantly. Because heavy rare earth oxides of such as Er, Tm, Yb and Lu have remarkable properties that shift the oxygen evolution overpotentials of nickel electrodes to more noble potentials, it is possible to improve high-temperature charge efficiency of nickel-metal hydride secondary batteries by adding them to nickel electrodes. Furthermore, addition of heavy rare earth oxides to MH electrodes depresses an acceleration of the alloy corrosion and improves service life of the battery at high temperatures. Accordingly, addition of heavy rare earth oxides is effective for NiMH batteries used in high-temperature applications such as electric vehicles (EVs), hybrid vehicles (HEVs) and rapid charge devices. In this study, we discussed how the addition of heavy rare earth oxides affects NiMH battery characteristics

  4. Direct Reuse of Rare Earth Permanent Magnets—Coating Integrity

    DEFF Research Database (Denmark)

    Høgberg, Stig; Holbøll, Joachim; Mijatovic, Nenad

    2017-01-01

    Rare earth permanent magnets can be reused directly as an alternative to traditional recycling methods, in which scrapped magnets are reprocessed into new magnets by undergoing many of the original energy-intensive and expensive production processes. Direct reuse entails using segmented magnet...... assemblies built by several small standard-sized magnets that can be reused directly in a number of different applications. A central part of the direct reuse strategy is to separate and demagnetize magnets by heating them to the Curie temperature. We investigated the validity of direct reuse as a rare earth...

  5. Annealed coated air-stable cobalt--rare earth alloy particles

    International Nuclear Information System (INIS)

    Smeggil, J.C.; Charles, R.J.

    1975-01-01

    A process is described for producing novel air-stable coated particles of a magnetic transition metal-rare earth alloy. An organometallic compound which decomposes at a temperature below 500 0 C is heated to produce a metal vapor which is contacted with particles of a transition metal-rare earth alloy to deposit a metal coating thereon. The coated particles are heated at a temperature ranging from 50 to 200 0 C for a period of time sufficient to increase their intrinsic coercive force by at least 10 percent. (U.S.)

  6. Photo- and electroluminescence of undoped and rare earth doped ZnO electroluminors

    International Nuclear Information System (INIS)

    Bhushan, S.; Pandey, A.N.; Kaza, B.R.

    1977-01-01

    A series of undoped and rare earth (Dy, Yb, Nd, Pr, Gd, La, Sm and Er) doped ZnO electroluminors have been prepared and their photo- (PL) and electroluminescence (EL) spectra at different concentrations of rare earth ions have been investigated. PL and EL spectra of undoped electroluminescence consist of three peaks. Due to the addition of the rare earth ions these peaks are shifted either to the longer or to the shorter wavelength side. The intensities are also either decreased or increased. Experimental results favour the donor-accepted model for this system. (Auth.)

  7. X-ray fluorescence analysis of terbium oxide for rare earth impurities

    International Nuclear Information System (INIS)

    Chandola, L.C.; Machado, I.J.; Mohile, A.N.

    1975-01-01

    A method for the determination of Sm 2 O 3 , Eu 2 O 3 , Gd 2 O 3 , Dy 2 O 3 , Ho 2 O 3 and Y 2 O 3 in terbium oxide is described. The sample is converted to terbium oxalate, mixed with boric acid binder in the ratio 2:1, pelleted at a pressure of 20 tons over a boric acid backing pellet and irradiated with x-rays from a tungsten tube operated by Philips PW 1140 generator. The secondary x-rays thus generated are analysed by a LiF (200) crystal in Philips PW 1220 x-ray fluorescence spectrometer using suitable detectors. The minimum determination limit (MDL) is 0.01% for all rare earth oxides determined except for Y 2 O 3 for which it is 0.005%. (author)

  8. Crystal chemistry and magnetic properties of ternary rare earth sulfides

    International Nuclear Information System (INIS)

    Plug, C.M.; Rijksuniversiteit Leiden

    1977-01-01

    The results of magnetic measurements on two groups of ternary rare earth sulphides are described, the MLnS 2 (M=Li, Na, K) type of compounds and the series Ln 2 ZrS 5 , where Ln denotes one of the rare earths. None of these compounds is metallic, excluding the possibility of RKKY-interaction. In chapter II a survey of the relevant theory on magnetic properties and crystal field splitting is given. In spite of the similarity in chemical properties of the rare earths, the crystal chemistry of their compounds is rather complex. This is due to the lanthanide contraction. The third chapter deals with the description and classification of the numerous crystal structures of both ternary and binary rare earth sulphides that have been observed. Rather simple relations between various structures are presented using a new method of structure classification. The magnetic interactions expected to be based on superexchange via the anions, which is usually very structure dependent. Experiments to study the crystallographic ordering, applying both X-ray and electron diffraction methods and the results of the magnetic measurements on the compounds MLnS 2 are reported in chapter IV. The compounds Ln 2 ZrS 5 are candidates for a systematic study of the variation of the magnetic properties along the rare earth series. The results of magnetic measurements on these compounds are presented in chapter V, combined with the results of specific heat measurements. Also the magnetic structure of two representatives, Tb 2 ZrS 5 and Dy 2 ZrS 5 , determined by neutron diffraction experiments below the ordering temperature, is reported

  9. The lattice dynamical studies of rare earth compounds: electron-phonon interactions

    International Nuclear Information System (INIS)

    Jha, Prafulla K.; Sanyal, Sankar P.; Singh, R.K.

    2002-01-01

    During the last two decades chalcogenides and pnictides of rare earth (RE) atoms have drawn considerable attention of the solid state physicists because of their peculiar electronic, magnetic, optical and phonon properties. Some of these compounds e.g. sulphides and selenides of cerium (Ce), samarium (Sm), yttrium (Y), ytterbium (Yb), europium (Eu) and thulium (Tm) and their alloys show nonintegral valence (between 2 and 3), arising due to f-d electron hybridization at ambient temperature and pressure. The rare earth mixed valence compounds (MVC) reviewed in this article crystallize in simple cubic structure. Most of these compounds show the existence of strong electron-phonon coupling at half way to the zone boundary. This fact manifests itself through softening of the longitudinal acoustic mode, negative value of elastic constant C 12 etc. The purpose of this contribution is to review some of the recent activities in the fields of lattice dynamics and allied properties of rare earth compounds. The present article is primarily devoted to review the effect of electron-phonon interactions on the dynamical properties of rare earth compounds by using the lattice dynamical model theories based on charged density deformations and long-range many body forces. While the long range charge transfer effect arises due to f-d hybridization of nearly degenerate 4f-5d bands of rare earth ions, the density deformation comes into the picture of breathing motion of electron shells. These effects of charge transfer and charge density deformation when considered in the lattice dynamical models namely the three body force rigid ion model (TRM) and breathing shell model (BSM) are quite successful in explaining the phonon anomalies in these compounds and undoubtedly unraveled many important physical process governing the phonon anomalies in rare earth compounds

  10. Separation of Yttrium from Rare Earth Concentrates in Fractional Hydroxide Precipitation

    International Nuclear Information System (INIS)

    Tri Handini; Purwoto; Mulyono

    2007-01-01

    Yttrium has been separated from rare earth concentrates by precipitation in fractional hydroxide using urea. The purpose of this research is to increase the yttrium rate resulting from the sedimentary process through separation of yttrium from other rare earth in fractional hydroxide precipitation using urea. In this research, we study the process variable of the concentration of urea, the ratio of feed volume to condensation volume of urea, as well as the temperature. Determination analysis of the rare earth rate is conducted using an X-ray spectrometer. The best result Y=92.89 % is obtained at a concentration of urea of 50 %, a level of precipitation of 3 times, and a temperature of 80°C. (author)

  11. Online preconcentration ICP-MS analysis of rare earth elements in seawater

    Science.gov (United States)

    Hathorne, Ed C.; Haley, Brian; Stichel, Torben; Grasse, Patricia; Zieringer, Moritz; Frank, Martin

    2012-01-01

    The rare earth elements (REEs) with their systematically varying properties are powerful tracers of continental inputs, particle scavenging intensity and the oxidation state of seawater. However, their generally low (˜pmol/kg) concentrations in seawater and fractionation potential during chemical treatment makes them difficult to measure. Here we report a technique using an automated preconcentration system, which efficiently separates seawater matrix elements and elutes the preconcentrated sample directly into the spray chamber of an ICP-MS instrument. The commercially available "seaFAST" system (Elemental Scientific Inc.) makes use of a resin with ethylenediaminetriacetic acid and iminodiacetic acid functional groups to preconcentrate REEs and other metals while anions and alkali and alkaline earth cations are washed out. Repeated measurements of seawater from 2000 m water depth in the Southern Ocean allows the external precision (2σ) of the technique to be estimated at mine water reference materials diluted with a NaCl matrix with recommended values in the literature. This makes the online preconcentration ICP-MS technique advantageous for the minimal sample preparation required and the relatively small sample volume consumed (7 mL) thus enabling large data sets for the REEs in seawater to be rapidly acquired.

  12. Cerium and rare earth separation process

    International Nuclear Information System (INIS)

    Martin, M.; Rollat, M.

    1986-01-01

    An aqueous solution containing cerium III and rare earths is oxidized in the anodic compartment of an electrolytic cell, cerium IV is extracted by an organic solvent, the organic phase containing Ce IV is reduced in the catodic compartment of the same electrolytic cell and cerium III is extracted in a nitric aqueous phase [fr

  13. Synthesis and physicochemical investigation of adducts of rare earth thenoyltrifluoroacetonates

    International Nuclear Information System (INIS)

    Anufrieva, S.I.; Snezhko, N.I.; Martynenko, L.I.; Pechurova, N.I.

    1982-01-01

    Adducts of rare earth thenoyltrifluoroacetonates (3) have been synthesized with tributylphosphate (TBP), trioctylphosphenoxide (TOPO), triphenylphosphenoxide (TPO) of 1:1 and 1:2 composition as well as with α, α'-dipyridine (Dipy), o-phenanthroline (Phen) of 1:1 composition. The separated adducts have been studied by methods of element analysis, X-ray phase and derivatographic analyses and IR spectroscopy. It is shown that the adducts are more thermostable compared to the corresponding rare earth thenoyltrifluoroacetonate hydrates

  14. Electronic structure and properties of rare earth and actinide intermetallics

    International Nuclear Information System (INIS)

    Kirchmayr, H.R.

    1984-01-01

    There are 188 contributions, experimental and theoretical, a few on rare earth and actinide elements but mostly on rare earth and actinide intermetallic compounds and alloys. The properties dealt with include 1) crystal structure, 2) magnetic properties and magnetic structure, 3) magnetic phase transformations and valence fluctuations, 4) electrical properties and superconductivity and their temperature, pressure and magnetic field dependence. A few papers deal with crystal growth and novel measuring methods. (G.Q.)

  15. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

    Thin rare earth (RE) oxide films are emerging materials for microelectronic, nanoelectronic, and spintronic applications. The state-of-the-art of thin film deposition techniques as well as the structural, physical, chemical, and electrical properties of thin RE oxide films and of their interface with semiconducting substrates are discussed. The aim is to identify proper methodologies for the development of RE oxides thin films and to evaluate their effectiveness as innovative materials in different applications.

  16. Magnetoelastic interaction in rare earth systems

    International Nuclear Information System (INIS)

    Dohm, V.

    1975-01-01

    A theory of rotationally invariant spin-lattice interactions in rare earth systems is presented. It is shown that rotational invariance to leading order is ensured only if rotational interactions of first and second order in the displacements are included simultaneously in the spin-lattice Hamiltonian. The rotational second-order interactions yield effects which are as large as those of the linear rotational interaction. It is pointed out that a corresponding statement should hold also for pure strain interactions. The phonon Green's function is calculated for the paramagnetic phase of rare earth systems. It is found that in an applied magnetic field the rotational interactions cause measureable changes of the phonon dispersion and the sound velocity even for cubic symmetry. These effects turn out to be of the same order of magnitude as the conventional field-dependent strain effects and are qualitatively different from the latter. The results of our theory are illustrated by the example of SmSb, and quantitative predictions for the transverse sound velocities are given. (orig.) [de

  17. Methods of Separation of Total Rare Earths in Low-Alloy Constructional Steels

    Science.gov (United States)

    1954-11-10

    investigation of the effects of added anions upon the absorption spectra of the rare earths elements has been continued. The effects of tartrate in...complexes, the equilibrium among the di-hydrogen cupric EDTA complex, uncomplexed cupric ions, the monohydrogen rare earth- EDTA complex and rare...solutions used are described. A polaro- graphic method for determining cupric ion concentration in support- ing KNOj solutions, and thereby supporting

  18. Recovery of thorium and rare earths by their peroxides precipitation from a residue produced in the thorium purification facility

    International Nuclear Information System (INIS)

    Freitas, Antonio Alves de

    2008-01-01

    As consequence of the operation of a Thorium purification facility, for pure Thorium Nitrate production, the IPEN (Instituto de Pesquisas Energeticas e Nucleares) has stored away a solid residue called RETOTER (REsiduo de TOrio e TErras Raras). The RETOTER is rich in Rare-Earth Elements and significant amount of Thorium-232 and minor amount of Uranium. Furthermore it contains several radionuclides from the natural decay series. Significant radioactivity contribution is generated by the Thorium descendent, mainly the Radium-228(T 1/2 =5.7y), known as meso thorium and Thorium-228(T 1/2 1.90y). An important thorium daughter is the Lead-208, a stable isotope present with an expressive quantity. After the enclosure of the operation of the Thorium purification facility, many researches have been developed for the establishment of methodologies for recovery of Thorium, Rare-Earth Elements and Lead-208 from the RETOTER. This work presents a method for RETOTER decontamination, separating and bordering upon some radioactive isotopes. The residue was digested with nitric acid and the Radium-228 was separated by the Barium Sulphate co-precipitation procedure. Finally, the Thorium was separated by the peroxide precipitation and the Rare-Earth Elements were also recovered by the Rare-Earth peroxide precipitation in the filtrate solution.(author)

  19. Calorimetric investigation of solution heat of rare earth sulfates in acid solutions

    International Nuclear Information System (INIS)

    Vasin, S.K.; Babkin, A.G.; Kessler, Yu.M.

    1978-01-01

    To determine the thermodynamic characteristics of sulfates of rare elements an adiabatic airtight calorimeter has been developed, enabling measurement of minor heat effects of processes in aggressive media with an absolute error of about 5x10 -3 cal, the temperature sensitivity being no less than 2x10 -5 C 0 . The calorimeter is schematically represented. Measured with the aid of the calorimeter was the heat of dissolution of TiOSO 4 x2H 2 O in chloric acid solutions

  20. A comparative study of CaWO4 and rare earth intensifying screens

    International Nuclear Information System (INIS)

    Ambiger, T.Y.; Ayappan, P.

    1978-01-01

    Three brands of commercially available calcium tungstate intensifying screens and a brand of rare earth screen emitting blue light have been used with two types of fast medical x-ray films, one imported and the other indigenous in various film-screen combinations and their sensitometric properties have been determined and compared. The rare earth screen has been found to be about 3 to 4 times faster than the tungstate screens without reduction in contrast. This indicates that the use of rare earth screen in medical radiography will help to reduce the patient dose by the same factor. (M.G.B.)

  1. Synthesis and physicochemical investigation of adducts of rare earth thenoyltrifluoroacetonates

    Energy Technology Data Exchange (ETDEWEB)

    Anufrieva, S.I.; Snezhko, N.I.; Martynenko, L.I.; Pechurova, N.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

    1982-11-01

    Adducts of rare earth thenoyltrifluoroacetonates (3) have been synthesized with tributylphosphate (TBP), trioctylphosphenoxide (TOPO), triphenylphosphenoxide (TPO) of 1:1 and 1:2 composition as well as with ..cap alpha.., ..cap alpha..'-dipyridine (Dipy), o-phenanthroline (Phen) of 1:1 composition. The separated adducts have been studied by methods of element analysis, X-ray phase and derivatographic analyses and IR spectroscopy. It is shown that the adducts are more thermostable compared to the corresponding rare earth thenoyltrifluoroacetonate hydrates.

  2. Thermoluminescence dosimetry of rare earth doped calcium ...

    Indian Academy of Sciences (India)

    Unknown

    CaAl2O4) doped with different rare earth ions have been studied and their suitability for radiation dosimetry applications is discussed. It is observed that monocalcium aluminate doped with cerium is a good dosimeter having linear response up to ...

  3. Rare earth elements as a tool for studying the formation of cemented layers in an area affected by acid mine drainage

    International Nuclear Information System (INIS)

    Grawunder, Anja; Lonschinski, Martin; Merten, Dirk; Büchel, Georg

    2015-01-01

    Highlights: • Spatially resolved analysis of 14 rare earth elements (REE) by LA-ICP-MS. • Positive correlation of Mn contents and (positive) Ce anomalies. • Linkage of the two cemented layer’s formation to soil solution and groundwater. - Abstract: In a profile with two cemented layers sampled in an area affected by acid mine drainage, both have rare earth element (REE) signatures with positive Ce anomalies in the Post Archean Australian Shale-normalised patterns. Both cemented layers have higher contents of environmentally relevant metals (Cd, Co, Cu, Fe, Mn, U, and Zn) than the over- and underlying unconsolidated Quaternary sediments and are depleted of Al, Ca, K, and Mg. The cemented layers are enriched in middle and heavy REE, but only the bulk pattern of the lower cemented layer reveals a positive Ce anomaly. For the upper cemented layer, this positive Ce anomaly was only determined by spatially resolved laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) studies only for segments with a high abundance of Mn, occurring as Mn phases as proven by energy dispersive X-ray spectroscopy. The Mn phases are formed secondarily to the ferric cement and are especially enriched in Ce and Co. The Ce anomaly of the lower cemented layer most probably is inherited from groundwater to the ferric cement, whereas the Ce anomaly of the upper cemented layer is the result of preferential scavenging of Ce onto the Mn phases compared to other REE

  4. Concentration of light rare earths process by amoniacal precipitation

    International Nuclear Information System (INIS)

    Aguilera, Y.; Rapado, M.; Consuegra, R.

    1996-01-01

    A procedure for the separation and concentration of light rare earths using a mixture of ammonia and water was developed. As a result technical concentrates of rare earths were obtained and the physical separation in the filtration step was improved. The filtration parameters (cake resistance r 0 and filtration web resistance R) were obtained for this process being they 5,5.10 11 cm/g and 3,4.10 13 cm -1 respectively. The proposed technology concentrates (Ce, La and Nd) with purities ranging from: 85-90 %, 85-87 % and 42-65 % respectively in only one precipitation step

  5. Peculiarities of rare-earth-element distribution in environmental objects

    International Nuclear Information System (INIS)

    Gorbunov, A.V.; Onischenko, T.L.; Gundorina, S.F.; Frontasyeva, M.V.

    1993-01-01

    The effect of the production of phosphorus fertilizers on the pollution of the environment by rare-earth elements is reviewed. The main sources of rare-earth element pollution in the environment are described. The levels of REEs in components of the environment - atmosphere, snow, different types of soil, native and agricultural types of vegetation - that provide evidence for their participation in the biological cycle of plants are considered. The high values of the correlation coefficients lead one to think that the REE distribution in vegetation occurs under specific laws true for this family of elements. (author) 9 refs.; 6 figs.; 5 tabs

  6. Novel online security system based on rare-earth-doped glass microbeads

    Science.gov (United States)

    Officer, Simon; Prabhu, G. R.; Pollard, Pat; Hunter, Catherine; Ross, Gary A.

    2004-06-01

    A novel fluorescent security label has been produced that could replace numerous conventional fluorescent dyes in document security. This label utilizes rare earth ions doped in a borosilicate glass matrix to produce sharp spectral fluorescence peaks with characteristic long lifetimes due to the rare earth ions. These are subsequently detected by an online detection system based on fluorescence and the long lifetimes to avoid any interference from other fluorophores present in the background. Security is further enhanced by the interaction of the rare earth ions with each other and the effect of the host on the emission spectra and therefore the number of permutations that could be produced. This creates a very secure label with various applications for the security market.

  7. Rare earth oxide doping in oxide cathodes

    International Nuclear Information System (INIS)

    Engelsen, Daniel den; Gaertner, Georg

    2006-01-01

    The effect on life performance and poisoning with O 2 by doping oxide cathodes with rare earth oxides and pseudo rare earth oxides, notably yttria, is qualitatively explained in terms of electrolysis of BaO during emission of electrons. Doped cathodes show less electrolysis and consume therefore less Ba during life: consequently, doped cathodes have a better life performance. However, the lower Ba-production makes doped cathodes more sensitive to oxygen poisoning. The experimentally found relation between conductivity and yttria concentration was the motive to propose a new model for the crystal imperfections in BaO. In this new imperfection model most Y 3+ -ions will combine with barium vacancies, therefore, the increase of the conductivity is modest and also the effect on the position of the Fermi level is modest. By assuming a combination of bulk and surface conductivity, the agreement between experiment and theory can be improved further

  8. Nano rare-earth oxides induced size-dependent vacuolization: an independent pathway from autophagy.

    Science.gov (United States)

    Zhang, Ying; Yu, Chenguang; Huang, Guanyi; Wang, Changli; Wen, Longping

    2010-09-07

    Four rare earth oxides have been shown to induce autophagy. Interestingly, we often noticed plentiful vacuolization, which was not always involved in this autophagic process. In this study, we investigated three other rare-earth elements, including Yttrium (Y), Ytterbium (Yb), and Lanthanum (La). Autophagic effect could be induced by all of them but only Y(2)O(3) and Yb(2)O(3) could cause massive vacuolization. Y(2)O(3) and Yb(2)O(3) treated by sonication or centrifugation to reduce particle size were used to test vacuolization level in HeLa cell lines. The results showed that rare earth oxides-induced vacuolization is size-dependent and differs from autophagic pathway. To further clarify the characteristics of this autophagic process, we used MEF Atg-5 (autophagy associated gene 5) knockout cell line, and the result showed that the autophagic process induced by rare earth oxides is Atg-5-dependent and the observed vacuolization was independent from autophagy. Similar results could also be observed in our tests on 3-methyladenine(3-MA), a well-known autophagy inhibitor. In conclusion, for the first time, we clarified the relationship between massive vacuolization and autophagic process induced by rare earth oxides and pointed out the size effect of rare earth oxides on the formation of vacuoles, which give clues to further investigation on the mechanisms underlying their biological effects.

  9. Two main and a new type rare earth elements in Mg alloys: A review

    Science.gov (United States)

    Kong, Linghang

    2017-09-01

    Magnesium (Mg) alloys stand for the lightest structure engineering materials. Moreover, the strengthening of Mg alloys in ductility, toughness and corrosion predominates their wide applications. With adding rare earth elements in Mg, the mechanical properties will be improved remarkably, especially their plasticity and strength. A brief overview of the addition of rare earth elements for Mg alloys is shown. The basic mechanisms of strengthening Mg alloys with rare earth elements are reviewed, including the solid solution strengthening, grain refinement and long period stacking ordered (LPSO) phase. Furthermore, the available rare earth elements are summarized by type, chemical or physical effects and other unique properties. Finally, some challenge problems that the research is facing and future expectations of ra-re-earth Mg alloys are stated and discussed.

  10. Thermochemical analysis on rare earth complex of gadolinium with salicylic acid and 8-hydroxyquinoline

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Sheng-Xiong, E-mail: 54xsx@163.com [Hunan Provincial Key Laboratory of Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan Province (China); Li, Ai-Tao; Jiang, Jian-Hong; Huang, Shuang; Xu, Xiao-Yan; Li, Qiang-Guo [Hunan Provincial Key Laboratory of Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan Province (China)

    2012-11-20

    Highlights: Black-Right-Pointing-Pointer A new novel rare earth complex Gd(C{sub 7}H{sub 5}O{sub 3}){sub 2}{center_dot}(C{sub 9}H{sub 6}NO) was synthesized and characterized. Black-Right-Pointing-Pointer The dissolution enthalpies of the relevant substances were determined. Black-Right-Pointing-Pointer The enthalpy change of the reaction was determined to be (211.54 {+-} 0.69) kJ mol{sup -1}. Black-Right-Pointing-Pointer The standard molar enthalpy of formation of complex was -(1890.7 {+-} 3.1) kJ mol{sup -1}. - Abstract: The rare earth complex, Gd(C{sub 7}H{sub 5}O{sub 3}){sub 2}{center_dot}(C{sub 9}H{sub 6}NO), was synthesized by the reaction of Gadolinium nitrate hexahydrate with salicylic acid (C{sub 7}H{sub 6}O{sub 3}) and 8-hydroxyquinoline (C{sub 9}H{sub 7}NO). And it was characterized by elemental analysis, UV spectra, IR spectra, molar conductance and thermogravimetric analysis. In a optimalizing calorimetric solvent, the dissolution enthalpies were determined by an advanced solution-reaction isoperibol microcalorimeter, respectively: {Delta}{sub s}H{sub m}{sup {Theta}} [2 C{sub 7}H{sub 6}O{sub 3}(s) + C{sub 9}H{sub 7}NO(s), 298.15 K] = 41.95 {+-} 0.44 kJ mol{sup -1}, {Delta}{sub s}H{sub m}{sup {Theta}} [Gd(NO{sub 3}){sub 3}{center_dot}6H{sub 2}O(s), 298.15 K] = -29.11 {+-} 0.39 kJ mol{sup -1}, {Delta}{sub s}H{sub m}{sup {Theta}} [Gd(C{sub 7}H{sub 5}O{sub 3}){sub 2}{center_dot}(C{sub 9}H{sub 6}NO)(s), 298.15 K] = -46.99 {+-} 0.39 kJ mol{sup -1} and {Delta}{sub s}H{sub m}{sup {Theta}} [Solution D(aq), 298.15 K] = -90.33 {+-} 0.37 kJ mol{sup -1}. The enthalpy change of the synthesized reaction was estimated to be {Delta}{sub r}H{sub m}{sup {Theta}}=211.54{+-}0.69 kJ mol{sup -1}. From data in the literature, through Hess' law, the standard molar enthalpy of formation of Gd(C{sub 7}H{sub 5}O{sub 3}){sub 2}{center_dot}(C{sub 9}H{sub 7}NO)(s) was calculated to be {Delta}{sub f}H{sub m}{sup {Theta}} [Gd(C{sub 7}H{sub 5}O{sub 3}){sub 2}{center_dot}(C{sub 9}H

  11. Application of 241Am EDXRF to the determination of rare earth samples of solvent extraction processes

    International Nuclear Information System (INIS)

    Yan Chunhua; Jia Jiangtao; Liao Chunsheng; Li Biaoguo

    1998-01-01

    A rapid energy dispersive X-ray fluorescence spectroscopy (EDXRF) analysis system is established to determine rare earth concentrations. The characteristic K-shell series X-rays of rare earths were excited by a 1.1 x 10 9 Bq 241 Am radioisotope source. The spectra were recorded and analyzed using a multi-channel analyzer, employing a high-purity Ge detector. In this method, the Compton scattering peak, absorption of elements, and specific simplification are considered. Samples of light, middle and heavy rare earths during separation processes in both hydrochloride solution and rare earth loaded organic phases were analyzed off-line. Some comparative results measured by ICP are also given. The results show that the method can be used for a wide range of rare earth concentrations (0.1-300 g l -1 rare earth oxide). Being rapid, effective, precise and non-destructive, the method can be applied to on-line analysis to determine rare earth concentrations during separation by solvent extraction. (orig.)

  12. Extreme magnetoresistance in magnetic rare-earth monopnictides

    Science.gov (United States)

    Ye, Linda; Suzuki, Takehito; Wicker, Christina R.; Checkelsky, Joseph G.

    2018-02-01

    The acute sensitivity of the electrical resistance of certain systems to magnetic fields known as extreme magnetoresistance (XMR) has recently been explored in a new materials context with topological semimetals. Exemplified by WTe2 and rare-earth monopnictide La(Sb,Bi), these systems tend to be nonmagnetic, nearly compensated semimetals and represent a platform for large magnetoresistance driven by intrinsic electronic structure. Here we explore electronic transport in magnetic members of the latter family of semimetals and find that XMR is strongly modulated by magnetic order. In particular, CeSb exhibits XMR in excess of 1.6 ×106% at fields of 9 T whereas the magnetoresistance itself is nonmonotonic across the various magnetic phases and shows a transition from negative magnetoresistance to XMR with fields above magnetic ordering temperature TN. The magnitude of the XMR is larger than in other rare-earth monopnictides including the nonmagnetic members and follows a nonsaturating power law to fields above 30 T. We show that the overall response can be understood as the modulation of conductivity by the Ce orbital state and for intermediate temperatures can be characterized by an effective medium model. Comparison to the orbitally quenched compound GdBi supports the correlation of XMR with the onset of magnetic ordering and compensation and highlights the unique combination of orbital inversion and type-I magnetic ordering in CeSb in determining its large response. These findings suggest a paradigm for magneto-orbital control of XMR and are relevant to the understanding of rare-earth-based correlated topological materials.

  13. Port Pirie rare earths plant stage 3

    International Nuclear Information System (INIS)

    1990-08-01

    SX Holdings Limited intends to establish a rare earths plant at Port Pirie, South Australia. The proposal involves three stages of development, Stage 3 being to develop a monazite cracking plant and associated rare earths separation facility with the capacity to process up to 8,000 t/a of monazite-type ores. The proposed initial capacity is 4,000 t/a. This Draft Environmental Impact Statement relates to Stage 3 and is based on a monazite processing capacity of 8,000 t/a. The justification of the project is given in terms of use and the market for rare earths, the economic and environmental benefits of the proposal, the site selection process, site rehabilitation, and the consequences of not proceeding. A detailed description of the project is given, including the treatment process, site development and facilities, the supply of raw materials, product and waste handling, transport and storage, plant commissioning, operation and decommissioning, construction and staffing. The environmental issues entailed in the proposed development are discussed and include social effects, land use and infrasturcture considerations, risk management and transport. Occupational and environmental radiation issues, including assessments of exposure pathways and doses, management and monitoring, disposal of monosite residue are also discussed. It is estimated that the effects of disposal of 2,330 t/year of radioactive slurry in the sub-aerial tailing disposal system at Olympic Dam will be negligible. Moreover, the gamma dose increases would not result in any significant increase in occupational exposures. 38 refs., tabs., ills

  14. The Brazilian nuclear industries - INB - in the field of the rare earth

    International Nuclear Information System (INIS)

    Blatt, Victoria

    1996-01-01

    The Brazilian Nuclear Industries - INB is responsible for the execution of part of the cycle of uranium as nuclear reactor fuel for alternative energy generation. Soon INB shall increase the participation in this cycle, through the implantation of the line of powder and pastille. INB is also the successor of the monazite processing industries. The last one was NUCLEMON that was incorporated by INB. The connection of INB with this area is due to the presence of the strategic elements uranium and thorium in the monazite. The know-how was and continues to be developed by a chemical team of the National Commission of Nuclear Energy (CNEN) with the collaboration of the technical team of INB. The ever wider applications of the individual Rare Earth in the most different fields of the electrical, electronics, communication, optical, metallurgical, catalysis and other industries, as well as INB incessant inquire for the economical workability, brought INB to appraise the position regarding to the industrial production of the Rare Earth. The choice is bringing to the separation and commercialization of the individual elements and/or in groups containing a reduced number of Rare Earth, instead of the production and commercialization of the mixture of monazitic Rare Earth. This paper illustrates through quantitative information some aspects regarding to reserves, mining and physical separations of the monazite, as well as projections about INB resuming its industrial activities with insertion of technical improvements in both, the chemical treatment of the monazite and the Rare Earth separation. In this field, there will be presented in this paper the qualitative and quantitative results recently reached in a large dimension pilot plant. These results add to the technical conquest reached in the late years by the foregoers of INB, and that will be also presented. The paper contains also some appreciations regarding to the perspectives of INB's ingression in the field of

  15. Rare-earth elements

    Science.gov (United States)

    Van Gosen, Bradley S.; Verplanck, Philip L.; Seal, Robert R.; Long, Keith R.; Gambogi, Joseph; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    The rare-earth elements (REEs) are 15 elements that range in atomic number from 57 (lanthanum) to 71 (lutetium); they are commonly referred to as the “lanthanides.” Yttrium (atomic number 39) is also commonly regarded as an REE because it shares chemical and physical similarities and has affinities with the lanthanides. Although REEs are not rare in terms of average crustal abundance, the concentrated deposits of REEs are limited in number.Because of their unusual physical and chemical properties, the REEs have diverse defense, energy, industrial, and military technology applications. The glass industry is the leading consumer of REE raw materials, which are used for glass polishing and as additives that provide color and special optical properties to the glass. Lanthanum-based catalysts are used in petroleum refining, and cerium-based catalysts are used in automotive catalytic converters. The use of REEs in magnets is a rapidly increasing application. Neodymium-iron-boron magnets, which are the strongest known type of magnets, are used when space and weight are restrictions. Nickel-metal hydride batteries use anodes made of a lanthanum-based alloys.China, which has led the world production of REEs for decades, accounted for more than 90 percent of global production and supply, on average, during the past decade. Citing a need to retain its limited REE resources to meet domestic requirements as well as concerns about the environmental effects of mining, China began placing restrictions on the supply of REEs in 2010 through the imposition of quotas, licenses, and taxes. As a result, the global rare-earth industry has increased its stockpiling of REEs; explored for deposits outside of China; and promoted new efforts to conserve, recycle, and substitute for REEs. New mine production began at Mount Weld in Western Australia, and numerous other exploration and development projects noted in this chapter are ongoing throughout the world.The REE-bearing minerals are

  16. Contribution to the study of rare earth separation by ion exchange, using ammonium lactate

    International Nuclear Information System (INIS)

    Gratot, I.

    1958-01-01

    Using the technique of chromatography on a column of Dowex 50 resin, heated to 87 deg. C, we have studied the separation of rare earths (from holmium to praseodymium) which may be produced with the cyclotron by heavy ions, α or protons. From an ammonium lactate solution M at pH 5, separations are carried out by varying the dilution as a function of the quantity of the target rare earth and of its position during elution. When weighable quantities of the rare earth (more than 5 mg) appear towards the end of the elution, the separation is little affected this case approaches that of a tracer mixture of rare earths; if on the other hand weighable quantities of the rare earth are washed through at the beginning of the chromatogram, the dilution must be adjusted in order to obtain a good separation. (author) [fr

  17. Determination of rare earth elements by liquid chromatography/inductively coupled plasma atomic emission spectrometry

    International Nuclear Information System (INIS)

    Yoshida, K.; Haraguchi, H.

    1984-01-01

    Inductively coupled plasma atomic emission spectrometry (ICP-AES) interfaced with high-performance liquid chromatography (HPLC) has been applied to the determination of rare earth elements. ICP-AES was used as an element-selective detector for HPLC. The separation of rare earth elements with HPLC helped to avoid erroneous analytical results due to spectral interferences. Fifteen rare earth elements (Y and 14 lanthanides) were determined selectively with the HPLC/ICP-AES system using a concentration gradient method. The detection limits with the present HPLC/ICP-AES system were about 0.001-0.3 μg/mL with a 100-μL sample injection. The calibration curves obtained by the peak height measurements showed linear relationships in the concentration range below 500 μg/mL for all rare earth elements. A USGS rock standard sample, rare earth ores, and high-purity lanthanide reagents (>99.9%) were successfully analyzed without spectral interferences

  18. Synthesis and crystal structure of rare earth complexes with o-nitrobenzoic acid and N, N-dimethylformamide

    Science.gov (United States)

    Zhao, Lifang; Chen, Yashao; Bao, Lin

    2010-03-01

    The rare-earth compound [Ce 0.5Sm 0.5( o-NBA) 3(DMF) 2] 2 (where o-NBA = o-nitrobenzoic acid, DMF = N, N-dimethylformamide) has been synthesized and structurally characterized. The crystal structure of the compound is characterized by Fourier transfer infrared spectroscopy (FT-IR), fluorescent emission spectroscopy (FES) and single-crystal X-ray diffraction. The results show that the compound crystallizes in a triclinic system, space group P-1 with a = 11.8284 (6) Å, b = 12.5082 (7) Å, c = 13.0203 (7) Å, α = 63.9650 (10)°, β = 66.3900 (10)°, γ = 71.7380 (10)°, V = 1563.7 (14) Å 3, Dc = 1.677 g/cm 3, Z = 1, F(0 0 0) = 790. Each Ln (III) atom is bridged by four o-nitro-benzoates and chelated by one o-nitrobenzoate. The Ln (III) atom is eight-coordinated by six oxygen atoms from five o-nitro-benzoates and two oxygen atoms from two DMF molecules. Hydrogen bonds and aromatic π⋯ π stacking interactions assemble the compound into a three-dimensional network. Luminescence measurement shows that the compound emits fluorescence.

  19. Diagnostic study about lanthanides (rare earths)

    International Nuclear Information System (INIS)

    Ribeiro, G.F.

    1985-01-01

    The world situation of rare earths (lanthanides) is evaluated, and a comparison of the Brazilian situation in respect to other countries is established, concerning the following aspects: geology of mineral deposits; main sources, uses, reserves and production; their consumption, prices and state-of-art of geological researches and industrial processes for physical and chemical separation / concentration of these elements. (C.L.B.) [pt

  20. Rare earth phosphors and phosphor screens

    International Nuclear Information System (INIS)

    Buchanan, R.A.; Maple, T.G.; Sklensky, A.F.

    1981-01-01

    Advances in the use of stabilized rare earth phosphors and of conversion screens using these materials are examined. In particular the new phosphors discussed in this invention consist of oxybromides of yttrium, lanthanum and gadolinium with a luminescent activator ion stabilized by an oxychloride or oxyfluoride surface layer and the conversion screens include trivalent cerium as the activator ion. (U.K.)

  1. Antiferromagnetic correlations in icosahedral R-Mg-Zn quasicrystals (R rare earth)

    Energy Technology Data Exchange (ETDEWEB)

    Charrier, B; Schmitt, D [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France); Ouladdiaf, B [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Powder neutron-diffraction experiments performed on R-Mg-Zn quasicrystals have shown for the first time the existence of magnetic ordering of the rare earth in these systems at low temperature (T{sub c} {<=} 6.5 K depending on the rare earth). Both narrow and broad magnetic diffraction peaks have been observed showing the presence of two different scales of magnetic correlations. (author). 3 refs.

  2. Use of EDTA for potentiometric back titration of rare earths and analysis of their mixtures

    International Nuclear Information System (INIS)

    Zayed, M.A.; Rizk, M.S.; Khalifa, H.; Omer, W.F.

    1987-01-01

    Advantage was taken of the stoichiometric reaction between mercury(II), rare earths, alkaline earths, heavy metal ions and EDTA in urotropine buffered media to determine rare earths by back-titration of excess EDTA in the course of estimating a variety of lanthanides or analysing their binary mixture with one of the alkaline earth metals by selective control of pH; or analysing their binary mixtures with heavy metals using fluoride as a good masking agent for rare earths; or analysing their ternary mixtures with both heavy and alkaline earth metals in two steps, one by selective control of pH and the other by masking of rare earths with fluoride at lower pH to estimate the heavy metal. The procedures given are simple, rapid and extremely reliable. 19 refs. (author)

  3. Separation of rare earth mixtures by gas chromatography using dipivaloylmethane as complexing agent

    International Nuclear Information System (INIS)

    Golubtsova, V.Yu.; Luchinkin, V.V.; Martynenko, L.I.; Murav'eva, I.A.; Sokolov, D.N.

    1981-01-01

    Possibility of using dipivaloylmethave for quantitative separation of rare earth element mixtures under the regime of chromatography for preparative and analytical purposes, is studied. Introduction of β-diketone surplus into the chromatographic solution is shown to remove the necessity of column conditioning. It is stated that chelate solution should have concentration above the threshold one. The developed method is applicable for quantitative separation of some rare earth mixtures for preparative purposes, as well as for the analysis of rare earth mixtures, containing components in equivalent quantities [ru

  4. Neural Network Modeling for the Extraction of Rare Earth Elements from Eudialyte Concentrate by Dry Digestion and Leaching

    Directory of Open Access Journals (Sweden)

    Yiqian Ma

    2018-04-01

    Full Text Available Eudialyte is a promising mineral for rare earth elements (REE extraction due to its good solubility in acid, low radioactive, and relatively high content of REE. In this paper, a two stage hydrometallurgical treatment of eudialyte concentrate was studied: dry digestion with hydrochloric acid and leaching with water. The hydrochloric acid for dry digestion to eudialyte concentrate ratio, mass of water for leaching to mass of eudialyte concentrate ratio, leaching temperature and leaching time as the predictor variables, and the total rare earth elements (TREE extraction efficiency as the response were considered. After experimental work in laboratory conditions, according to design of experiment theory (DoE, the modeling process was performed using Multiple Linear Regression (MLR, Stepwise Regression (SWR, and Artificial Neural Network (ANN. The ANN model of REE extraction was adopted. Additional tests showed that values predicted by the neural network model were in very good agreement with the experimental results. Finally, the experiments were performed on a scaled up system under optimal conditions that were predicted by the adopted ANN model. Results at the scale-up plant confirmed the results that were obtained in the laboratory.

  5. Effect of the kind of alkaline and rare earth ions on the structure of a glass rich in earth

    International Nuclear Information System (INIS)

    Quintas, Arnaud; Caurant, Daniel; Majerus, Odile; Lenoir, Marion; Dussossoy, Jean-Luc; Charpentier, Thibault; Neuville, Daniel R.; Gervais, C.

    2006-01-01

    In the framework of a structural study of a nuclear wastes containment glass of type alumino borosilicate and rich in rare earths, the influence of the kind of alkaline or rare earth ions is analyzed. For that, two glasses series have been prepared in which the Na + ion (respectively Ca 2+ ions) present in the standard composition is totally substituted by another alkaline ion Li + , K + , Rb + or Cs + (respectively another rare earth ion Mg 2+ , Sr 2+ or Ba 2+ ). These glasses, analyzed by optical absorption, Raman and 27 Al or 11 B NMR spectroscopies have revealed the strong impact of the kind of the modifying ion as well as the structure of the vitreous lattice (variation of the ratio BO 3 /BO 4 and local variations of the polymerization degree) than the local surroundings of the rare earth (decrease of the covalency degree of the bond Nd-O with the increase of the field force of the modifying ion). (O.M.)

  6. Exploitation of rare earth catalysts in polymer syntheses

    Institute of Scientific and Technical Information of China (English)

    Shen Zhiquan

    2006-01-01

    The studies over forty years on rare earth catalysts in polymer syntheses of diene,alkyne,alkylene oxide,thiirane, carbon dioxide copolymerization, lactide,caprolactone,cyclic carbonate and so forth in China have been reviewed.

  7. Relationship between accumulation of rare earth element in tumor and ionic radius

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, N [Kanazawa Univ. (Japan). School of Medicine

    1975-02-01

    The accumulation of rare earth elements in the different organs of Ehrlich's tumor-bearing mice at 48 hours after intraperitoneal administration was measured by a Ge(Li) semiconductor detector. Accumulation of all the rare earth elements was the highest in the pancreas. Accumulation of /sup 152/Eu in the different organs of Ehrlich's tumor-bearing mice was very high. The accumulation of rare earth elements in Ehrlich's tumor was lower than the accumulation of /sup 67/Ga and /sup 46/Sc. The tumor-organ concentration ratio of rare earth elements was remarkably lower than the accumulation of /sup 67/Ga and /sup 46/Sc. However, the accumulation of /sup 152/Eu in Ehrlich's tumor was somewhat higher than that of /sup 67/Ga. The relationship between the accumulation and the carrier content was examined. The lower the carrier content was, the higher was the accumulation in different organs. However, the carrier effect of rare earth on the uptake in different organs elements was slight. The author postulated that the elements in which the ionic radius is similar to that of Mg(0.62 A) or Ca(0.99 A) are abundant in the tumor cell membrane, and they might pass through the tumor cell membrane much more easily than would the other elements. However, the result was negative.

  8. Research on manufacturing aluminum - rare earth alloy with a high content of rare earth (> 20% RE) from total rare earth oxides by thermit reduction

    International Nuclear Information System (INIS)

    Ngo Trong Hiep; Dam Van Tien; Tran Duy Hai; Ngo Xuan Hung and Ly Thanh Vu

    2004-01-01

    In this report, several theoretical principles of thermit reduction method used for metal oxides to obtain metals, ferroalloys and ligatua with technical purity are presented. Manufacture of aluminum-rare earth alloys by thermit reduction is also described in the report. Data that are generalized based on thermo-kinetic calculation of the thermit reduction and selection of technological flow-sheet based on thermal effect will partly clarify research results in investigating typical features of the process and identify measures to reduce metal loss in discharged slags. (author)

  9. Social and Environmental Impact of the Rare Earth Industries

    Directory of Open Access Journals (Sweden)

    Saleem H. Ali

    2014-02-01

    Full Text Available The use of rare earth elements in various technologies continues to grow despite some alternatives being found for particular uses. Given a history of ecological concerns about pollution from rare earth mines, particularly in China, there are growing social and environmental concerns about the growth of the mining and mineral processing in this sector. This is best exemplified by the recent social and environmental conflict surrounding the development of the Lynas Advanced Materials Plant (LAMP in Kuantan, Malaysia which led to international activism and claims of environmental and social injustice. This paper analyses the structure of environmental and social conflicts surrounding rare earth minerals and opportunities for improving the social and environmental performance of the sector. Many of these elements are used for green technologies. Opportunities exist that offer a more circular supply chain following industrial ecological principles through which reuse and recycling of the materials can provide a means of mitigating social and environmental conflicts in this sector. In addition, public engagement processes that recognize community concerns about radiation, and transparent scientifically predicated decision-making through an appropriate governance structure within regulatory organizations are also presented.

  10. The magnetoresistivity of some rare-earth metals

    International Nuclear Information System (INIS)

    Webber, G.D.

    1978-10-01

    The thesis describes measurements of the low temperature transverse magnetoresistivities of single crystals of rare-earth metals in magnetic fields up to 8 Tesla. A general introduction to the rare-earths, their magnetic properties and a review of the basic theory and mechanism of magnetoresistivity is given. Details of the crystal structure, growth of single crystals and sample mounting method follow. The experimental equipment and measuring techniques are then described. The low temperature transverse magnetoresistivity of polycrystalline lanthanum and single crystal praseodymium for the temperature range 4.2 - 30K is measured. The separation of the spin-disorder and Fermi-surface orbital effect contributions are described and the theoretical and experimental spin-disorder values compared. Magnetoresistivity measurements for neodymium single crystals (4.2 - 30K) are compared with the magnetic properties determined from neutron diffraction studies. Results for gadolinium single crystals (4.2 - 200K) are compared for two different impurity levels and with previous work. (UK)

  11. China's Rare Earth Supply Chain: Illegal Production, and Response to new Cerium Demand

    Science.gov (United States)

    Nguyen, Ruby Thuy; Imholte, D. Devin

    2016-07-01

    As the demand for personal electronic devices, wind turbines, and electric vehicles increases, the world becomes more dependent on rare earth elements. Given the volatile, Chinese-concentrated supply chain, global attempts have been made to diversify supply of these materials. However, the overall effect of supply diversification on the entire supply chain, including increasing low-value rare earth demand, is not fully understood. This paper is the first attempt to shed some light on China's supply chain from both demand and supply perspectives, taking into account different Chinese policies such as mining quotas, separation quotas, export quotas, and resource taxes. We constructed a simulation model using Powersim Studio that analyzes production (both legal and illegal), production costs, Chinese and rest-of-world demand, and market dynamics. We also simulated new demand of an automotive aluminum-cerium alloy in the US market starting from 2018. Results showed that market share of the illegal sector has grown since 2007-2015, ranging between 22% and 25% of China's rare earth supply, translating into 59-65% illegal heavy rare earths and 14-16% illegal light rare earths. There will be a shortage in certain light and heavy rare earths given three production quota scenarios and constant demand growth rate from 2015 to 2030. The new simulated Ce demand would require supply beyond that produced in China. Finally, we illustrate revenue streams for different ore compositions in China in 2015.

  12. Rare earth (3) pivalates

    International Nuclear Information System (INIS)

    Kuz'mina, N.P.; Martynenko, L.I.; Zoan An' Tu; Ch'eu Tkhi Nguet; Troyanov, S.I.; Rykov, A.N.; Korenev, Yu.M.

    1994-01-01

    Depending on synthesis conditions rare earth pivalates can be obtained in the form of either adducts NPiv·HPiv or hydrates MPiv 3 ·mH 2 O. Adducts are the most stable form of pivalates. Heating of adducts result in formation of corresponding MPiv 3 . MPiv 3 ·nHPiv compounds are characterized by IR-spectroscopy and thermal analysis data. Behaviour of MPiv 3 was studied in the regime of vacuum sublemation. Using mass spectroscopy of NdPiv 3 it was shown that gaseous phase above MPiv 3 had complex composition and contained ligomer fragments. X-ray structure analysis of [NdPiv 3 ·3HPiv] was conducted

  13. Thermoelectric transport in rare-earth compounds

    International Nuclear Information System (INIS)

    Koehler, Ulrike

    2007-01-01

    This work focuses on the thermoelectric transport in rare-earth compounds. The measurements of the thermal conductivity, thermopower, and Nernst coefficient are supplemented by investigations of other quantities as magnetic susceptibility and specific heat. Chapter 2 provides an introduction to the relevant physical concepts. Section 1 of that chapter summarizes the characteristic properties of rare-earth systems; section 2 gives an overview on thermoelectric transport processes in magnetic fields. The applied experimental techniques as well as the new experimental setup are described in detail in Chapter 3. The experimental results are presented in Chapter 4-6, of which each concentrates on a different subject. In Chapter 4, various Eu clathrates and the skutterudite-like Ce 3 Rh 4 Sn 13 are presented, which have been investigated as potential thermoelectric materials for applications. Chapter 5 focusses on the study of the energy scales in the heavy-fermion series Lu 1-x Yb x Rh 2 Si 2 and Ce x La 1-x Ni 2 Ge 2 by means of thermopower investigations. Chapter 6 is dedicated to the thermoelectric transport properties of the correlated semimetal CeNiSn with special emphasis on the Nernst coefficient of this compound. (orig.)

  14. K isomerism and collectivity in neutron-rich rare-earth isotopes.

    OpenAIRE

    Patel, Zena

    2016-01-01

    Neutron-rich rare-earth isotopes were produced by in-flight fission of 238U ions at the Radioactive Isotope Beam Factory (RIBF), RIKEN, Japan. In-flight fission of a heavy, high-intensity beam of 238U ions on a light target provides the cleanest secondary beams of neutron-rich nuclei in the rare-earth region of isotopes. In-flight fission is advantageous over other methods of nuclear production, as it allows for a secondary beam to be extracted, from which the beam species can be separated an...

  15. Separation of rare earth metal using micro solvent extraction system

    International Nuclear Information System (INIS)

    Nishihama, S.; Tajiri, Y.; Yoshizuka, K.

    2005-01-01

    A micro solvent extraction system for the separation of rare earth metals has been investigated. The micro flow channel was fabricated on a PMMA plate. Extraction equilibrium was quickly achieved, without any mechanical mixing. The solvent extraction results obtained for the Pr/Sm binary solutions revealed that both rare earth metals are firstly extracted together. Following, the Pr is extracted in the organic solution and Sm remains in the aqueous phase. The phase separation can be successively achieved by contriving the cross section of the flow channel

  16. Significant improvement of accuracy and precision in the determination of trace rare earths by fluorescence analysis

    International Nuclear Information System (INIS)

    Ozawa, L.; Hersh, H.N.

    1976-01-01

    Most of the rare earths in yttrium, gadolinium and lanthanum oxides emit characteristic fluorescent line spectra under irradiation with photons, electrons and x rays. The sensitivity and selectivity of the rare earth fluorescences are high enough to determine the trace amounts (0.01 to 100 ppM) of rare earths. The absolute fluorescent intensities of solids, however, are markedly affected by the synthesis procedure, level of contamination and crystal perfection, resulting in poor accuracy and low precision for the method (larger than 50 percent error). Special care in preparation of the samples is required to obtain good accuracy and precision. It is found that the accuracy and precision for the determination of trace (less than 10 ppM) rare earths by fluorescence analysis improved significantly, while still maintaining the sensitivity, when the determination is made by comparing the ratio of the fluorescent intensities of the trace rare earths to that of a deliberately added rare earth as reference. The variation in the absolute fluorescent intensity remains, but is compensated for by measuring the fluorescent line intensity ratio. Consequently, the determination of trace rare earths (with less than 3 percent error) is easily made by a photoluminescence technique in which the rare earths are excited directly by photons. Accuracy is still maintained when the absolute fluorescent intensity is reduced by 50 percent through contamination by Ni, Fe, Mn or Pb (about 100 ppM). Determination accuracy is also improved for fluorescence analysis by electron excitation and x-ray excitation. For some rare earths, however, accuracy by these techniques is reduced because indirect excitation mechanisms are involved. The excitation mechanisms and the interferences between rare earths are also reported

  17. Rare earth aerosol analysis by x-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Citron, I.M.; Mausner, L.F.

    1982-01-01

    An analytical method for the determination of four lanthanides in air filter samples is described. The method involves simultaneous quantitative determinations of La, Ce, Pr, and Nd at the microgram level by x-ray fluorescence spectrometry without chemical separation of these rare earths and without serious interferences from the dust matrices on the filters. The method has been used successfully to analyze some air filter samples collected at a rare earth processing refinery in Illinois. A description of the development of the method is given as well as the results obtained by using this method on the air filter samples. The reproducibility of the results was generally +-5%

  18. The determination of the rare earth elements in naturally-occurring materials zy flame spectroscopy

    International Nuclear Information System (INIS)

    Watts, J.C.

    1975-01-01

    Because the quantitative collection of the rare-earth elements retains natural abundance ratios, adequate analytical methodology incorporates their individual sensitivities, and tolerates their mutual contamination. To achieve these ends, the sensitivities of 15 rare-earths in flame emission were determined in the unseparated nitrous oxide/acetylene flame, their mutual interference ascertained at practical concentrations, and useful emission lines selected for their determination in natural materials. Sources of atomic emission interference were extraneous in origin. Fe in the determination of Dy and Zr in the determination of Nd. Inter-element interferences of the rare-earth elements were minimal after wavelength selection and reduction of the spectral band width. For comparison, five rare earths were determined by flame AAS. (author)

  19. Science and technology of the rare earth elements

    International Nuclear Information System (INIS)

    Azzouz, Abdelkrim; Chegrouche, Salah; Telmoune, Sid-Ali; Layachi, Lazhar

    1992-07-01

    The present work studies the chemical physics properties, the different methods of analysis (neutron activation, emission spectrometry, chromatography), and the techniques of separation of rare earth (electrodeposition, thermic decomposition, salts distillation and ions exchange)

  20. Clinical comparison of conventional and rare earth screen-film systems for cephalometric radiographs

    International Nuclear Information System (INIS)

    Kaugars, G.E.; Fatouros, P.

    1982-01-01

    This study compared cephalometric and P-A skull films taken with conventional (CaWO4) screens and rare earth screens. Patient exposure was reduced by 17 to 55 percent on two different x-ray machines by the use of rare earth screens. Results from 130 clinical evaluations showed that the diagnostic quality of radiographs taken with either system was roughly comparable. This presents a persuasive argument for the use of rare earth screens since the diagnostic quality of the films can be maintained while significantly reducing the patient's exposure to radiation

  1. Rare Earth Oxide Fluoride Nanoparticles And Hydrothermal Method For Forming Nanoparticles

    Science.gov (United States)

    Fulton, John L.; Hoffmann, Markus M.

    2003-12-23

    A hydrothermal method for forming nanoparticles of a rare earth element, oxygen and fluorine has been discovered. Nanoparticles comprising a rare earth element, oxygen and fluorine are also described. These nanoparticles can exhibit excellent refractory properties as well as remarkable stability in hydrothermal conditions. The nanoparticles can exhibit excellent properties for numerous applications including fiber reinforcement of ceramic composites, catalyst supports, and corrosion resistant coatings for high-temperature aqueous solutions.

  2. Microhardness of epitaxial layers of GaAs doped with rare earths

    International Nuclear Information System (INIS)

    Kulish, U.M.; Gamidov, Z.S.; Kuznetsova, I.Yu.; Petkeeva, L.N.; Borlikova, G.V.

    1989-01-01

    Results of the study of microhardness of GaAS layer doped by certain rare earths - Gd, Tb, Dy - are presented. The assumption is made that the higher is the value of the first potential of rare earth impurity ionization (i.e. the higher is the filling of 4f-shell), the lower is the effect of the element on electric and mechanical properties of GaAs epitaxial layers

  3. Field-induced valence transition in rare-earth system

    International Nuclear Information System (INIS)

    Chattopadhaya, A.; Ghatak, S.K.

    2000-01-01

    The magnetic field-induced valence transition in rare-earth compound has been examined based on a pseudospin S=1 Ising model proposed earlier for valence transition. The model includes finite mixing between two pertinent ionic configurations (magnetic and non-magnetic) separated by an energy gap and with intersite interaction between rare-earth ions. Using the mean field approximation the magnetic behaviour and the critical field (H c ) for transition are obtained as a function of energy gap and temperature. The phase boundary defined in terms of reduced field H c /H co and reduced temperature T/T v (T v being valence transition temperature in absence of field) is nearly independent of energy gap. These results are in qualitative agreement with experimental observation in Yb- and Eu-compounds

  4. Investigation of the evaporation of rare earth chlorides in a LiCl-KCl molten salt

    International Nuclear Information System (INIS)

    Sung Bin Park; Dong Wook Cho; Moon Sik Woo; Sung Chan Hwang; Young Ho Kang; Jeong Guk Kim; Hansoo Lee

    2011-01-01

    Uranium dendrites which were deposited at a solid cathode of an electrorefiner contained a certain amount of salts. These salts should be removed for the recovery of pure metal using a cathode processor. In the uranium deposits from the electrorefining process, there are actinide chlorides and rare earth chlorides in addition to uranium chloride in the LiCl-KCl eutectic salt. The evaporation behaviors of the actinides and rare earth chlorides in the salts should be investigated for the removal of salts in the deposits. Experiments on the salt evaporation of rare earth chlorides in a LiCl-KCl eutectic salt were carried out. Though the vapor pressures of the rare earth chlorides were lower than those of the LiCl and KCl, the rare earth chlorides were co-evaporized with the LiCl-KCl eutectic salt. The Hertz-Langmuir relation was applied for this evaporation, and also the evaporation rates of the salt were obtained. The co-evaporation of the rare earth chlorides and LiCl-KCl eutectic were also discussed. (author)

  5. Investigations on the determination of traces of some rare earths (Eu, Sm, Gd, Y) in oxides of rare earths (Y2O3, Sm2O3, Gd2O3) by emission spectrography in d.c. arc

    International Nuclear Information System (INIS)

    Dittrich, K.; Gajek, M.; Luan, P.

    1978-01-01

    The evaporation of traces and matrices of rare earth elements was investigated in different atmospheres. It was found, that low-boiling rare earths elements, because of their extended formation of carbides evaporate more slowly than high-boiling rare earths elements. The evaporation of the traces depends on the matrices. 3 cases for the determination of traces of rare earths elements in oxides of other rare earths elements are derived from the results of the evaporation: Low- to high-boiling traces of rare earths elements in low-boiling matrices of rare earths elements, low-boiling traces in medium- to high-boiling matrices, and medium- to high-boiling traces in medium- to high-boiling matrices. The results of the determination are: in Y 2 O 3 : 14 ppm Sm, 2 ppm Eu; in Gd 2 O 3 : 18 ppm Y, 3 ppm Sm, 2 ppm Eu; in Sm 2 O 3 : 70 ppm Y, 370 ppm Gd, 16 ppm Eu. (author)

  6. Ion exchange separation of rare earths. I

    International Nuclear Information System (INIS)

    Nghi, Nguyen danh; Matous, K.

    1977-01-01

    The optimal conditions of separating selected rare earths by two ion exchange chromatography using Ostion KS cation exchange resin were studied. The effect of acetic acid concentration in the sorption solution was investigated. The elution process was studied in dependence on the concentration of Na 2 H 2 EDTA, on the total concentration of EDTA 4- ion, on elution agent flow, and on temperature. The optimal conditions were determined by evaluating integral elution curves and changes in acid concentration for systems Y-Pr, La-Pr, Er-Pr, Eu-Pr as follows: The sorption solution requires the presence of Na 2 H 2 EDTA of 0.03M in concentration. The basic elution solution was prepared in the following way: 0.183M Na 2 Mg 2 EDTA, 9.6x10 -3 M Na 2 H 2 EDTA, 3.84x10 -3 M CH 3 COOH, 2.30x10 -2 M CH 3 COONH 4 , 2.30x10 -2 M (NH 4 ) 2 SO 4 . Approximate pH 5.7 to 6.0. The optimal elution solution was prepared by diluting the basic solution so that the total concentration of EDTA 4- equalled 0.075M. The optimal flow was determined to be 0.86 ml.cm -2 .min -1 at a temperature of 55 degC. (author)

  7. Activation analysis of rare-earth elements in opium and cannabis samples. [Neutron reactions

    Energy Technology Data Exchange (ETDEWEB)

    Henke, G [Muenster Univ. (Germany, F.R.). Inst. fuer Pharmazeutische Chemie

    1977-01-01

    Rare-earth concentrations in 65 Opium, Cannabis and Cannabis resin samples seized from various parts of the world were determined by destructive NAA. Because of the greater concentrations of Ca, P, K, Fe, Na and Si in plant materials, rare-earth elements were isolated after neutron irradiation and determined by gamma-spectrometry. The main steps of the method are: Preashing of 1 g Cannabis resin, 2.5 g Cannabis, or 7.5 g Opium, respectively, in quartz ampoules (5 h, 500 deg C). Neutron irradiation, 24 h at 5x10/sup 13/n cm/sup -2/sec/sup -1/. Cooling period 2-3 days. After addition of 0.1 ..mu..Ci /sup 139/Ce and rare-earth carriers wet ashing of irradiated samples with H/sub 2/SO/sub 4//HNO/sub 3/, followed by alternate addition of HNO/sub 3/ and H/sub 2/O/sub 2/ (30%). Precipitation and removal of silicates, precipitation of fluorides, precipitation of hydroxides. Dissolution of hydroxides in HCl. Extraction with di-(2-ethylhexyl)phosphate (DEHP)/toluene and twice back-extraction of rare earths, gamma-spectrometry of HCl phase. Due to sample activity and half-life of nuclides, three measurements were made on each sample: 2 days (for La, Sm, Gd, Ho, Er, Yb); 14 days (for Nd, Lu) and 30 days after irradiation (for Ce, Eu, Tb). Great variations in absolute element concentrations, but only small significant differences of rare earth concentration ratios were found, indicating inconsiderable biogeochemical fractionation. The mean values of these ratios correspond to the relative abundances of the rare earths in the upper continental earth's crust.

  8. Rare earth metals in North America; Zeldzame aardmetalen in Noord-Amerika

    Energy Technology Data Exchange (ETDEWEB)

    Louzada, K.

    2012-11-15

    The uncertain supply of rare earth metals (Rare Earth Elements) from China for the high tech industry in the U.S. is a barrier for innovation and the high-tech manufacturing industry. Many rare earths are applied in permanent magnets for sustainable energy generation and for energy storage systems in for example electric cars. Also other sectors feel the pressure of shortages. The federal government in the USA and US companies use the opportunity to encourage research into recycling, reducing the use and finding alternatives for rare earths. Canada sees in the uncertain supply and dwindling reserves in the USA and elsewhere an economic opportunity. Canada can start the development of hitherto unprofitable reserves of valuable materials. Both in the USA and Canada, the number of exploration projects in the mining industry has grown significantly [Dutch] De onzekere aanvoer van zeldzame aardmetalen (Rare Earth Elements) uit China voor de hightechindustrie vormt in de VS een hindernis voor innovatie en voor de hightech maakindustrie. Met name in permanente magneten voor duurzame energieopwekking en energieopslagsystemen voor bijvoorbeeld elektrische auto's worden veel zeldzame aardmetalen verwerkt. Ook andere sectoren staan onder druk. De federale overheid en bedrijven in de VS maken van de gelegenheid gebruik om onderzoek naar de recycling, vermindering van het gebruik en alternatieven voor zeldzame aardmetalen te stimuleren. Canada ziet de onzekere aanvoer en slinkende reserves in de VS en elders als een economische kans. Het land kan tot nu toe onrendabele voorkomens van de waardevolle materialen gaan ontwikkelen. Zowel in de VS als in Canada is het aantal exploratieprojecten in de mijnbouw aanzienlijk gegroeid.

  9. Structure and spectroscopy of rare earth – Doped lead phosphate glasses

    International Nuclear Information System (INIS)

    Pisarski, Wojciech A.; Żur, Lidia; Goryczka, Tomasz; Sołtys, Marta; Pisarska, Joanna

    2014-01-01

    Highlights: • Lead phosphate glasses doped with rare earth ions were prepared. • The local structure was examined using X-ray diffraction and spectroscopic methods. • Different structural phosphate groups are present in lead phosphate glasses. • The electron–phonon coupling strength and phonon energy of the glass host was determined. • Several observed emission bands are due to 4f–4f electronic transitions of rare earth ions. -- Abstract: Lead–gallium phosphate glasses doped with rare the earth ions (Eu 3+ , Dy 3+ , Tb 3+ , Er 3+ ) were synthesized. The structure of obtained glasses was examined by means of use: X-ray diffraction (XRD), nuclear magnetic resonance ( 207 Pb and 31 P NMR), fourier transform infrared (FT-IR) and Raman spectroscopy. In contrast to fully amorphous Ln-doped samples (Ln = Eu, Dy, Tb), in Er-doped sample the GaPO 4 crystalline phase was identified. It was found from the NMR, FT-IR and Raman spectroscopic techniques that, different structural phosphate groups were present in lead phosphate glasses. Based on absorption measurements, the UV–VIS cut-off wavelength for lead phosphate glass was determined and its value is close to 305 nm. Excitation and emission spectra of rare earths were also detected. From excitation spectra of Eu 3+ the electron–phonon coupling strength and phonon energy of the glass host were determined. Due to 4f 6 –4f 6 (Eu 3+ ), 4f 8 –4f 8 (Tb 3+ ), 4f 9 –4f 9 (Dy 3+ ) and 4f 11 –4f 11 (Er 3+ ) electronic transitions of trivalent rare earth ions several luminescence bands were stated

  10. Synthesis, characterization and thermal behavior of rare earth amido sulfonates

    International Nuclear Information System (INIS)

    Luiz, Jose Marques; Nunes, Ronaldo Spezia; Matos, Jivaldo do Rosario

    2013-01-01

    Hydrated compounds prepared in aqueous solution by reaction between amidosulfonic acid [H 3 NSO 3 ] and suspensions of rare earth hydroxycarbonates [Ln 2 (OH) x (CO 3 ) y .zH 2 O] were characterized by elemental analysis (% Ln, % N and % H), infrared spectroscopy (FTIR) and thermogravimetry (TG). The compounds presented the stoichiometry Ln(NH 2 SO 3 ) 3 .xH 2 O (where x = 1, 5, 2.0 or 3.0). The IR spectra showed absorptions characteristic of H 2 O molecules and NH 2 SO 3 groups. Degree of hydration, thermal decomposition steps and formation of stable intermediates of the type [Ln 2 (SO 4 ) 3 ] and (Ln 2 O 2 SO 4 ), besides formation of their oxides, was determined by thermogravimetry. (author)

  11. Partition of rare-earths in phosphates laterites from Maicuru, Brazil - PA

    International Nuclear Information System (INIS)

    Lemos, V.P.; Costa, M.L. da.

    1987-01-01

    The phosphatic laterites of Maicuru-Para are formed of aluminium phosphates, mainly of the crandallite group, followed by wardite, augellite and senegallite. The crandallite group is represented in the form of the solid solution goyazite-florencite-crandallite, in variable proportions. In three samples, the florencite occurs as the predominant member, while in the others crandallite is the main mineral. The unit-cell dimension of florencites, in two samples, measured are the same as those of the florencites from other deposits. The rare earths occur mainly in this mineral group with predominance of the light rare earth elements. This is well observed in the condrite normalized REE patterns. These enrichments are not regular. The geochemical characteristics of the rare earth distribution in the crandallites of Maicuru, leads tho suggest this mineral was formed from distinct lithologies. (author) [pt

  12. Application and evaluation of the mass spectrometric isotope dilution technique in the determination of rare earths in geological materials

    International Nuclear Information System (INIS)

    Moraes, N.M.P. de.

    1988-01-01

    Establishment of the experimental procedures employed in the rare earth element determination of geological samples by mass spectrometric isotope dilution analysis is discussed in the present work. The procedures involve preparation and calibration of the isotope tracers isotope dilution, dissolution in a teflon pressure vessel, chemical separation and isotope analysis using a fully automated Micromass VG ISOTOPES model 354 thermal ionization mass spectrometer. For the initial chemical separation of total rare earths the cationic resin was employed and HC1 and HNO 3 acids as eluents. In the second step rare earths elements were separated into individual (La, Ce and Nd) and subgroups (Sm-Eu-Gd, Yb-Er-Dy) fractions using the same cationic resin and α-HIBA as eluent. Nine elements La, Ce, Nd, Sm, Eu, Gd, Dy, Er and Yb are determined by this method in the ''United States Geological Survey'' (USGS) standard samples GSP-1, AGV-1 and G-2, with an overall precision of +- 1 to 2% and an accuracy of 5%. The concentration of rare earth element determined in the standard sample PCC-1 showed that the total analytical blanks are in submicrogram levels. The concentration of rare earth elements in the same USGS standard samples were also determined by Instrumental neutron activation analysis, neutron activation analysis with chemical separation before irradiation and inductively coupled argon plasma spectroscopy. The chemical procedures employed for these methods are the same as that used for mass spectrometric isotope dilution. Based on the results obtained, each method was evaluated pointing out their merits and defects. The study clearly showed that the chemical procedure employed for all these techniques was satisfactory. (author) [pt

  13. Anomalies in photofission of rare earth nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gann, A.V.; Nazarova, T.S.; Noga, V.I.; Ranyuk, Y.N.; Sorokin, P.V.; Telegin, Y.N.

    1979-09-01

    Measurements of photofission produced by 1-GeV bremsstrahlung in the heavy rare earth elements show an anomalously large cross section compared to that predicted by the liquid drop model. These measurements check the results obtained previously with 1-GeV protons by Andronenko et al. (JETP Lett. 24, 573 (1976)).

  14. An Operationally Simple Method for Separating the Rare-Earth Elements Neodymium and Dysprosium.

    Science.gov (United States)

    Bogart, Justin A; Lippincott, Connor A; Carroll, Patrick J; Schelter, Eric J

    2015-07-06

    Rare-earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-earth metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-(t) BuNO)C6 H4 CH2 }3 N](3-) (TriNOx(3-) ), feature a size-sensitive aperture formed of its three η(2) -(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/ [M(TriNOx)]2 (M=rare-earth metal). Differences in the equilibrium constants (Keq ) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio SNd/Dy =359. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. A political economy of China's export restrictions on rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Pothen, Frank [Zentrum fuer Europaeische Wirtschaftsforschung GmbH (ZEW), Mannheim (Germany); Fink, Kilian [Frankfurt Univ. (Germany)

    2015-04-20

    We investigate why governments restrict exports of exotic raw materials taking rare earth elements as a case study. Trade restrictions on exotic materials do not have immediate macroeconomic effects. Relocating rare earth intensive industries is found to be the main reason behind China's export barriers. They are part of a more extensive strategy aiming at creating comparative advantages in these sectors and at overcoming path dependencies. Moreover, export barriers serve as a second-best instrument to reduce pollution and to slow down the depletion of exhaustible resources. Growing domestic rare earth consumption renders those increasingly ineffective. Rising reliance on mine-site regulation indicates that this fact is taken into account. Rare earth extraction is dominated by a few large companies; the demand side is dispersed. That speaks against successful lobbying for export restrictions. It appears as if the export barriers are set up to compensate mining firms.

  16. Synergistic extraction and separation of yttrium from heavy rare earths using mixture of sec-octylphenoxy acetic acid and bis(2,4,4-trimethylpentyl)phosphinic acid

    International Nuclear Information System (INIS)

    Sun Xiaobo; Zhao Junmei; Meng Shulan; Li Deqian

    2005-01-01

    Synergistic extraction and separation of yttrium (Y) from heavy rare earths (HRE) in chloride medium using mixture of sec-octylphenoxy acetic acid (CA-12, HA) and bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex272, HL) in n-heptane has been investigated. The synergistic enhancement coefficients, R max , were obtained for Ho 3+ (5.12), Y 3+ (5.34), Er 3+ (7.04), Tm 3+ (7.50), Yb 3+ (13.12) and Lu 3+ (17.58). The separation factors (SF) between Y 3+ and HRE were obtained, and it was found that Er 3+ would form the new complex as ErH 6 A 4 L 5 in the mixture system. A cation exchange mechanism was proposed. The equilibrium constant, formation constant and thermodynamic parameters such as ΔG = -18.48 kJ/mol, ΔH = -1.36 kJ/mol and ΔS = 0.058 kJ/mol were determined. The CA-12 and Cyanex272 mixture system showed higher extraction efficiency, larger separation factors as well as excellent stripping behaviors. The application potential of the mixture system to separate Y from HRE has been discussed

  17. The Effect of Rare Earth on the Structure and Performance of Laser Clad Coatings

    Science.gov (United States)

    Bao, Ruiliang; Yu, Huijun; Chen, Chuanzhong; Dong, Qing

    Laser cladding is one kind of advanced surface modification technology and has the abroad prospect in making the wear-resistant coating on metal substrates. However, the application of laser cladding technology does not achieve the people's expectation in the practical production because of many defects such as cracks, pores and so on. The addiction of rare earth can effectively reduce the number of cracks in the clad coating and enhance the coating wear-resistance. In the paper, the effects of rare earth on metallurgical quality, microstructure, phase structure and wear-resistance are analyzed in turns. The preliminary discussion is also carried out on the effect mechanism of rare earth. At last, the development tendency of rare earth in the laser cladding has been briefly elaborated.

  18. Adducts of rare earth tris-acetylacetonates with dimethyl sulfoxide

    International Nuclear Information System (INIS)

    Dzyubenko, N.G.; Kalenichenko, Yu.V.; Martynenko, L.I.

    1988-01-01

    Adducts of rare earth and yttrium (r.e.e., M) acetylacetonates with dimethyl sulfoxide (DMSO), MA 3 xnDMSO are synthesized. The acetylacetonates of light r.e.e. (M=La-Tb) are shown by different physico-chemical methods to form diadducts of the MA 3 x2DMSOxH 2 O composition, where A - -acetylacetonate-ion, and the acetyl-acetonates of heavy r.e.e. (M=Dy-Lu, Y)-monoadducts MA 3 xDMSO. The estimation of adduct thermal stability is carried out using the values of seeming activation energy of their thermal degradation. Monoadducts are shown to give volatile forms of rare earth acetylacetonates during heating in vacuum, and diadducts do not form volatile forms of acetylacetonates

  19. Exchange interactions in two-state systems: rare earth pyrochlores

    Science.gov (United States)

    Curnoe, S. H.

    2018-06-01

    The general form of the nearest neighbour exchange interaction for rare earth pyrochlores is derived based on symmetry. Generally, the rare earth angular momentum degeneracy is lifted by the crystal electric field (CEF) into singlets and doublets. When the CEF ground state is a doublet that is well-separated from the first excited state the CEF ground state doublet can be treated as a pseudo-spin of some kind. The general form of the nearest neighbour exchange interaction for pseudo-spins on the pyrochlore lattice is derived for three different types of pseudo-spins. The methodology presented in this paper can be applied to other two-state spin systems with a high space group symmetry.

  20. A divalent rare earth oxide semiconductor: Yttrium monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Kaminaga, Kenichi; Sei, Ryosuke [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); Department of Chemistry, Tohoku University, Sendai 980-8578 (Japan); Hayashi, Kouichi [Department of Environmental and Materials Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Happo, Naohisa [School of Information Sciences, Hiroshima City University, Hiroshima 731-3194 (Japan); Tajiri, Hiroo [Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8, Sayo 679-5198 (Japan); Oka, Daichi; Fukumura, Tomoteru, E-mail: tomoteru.fukumura.e4@tohoku.ac.jp [Department of Chemistry, Tohoku University, Sendai 980-8578 (Japan); Hasegawa, Tetsuya [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan)

    2016-03-21

    Rare earth oxides are usually widegap insulators like Y{sub 2}O{sub 3} with closed shell trivalent rare earth ions. In this study, solid phase rock salt structure yttrium monoxide, YO, with unusual valence of Y{sup 2+} (4d{sup 1}) was synthesized in a form of epitaxial thin film by pulsed laser deposition method. YO has been recognized as gaseous phase in previous studies. In contrast with Y{sub 2}O{sub 3}, YO was dark-brown colored and narrow gap semiconductor. The tunable electrical conductivity ranging from 10{sup −1} to 10{sup 3} Ω{sup −1 }cm{sup −1} was attributed to the presence of oxygen vacancies serving as electron donor. Weak antilocalization behavior observed in magnetoresistance indicated significant role of spin-orbit coupling as a manifestation of 4d electron carrier.

  1. Recent advances in syntheses and biomedical applications of nano-rare earth metal-organic framework materials

    Directory of Open Access Journals (Sweden)

    Xin Pengyan

    2017-12-01

    Full Text Available In recent years,the syntheses of nano-rare earth metal-organic framework (MOF materials and their applications in biomedicine,especially in the diagnosis and treatment of cancer have attracted extensive attentions.On the one hand,nano-rare earth MOFs,which have unique optical and magnetic properties,are promising multimodal imaging contrast agents for biomedical imaging,such as fluorescence imaging and magnetic resonance imaging.On the other hand,nano-rare earth MOFs have various compositions and structures,and excellent intrinsic properties such as large specific surface area,high pore volume and tunable pore size,which enable them to perform as promising nanoplatforms for drug delivery.Therefore,nano-rare earth MOFs may provide a new platform for the development of diagnostic and therapeutic reagents.In this article,the recent advances in the syntheses of nano-rare earth MOFs and their applications in biomedicine are summarized.

  2. Transferred hyperfine interaction between the rare-earth ions and the fluorine nuclei in rare-earth trifluorides

    DEFF Research Database (Denmark)

    Hansen, P. E.; Nevald, Rolf; Guggenheim, H. G.

    1978-01-01

    The isotropic and anisotropic transferred hyperfine interactions between F ions in the two chemically inequivalent sites and the rare-earth ions (R) have been derived from 19F NMR measurements in the temperature region 100-300 K on single crystals of TbF3 and DyF3. The isotropic interactions are ...... to vary only slightly with temperature. They are further assigned to definite R's in the unit cell, which cannot be done from macroscopic magnetic measurements....

  3. Rare-Earth Tantalates and Niobates Single Crystals: Promising Scintillators and Laser Materials

    Directory of Open Access Journals (Sweden)

    Renqin Dou

    2018-01-01

    Full Text Available Rare-earth tantalates, with high density and monoclinic structure, and niobates with monoclinic structure have been paid great attention as potential optical materials. In the last decade, we focused on the crystal growth technology of rare-earth tantalates and niobates and studied their luminescence and physical properties. A series of rare-earth tantalates and niobates crystals have been grown by the Czochralski method successfully. In this work, we summarize the research results on the crystal growth, scintillation, and laser properties of them, including the absorption and emission spectra, spectral parameters, energy levels structure, and so on. Most of the tantalates and niobates exhibit excellent luminescent properties, rich physical properties, and good chemical stability, indicating that they are potential outstanding scintillators and laser materials.

  4. Identification and determination of natural radioactive impurities in rare earth chlorides

    International Nuclear Information System (INIS)

    Gu, M.J.; Cen, Y.H.; Tang, T.Y.; Chang, J.X.

    1988-01-01

    227 Ac, 228 Th, 226 Ra, 210 Po and 210 Pb can be present at rare earth chlorides. A radiochemical procedure is presented for the identification and determination of natural radioactive impurities in rare earth chlorides. The determination limits for these radionuclides were 1.5x10 -4 to 3x10 -1 Bq/g. The relative standard deviations for determining 10 -2 Bq/g radionuclides were usually less than +-7%. (author) 9 refs.; 3 figs.; 2 tabs

  5. An operationally simple method for separating the rare-earth elements neodymium and dysprosium

    Energy Technology Data Exchange (ETDEWEB)

    Bogart, Justin A.; Lippincott, Connor A.; Carroll, Patrick J.; Schelter, Eric J. [Department of Chemistry, University of Pennsylvania, Philadelphia, PA (United States)

    2015-07-06

    Rare-earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-earth metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-"tBuNO)C_6H_4CH_2}{sub 3}N]{sup 3-} (TriNOx{sup 3-}), feature a size-sensitive aperture formed of its three η{sup 2}-(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/[M(TriNOx)]{sub 2} (M=rare-earth metal). Differences in the equilibrium constants (K{sub eq}) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio S{sub Nd/Dy}=359. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Radioactive rare earths from fallout for study of particle movement in the sea

    International Nuclear Information System (INIS)

    Sugihara, Thomas T.; Bowen, Vaughan T.

    1962-01-01

    As part of an extensive study of the distribution of long-lived radionuclides from fallout in the Atlantic Ocean, a large number of measurements of cerium-144 and promethium-147 concentration have been made. Comparison of these concentrations as they vary both horizontally and vertically, with simultaneously measured concentrations of strontium-90, indicates that the rare earths are generally depleted in surface water, by comparison with the nuclides known to be soluble. This observation, coupled with frequent observation of rare-earth enrichment at depth, leads us to postulate rapid vertical transport of rare earths by attachment to particles undergoing sedimentation. This is completely plausible in terms of the 'radiocolloid' behaviour generally observed for rare earths at sea-water pH. An attempt is made to interpret this study in the overall picture of the marine geochemistry of the trivalent cations, as well as to emphasize the unique and generally useful aspects of the fallout tracer experiment. (author) [fr

  7. The use of rare earth radiotracers in the study of solvent extraction kinetics

    International Nuclear Information System (INIS)

    Lim, T.M.; Tran, T.

    1993-01-01

    The suitability of rare earth radionuclides as tracers in research and industry are assessed. In general, the most desirable characteristics of radiotracers for process studies are a half-life in the range 5-200 days, a high yield, high energy γ-emission and low cost of production. The majority of rare earths have at least one radionuclide with acceptable characteristics. The application of radiotracers to the study of kinetics of rare earth solvent extraction have been studied using a modified Lewis cell. Terbium-160 was selected as the most suitable rare earth radionuclide for our experiments. Samples of both aqueous and organic phases were continuous withdrawn, monitored using an automated γ-counting system based on two sodium iodide detectors and then pumped back to the Lewis cell. Excellent results were obtained and the rate of extraction was shown to be first order with respect to the terbium concentration. 6 refs., 1 tab., 7 figs

  8. Structurally triggered metal-insulator transition in rare-earth nickelates.

    Science.gov (United States)

    Mercy, Alain; Bieder, Jordan; Íñiguez, Jorge; Ghosez, Philippe

    2017-11-22

    Rare-earth nickelates form an intriguing series of correlated perovskite oxides. Apart from LaNiO 3 , they exhibit on cooling a sharp metal-insulator electronic phase transition, a concurrent structural phase transition, and a magnetic phase transition toward an unusual antiferromagnetic spin order. Appealing for various applications, full exploitation of these compounds is still hampered by the lack of global understanding of the interplay between their electronic, structural, and magnetic properties. Here we show from first-principles calculations that the metal-insulator transition of nickelates arises from the softening of an oxygen-breathing distortion, structurally triggered by oxygen-octahedra rotation motions. The origin of such a rare triggered mechanism is traced back in their electronic and magnetic properties, providing a united picture. We further develop a Landau model accounting for the metal-insulator transition evolution in terms of the rare-earth cations and rationalizing how to tune this transition by acting on oxygen rotation motions.

  9. Rare earth metals-primary resources and prospects of processing secondary resources in India

    International Nuclear Information System (INIS)

    Pandey, B.D.

    2015-01-01

    The importance of Rare earth metals (REMs) in modern technological applications is associated with their spectroscopic and magnetic properties. The occurrence of rare earths in mixed form is commonly reported and their separation to the individual metal is a challenging task because of the similar chemical properties. The economical processing of the primary ores of rare earths is limited to a few countries and their supply at the international level is currently dominated by China. Hence assessing the present scenario of the primary resources of rare earths vis-à-vis their applications and demand is crucial at this stage, besides looking at the alternate resources to ensure availability of REMs; such aspects are covered in the manuscript. In view of the environmental concerns in the processing of ores such as monazite, xenotime, bastnasite, etc, and increasing demand of REMs, corresponding increase in demand of the raw materials has been recorded. It is therefore, necessary to utilize the end-of the-life rare earth containing materials as a rich resource by developing an appropriate recycling technology, which is emerging as a high priority area. To recover the REMs, major secondary resources such as electronic wastes, industrial wastes, spent catalysts and magnets, and phosphors powder, etc, have been considered for now. This will not only open the prospects of utilizing the wastes containing REMs, but will also limit the imports while lowering the production cost and decreasing the load on the primary reserves. The paper also examines the efficient recycling methods to recover a fairly good amount of rare earths which are relevant to India in view of the limited exploitation of the ores. Recovery of REMs from secondary resources using mechanical treatment followed by hydrometallurgical methods is prevalent and the same is reviewed in some detail. The recent R and D work pursued at CSIR-NML to extract (leaching and metal separation using some phosphatic reagents

  10. Assessment of trading partners for China's rare earth exports using a decision analytic approach.

    Science.gov (United States)

    He, Chunyan; Lei, Yalin; Ge, Jianping

    2014-01-01

    Chinese rare earth export policies currently result in accelerating its depletion. Thus adopting an optimal export trade selection strategy is crucial to determining and ultimately identifying the ideal trading partners. This paper introduces a multi-attribute decision-making methodology which is then used to select the optimal trading partner. In the method, an evaluation criteria system is established to assess the seven top trading partners based on three dimensions: political relationships, economic benefits and industrial security. Specifically, a simple additive weighing model derived from an additive utility function is utilized to calculate, rank and select alternatives. Results show that Japan would be the optimal trading partner for Chinese rare earths. The criteria evaluation method of trading partners for China's rare earth exports provides the Chinese government with a tool to enhance rare earth industrial policies.

  11. Prospective analysis of the flows of certain rare earths in Europe at the 2020 horizon.

    Science.gov (United States)

    Rollat, Alain; Guyonnet, Dominique; Planchon, Mariane; Tuduri, Johann

    2016-03-01

    This paper proposes a forecast of certain rare earth flows in Europe at the 2020 horizon, based on an analysis of trends influencing various actors of the rare earth industry along the value chain. While 2020 is indicated as the forecast horizon, the analysis should be considered as more representative of the next decade. The rare earths considered here are used in applications that are important for a low-carbon energy transition and/or have a significant recycling potential: NdFeB magnets (Pr, Nd, Dy), NiMH batteries (Pr, Nd) and fluorescent lamp phosphors (Eu, Tb, Y). An analysis of major trends affecting the rare earth industry in Europe along the value chain (including extraction, separation, fabrication, manufacture, use and recycling), helps to build a scenario for a material flow analysis of these rare earths in Europe. The scenario assumes in particular that during the next decade, there exists a rare earth mine in production in Europe (with Norra Kärr in Sweden as a most likely candidate) and also that recycling is in line with targets proposed in recent European legislation. Results are presented in the form of Sankey diagrams which help visualize the various flows for the three applications. For example, calculations forecast flows from extraction to separation of Pr, Nd and Dy for magnet applications in Europe, on the order of 310 tons, 980 tons and 80 tons rare earth metal resp., while recycled flows are 35 tons, 110 tons and 30 tons resp. Calculations illustrate how the relative contribution of recycling to supply strongly depends on the situation with respect to demand. Considering the balance between supply and demand, it is not anticipated any significant shortage of rare earth supply in Europe at the 2020 horizon, barring any new geopolitical crisis involving China. For some heavy rare earths, supply will in fact largely outweigh demand, as for example Europium due to the phasing out of fluorescent lights by LEDs. Copyright © 2016 Elsevier Ltd

  12. Thermoelectric transport in rare-earth compounds

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, Ulrike

    2007-07-01

    This work focuses on the thermoelectric transport in rare-earth compounds. The measurements of the thermal conductivity, thermopower, and Nernst coefficient are supplemented by investigations of other quantities as magnetic susceptibility and specific heat. Chapter 2 provides an introduction to the relevant physical concepts. Section 1 of that chapter summarizes the characteristic properties of rare-earth systems; section 2 gives an overview on thermoelectric transport processes in magnetic fields. The applied experimental techniques as well as the new experimental setup are described in detail in Chapter 3. The experimental results are presented in Chapter 4-6, of which each concentrates on a different subject. In Chapter 4, various Eu clathrates and the skutterudite-like Ce{sub 3}Rh{sub 4}Sn{sub 13} are presented, which have been investigated as potential thermoelectric materials for applications. Chapter 5 focusses on the study of the energy scales in the heavy-fermion series Lu{sub 1-x}Yb{sub x}Rh{sub 2}Si{sub 2} and Ce{sub x}La{sub 1-x}Ni{sub 2}Ge{sub 2} by means of thermopower investigations. Chapter 6 is dedicated to the thermoelectric transport properties of the correlated semimetal CeNiSn with special emphasis on the Nernst coefficient of this compound. (orig.)

  13. Costs and benefits of rare earth screens

    International Nuclear Information System (INIS)

    Taylor, F.E.

    1977-01-01

    The British Institute of Radiology has submitted evidence (Royal Commission on Environmental Pollution, 1976, Sixth Report, Nuclear Power and the Environment. Cmnd 6618, HMSO, London) leading to the conclusion that the introduction of rare earth screens in medical radiography is not financially practical at present in the U.K. This conclusion is questioned. The cost of reducing the genetic dose from medical radiography should be compared with the costs of reducing that from other sources such as nuclear power wastes, since the risks are to future generations in both cases. The cost of reducing public exposure by the use of rare earth screens in U.K. hospitals is calculated to be about Pound1 per man-rad; a total annual genetic collective dose of nearly 300,000 man-rad could be saved. An anomalous situation is presented by the great discrepancies between this cost, and published estimates both of the cost of the detriment associated with the genetic collective dose and of the value incorporated into the design objective for nuclear reactors. (U.K.)

  14. Diversification of the rare-earth business in the existing enterprises

    Science.gov (United States)

    Bogdanov, S. V.; Grishaev, S. I.; Yazev, V. A.

    2013-12-01

    The development of the modern rare-earth business is analyzed, and the possibilities of using a mathematical description of the prospects of this business on the basis of nonlinear evolution equations are estimated. The well-known methods of describing the life cycle of the economic activity of a commercial company in the closed multisector model of market economics is used to determine the boundaries of changing the average labor productivity during the diversification of business on operating Russian enterprises that produce a wide range of products and are intended to manufacture new types of high-technology rare-earth metal products.

  15. The role of rare earths in narrow energy gap semiconductors

    International Nuclear Information System (INIS)

    Partin, D.L.; Heremans, J.; Morelli, D.T.; Thrush, C.M.

    1991-01-01

    Narrow energy band gap semiconductors are potentially useful for various devices, including infrared detectors and diode lasers. Rare earth elements have been introduced into lead chalcogenide semiconductors using the molecular beam epitaxy growth process. Europium and ytterbium increase the energy band gap, and nearly lattice-matched heterojunctions have been grown. In some cases, valence changes in the rare earth element cause doping of the alloy. In this paper some initial investigations of the addition of europium to indium antimonide are reported, including the variation of lattice parameter and optical transmission with composition and a negative magnetoresistance effect

  16. Enhanced Laser Cooling of Rare-Earth-Ion-Doped Composite Material

    International Nuclear Information System (INIS)

    You-Hua, Jia; Biao, Zhong; Xian-Ming, Ji; Jian-Ping, Yin

    2008-01-01

    We predict enhanced laser cooling performance of rare-earth-ions-doped glasses containing nanometre-sized ul-traBne particles, which can be achieved by the enhancement of local Geld around rare earth ions, owing to the surface plasma resonance of small metallic particles. The influence of energy transfer between ions and the particle is theoretically discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption is predicted. It is concluded that the absorption are greatly enhanced in these composite materials, the cooling power is increased as compared to the bulk material

  17. Structure and properties of rare earth-rich glassed for nuclear waste immobilisation

    International Nuclear Information System (INIS)

    Bardez, I.

    2004-11-01

    A new nuclear glass composition, able to immobilize highly radioactive liquid wastes from high burn-up UO 2 fuel, was established and its structure studied. The composition of the selected rare earth-rich glass is (molar %): 61.79 SiO 2 - 8.94 B 2 O 3 - 3.05 Al 2 O 3 - 14.41 Na 2 O - 6.32 CaO - 1.89 ZrO 2 - 3.60 RE 2 O 3 (with RE = La, Ce, Pr and Nd). The aim of this study was to determine the local environment of the rare earth in this glass and also to glean information about the effect of glass composition on the rare earth neighbouring (influence of Si, B, Al, Na and Ca contents). To this end, several series of glasses, prepared from the baseline glass, were studied by different characterisation methods such as EXAFS spectroscopy at the neodymium LIII-edge, optical absorption spectroscopy, Raman spectroscopy and 29 Si, 27 Al and 11 B MAS-NMR. By coupling all the results obtained, several hypotheses about the nature of the rare earth neighbouring in the glass were proposed. (author)

  18. Study on the extraction of rare earth elements in liquid bismuth

    International Nuclear Information System (INIS)

    Harada, M.; Adachi, M.; Kai, Y.; Koike, K.

    1987-01-01

    Three factors, which are important for the extraction of rare earth elements in liquid bismuth - molten salt system, were studied, i. e., the equilibrium distribution of neodymium, samarium and bismuth between molten LiCl - liquid Bi-Li alloys, the extraction rate of rare earths, and the characteristics of the extractor with drop dispersion. The rare earth elements were extracted through redox reactions. In high range of Li-mole fraction in the alloy phase, X Li , the distribution of neodymium and bismuth in the salt phase markedly increased as X Li increased. The anomalous increase is attributed to the formation of the compound comprised of Nd, Li, Bi and oxygen in the salt phase. The redox reaction processes were very fast and the extraction rates for rare earths are controlled by the diffusion processes of the solute and the metallic lithium. The process for the formation of liquid metal drops in the continuous phase is predictable from semiempirical correlations reported for aqueous solution - organic solvent systems. The height of droplet bed being accumulated on drop settling portion is predictable from the coalescence time of single drop to a flat metal interface. The coalescence of metal drop to clean interface was very fast. The extractor type of liquid metal dispersion in molten salt is suitable for the extraction process in the fuel reprocessing of MSR or MSBR. (author)

  19. Rare-earth element geochemistry in the Luanga Mafic-Ultramafic Complex, Para

    International Nuclear Information System (INIS)

    Suita, M.T.F.; Nilson, A.A.

    1989-01-01

    Six whole-rock samples (harzburgite, orthopyroxenic and norite) of the Luanga Mafic-Ultramafic Complex (Para) were analysed for rare-earth elements (REE) through plasma spectrometry. The Luanga Complex is a deformed and metamorphosed layered mafic-ultramafic body of Archaean age. The Complex underwent medium-grade metamorphism in three stages. The first stage (medium grade) involved local formation of tremolite and reduction of Ca content in plagioclase. The second stage (low grade) consisted of serpentinization of amphibole or ortopyroxene forming bastile and generation of albite + epidote + white mica + actinolite from plagioclase. The third stage involved renewed serpentinization and/or talcification of pre-existing minerals (including serpentine) along fracture and fault surfaces. The analysed rocks display light rare-earth element (LREE) enrichment up to sixty times the composition of the Leedly chondrite and La/Yb ratios from 6.2 to 20.0 they are low in medium rare-earth elements (MREE), displaying discrete to strong negative Eu anomaly even in plagioclase cumulates and are slightly enriched in heavy rare-earth elements (HREE), usually higher than chondrite values. The low MREE area related to the occurrence of orthopyroxene (bronzite) in a way similar to the pattern of alpine periodotites, while HREE enrichment is compatible with the presence of bronzite and Mg-olivine, probably an inherited igneous feature. (author) [pt

  20. Analysis of “Favorable Growth Element” Based on Rare Earth-aluminum Composite Mechanism of Compound Process

    Science.gov (United States)

    Hao, Baohong; Zeng, Qihui; Zhao, Jin

    2018-01-01

    Under the background that failure resulted in by high temperature once only aluminum oxide is used as the gasoline additive. This paper, with the purpose to solve this problem, is to synthesize AcAl oxide for gasoline additive. In order to get the rare-earth-aluminum oxide, first, a complex model of rare earth oxide based on theories about ion coordination is established. Then, by the complex model, the type of “compound growth unit” when rare earth elements join the hydrothermal conditions and the inclination that “diversification” might probably happen are deduced. Depending on the results got by complex model, this paper introduces the type of compound and its existence conditions of “Compound growth unit” owned by stable rare-earth-aluminum oxide. By adjusting the compositions of modifier, compound materials of rare earth-aluminum oxide used for gasoline additive is made. By XRD test, aperture test, adsorption test and desorption test, the theoretical deduction is proved to be right. From the experiment, it is concluded that: a dense environment is the pre-condition to form rare-earth-aluminum polymer, which is also an essential condition for the polymer to update to a favorable growth unit and produce mesoporous rare-earth-aluminum oxide with high activity.