Top PDF Production method for making rare earth compounds

Production method for making rare earth compounds

Production method for making rare earth compounds

A method of making a rare earth compound, such as a earth-transition metal permanent magnet compound, without the need for producing rare earth metal as a process step, comprises carbothermically reacting a rare earth oxide to form a rare earth carbide and heating the rare earth carbide, a compound-forming reactant (e.g. a transition metal and optional boron), and a carbide-forming element (e.g. a refractory metal) that forms a carbide that is more thermodynamically favorable than the rare earth carbide whereby the rare earth compound (e.g. Nd.sub.2 Fe.sub.14 B or LaNi.sub.5) and a carbide of the carbide-forming element are formed.
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Global Production Estimation of Rare Earth Elements and Their Environmental Impacts on Soils

Global Production Estimation of Rare Earth Elements and Their Environmental Impacts on Soils

In addition to their use in industry, REEs are more widely applied to cropland as microelement fertilizers due to their abilities to increase yields and improve qualities of crops. As a result, more and more REEs are moving into the ecosystems. They accumulate in soils, bioaccumulate in crops, and enter the food chain, causing a prob- lem of REE environmental pollution special to China. In recent years, REE environmental effects have become of great concern [25]. Some work should be done to and a method should be developed that can reliably esti- mate bioavailability of REEs to plants and thereby evaluate the potential health risk of REEs in soils and predict their impact on the ecosystem.
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Theoretical Study of the Rare Earth Compounds Lafe13 Xtx (T= Cr, Cu, Ga, Mn, Ni) and Curie Temperature Variation

Theoretical Study of the Rare Earth Compounds Lafe13 Xtx (T= Cr, Cu, Ga, Mn, Ni) and Curie Temperature Variation

I(n) is uniquely determined by a geometrical crystal structure, not related to the concrete element category. Thus, the interatomic pair potentials can be obtained from the known cohesive energy function E(x).The in- teratomic pair potential in distinct atoms can be obtained by the same inversion method, and they are used to study the rare earth intermetallics structures. Which are close to the Morse function, that is:

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Electronic Properties of Rare Earth Monopnictides

Electronic Properties of Rare Earth Monopnictides

density of the conduction electrons. This is due to fact that the plasmon energy depends on the density of the conduction electrons and effective number of the valence electrons, which changes when a metal form a compounds. We have calculated the electronic properties of rocksalt structured rare earth pnictides using this idea. In our proposed approach only plasmon energy is required as input, to evaluated various electronic properties of these materials and the method turns out to be widely applicable.

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Electro-Membrane Technology for Extraction of Valuable Compounds and Rare Earth Elements from the Red Mud

Electro-Membrane Technology for Extraction of Valuable Compounds and Rare Earth Elements from the Red Mud

On site production of sodium hypochlorite (NaClO) is based on the new technology of electrodialysis of sodium chloride. First the salt is dissolved by pure water in special reactor and crude brine is moved into brine precipitation reactor, where the undissolved impurities are precipitated, and the solution is additionally cleaned by brine filter and enters the special tank. From this tank the solution is pumped into electrodialyzer were under the action of electric potential it dissociates into Na + and Cl - ions which are separated by ion-exchange membranes and form the sodium hydroxide and chlorine containing gas.
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Carbide/nitride grain refined rare earth iron boron permanent magnet and method of making

Carbide/nitride grain refined rare earth-iron-boron permanent magnet and method of making

A method of making a permanent magnet wherein 1) a melt is formed having a base alloy composition comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and 2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties.
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Carbide/nitride grain refined rare earth iron boron permanent magnet and method of making

Carbide/nitride grain refined rare earth iron boron permanent magnet and method of making

A method of making a permanent magnet wherein 1) a melt is formed having a base alloy composition comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and 2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties.
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Method for treating rare earth transition metal scrap

Method for treating rare earth transition metal scrap

Rare earth-transition metal (e.g., iron) scrap (e.g., Nd-Fe-B scrap) is flux (slag) remelted to reduce tramp non- metallic impurities, such as oxygen and nitrogen, and metallic impurities, such as Li, Na, Al, etc., picked up by the scrap from previous fabrication operations. The tramp impurities are reduced to concentrations acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. The scrap is electroslag or inductoslag melted using a prefused, rare earth fluoride-bearing flux of CaF.sub.2, CaCl.sub.2 or mixtures thereof or the slag resulting from practice of the thermite reduction process to make a rare earth-iron alloy.
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Simple and efficient method for detection of traces of rare earth elements in minerals by raman spectroscopy instrumentation

Simple and efficient method for detection of traces of rare earth elements in minerals by raman spectroscopy instrumentation

Due to their similar geochemical proper- ties and origin in the same deposits, the fifteen lanthanides of the periodic table, accompanied by scandium and yttrium, are classified as the rare earth elements (REEs) or rare earth metals (REMs) [1]. Although these elements play im- portant roles in inorganic and general chemistry [2, 3], no substantial progress has been noted in the teaching of their chemistry in the educational curriculum demonstrated by the small number of papers [3–13], most of them published in the first half of the 20 th century.
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Rare earth elements in olivine:determination, occurrence and behaviour

Rare earth elements in olivine:determination, occurrence and behaviour

detectable signal. The latter leads to lower plasma temperature and associated increased oxide rates. The ThO/Th + ratio was monitored for experiments run in both standard and KED mode and found to be consistently below 0.2% in standard mode and below 2% in KED mode. No correction for oxide interference was employed but possible analytical artefacts due to unaccounted oxide interference were tested by quantifying the data with two reference materials with very different relative REE abundance: BHVO-2G (Basalt, Hawaiian Volcanic Observatory, a natural reference material with Oddo-Harkins effect abundances) and NIST SRM 612 (an artificial equal atom reference material). The resulting REE patterns of samples were statistically not resolvable despite the very different relative production rates of LREE and MREE oxides from these reference materials, showing that oxide formation had a negligible effect on final measured values. The agreement between REE concentrations for those samples run in both standard and KED mode provides additional support for uncorrected oxide
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Superconductivity and magnetism in rare earth nickel borocarbides

Superconductivity and magnetism in rare earth nickel borocarbides

reorientation which appears to be of first order between the two rhombic phases was observed, and this too was found to increase with temperature, which contradicts recent results obtain[r]

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Dielectric Properties Of Light Rare-Earth Titanates

Dielectric Properties Of Light Rare-Earth Titanates

The measurement of capacitance (C) and quality factor (Q) of pressed and sintered pellets of the studied titanates have been done at different temperature using two electrode method. The loaded sample holder was then put in a furnace. The capacitance and Q factor of the sample have been measured using Autocompute LCR-Q meter (APLAB 4910, India). The temperature of the sample inside the furnace was raised by a rectangular furnace which automatically records the temperature with chromal-alumel thermocuple fitted inside it. The dielectric constant (K') and dielectric loss (K") of the material have been determined using the following formula
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5.6 Binary rare earth alloys

5.6 Binary rare earth alloys

γ 11 = 1 ; γ 12 = γ 21 = γ ; γ 22 = γ 2 . (5.6.4c) In spite of the great simplification introduced through the random-phase approximation, the RPA equation for the alloy is still very complicated, because χ r (i, ω) depends on the randomness, and it cannot be solved without making quite drastic approximations. The simplest result is obtained by neglecting completely the site-dependence of χ r (i, ω), and consequently replacing c i in (5.6.4b) by its average value c. This pro- cedure corresponds to the replacement of each individual angular mo- mentum J ri by the average c J 1i + (1 − c) J 2i , and it is known as the virtual crystal approximation (VCA). In this approximation, (5.6.4) may be solved straightforwardly after a Fourier transformation, and defining the T-matrices according to
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The ferromagnetic properties of the rare earth metals

The ferromagnetic properties of the rare earth metals

It is to be noted that these absolute saturation moments were obtained using data from the temperature range of 3l0 - 80°K only, and therefore only attempt to point out what the approxim[r]

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Thermal expansion of rare earth metals

Thermal expansion of rare earth metals

A high temperature dilatometric investigation of the rare earth metals was undertaken as part of a broad program of study of these elements, the ultimate goal being better understanding of metals in general. The more immediate goal, in addition to determining the coefficients of expansion quantitatively, was to detect evidence of any crystalline transformations which may occur and particularly to cast some light on certain high temperature transitions already discovered in several of these metals. The rare earth metals included in this investigation were lanthanum, cerium, praseodymium, neodymium, gadolinium, terbium, dysprosium, erbium, and ytterbiumo
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Palladium-Rare Earth Alloys130-140

Palladium-Rare Earth Alloys130-140

9 Diffusion coefficients versus temperature for a vacuum annealed and slow cooled palladium-8 atomic per cent yttrium alloy show the different behaviours of the mat[r]

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Rare Earth Element Phases in Bauxite Residue

Rare Earth Element Phases in Bauxite Residue

from bauxite residue, REEs have been indicated to occur in calcium titanate phases that were created 171.. in the Bayer process.[r]

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The Hubbert Curve and Rare Earth Elements Production

The Hubbert Curve and Rare Earth Elements Production

Figure 6 shows both global yearly production and global theoretical yearly production over time. Like with the previous figures 2 and 4, this graph demonstrates that while theoretical cumulative production follows actual cumulative production, actual yearly production is much more volatile than the predicted yearly production. Though the variation is not as pronounced as it was for U.S. yearly production, it is still varying across the theoretical yearly production. According to Hubbert’s equations, maximum annual production should have occurred between 2021 and 2022 at a value of 145,588.4108 metric tons. The ability of this Hubbert curve to create accurate predictions of future is doubtful once again due to the simplicity of the model. It was shown previously shown that accurate predictions for China’s REE production were not created which is problematic for global predictions due to China composing over 90% of global rare earth element production in recent years. This once again confirms that the Hubbert curve cannot be used to create accurate predictions of future rare earth element production.
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Solid state spectroscopy : rare earth   hybride centres in the alkaline earth fluorides

Solid state spectroscopy : rare earth hybride centres in the alkaline earth fluorides

calcium and strontium fluoride containing cerium and pras.eo­ dymium were examined in the infrared. Typical absorption spectra obtained at liquid nitrogen temperature are reproduc­ ed in figure 3 . For each host the predominant tetrahedral substitutional site absorption can be clearly seen at 965 cm -1 in calcium fluoride and 893 cm-1 in strontium fluoride. The previously reported local mode lines associated with rare earth hydride ion tetragonal pairs in calcium fluoride are reproduced and similar lines appear in the strontium fluoride spectra. New tetragonal hydride ion sites correlated in in� tensity with these lines in strontium fluoride have recently been observed in this laboratory by ESR ( 4o ) which confirms
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The heats of combustion of some rare earth metals

The heats of combustion of some rare earth metals

RESULTS OF COMBUSTION OF THE METALS The heat of combustion was determined from the temperature rise of the calorimeter, AT, and the water equivalent, W... where Qc = the heat leakage cor[r]

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