rare earth metals

atmosphere. Then, the tablet was placed in a mortar and ground easily into powders with a pestle. In this way, we have succeeded in reclaiming rare earth metals from bond magnets. We believe that our assumption (i.e., slight sintering of the magnetic particles) was right and that the dissolution of the sintered layer led to the successful pulverization of the lightly-sintered particles. It should also be noted that the use of a diluted acid is crucially important for the dissolution of metals, because concentrated acids often lead to the passivation of the metals.

The static polarizabilities ( ω = 0 ) have been calculated for the jellium atoms of the transition metals and the rare earth metals. These are compared with the density functional-based code for the neutral atoms of these systems by Zangwill and Liberman [32], and the results are displayed in Figure 9. In the case of the TMs both the neutral and jellium atoms show monotonically decreasing static polarizabilities with increasing atomic number ( Z ). In fact, the values may be fitted to an exponential decay function of the form

The results of the research interaction between ash and slag samples from Vladivostok TPP’s landfills saturated with underburning and ammonium hydrodifluoride were given. It was found out that the reactions of the main components of a concentrate with NH 4 HF 2 are flowing with creation of complex ammonium fluoro-metalate. It is shown that the distribution of REM (rare earth metals) between foam and heavier products is going during the flotation process of carbon-containing ash and slag samples without significant concentrating. It is shown that the water leaching of fluoridated product lets transfer silicone, aluminum and iron salts into solution and concentrate rare earth elements in insoluble residue in the form of complex salts of NaLnF 4 general formula. We propose a schematic diagram of hydrodifluoride recycling of carbon-containing sample, which provides concentrating of REM with incomplete separation of macro-components.

This work is a continuation of a previous work where metal contamination of the harvested rain water of Gaza strip in Palestine was assessed by analysis of different heavy metals (Ba, Cu, Zn, Co, Mn, V, Al, Pb, Cr, Ni, As, U, and Cd) and results showed that 8 trace metals is higher than the allowed WHO limits in drinking water. The present paper reports analytical results for some rare metals (Rb, Zr, Ti, Tl, Sb, Sc, Y), and rare earth metals (La, and Ce) which have no maximum allowed concentrations by WHO or any other regulation agencies.

Spectrophotometric determination of the amounts of dissolved ironin produced water without and in the existence of 400 ppm of rare earth metals after exposing coupons for 6 days at 25°C are summarized in Table (5). Iron content in the produced water before immersion of coupons is 0.30 ppm represented in Table (1). After data correction and rounded, the amount of dissolved iron is low in the case of rare earth metals with respect to blank. The dissolution of metal in the existence of rare earth metals is low with respect to the blank. From the amount of dissolved iron, the surface coverage (ϴ) and %IE were calculated as follows [35]:

An isothermally jacketed calorimeter has been constructed to measure the changes in heat content accompanying the solution of some rare earth metals and compounds. To check the performance of the apparatus, the integral heats of solution of potassium nitrate in water at 25°C have been measured. The values corrected to infinite dilution by use of relative apparent molal heat content data in the literature give 8384 +/- 12 cals/mole. The result agrees well with the values reported by others.

Taking into account the resource potential of the Khibiny group of apatite deposits, increasing the depth of processing of these ores for the rare-earth metals (REM) extracting purposes is a strategic task. Ontheotherhand, apatite concentrate is characterized by a low REM content (0, 4-1%), so that the lanthanides contained in the apatite composition were not extracted for the economic reasons. During the processing of apatite concentrate, the distribution of REM in solutions of phosphoric acid (15- 20%) and solid industrial waste - phosphogypsum (85- 80%) occurs [1]. Therein the larger halfofmorevaluable heavy subgroup of REM, including Y, Yb, Er and Dy compounds, are dissolved in the phosphoric acid solutions. Duetosimilarity of lanthanides’ chemical properties, extraction processes is widely used for individual REM recovery.

A modified cellular method developed by Raimes was extended to scandium, yttrium, and the rare earth metals. The assumption that the valence electrons are free and share the same ground state wave functions at zero wave number, was capable of giving fairly good agreement between the calculated and experimental values of the atomic radii, compressibilities, and total energies of the trivalent rare-earth metals as well as for scandium and yttrium. In addition the calculated variation of atomic radius and compressibility of the hexagonal rare-earth metals with atomic number was in qualitative agreement with experiment. Calculations based on the assumption that europium and ytterbium are divalent in the solid state were capable of giving reasonable agreement with the observed atomic radii and compressibilities of these elements. Calculations for cerium did not give satisfactory agreement with the assumption of either a trivalent or quadrivalent atomic core. This failure probably results from the fact that the assumption of equivalent behavior of the valence electrons at zero wave number is quite poor for this element. The compressibilities of promethium and scandium were predicted.

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

By applying the layer-by-layer condensation of low-alloy copper and refractory metals (tungsten, molybde- num or chromium) or carbon and moving the substrate out of the zone of vapor flow while it is rotating, it is possible to perform tempering from vapor and obtain materials with the structural elements typical of nanomate- rials. Investigated composites are characterized by a specific microlayer structure with alternating layers of Cu-Zr-Y low alloy and refractory metals from 0.1 to 0.4 μm thick (Figure 3(a) and Figure 3(b)). The grain size of copper in the composite is 0.1 - 0.3 µm and that of tungsten (molybdenum or chromium) from 0.01 - 0.02 µm. Composites Cu-Zr-Y-C has layered structure with cuprum grain size 0.1 - 0.3 μm and disperse particles of car- bon which mean size does not exceed 200 Å (Figure 3(c) and Figure 3(d)).

Chemical oxidation is the principle method of etching a metal surface for microscopic examination and the rare earths were etched in this manner... At room temperature, the nitric acid-a[r]

The same experiments using a tantalum or molybdenum vessel showed no detectable contamination of the rare earth metal& Work conducted by Daane 11 at the Ames Laboratory, on methods of we[r]

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]

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]

The aim is to produce an automated ultrasound measurement system which can perform velocity and attenuation measurements as a function of temperature, frequency and applied magnetic fiel[r]

Schiff bases can be considered as a very important class of organic compounds due to their ability to form stable complexes with wide range of transition and rare-earth metal ions in different oxidation states via N and O atoms. They have the potential to be used in many areas such as electrochemistry, bioinorganic, catalysis, metallic deactivators, separation processes, and environmental chemistry. They are becoming important materials in the pharmacological, dye, plastic industries as well as in the field of liquid crystal technology 1 – 5 .

There are several supply chain risks inherent in a global market wherein the supply of virtually all of a raw material critical to the development of many products is largely controlled by one supplier. At present, “both production of rare earth materials in China and export of those materials outside of China are strictly controlled by government imposed quotas” (Molycorp Minerals, 2009). Japan, a country that manufactures and exports many products that use rare earth metals, was exposed to and negatively impacted by one such risk. In September 2010, China placed what seemed to be an unannounced and unofficial embargo on the export of rare earth metals to Japan—a claim that was repeatedly denied by the Chinese government (Humphries, 2010). An incident that was initially thought to be related to longstanding maritime wars between China and Japan was heightened when China subsequently began halting exports to other countries as well. China’s export quotas continued to be reduced in 2011 and this has created significant upward price pressure on many of the scarce metals.

earth chlorides can be directly used as raw material for the molten salt electrolysis or metallothermic reduction. How- ever, in practice, almost all rare earth metals are presently pro- duced by the rare earth oxide electrolysis. Thus, if the chlo- rides are supplied as raw material for conventional process, we have to convert the obtained chlorides to oxides. In a flow containing oxygen gas, the conversion of the rare earth chlo- rides to oxychlorides is relatively easy. But, converting the rare earth oxychlorides to the corresponding oxides in a flow of dry air or pure O 2 requires very low partial pressure of chlo-

into the unoccupied 4 f levels by tuning the photon energy through the 4d-4 f threshold. The resonant excitation of 4d electrons into unoccupied 4 f levels not only leads to a strong enhancement of the photon absorption cross section, but has also an impact on the photoelectron spectra, depending on the channel into which the 4d hole decays. A 4d-4 f reso- nance in a rare-earth metal can decay in two principal ways: 共 a 兲 Resonant or nonresonant Auger decay: in the latter case the electron excited upon the 4d-4 f resonance tunnels through the potential barrier, leading to a singly positive ion- ized state due to the 4d core hole which then predominantly decays via an Auger process, 8 while in a resonant Auger decay it remains as a spectator during the recombination pro- cess. The spectator 4 f electron affects the kinetic energy of the outgoing electrons, which leads to an energy shift with respect to a normal Auger decay having the same final state. 共 b 兲 Autoionization: the electron excited upon the 4d-4 f reso- nance fills the 4d core hole, leading to electron emission from the VB or the 5s, 5 p, or 4 f core levels. The final state after autoionization is the same as after direct photoemission from the VB or the 5s, 5 p, or 4 f core levels, which leads to a photon-energy-dependent modulation of the intensities of these levels in the photoelectron spectrum due to interference between direct emission and emission due to autoionization. To induce a replicate core level via 4d-4 f resonance, there would have to be a resonant Auger decay of the exci- tation which involves the core level and a level at lower binding energy but not the 4 f levels. The main line would then be direct photoemission from the core level 共 no addi- tional 4 f electron due to the 4d-4 f resonance 兲 , while its low-binding-energy replica would be the aforementioned resonant Auger decay because of the better core-hole screen- ing due to the additional f electron in the final state. Up to now studies of the decay mechanisms of the 4d-4 f resonant excitation in rare-earth metals have not revealed the exis- tence of a decay channel which does not involve at least one f electron. 9–12 In this paper we will demonstrate that in the case of Eu metal the decay channels of the 4d-4 f resonant

Ionic liquids show unique properties such as nonvolatility (negligible vapor pressure), thermal stability, nonflammable nature, lower reactivity, strong ability to dissolve a large variety of organic and inorganic compounds... That’s why we should study the potential of it to the extraction of rare earth (lanthanides plus Sc and Y) and heavy metals. Indeed, heavy metals are a big problem for industrial companies who want to recycle the waste like mercury or cadmium to be more economically profitable as well as for the environment. There is a much bigger application. In fact, the extraction of rare earth metals is becoming more and more important due to the fact that it’s everywhere in technological devices like cellphones, television, computers, tablet, permanent magnets... So, we