Rare earth metals(REM)

Top PDF Rare earth metals(REM):

Study of iron stripping from DEHPA 
		solutions during the process of rare earth metals extraction from 
		phosphoric acid

Study of iron stripping from DEHPA solutions during the process of rare earth metals extraction from phosphoric acid

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. Therein the larger half of more valuable heavy subgroup of REM, including Y, Yb, Er and Dy compounds, are dissolved in the phosphoric acid solutions. Complex composition of the apatite concentrate processing products and low concentration of heavy REM subgroup relatively to metal impurities and light REM inhibits REM extraction and separation process, and, probable, is responsible for low extractant capacity for individual compounds of REM. Iron (3+) ions have a significant impact on rare-earth metals extraction process. This impact is caused by the competitive participation of these ions in the extraction process, which, with account of their much higher concentration in EPA solutions, compared with rare-earth ions, leads to decrease in the extractant capacity for REM. Therefore, the study of the purification of the extract from iron ions (3+) is a relevant problem.
Show more

5 Read more

Distribution of Rare Earth Metals in Technogenic Wastes of Energy Enterprises (Results of the Laboratory Studies)

Distribution of Rare Earth Metals in Technogenic Wastes of Energy Enterprises (Results of the Laboratory Studies)

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.
Show more

6 Read more

Rare earth metals are essential for the United States military and economic

Rare earth metals are essential for the United States military and economic

R are earth metals are essential for the United States’ military and economic well-being. Yet the U.S. has been particularly lax when it comes to securing the supply of these metals. The U.S. has gone from the world’s top producer and supplier of rare earths to being completely dependent on one country – China – for its supply. China’s dominance in the rare earths market will have profound implications for U.S. national security in the next couple of years. As it is, some analysts already believe it is too late to avoid a global shortage of rare earth metals, placing the U.S. in greater risk. The U.S. needs to take steps now to remedy this situation.
Show more

7 Read more

Analysis of Different Rare Metals, and Rare Earth Metals in Harvested Rain Water in Gaza Strip/Palestine by ICP/MS Data and Health Aspects

Analysis of Different Rare Metals, and Rare Earth Metals in Harvested Rain Water in Gaza Strip/Palestine by ICP/MS Data and Health Aspects

This rain water samples harvested for drinking and agriculture from Gaza collected in November 2012 were analyzed for different rare metals (Rb, Zr, Ti, Tl, Sb, Sc, Y), and rare earth metals (La, and Ce). These metals usually have no maximum accepta- ble limits as there is no sufficient data about their toxicity to human health. Their control should be therefore controlled in water to monitor their concentration in water (ground, harvested, etc.). This study was conducted to determine the water quality of harvested water which is used for drinking in the study area. 43 water samples were collected in November 2012 during the first rain from house wells and rain water pools. The concentrations of the metals detected in the collected harvested rainwater vary significantly between the 43 samples, and all of them were detected in all water samples analyzed in this study. The results obtained from this study suggest a possible risk to the population of the study area given the high concentration of some metals that have no maximum allowed concentration, and the fact that for many people in the study area, harvested rain water is a main source of their water supply.
Show more

8 Read more

Heats of solution and related thermochemical properties of some rare earth metals and chlorides

Heats of solution and related thermochemical properties of some rare earth metals and chlorides

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.

84 Read more

Rare earth metals asecofriendly corrosion inhibitors for mild steel in 
produced water

Rare earth metals asecofriendly corrosion inhibitors for mild steel in produced water

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]:
Show more

14 Read more

Formation of Icosahedral Quasicrystals and 1/1 Crystal Approximants in Al Pd RE (RE: Rare Earth Metals) Systems

Formation of Icosahedral Quasicrystals and 1/1 Crystal Approximants in Al Pd RE (RE: Rare Earth Metals) Systems

In the present study, we have done further experiments to demonstrate the validity of the formation conditions of the i-phase by replacing Al with Ga, or Sc with other RE (rare earth metals) in the constituent elements of the Al-Pd-Sc alloy. We note that the replacements keep the e=a ¼ 2:10 where all the replacement elements are assumed as trivalent except for Yb which is usually assumed as divalent in the quasicrystalline formations.

5 Read more

A calculation of the elastic constants of yttrium and the rare earth metals

A calculation of the elastic constants of yttrium and the rare earth metals

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.
Show more

114 Read more

Infrared Polarizabilities of 3d Transition and Rare Earth Metals

Infrared Polarizabilities of 3d Transition and Rare Earth 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

15 Read more

Effect of Partial Substitutions of Rare earth Metals for Na site on the Thermoelectric Properties of NaxCo2O4 Prepared by the Polymerized Complex Method

Effect of Partial Substitutions of Rare earth Metals for Na site on the Thermoelectric Properties of NaxCo2O4 Prepared by the Polymerized Complex Method

was detected in the XRD pattern, could not be observed. The Yb content in the matrix phase from the EDX analysis mostly corresponded to the nominal composition. In general, the ionic radius of rare-earth metals becomes smaller with increasing the atomic weight. Consequently, in case of Yb, which has the smallest ionic radius in Nd, Sm, Dy and Yb, the Yb content in matrix phase highly increased compared to the other rare-earth metal substitutions. From these findings, it was found that the PC method is an effective technique to substitute rare-earth metals for Na-site.
Show more

7 Read more

Reclaim of Rare Earth Metals from Bond Magnets by Means of Thermally Activated Semiconductors (TASC)

Reclaim of Rare Earth Metals from Bond Magnets by Means of Thermally Activated Semiconductors (TASC)

resources as their name once implied. The amount of the reserve is said to be about 130 million tons, of which about 48.3% is held by China. In addition, the production of rare earths is centered on China and its market share is about 97% in 2009. The present situation really reflects the state of oligopoly (i.e., a state of seller’s market). Because of this, the supply of rare earth metals can easily be influenced by political situations and thus unstable at times. In addition, the price has constantly and drastically been rising every year. In order to obviate the present situation, it is urgently necessary to break up the rare-earth suppliers into several countries other than China. At the same time, we need to accelerate the reclaim and reuse of rare earth metals from the disposals.
Show more

6 Read more

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
Show more

79 Read more

Microlayered Composite Materials on Basis of Copper, Refractory, Rare Earth Metals, and Carbon for Electrical Contacts and Electrodes

Microlayered Composite Materials on Basis of Copper, Refractory, Rare Earth Metals, and Carbon for Electrical Contacts and Electrodes

cesses is to press the refractory metals, sinter the pressed porous compact at a high temperature, and infiltrate with copper. Other traditional manufacturing process is hot-pressing of powder mix of refractory metals or car- bon and copper. All this is done under very closely controlled conditions. Despite many years of experience with these materials, studies of their properties proceed within the system concerned in connection with the improved technical possibilities to control the material composition, dispersion and distribution of the refractory compo- nent in the product volume [1]-[7].
Show more

10 Read more

Electropolishing the rare earth metals

Electropolishing the rare earth metals

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]

18 Read more

Preparation of rare earth metals

Preparation of rare earth metals

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]

31 Read more

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]

60 Read more

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]

19 Read more

The need for reclamation of critical materials, such as rare earth metals

The need for reclamation of critical materials, such as rare earth metals

• Modernize US policies on production, processing, manufacturing., recycling, environmental protection – focus on minerals for military security & strong economy. • Direct DOI to c[r]

32 Read more

Pentadentate N2O3 Schiff Base Complexes of Rare Earth Metals

Pentadentate N2O3 Schiff Base Complexes of Rare Earth Metals

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 .
Show more

5 Read more

Automated ultrasound studies of magnetoelastic effects in rare earth metals and alloys

Automated ultrasound studies of magnetoelastic effects in rare earth metals and alloys

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]

161 Read more

Show all 6862 documents...