Compositions Of Impurities Research Articles

Luminescence for sedimentary provenance quantification in river basins: A methodological advancement

Multiple luminescence signals such as optically stimulated luminescence, infrared stimulated luminescence and thermoluminescence etc. are characteristic of the crystal/material. Recent studies have shown the potential of luminescence signals for sedimentary provenance studies, sediment fingerprinting and tracking. It is based on the premise that different provenances have different compositions of trace impurities in minerals which are responsible for the luminescence properties of the minerals. However, use of luminescence for provenance studies is still in its developmental stage and needs validation in modern sediments. The current work utilizes the differences in the luminescence signals from different geological provenances to quantitatively estimate the sediment influx to the mainstream from its tributaries based on a 2-component mixing model. Samples from natural river confluences and control samples prepared by mixing two samples in a known proportion by weight were used to estimate the sediment flux based on the luminescence characteristics. This study successfully demonstrates the use of luminescence parameters for sediment fingerprinting and budgeting using natural and controlled samples.

Applications of two electric arc plasma torches for the beneficiation of natural quartz

Experimental beneficiation processes of quartz concentrate in arc plasma torches of two different types and electric powers were studied. An emission scanning electron microscope and a universal laser analyzer were used to investigate the structures as well as the size distributions of grains and microparticles. Inductively coupled plasma-mass spectrometry was used to determine the chemical compositions of nonstructural solid-phase mineral impurities in quartz concentrate. Results related to the modified grains’ structure and size distribution, the compositions of impurities, and the gas-liquid inclusions in the quartz concentrate were investigated. The total impurities concentrations in the processed grains were found to satisfy the IOTA-STD standard (industry standard for grading high quality fused quartz products). The optimal condition (i.e., the optimal specific plasma enthalpy) for the production of high-purity quartz in arc plasma torches was found to depend on the geological-genetic type and the structural and textural features (i.e., chemical composition and gas-liquid inclusions) of the quartz concentrate.

Detection and estimation of capillary interparticle forces in the material of a fluidized bed reactor at high temperature by powder flow characterization

Two ceramic powder samples having different compositions of surface impurities and particle size distributions were considered. These two samples resulted from a high temperature fluidized bed reactor which in its operation showed changes of working condition that might be attributed to the onset of strong interparticle forces. The flow behaviour of these powders was characterized by the High Temperature Annular Shear Cell (HT-ASC), between ambient temperature and 500 °C. Furthermore, a model is developed to relate the change of the powder flowability to the formation of a liquid phase due to the melting of particle impurities present on the particle surface. In particular, the model is used to predict, on the base of the salt composition, the intensity of the interparticle forces at different temperatures. The interparticle forces predicted by the model can be compared with those that can be inferred from the powder flow properties measured with the HT-ASC. Therefore, it is demonstrated that it is possible to derive a theoretical model to predict interparticle forces in a particulate material relevant to fluidized bed reactor, on the basis of the impurities composition. Furthermore, it is demonstrated the possibility to correctly estimate the intensity of average interparticle forces in the same kind of material by the interpretations of bulk flow properties measured with a shear tester, even in the case in which capillary forces take the place of the much weaker van der Walls forces. More in general, the paper suggests a method by which powder rheology can be used to indirectly evaluate the effects of the interparticle forces on fluidization processes even in case in which strong capillary interaction occur.

The influence of CO2 mixture composition and equations of state on simulations of transient pipeline decompression

In a CO2 transport pipeline, decompression can occur either due to planned maintenance or accidental rupture. We investigate the impact of modelling simplifications and assumptions regarding the purity of CO2 on the decompression of an industrial scale transport pipeline. Using industrially relevant compositions of impurities we both calculate simplified (isentropic) decompression curves as well as perform full-scale fluid simulations using models for heat transfer, friction and choked flow. Herein, we compare the use of the Peng–Robinson cubic equation of state (EOS) with the use of the highly accurate EOS-CG and GERG-2008 EOS.We find that the saturation pressure can change significantly when certain impurities are present, even when in small quantities. A simplifying assumption that CO2 is pure can therefore lead to significant underestimation of the fluid pressure during the decompression, with consequences for the prediction of running ductile fractures. The choice of EOS was found to mainly affect the velocities of the initial decompression wave, with the long-time evolution of the pipeline decompression remaining relatively unchanged. The temperature minimum did neither depend significantly on the choice of EOS nor the presence of impurities.

Anisotropic resonant magnetoplasticity of NaCl crystals in the Earth’s magnetic field

Resonant relaxation of the dislocation structure under the action of crossed magnetic fields, i.e., constant magnetic field of the Earth (BEarth) and alternating radio-frequency field (\(\tilde B\)), has been experimentally studied in a series of dielectric (NaCl) crystals with various compositions of impurities under variations in the frequency, direction of the pumping field \(\tilde B\), and orientation of the samples in the Earth’s magnetic field. The frequency dependence of the dislocation path length l(ν) exhibits peaks with various heights (lmax) and resonant frequencies (νres). The maximum resonant effect has been observed for dislocations with the direction L orthogonal to the plane of crossed magnetic fields in a configuration of mutually perpendicular vectors {L, \(\tilde B\), BEarth} belonging, together with sample edges {a, b, c}, to the 〈100〉 system. Variation of the concentration C of calcium impurity in crystals of the NaClCa series only influenced the resonant peak height as \(l_{\max } \propto 1/\sqrt C \). Rotation of the magnetic field \(\tilde B\) in the (b, c) plane from direction \(\tilde B\) ⊥ BEarth to \(\tilde B\) ∥ BEarth also did not influence the frequency of the resonance but changed its amplitude. Depending on the crystal type, this influence changed from rather insignificant (in crystals of the NaClLOMO series) to complete suppression of the effect for \(\tilde B\) ∥ BEarth (in the NaClNik series). The resonant frequency νres is sensitive to orientation of the sample with respect to BEarth. Upon rotation of the crystal by the angle θ = ∠(c, BEarth) about the a ⊥ BEarth edge, the initial peak for dislocations L ‖ a at the crystal orientation θ = 0 and the frequency νres0 is replaced by a pair of peaks at frequencies ν1, 2 ≈ νres0cosθ1, 2, where θ1 = 90° − θ and θ2 = θ. Previously, these peaks were observed separately in NaClNik crystals for \(\tilde B\) ∥ c and \(\tilde B\) ∥ b. In the present study, these peaks have been observed simultaneously for both orientations of \(\tilde B\) in NaClLOMO and NaClCa crystals, where the resonance is not completely suppressed for \(\tilde B\) ∥ BEarth.

The first discovery of uytenbogaardtite in Taimyr (Konechnoe ore occurrence)

Uytenbogaardtite has been observed when examining the ores of the Konechnoe gold ore occurrence, West Taimyr, which is the first find for the entire Taimyr-Severnaya Zemlya region. It is associated with native gold (fineness 520–560‰), pyrite, and sphalerite. Sphalerite is characterized by Fe, Cd, Ag, and Cu impurities. Zinc is present in siderite. In the ores of the Konechnoe ore occurrence, there is also native gold of the early generation with sphalerite, the latter containing chalcopyrite lamellae and being in association with arsenopyrite, pyrite, and galena. The peculiar compositions of microinclusions and impurities in sphalerite and other minerals and the presence of accessory minerals, such as monazite and apatite, reflect the specific metallogenic and geochemical characteristics of the Minina-Bol’shevik structural-metallogenic zone and serve as indicators of the potential of the North Taimyr area in terms of gold, silver, zinc, copper, lead, cadmium, strontium, thorium, and lanthanides.

An investigation on recycling the recovered uranium from electro-refining process in a CANDU reactor

Feasibility studies for recycling the recovered uranium from electro-refining process of pyroprocessing into a Canada Deuterium Uranium (CANDU) reactor have been carried out with a source term analysis code ORIGEN-S, a reactor lattice analysis code WIMS-AECL, and a Monte Carlo analysis code MCNPX. The uranium metal can be recovered in a solid cathode during an electro-refining process and has a form of a dendrite phase with about 99.99% expecting recovery purity. Considering some impurities of transuranic (TRU) elements and fission products in the recovered uranium, sensitivity calculations were also performed for the compositions of impurities. For a typical spent PWR fuel of 3.0 wt.% of uranium enrichment, 30 GWD/tU burnup and 10 years cooling, the recovered uranium exhibited an extended burnup up to 14 GWD/tU. And among the several safety parameters, the void reactivity at the equilibrium state was estimated 15 mk. Additionally, a simple sphere model was constructed to analyze surface dose rates with the Monte Carlo calculations. It was found that the recovered uranium from the spent PWR fuel by electro-refining process has a significant radioactivity depending on the impurities such as fission products.

Synthesis of Ti3SiC2 bulks by infiltration method

T3SiC2 bulks have been synthesized by infiltrating Si liquid into porous precursor pellets composed of solid TiC and Ti powders. Silicon pellets were placed at the bottom of the precursor pellets as the liquid source. The starting compositions can be represented by the formula 2TiC+Ti+xSi, where x=1.0, 1.2, 1.5 and 1.8, respectively. The phase formation and microstructure of the bulks were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS) system. The results demonstrated that the TiC/Ti precursor pellet could only react with Si completely when the x value is 1.8. Impurities SiC, Ti–Si binary compounds and Ti8C5 appeared along the silicon diffusion direction. It is found that the compositions of impurities strongly depended on the Si-concentration. Reaction mechanism of this Ti3SiC2 infiltration synthesis has also been discussed based on the Si-concentration changes on the diffusion path.

Potential Flue Gas Impurities in Carbon Dioxide Streams Separated from Coal-Fired Power Plants

For geological sequestration of carbon dioxide (CO2) separated from pulverized coal combustion flue gas, it is necessary to adequately evaluate the potential impacts of flue gas impurities on groundwater aquifers in the case of the CO2 leakage from its storage sites. This study estimated the flue gas impurities to be included in the CO2 stream separated from a CO2 control unit for a different combination of air pollution control devices and different flue gas compositions. Specifically, the levels of acid gases and mercury vapor were estimated for the monoethanolamine (MEA)-based absorption process on the basis of published performance parameters of existing systems. Among the flue gas constituents considered, sulfur dioxide (SO2) is known to have the most adverse impact on MEA absorption. When a flue gas contains 3000 parts per million by volume (ppmv) SO2 and a wet flue gas desulfurization system achieves its 95% removal, approximately 2400 parts per million by weight (ppmw) SO2 could be included in the separated CO2 stream. In addition, the estimated concentration level was reduced to as low as 135 ppmw for the SO2 of less than 10 ppmv in the flue gas entering the MEA unit. Furthermore, heat-stable salt formation could further reduce the SO2 concentration below 40 ppmw in the separated CO2 stream. In this study, it is realized that the formation rates of heat-stable salts in MEA solution are not readily available in the literature and are critical to estimating the levels and compositions of flue gas impurities in sequestered CO2 streams. In addition to SO2, mercury, and other impurities in separated CO2 streams could vary depending on pollutant removal at the power plants and impose potential impacts on groundwater. Such a variation and related process control in the upstream management of carbon separation have implications for groundwater protection at carbon sequestration sites and warrant necessary considerations in overall sequestration planning, engineering, and management.

Formation processes and main properties of hollow aluminosilicate microspheres in fly ash from thermal power stations

The main parameters of aluminosilicate microspheres formed at thermal power stations in Russia were studied; these parameters are responsible for the prospective industrial application of these microspheres. A comparative analysis of the properties of mineral coal components, the conditions of coal combustion, and the effects of chemical and phase-mineralogical compositions of mineral impurities in coals from almost all of the main coal deposits on the formation of microspheres was performed. The effects of thermal treatment conditions on gas evolution processes in mineral particles and on the fraction of aluminosilicate microspheres in fly ash were considered. It was found that the yield of microspheres was higher in pulverized coal combustion in furnaces with liquid slag removal, all other factors being equal. The regularities of microsphere formation were analyzed, and the mechanism of microsphere formation in fly ash during the combustion of solid fuels was considered.

Residual flaws due to formation of oxygen bubbles in anodic alumina

Flaws in anodic alumina films are localized sites where the film material is modified morphologically, structurally, or chemically compared with adjacent regions of uniform amorphous alumina. The flaws are preferred sites of pitting and dielectric breakdown, which are of importance to the corrosion resistance and electronic applications of aluminium respectively. Although flaws have been categorized in general terms as either mechanical or residual, there is no detailed understanding of the precise origin and nature of flaws and their mechanisms of influence in pitting and dielectric breakdown. Consideration is given here to the formation of oxygen bubbles within anodic alumina, by oxidation of O 2− ions in the vicinity of the metal/film interface, which are suggested to be one type of residual flaw. The compositions of impurities or second phase particles, which may lead to generation of oxygen bubbles, are examined in the light of systematic investigations of anodizing of binary aluminium alloys.

Corrosion fatigue testing of eight different steels in an Icelandic geothermal environment

Rotating bending tests were carried out on eight different steels in geothermal steam from three different geothermal environments. The steels ranged from high-strength turbine blade to low-strength steels, and from high- to low-alloy steels. The testing environments were geothermal steam from three different sites containing different amounts and compositions of non-condensable gases (CO 2,H 2S and H 2) and other impurities. Fatigue testing in air was carried out for reference. This paper describes the final results from the Icelandic part of the Nordic Industrial fund project ‘Fatigue under spectrum loading and in corrosive environments”.

Composition of impurities in tetrabutyltin prepared by grignard reaction

1. The compositions of impurities in tetrabutyltin prepared by the Grignard reaction were determined. 2. The products used for the synthesis of tetrabutyltin were the main source of impurities.