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Abstract  

Epithermal Instrumental Neutron Activation Analysis has been used to measure the concentration of uranium in eutectic salt solutions in support of a research program in which the actinide elements are separated from rare earths and other fission products using high-temperature electo-deposition. The uranium response over three decades in concentration follows a negative power function; and high concentrations of samarium interfere with the determination of uranium but can be accurately corrected. The EINAA method was successfully used to analyze NIST SRM 278 Obsidian and NIST SRM 1566a Fly Ash.

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Abstract  

Trace element partitioning was studied at a pulverized-lignite fired power plant in Texas. Concentrations of 41 elements were determined by neutron activation analysis (NAA) for lignite fuel and combustion effluents collected during 10 consecutive days. Elements studied were grouped into three classes according to their enrichment factors and the relationship between their concentrations and particle size. In general, the concentration enhancement in fly ash and the difference in enhancement between elements placed in different classes are shown to be less significant in this study than for other partitioning studies on higher rank coals.

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Abstract  

We have examined the leachability of the toxic elements cadmium, arsenic, mercury, and selenium from solid wastes. The solid wastes studied are municipal incinerator ash, coal fly ash, hospital incinerator ash, raw sewage sludge, sewage incinerator bottom ash, and sewage incinerator lagoon ash (which is a combination of bottom and fly ashes). Cadmium displayed the greatest leachability in all waste types, with 76% leached from the municipal refuse incinerator ash. Although the sources of elements in the wastes are diverse, the leachability and hence the bioavailability in the incinerator ash appears mainly determined by the volatility of the element.

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Abstract  

Oil shale ashes from the PAMA demonstration power plant in the Negev region of Israel are produced by fluidized bed combustion (700–850C) under short residence time. The FED is organic-rich calcareous raw material rich in carbonate rather than clays. Thus it is important to ascertain whether the calcite in the ashes is original natural calcite from the raw material or the product of recarbonation of lime. Three groups of ashes from the power plant, Ash Cooler (AC), Fly Ash (FAS) and Boiler Bank (BB) were examined using XRD, FT-IR, SEM and isotope analysis methods. The recarbonated calcite is distinguished from the natural original by smaller crystal size, lower degree of crystallinity and the presence of impurities. High negative δ13C values in oil shale ashes are explained by assuming recarbonation of lime with CO2 originating from the combustion of the organic matter of the raw oil shale. Fly Ash, FAS, and BB, produced from organically-rich FED, contain more recarbonated calcite than bottom ash, AC. This observation can be explained by the larger grains of the AC, which do not reach the highest temperature area, and thus most of the original calcite does not decompose.

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Summary  

A simple sample decomposition and laser fluorimetric determination of uranium at trace level is reported in certain refractory minerals, like ilmenite, rutile, zircon and monazite; environmental samples viz. soil and sediments; industrial waste materials, such as, coal fly ash and red mud. Ilmenite sample is decomposed by heating with ammonium fluoride. Rutile, zircon and monazite minerals are decomposed by fusion using a mixture of potassium bifluoride and sodium fluoride. Environmental and industrial waste materials are brought into solution by treating with a mixture of hydrofluoric and nitric acids. The laser induced fluorimetric determination of uranium is carried out directly in rutile, zircon and in monazite minerals and after separation in other samples. The determination limit was 1 μg . g-1 for ilmenite, soil, sediment, coal fly ash and red mud samples, and it is 5 μg . g-1 for rutile, zircon and monazite. The method is also developed for the optical fluorimetric determination of uranium (determination limit 10 μg . g-1) in ilmenite, rutile, zircon and monazite minerals. The methods are simple, accurate, and precise and they require small quantity of sample and can be applied for the routine analysis.

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Abstract  

Sorption of124Sb(III) from benzene, toluene, o-xylene and nitrobenzene on treated fly ash, pyrolysis residue and bentonite clay was studied at room temperature using the batch method. In comparison to a former study for the sorption of124Sb(V), the results revealed relatively higher sorption of the trivalent state than the pentavalent one. According to the type of the nonpolar solvent used, the order of uptake of the radioactive isotopes was often o-xylenetoluene>benzene. The sorption tendency of the sorbents used towards the radionuclides was: bentonitepyrolysis residue>treated fly ash. Sorption from an aqueous medium on the same sorbents has also been investigated for124Sb(III) compared to124Sb(V),152Eu(III) and their mixtures. The obtained results showed that the order of uptake of the different radionuclides was: Eu(III)>>Sb(III)>Sb(V)>mixture. The investigation was extended to the desorption studies of these radionuclides in the acidic and the neutral media from the dried radioactivity loaded sorbents.

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calcium fly ash geopolymer concrete with alccofine , Advances in Concrete Construction , Vol. 5 , No. 1 , 2017 , pp. 17 – 29 . [2] Ondova M

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Abstract  

The rate of heat evolution as well as total heat output are strongly affected by other components of hydrating mixture, apart from neat portland cement, such as slag, fly ash and other industrial by-products; among them the wastes from fluidised bed combustion (FBC) has been taken into account recently. In this study the calorimeter was applied to follow the early hydration of cements produced with these materials. They interact with cement paste in a few ways: as set controlling agent and as active pozzolanic admixtures. Thus the rate of heat evolution/hydration is modified, depending on the composition of clinker and percentage of waste in the mixture. After the series of measurements for clinker-waste mixture hydrated systems also some ‘model’ mixtures were investigated to separate the effects from particular waste components.

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The hydration processes of mixtures containing calcined gypsum, blastfurnace slag or fly ash, portland cement and/or hydrated lime, able to generate calcium trisulphoaluminate and silicate hydrates, have been studied by means of differential thermal analysis. Samples were aged at 55°,70° and 85°C for 16, 24 and 48 hours, followed by a further curing at room temperature and humidity up to 28 days.

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Abstract  

The k 0-IAEA program developed for implementation of the single comparator instrumental neutron activation analysis method (k 0-INAA) has been used for elemental analysis with NIRR-1 irradiation and counting facilities. The existing experimental protocols for routine analysis based on the relative method were used to test the capability and reliability of the program for the analyses of geological and biological samples. The Synthetic Multi-element Standards (SMELS) types I, II and III recommended by the international k 0 user community for the validation of k 0-NAA method in NAA laboratories, furthermore, the following standard reference materials: NIST-1633b (Coal Fly Ash) and IAEA-336 (Lichen) were analyzed. Results obtained with the version 3.12 of the k 0-IAEA program were found to be in good agreement with the data obtained with the established relative method using WINSPAN-2004 software. Detection limits for elemental analysis of geological and biological samples with NIRR-1 facilities are provided.

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