bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reducing the long-term environmental impact of wastes arising from uranium mining
Authors: Hart Kaye 
Published: April 2008

Abstract
Uranium mining and milling produces significant quantities of solid and liquid wastes. Solid wastes include waste rock arising from the mining activity and tailings produced by processing of the ore through the millin circuits. Of these, tailings have the most pronounced impact on the environment as they represent almost the entire mass of material processed in the milling circuits and also contain over 85% of the original radioactivity present in the ore. Modern rehabilitation schemes for tailings impoundments include a number of layers designed to prevent infiltration of water, oxidation of minerals, capillary rise of salts, and release of Rn, thereby minimizing the impact of the disposal of tailings on the environment. Although the effectiveness of these engineered barriers may degrade with time, it is possible, using evidence from natural systems and archaeological constructions, to provide evidence of the long-term isolation of the contaminants contained in the uranium tailings from the environment.
Anthropogenic radionuclide emissions into the environment
Authors: Eikenberg J. , Beer H. , Bajo S. 
Published: April 2008

Abstract

Two sources contribute essentially to the presence of anthropogenic radioisotopes in the environment: (i) release from nuclear materials with a major fraction derived from the nuclear bomb testing period during the period 1950–1963 and (ii) emissions from the nuclear industry, such as waste waters from U-mine tailing or nuclear fuel reprocessing plants. This chapter focuses mainly on the major source responsible for global surface contamination, that is, radioisotope aerosol deposition after release into the atmosphere. The atmospheric emissions were caused mainly via surface atomic bomb tests and reactor accidents, with the Chernobyl reactor catastrophe as the most important contribution. In contrast with most fission products, almost all actinides (which are produced via neutron capture reactions) are rather long lived and can be measured in environmental samples with high precision. Some of the actinides (i.e., U, Pu, Cm) consist of various isotopes (e.g.,
238,239,240,241
Pu) and hence can be used to distinguish between soil contamination from different emission sources. Approaches are therefore presented for calculating the different fractions of contaminants by use of characteristic isotopic signatures.
Atmospheric impact of the fossil fuel cycle
Authors: Golomb D. S. , Fay J. A. 
Published: April 2008

Abstract
Fossil fuels supply about 86% of the global primary energy consumption for transportation, industrial, commercial, and residential uses. While a minor part of fossil fuels is used as a raw material for the chemical industry, the vast majority is combusted providing heat, mechanical, and electric energy for the urban-industrial society. Owing to the combustion of fossil fuels, copious quantities of pollutants are emitted into the air and impact on the local, regional, and global air quality. It is technologically possible to significantly reduce the emissions of most pollutants, albeit at considerable energy and economic penalty. However, the reduction of emissions of carbon dioxide, one of the principal products of fossil fuel combustion, poses technological, economic, societal, and political problems of enormous magnitude. In recent decades it has become evident that rising levels of atmospheric carbon dioxide (and other greenhouse gases) will cause global warming and other climate changes.
Coal combustion wastes: characterization, reuse and disposal
Authors: Glasser F. P. 
Published: April 2008

Abstract
Coal extraction and combustion produce a number of waste streams, some of which can be utilized. Fly ash from the combustion of pulverized coal is characterized; it finds application as a partial replacement for Portland cement in concrete. Relatively few uses exist for other wastes, much of which is stockpiled, stored, or landfilled. These leave a legacy for future generations that must be managed to minimize geochemical impacts on air, soil, and groundwater quality.
The chemistry and mineralogy of coal and coal combustion products
Authors: Tishmack Jody K. , Burns Perre E. 
Published: April 2008

Abstract
The generation of electricity by thermal conversion of coal results in significant volumes of solid waste. Most of these materials are disposed of in surface impoundments near coal-fired power plants or in active coal mines. Disposal rates vary from country to country. In the USA, 60–70 wt% of these materials are disposed. Although these materials rarely meet the definition of hazardous, leachate tests on some coal ash have shown them capable of producing elevated concentrations of some regulated metals. As a result of the well-documented environmental concerns posed by coal combustion, and the disposal of coal combustion products (CCPs), a large body of research has focused on characterizing the mechanisms of mobilization and attenuation of trace elements in coal and its ash. However, groups opposed to coal combustion or unregulated disposal of ash overlook the value of these materials as well-proven replacements for aggregate, cement, or soil in numerous engineering and agricultural applications. An extensive body of knowledge has been gathered describing the variability and versatility of these materials. It has been shown that proper utilization or management of ash requires a good understanding of its chemical, physical, and mineralogical properties. This chapter is intended to provide a broad overview of the chemistry and mineralogy of coal, and the combustion products that are formed when coal is burned.
The beneficiation of coal combustion ash
Authors: Groppo John , Robl Thomas , Hower James C. 
Published: April 2008

Abstract

Pulverized coal combustion ash is an important source of strategic materials in the USA. Bottom ash is used as a source of aggregate for use in concrete and masonry units (blocks). It is processed primarily to improve its grading. A top size is removed and the finest sizes are removed via wet or dry screens. Pyrite and rock may also be present with the ash. These materials can be removed by spiral concentrators and jigs. In some cases high-quality/high-value lightweight aggregates are produced from stored bottom ash. Fly ash is used as a pozzolanic additive to Portland cement concrete. In addition to partially replacing the cement, it contributes substantially to the durability of the concrete. The advent of low-NO
x
burners and selective catalytic reduction (SCR) supported ammonia injection has altered the character of the fly ash, particularly the Class F, low-Ca type, by generally increasing the amount of unburned carbon. This contaminant adsorbs air-entrainment reagents and can decrease the resistance of the concrete to freeze-thaw damage. Over the past decade several technologies and approaches have been developed to remove the carbon from the fly ash, including: air classification; electrostatic separation; and fluidized-bed combustion. Other approaches such as microwave heating also show promise. Froth flotation has been successfully applied to wet ash. The amount of ash that is beneficiated has increased to a current level of about 1 million tons per year in the USA, which is expected to grow in time due to the need for predictable materials with constant characteristics. The primary environmental advantage of ash beneficiation is that it enables the use of combustion ash that would otherwise be disposed as waste. High-quality, consistent products can be generated, thus increasing the usefulness and acceptance of these processed products in both traditional and emerging markets. By doing so, the amount of ash that is utilized will be increased, thus reducing the amount of ash that is disposed, while conserving other resources such as aggregate and sand for other uses not applicable to combustion ash.
Environmental impact of geothermal energy utilization
Authors: Arnórsson Stefán 
Published: April 2008

Abstract
Presently geothermal energy accounts for 0.25% of the annual world-wide energy consumption. Extraction of heat from geothermal reservoirs involves drillings. Exploitation of geothermal resources is generally far less a cause of pollution than fossifuel combustion, making it preferable as a source for power and heat. Geothermal energy exploitation has locally some adverse environmental effects. Possible effects include scenery spoliation, drying out of hot springs, soil erosion, noise pollution, and chemical pollution of the atmosphere and of surface- and groundwaters. Exploitation may enhance seismic activity and cause land subsidence. The development of geothermal fields must sometimes be evaluated against the value of tourism. Various measures have been successfully employed to reduce the adverse environmental effects of geothermal energy utilization. The most important ones are directional drilling and injection of spent geothermal fluid. Future use of geothermal resources should specifically consider further use of geothermal heat pumps, extraction of chemicals from spent geothermal fluids to yield useful byproducts, integrated multiple use of high-temperature systems, and furthering of technology to develop hot-dry-rock systems including those occurring in the roots of active volcanic geothermal systems.
Corrosion and stability of vitrified material derived from municipal solid waste
Authors: Perret D. , Stille P. , Crovisier J.-L. , Shields G. , Mäder U. , Schenk K. , Chardonnens M. 
Published: April 2008

Abstract
Advanced high-temperature technologies for the treatment of municipal solid wastes or residues from conventional incineration can produce vitrified materials with superior physical and chemical characteristics compared to conventional residues (bottom ash, fly ash, filter cake). These materials, which may contain significant metal concentrations, exhibit favourable thermodynamic characteristics and very low contaminant release when subjected to corrosion. Owing to low leachability, these materials could possibly be used as secondary raw materials for civil engineering applications, although the energy demand for their production is high. This chapter presents the physical and chemical characteristics of a range of vitrified materials originating from various high-temperature technologies; their behaviour under highly aggressive conditions of corrosion and their thermodynamic stability are also presented. It is concluded that such high-temperature materials are indeed less likely to be damaging to the environment than conventional residues.
Chemistry and mineralogy of municipal solid waste incinerator bottom ash
Authors: Eggenberger Urs , Schenk Kaarina , Mäder Urs 
Published: April 2008

Abstract

A petrographic study was conducted on a suite of bottom ash samples from 28 municipal solid waste incinerators in Switzerland. Chemical and mineralogical analyses of bottom ash from waste combustors with comparable technology show similar major oxide composition. A significant decrease of SiO
2
was observed in comparison to the chemical composition of bottom ash from 10 years ago. In contrast to major oxide contents, heavy metal concentrations vary significantly in the bottom ash samples, but without any correlation to the type of input waste or plant operating conditions. Similar types and contents of crystalline phases were observed in all samples. The content of newly formed melilite increases with decreasing bulk Si/Ca ratio, indicating that the type of Ca-Mg-Al-silicates crystallizing during incineration and cooling follow petrogenetic rules. A considerable recycling potential for ferrous and non-ferrous metals was identified in the bottom ash. Optimized mechanical metal separation technologies could reduce the waste volume, heavy metal content, H
2
production, and exothermic reactions of the bottom ash in landfills and might be economically viable.
Incinerator waste as secondary raw material: examples of applications in glasses, glass-ceramics and ceramics
Authors: Barbieri Luisa , Lancellotti Isabella 
Published: April 2008

Abstract
The recovery and beneficiation of solid waste residues (bottom and fly ash) produced during incineration of municipal wastes are very important goals from the environmental and economic point of view. Some technologies allow not only to reduce the volume of incinerator waste but also to generate products of economic value by vitrification, devitrification, and ceramic processes. Bottom ash is preferable compared to fly ash as a secondary raw material. Mixed with glass cullet, bottom ash can be easily transformed into homogeneous and inert glasses, which can be transformed into glass fibres or sintered glass-ceramics after controlled thermal treatments. Alternatively, bottom ash can be used to produce tiles, in particular glazed tiles containing vitrified bottom ash in the ceramic body, and possibly bricks. The results presented in this review are promising and in accordance with the waste minimization policy as well as resources conservation.
Environmental impact of energy recovery from waste tyres
Authors: Gieré Reto , LaFree Sara T. , Carleton Loran E. , Tishmack Jody K. 
Published: April 2008

Abstract
Accumulation of millions of worn automotive tyres poses a considerable environmental problem. As an important part of the solid waste stream in today’s society, worn tyres have traditionally been discarded in landfills or stored in stockpiles. Over the past several decades, however, innovative alternatives to disposal have been developed, partly as a result of high tipping fees charged by landfill operators. Because of their high heat content and their low levels of moisture and nitrogen compared to coal, tyres are ideally suited for energy recovery through combustion. Utilization of waste tyres as supplemental or alternate fuel in various industrial combustion facilities, thus, has become one of the most important alternatives to disposal. Combustion processes, however, generate gaseous pollutants and solid waste materials, which must be disposed of or re-used as secondary raw materials. It is therefore important to characterize these combustion products in order to assess the environmental impacts of energy recovery from scrap tyres. Studies have shown that substantial reductions of some environmental pollutants can be achieved by partially replacing conventional fuels with waste tyres. On the other hand, using tyres as fuel may lead to considerable increases in the levels of other pollutants. Most notable among the effects of tyre combustion are, relative to conventional fuels, a pronounced decrease in the emission of nitrogen oxides into the atmosphere, and a generally significant increase in atmospheric zinc emissions as well as in the zinc contents of the solid combustion products. The geochemical effects on solid and gaseous combustion products are more or less pronounced depending on fuel composition, conditions of combustion, type of facility, and effectiveness of air pollution control devices. Thus, the use of tyre fuel has environmental impacts that must be weighed against the benefits of reducing the large volume of waste tyres in the global waste stream.
Colloid influence on the radionuclide migration from a nuclear waste repository
Authors: Geckeis Horst 
Published: April 2008

Abstract

Colloid formation is discussed as a possible pathway for the radionuclide release from a nuclear waste repository. An assessment of the colloid relevance on radionuclide migration requires insight into the possible colloid generation mechanisms, their stability and mobility under given groundwater conditions. In various experiments dedicated to the investigation of nuclear waste form behaviour in contact with groundwater, colloidal species are observed mainly for the tri- and tetravalent actinides even in rather high ionic strength solutions where destabilization of colloids is expected. Experimental evidence of laboratory and field studies suggests colloid instability in saline groundwater with time. Groundwater of low ionic strength and high pH enhances colloid stability, as demonstrated in various laboratory and field experiments. The results of an
in situ
colloid characterization study at the Äspö hard rock laboratory in Sweden are discussed as an example. The mechanism of radionuclide interaction with colloids and notably the reversibility of the radionuclide-colloid binding are other key issues of colloid studies. Kinetic stabilization of the radionuclide binding to colloids may lead to a considerable enhancement of the colloid-mediated radionuclide migration. Substantial kinetic inhibition of actinide dissociation from humic colloids has been established by studying the behaviour of natural humic colloid borne U, Th and rare earth elements. Such behaviour might be explained by the incorporation of these elements into inorganic nanoparticles stabilized by humic coating. Spectroscopic evidence for the occurrence of actinide incorporation into colloidal structures is briefly discussed and the importance of considering the kinetics involved in all kinds of colloidal processes is emphasized. The enhanced migration of tri- and tetravalent actinide ions has been observed recently in various
in situ
dipole tests at the Grimsel hard rock laboratory in Switzerland. Such experimental findings underline the necessity of further studies on the colloid influence on actinide mobility. Moreover, an improved understanding of colloid-rock interaction mechanisms is required, which is essential for the description and prediction of colloid filtration processes.
Hydrological and geochemical factors controlling leachate composition in incinerator ash landfills
Authors: Johnson C. Annette , Abbaspour Karim C. 
Published: April 2008

Abstract

The hydrological and geochemical processes that control leachate composition are discussed for two examples, the first being a landfill containing municipal solid waste incinerator (MSWI) bottom ash, Landfill Lostorf, and the second a lysimeter containing blocks of cement-stabilized MSWI air pollution control (APC) residues. In both examples the leachate consists of a component that takes months to years to pass through the landfill and rainwater that passes through the landfilled material via preferential flow paths. The composition of the leachate is relatively constant and is only diluted with rainwater during rain events. The concentration of major leachate components (Na
+
, K
+
, Cl
−
and OH
−
) is controlled by diffusion processes and by the precipitation of solubility-controlling phases (Ca(II), Al(III), SO
4
2
− and Si(IV)). The observed concentrations of some relatively insoluble heavy metal and metalloid species may be explained by the precipitation of secondary phases. More soluble species may be adsorbed on surfaces of or incorporated in minerals, but the mechanisms remain to be elucidated.
Shaken but not always stirred. Impact of petroleum charge mixing on reservoir geochemistry
Authors: Wilhelms Arnd , Larter Steve 
Published: April 2008

Abstract
Essentially all petroleums are mixtures with different components charged from source rocks at different temperatures. This heterogeneous charge is the basis for compositional differences in reservoirs that are the basic elements of reservoir geochemical approaches. Because many classical petroleum geochemical tracers of source facies and maturity, such as the cyclic biomarker hydrocarbons, show several orders of magnitude variation in concentration in petroleum systems these compounds do not reliably track facies or maturity signals in mixed oil situations. Light hydrocarbon and aromatic hydrocarbon parameters are more reliable in this sense but, as mixtures are the norm, the concept of the maturity of oils needs revising. We suggest an alternative approach is needed which tracks the maturity/petroleum mass fraction relationships for reservoired oils (mass fraction maturity) and allows the bracketing of source kitchen maturity. We strongly advise against using compound ratios in reservoir geochemical studies without having knowledge of the compounds concentration range variations within the petroleum system being studied.
New insights into reservoir filling and mixing processes
Authors: Stainforth John G. 
Published: April 2008

Abstract
A common assumption is that hydrocarbon charge homogenizes with the petroleum already in a trap: thus, compositional gradients reflect only subsequent segregation of the petroleum under the combined influences of gravity, temperature and diffusion. Since such homogenization would entail an unfavourable generation of potential energy, a more plausible hypothesis is that hydrocarbons stack into traps roughly in the density sequences in which they arrive. The commonly accepted model suggests that homogeneous and gravitationally unstable petroleum columns move towards graded equilibrium ones, whereas the hypothesis preferred here implies that they gradually diffuse towards equilibrium from the opposite direction, i.e. poorly mixed initial states.

According to this hypothesis, trends of oil GOR and bubble point (
P
b
) are controlled by either (a) the charge GOR or (b) the evolving PT conditions at the GOC, depending on the gassiness of the charge. By contrast, API gravity trends mainly reflect the integrated maturity histories of source rock kitchens during the trap filling regardless of the charge gassiness. Because trap and kitchen histories are usually (very) different, a wide spectrum of API and GOR (and
P
b
) combinations is possible, from minor API gradients coupled with large GOR gradients and
vice versa
.