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High temperature interactions of alkali vapors with solids during coal combustion and gasification.Punjak, Wayne Andrew January 1988 (has links)
The high temperature interactions of alkali metal compounds with solids present in coal conversion processes are investigated. A temperature and concentration programmed reaction method is used to investigate the mechanism by which organically bound alkali is released from carbonaceous substrates. Vaporization of the alkali is preceded by reduction of oxygen-bearing groups during which CO is generated. A residual amount of alkali remains after complete reduction. This residual level is greater for potassium, indicating that potassium has stronger interactions with graphitic substrates than sodium. Other mineral substrates were exposed to high temperature alkali chloride vapors under both nitrogen and simulated flue gas atmospheres to investigate their potential application as sorbents for the removal of alkali from coal conversion flue gases. The compounds containing alumina and silica are found to readily adsorb alkali vapors and the minerals kaolinite, bauxite and emathlite are identified as promising alkali sorbents. The fundamentals of alkali adsorption on kaolinite, bauxite and emathlite are compared and analyzed both experimentally and through theoretical modeling. The experiments were performed in a microgravimetric reactor system; the sorbents were characterized before and after alkali adsorption using scanning Auger microscopy, X-ray diffraction analysis, mercury porosimetry and atomic emission spectrophotometry. The results show that the process is not a simple physical condensation, but a complex combination of several diffusion steps and reactions. There are some common features among these sorbents in their interactions with alkali vapors: In all cases the process is diffusion influenced, the rate of adsorption decreases with time and there is a final saturation limit. However, there are differences in reaction mechanisms leading to potentially different applications for each sorbent. Bauxite and kaolinite react with NaCl and water vapor to form nephelite and carnegieite and release HCl to the gas phase. However, emathlite reacts to form albite and HCl vapor. Albite has a melting point significantly lower than nephelite and carnegieite; therefore, emathlite is more suitable for lower temperature sorption systems downstream of the combustors/gasifiers, while kaolinite and bauxite are suitable as in-situ additives.
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Insoluble oxide product formation and its effect on coke dissolution in liquid ironChapman, Michael Wallace. January 2009 (has links)
Thesis (Ph.D.)--University of Wollongong, 2009. / Typescript. Includes bibliographical references: leaf 248-256.
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Quality and postharvest performance of cut roses grown in root media containing coal bottom ashCross, Marlene Karen, January 2000 (has links)
Thesis (Ph. D.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains viii, 128 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references (p. 108-115).
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NON-INVASIVE CHARACTERIZATION OF UNSATURATED ZONE TRANSPORT IN DRY COAL ASH DUMPS: A CASE STUDY OF TUTUKA, SOUTH AFRICAMuchingami, Innocent I. January 2013 (has links)
Doctor Scientiae / The management of the large volumes of solid wastes produced as coal combustion
residue is of particular concern due to the presence of leachable metals and salts which
may constitute a long term environmental risk and potential contamination of both
surface and groundwater systems of the surrounding environment. In order to
implement an efficient monitoring scheme and to assess the impact of the ash dump on
the hydrologic system, a thorough knowledge on the migration of solutes fluxes in dry
ash dumps as well as the controls on the transport of these solutes to the underlying
groundwater system is required.
The conventional methods which have been widely used for such applications are
centred on extracting and analysing several samples from observation wells are drilled
on the dump. This has however created a potentially hazardous situation as the
installation of monitoring wells may result in the creation of new fluid pathways and
results in further migration of leachates. Nevertheless, non–invasive characterization
has often been useful in the determination of subsurface hydraulic properties and is a
key step towards the solution of real-life problems in hydrology, hydrogeology and soil
science. In contaminant transport non-invasive methods have often proved to be an
efficient tool as compared to traditional drilling and sampling techniques which in most
cases results in the creation of preferential flow paths and do not allow for the space
and time resolution needed for the monitoring of hydrological and environmental
processes.
In this context, this study seeks to develop a generic conceptual model for the ash
dump through the use of non-invasive geophysical techniques and numerical modelling techniques at the Tutuka Ash dump, Mpumalanga South Africa. Changes in electrical
resistivity were used correlate changes in moisture contents during moisture and salt
leachate ingression in ash dumps with a sufficient accuracy. A determination of the
suitability of Archie‘s law to describe the relationship between electrical resistivity and
solute transport ash medium was achieved through empirical laboratory experiments.
Electrical resistivity tomography was then used as an appropriate tool for the elucidation
of potential flow paths and brine dispersion in the ash dump. The flow rates through the
ash dump were estimated by considering the rate of brine injection and the distance
travelled by the brine plume over the time spanned in time lapse infiltration experiments.
Additional geophysical profiles managed to show the lithostratigraphy of underlying
hydro-geology, thereby ensuring that the knowledge of the geology can be established
without the application of any intrusive methods.
To ensure that development of the conceptual model of the unsaturated zone transport
of the ash dump was developed with sufficient accuracy, numerical models were also
used to describe solute transport in the vadose zone. The HYDRUS2D numerical
package was used simulate the flux dynamics within the unsaturated zone of the coal
ash medium, so as to develop a conceptual understanding of water flow and salt
transport through the unsaturated zone of the coal ash medium. The results from the
study suggested a conceptual solute transport model that consists of a two layers. The
upper layer represented the unsaturated zone of the ash dump which was the source of
any potential contaminant transport that could be of concern. The lower layer describe
the underlying the subsurface environment to the ash dump which include the soil zone,
the shallow aquifer and the deep fractured rock aquifer. To enable this conceptualisation, results from the numerical simulations and
geophysical interpretations of the electrical resistivity profiles were the critical
components for optimising the site-specific subsurface water flow and solute transport
processes, as well as producing the most acceptable conceptualisation of the ash dump
system that could be used in hazard assessment and mitigation against potential
groundwater pollution. The conceptual models developed in this study proposed an
explanation on impact of the ash dump to the hydro-geologic and the eco-hydrologic
environment by proposing a scenario of contamination of the underling ash dump and
the existing. In this regard, the study managed to provide important scenarios that may
be necessary during mitigation procedures for both the ash dump and the wetland.
Key words: non-invasive, coal ash, time lapse, electrical resistivity tomography,
numerical models, HYDRUS2D, conceptual model.
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Beyond Waste: Uncovering the Hidden Potential of Coal AshTanrikulu, Dilek 27 July 2023 (has links)
The thesis lies at the intersection of the concepts of "beyond" meaning surpassing and "waste" referring to the materials and resources that are often discarded or overlooked, are the focus of this project. Overall, the project represents a commitment to surpassing conventional limits and transforming waste into a valuable resource.
This project also proposes a new ethical architectural practice that seeks to challenge traditional design approaches by exploring the potential of waste as a valuable input in building design. By deviating from conventional methods and proposing new ideas, the study aims to rethink traditional practices and create a new view toward the incorporation of waste in architecture. By adopting the principles outlined in the book "Cradle to Cradle" the project embraces the 4 R's of recycling, reducing, reusing, and recovering, demonstrating how waste can be transformed into valuable input in building design.
This ethical framework emphasizes the reuse, recycling, repurposing, and recovery of waste in architecture. Through this project, the aim is to challenge the current ways in which architecture is designed, with a view toward promoting sustainable practices and a more responsible approach to architectural design.
Ultimately, this thesis offers a new ethical perspective on how waste can participate in the way we design buildings, and presents a potential pathway towards a more sustainable future for the field of architecture. / Master of Architecture / This project focuses on the concept of surpassing conventional limits and transforming waste into a valuable resource. It proposes an ethical architectural practice that challenges traditional design approaches by exploring the potential of waste in building design. By adopting the principles of reducing, reusing, recycling, and regulating, the project demonstrates how waste can be transformed into valuable input. The goal is to promote sustainable practices and a responsible approach to architectural design. Ultimately, this thesis offers a new perspective on how waste can contribute to the way we design buildings, paving the way for a more sustainable future in architecture.
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A preliminary investigation of microbubble flotation of fine coalHalsey, Gregory S. January 1986 (has links)
Although froth flotation is generally recognized as the most viable means of cleaning fine coal, a loss in recovery rate and selectivity is encountered when attempting to apply the process to clean ultrafine coals. In this work, batch flotation tests were conducted on several Appalachian coals using microbubbles in a cylindro-conical flotation column. Results indicate that this technique shows improvements over the conventional technique using larger bubbles, when the coal is ultrafine. The improvement in recovery rate with the microbubbles is due to improved hydrodynamic conditions which are more conducive to bubble/particle collision, while the improvement in selectivity is due to the absence of turbulent wakes. / M.S.
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Continuous column flotation of ultrafine coal using microbubblesKeyser, Paul Martin January 1987 (has links)
A flotation column has been developed Incorporating the use of fine air bubbles (less than 100 microns) to remove ash-forming minerals from micronized coal. The microbubble generator used In this work has been characterized and found to yield a very narrow size distribution. Microbubble column flotation tests have been conducted to study a series of operating variables such as time, bubble size, feed rate, feed point, feed percent solids, column height, bubble number concentration, make-up water addition and countercurrent wash water addition. The results show that i) fine air bubbles are Inherently better suited for floating small particles; ii) both ash and recovery rates Increase with Increasing feed rate, distance of the feed point from the tailings port, feed percent solids and bubble number concentration; iii) taller columns result In Improved recovery and ash rejection; and iv) the countercurrent wash water addition minimizes the entrainment of mineral matter to the froth product. Proper control of these parameters makes It possible to produce super clean coal (< 2% ash). / M.S.
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Trace Elemental Analysis of Ashes in the Combustion of the Binder Enhanced d-RDF by Inductively Coupled Plasma Atomic Emission SpectroscopyTai, Chia-Hui 11 1900 (has links)
Incineration is an attractive solution to the problems of disposing of municipal solid wastes and supplying energy. Because up to 25 percent of the waste in refuse-derived-fuel systems is ash, the physical and chemical characteristics of ash become more and more important for its potential impacts and methods suitable for their disposal. Trace elements concentration in ash is of great interest because of its relationship to regulatory criteria under the Resource Conservation and Recovery Act (RCRA) regarding toxicity and hazards. The applications of a microwave oven sample dissolution method has been tested on a variety of standard reference materials, with reproducible and accurate results. Fourteen trace elements, As, Ba, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, Tl, V, and Zn, from the dissolved ash samples were determined by inductively coupled plasma atomic emission spectrometry.
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Experimental vegetation of bottom ash and scrubber sludge at Kansas City Power & Light Company's Lacygne generating stationMulhern, Daniel Wayne. January 1984 (has links)
Call number: LD2668 .T4 1984 M84 / Master of Science
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An evaluation of the effectiveness of coal ash as an amendment for acid soilsMbakwe, Ikenna 12 1900 (has links)
Thesis (MScAgric (Soil Science))--Stellenbosch University, 2005. / Soil acidity is one of the greatest limitations to crop production in most soils of the
world. The increasing high costs of conventional liming materials have made it
necessary to explore the possibilities of using cheaper substitutes. In South Africa, 16
million hectares of land are naturally acid while on the other hand, the country’s coalfired
power plants generate 28 million tons of mostly alkaline coal ash per year,
disposal of which is increasingly becoming difficult. The use of coal ash as an
agricultural soil amendment while solving the liming needs of local farmers, may also
present a safe and more economical disposal option. This study was carried out to
evaluate the effectiveness of coal ash as an agricultural liming material. A greenhouse
experiment was conducted using maize as test crop. A field experiment was also
established on Beestepan Farm in Middelburg, Mpumalanga Province using dry beans
as test crop for the first season. In both experiments, fresh unweathered coal ash from
Duvha power station (CCE 10%), dolomitic lime (CCE 77%) and calmasil (calcium
silicate slag, CCE 99%) were applied to acidic sandy loam soils in the presence or
absence of gypsum. Both calmasil and dolomitic lime were applied at equivalent rates
of 0, 1, 2, and 4 tons/ha, and rates of 0, 7, 14 and 28 tons/ha were used for ash.
Gypsum was applied at a rate of 4 tons/ha. All treatments were applied in three
replications. Results showed that liming increased soil pH, improved soil nutrient
status and plant uptake of base cations, and enhanced yield. In the greenhouse, coal
ash decreased exchangeable acidity from 13.0 mmolc/kg to 6.67 mmolc/kg, increased
Ca levels from 200 mg/kg to 379 mg/kg, and increased Mg levels from 25.9 mg/kg to
42.0 mg/kg. Nitrate levels were also raised from 4.4 mg/kg to 14.8 mg/kg
hypothetically as a result of the increase in the activity of nitrifying bacteria following
a decrease in soil acidity after ash application. Maize yield in the greenhouse was not
significantly affected by ash or by other liming materials, and the sufficient watering
and consequent elimination of aluminium-induced drought stress is put forward as
having masked crop responses to acidity. In the field, coal ash reduced exchangeable
acidity from 10.0 mmolc/kg to 5.88 mmolc/kg, increased Ca levels from 71 mg/kg to
132 mg/kg, and increased Mg levels from 7.3 mg/kg to 17 mg/kg. The increase in
bean yield from 958 kg/ha to 1724 kg/ha by ash was similar to that realized by
dolomitic lime and calmasil. Gypsum had little effect on soil acidity, but it
substantially improved soil Ca and sulfate levels, and enhanced bean yield in the field experiment. The study demonstrated that coal ash could be effective as a liming
material, and underscores the need for a cost-benefit assessment of ash use
necessitated by the relatively higher rates of ash required to obtain significant soil and
plant responses.
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