• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1129
  • 302
  • 164
  • 70
  • 48
  • 29
  • 26
  • 15
  • 8
  • 8
  • 8
  • 8
  • 8
  • 8
  • 7
  • Tagged with
  • 2491
  • 596
  • 350
  • 276
  • 227
  • 220
  • 217
  • 196
  • 192
  • 186
  • 156
  • 152
  • 139
  • 125
  • 124
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
571

“FROM THE ‘COAL WARS’ TO THE ‘WAR ON COAL’: A MOVEMENT TO PRESERVE THE ILLINOIS COAL INDUSTRY, 1892–2014”

Lybeck, Geoff 01 August 2022 (has links)
This study describes the Illinois coal industry’s response to the rising challenges of air pollution regulation and competition in the energy market from natural gas and oil throughout the twentieth century. Importantly, this dissertation fills a significant gap in the historiography of Illinois coalmining, and is the first historical study based on two key, yet unused, sets of historical documents. This is a mining history and a cultural history of a system of understanding and knowledge that first developed in the Illinois Mining Institute and then in State of Illinois organizations. As the industry’s leaders organized their approaches to resolving issues they generated a culture of industry preservationism based on the ideas of mechanization, automation, expansion, research and development, politics and policy, and coal preparation and conversion. In doing so, they came to identify their movement with modernity and as they looked ahead in time with futurity. These ideas became the principles around which they forged their social connections and formed their understandings of the problems the industry faced. This study spans from a period often defined by its volatile and contentious labor–management negotiations and labor unrest, the so-called “coal wars,” to the announcement of U.S. President Barack Obama’s Clean Power Plan, which according to some began his Administration’s so-called “war on coal.” This study illustrates four major historical shifts during this century-long transformation: First, this movement of Illinois coal industry preservationism, focused on interfuel completion and air pollution control, diverged from the industry’s ongoing response to organized labor. Second, in response to the rise of environmentalism and federal environmental regulations, industry leaders and State of Illinois officials began to expand on the integration of the principles of Illinois coal industry preservationism and the state’s political and policy agendas. Third, despite that industry leaders had sustained the production of Illinois coal for many decades, the movement declined in the wake of the 1990 Clean Air Act Amendments and the rise of the natural gas industry in the energy market during the first two decades of the twenty-first century. Fourth, in reaction to the constraints of the domestic market and pollution laws, the Illinois coal industry began to sell the majority of its product overseas. Additionally, this study highlights few historical continuities. For one, those seeking to preserve the Illinois coal industry espoused the idea that their industry played a key role in the nation’s security and energy independence. They likewise held the belief that technological solutions would continue to solve the industry’s problems. The people behind this movement had every reason to view their industry through those lenses. After all, Illinois coal had helped the country win two world wars, and it offered a potential solution to the oil supply crises that resulted from cold war upheavals. In the end, however, the two problems that pushed industry leaders to generate the movement in the first place, interfuel competition and air pollution regulation, left it fractured, diminished, and in decline.
572

A study of fine coal dewatering by high temperature and pressure filtration

Wang, Ching Ting January 1966 (has links)
The removal of water from fine coal (minus 3/8 inch, especially minus 48 mesh Tyler) has been a major problem of the coal industry. Thermal dryers have been used exclusively as a means of reducing the fine coal moisture. Because of its high capital, operating costs, and safety hazards, an alternate method of moisture reduction is highly desirable in the coal industry. The major effort of this thesis was directed towards the development of a method to dewater fine coal by the application of high temperature and pressure to a filter slurry. This method might have the possibility of replacing conventional thermal dryers for fine coal drying. In addition, the effect of temperature, pressure, dry cycle time, slurry density, cake thickness, and evaporation on filter cake moisture were studied simultaneously. The fine coal sample was obtained from The Itmann Coal Mine, Consolidation Coal Company. It contained 47.3 percent minus 100 mesh Tyler and 30 percent minus 200 mesh Tyler material in size. A small eight inch in diameter laboratory pressure filter with a heater and agitating device were used for this study. Filter cake moisture decreased with increasing temperature and pressure. The moisture reduction did not vary proportionally with increasing temperature and pressure, but diminished with increasing temperature and pressure. The effect of dry cycle time on filter cake moisture was substantially reduced as the dry cycle time was increased over 90 seconds. The filter cake moisture decreased at an average of 2.5 percent when the slurry density varied from 30 to 50 percent in 10 percent increments. The filter cake moisture decreased approximately one percent for 1/4 inch decrements from 1 1/4 to 1/2 inch cake thickness. Approximately three to five percent moisture reduction was effected by evaporation, depending upon the cake temperature and ambient conditions. Finally, results indicated that the filter cake moisture could be substantially reduced to 9.5 percent by using a temperature of 260 degrees Fahrenheit, a pressure of 60 pounds per square inch, and a cake thickness of 1/2 inch with a dry cycle time of two minutes. Evaporation resulting from the residual heat in the cake caused a further reduction in the moisture content from 9.5 percent to 5.1 percent. The highest capacity obtained from this study was 2905.66 pounds of dry coal per hour per square foot form rate. The total heat requirement to produce one ton of dry coal containing 5.1 percent moisture was 157,950 British Thermal Units if all the heat losses except the heat in the discharged cake could be saved. This level of heat requirement is significantly less than that of conventional thermal dryers. The proposed method of this investigation may be capable of replacing conventional thermal dryers for fine coal drying, if measures are taken to recover as much heat as possible by counter-current heating of the intake slurry with the hot filtrate. Less cost and concurrent advantages for safety and air pollution are additional advantages over conventional thermal dryers. / M.S.
573

Characterizing Trace Element Associations in the Pittsburgh No. 8, Illinois No. 6 and Coalburg Coal Seams

Conaway, Shawn Michael 04 February 2002 (has links)
Coal preparation is widely regarded as a cost effective method for reducing the amounts of potentially hazardous air pollutant precursors (HAPPs) that occur as trace elements in the run-of-mine coals. Unfortunately, many existing coal preparation plants are inefficient in removing trace elements because of poor circuit design and inadequate liberation of coal and mineral matter. These problems are often difficult to correct in the absence of characterization data regarding the mineralogical association and washability of trace elements in run-of-mine coals. Therefore, the first step in removing the trace elements through coal preparation is to characterize the modes of association for trace elements in a coal seam. The purpose of this project was to link the occurrence of specific trace elements to the mineralogy and washability characteristics of different eastern U.S. coal seams. Detailed characterization studies were carried out using scanning electron microscopy (SEM) coupled with automated image analysis (AIA) to establish the association between different trace elements and the various components contained in coal. The first step in this analysis required the preparation of 11 different density fractions from a run-of-mine sample of 65 x 100 mesh Pittsburgh No. 8 coal. The samples were then examined using the scanning electron microscope (SEM) to establish the individual mineral constituents contained within each gravity fraction. For comparison, each gravity fraction was also carefully analyzed for trace element content by atomic adsorption spectroscopy (AA). The contribution of various mineral components to the trace element concentrations was determined in the present work using statistical procedures, i.e., individual linear regression and multiple linear regression. After completing the SEM analyses, washability (float-sink) tests were performed on three different coal seams. In this work, several size fractions from each of three different run-of-mine coals were subjected to float-sink testing and release analysis. Because of the overwhelming amount of data, statistical analyses were conducted to show the key relationships identified by this work. The data collected from this study show that trace elements are primarily associated with the mineral matter present in run-of-mine coal. The washability work also shows that the trace elements are concentrated in the heavier specific gravity classes. The characterization work shows that majority of the trace elements are associated with the ash-forming mineral matter and pyrite. The only element found to have a strong association with organic matter was beryllium. The information obtained from this work suggests that a properly designed coal preparation plant can remove substantial amounts of trace elements prior to coal combustion. / Master of Science
574

Energy-water nexus : sustainability of coal and water resources

Hebel, Anna Kathleen 01 November 2010 (has links)
Energy and water are two precious natural resources with which demand will continue to grow with increased population growth. Coal provides a cheap and abundant source of energy but with important environmental effects on air and water. An analysis of the current coal production in Texas, one of the leading providers of energy in the United States, will be discussed along with the possibility of creating a coal-to-liquids market in Texas from existing and future coal mining operations. An in-depth discussion into the water requirements for traditional coal production and coal-to-liquids will assist in analyzing its possible production and sustainability. / text
575

APPLICATION OF CONDITIONAL SIMULATION MODEL TO RUN-OF-MINE COAL SAMPLING FREQUENCY DETERMINATION AND COAL QUALITY CONTROL AT THE POWER PLANT (BLENDING, GOAL PROGRAMMING, MICROCOMPUTER).

BARUA, SUKHENDU LAL. January 1985 (has links)
Run-of-mine (ROM) coal sampling is one of the most important factors in determining the disposition of ROM coal for an overall emission control strategy. Determination of the amount of sample, or still better, the frequency of ROM coal sampling is thus essential to the analysis of overall emission control strategies. A simulation model of a portion of the Upper Freeport coal seam in western Pennsylvania was developed employing conditional simulation. On the simulated deposit, different mining methods were simulated to generate ROM coal data. ROM coal data was statistically analyzed to determine the sampling frequency. Two schemes were suggested: (1) the use of geostatistical techniques if there is spatial correlation in ROM coal quality, and (2) the use of classical statistics if the spatial correlation in ROM coal quality is not present. Conditions under which spatial correlation in ROM coal quality can be expected are also examined. To link the ROM coal and coals from other sources to coal stockpiles and subsequently to solve coal blending problems, where varying qualities of stockpiled coals are normally used, an interactive computer program was developed. Simple file-handling, for stockpiling problems, and multi-objective goal programming technique, for blending problems, provided their solutions. The computer program was made suitable for use on both minicomputer and microcomputer. Menu-driven and interactive capabilities give this program a high level of flexibility that is needed to analyze and solve stockpiling and blending problems at the power plant.
576

Assessing the change in hydro-geochemical properties of fly ash over time when disposed into opencast coal mines in Mpumalanga, South Africa

Johnson, Angelo Gerald January 2019 (has links)
Masters of Science / Eskom supplies to 95% of South Africa’s energy needs and it primarily comes from coal combustion at their coal–fired power stations. Large volumes of fly ash are generated at these coal-fired power stations as a by-product of the coal combustion process. Fly ash is disposed onto landfills at the respective power stations and these landfills are currently running out of storage space. Subsequently, there are concerning environmental impacts upon the natural water environment resulting from coal mining. More specifically, the discharge of acid mine (AMD) water from historical coal mines impact negatively on the water quality in the nearby rivers and dams in the Witbank area. Therefore, as a consequence of the limited space at fly ash landfills, Eskom has embarked on finding alternative ways to re-use fly ash in different applications such as: soil amelioration and land reclamation, road construction as well as brick and cement development. This study focussed on the feasibility of disposing fly ash into the backfill of historical and future coal mines with the intention to firstly reduce fly ash disposal at existing landfills and secondly to improve the decant water quality of the coal mines in the Witbank area. Globally, fly ash has been successfully used in mine backfilling and AMD treatment in countries such as United States of America and India, due to cementitious properties of their fly ash. However, there is limited knowledge on how South African fly ash would behave under backfilled conditions of opencast coal mines where it will be exposed to acidic water environments. This is due to the fact that South African fly ash is considered a Level 3 type hazardous waste, due to its heavy metal concentrations. This waste classification is unique and the strictest compared to global classifications and these methodologies specify that fly ash should be disposed onto lined waste disposal sites due to the potential leaching of heavy metals from these waste sites. It is important to understand the hydrogeological and hydro-geochemical properties of fly ash over time once it is exposed to acid mine water. Field and laboratory tests were conducted to understand these hydrogeological and hydro-geochemical properties of fly ash. Falling head hydraulic tests were conducted at two existing ash landfill sites to determine the hydraulic conductivity (K) of ash of different age. The results exhibit a decreasing trend in K with increasing age. This is due to the pozzolanic nature of fly ash and secondary mineralization of gypsum which causes the fly ash to harden in the presence of water from irrigation for dust suppression together with precipitation over time. Laboratory testing included the use of constant head Darcy column tests to determine the change in K and geochemical properties of the leachate over time. Natural AMD with a pH of 2.5 and a metal composition was used as influent and the leachate were routinely collected and analysed for metal concentrations. The hydraulic conductivity of the fly ash showed a decreasing trend over time. During the placement of coal ash, the moisture allows pozzolanic reactions to solidify the coal ash and lowers the K, towards 10-1 m/d, relative to fresh ash. Secondary mineralization of calcium minerals, in the coal ash contributes to a further decrease in the K, by another order of magnitude from 10-1 m/d towards 10-2 m/d. Sulphate and iron minerals from the AMD also played a major role in the decreasing K as they accumulate in void spaces and having a clogging effect, decreasing the K to 10-3 m/d. The alkaline nature of the coal ash initially neutralizes the acidic levels of AMD from an inflow pH = 2.5 to an outflow pH = 11. Acidification of the outflow towards a pH = 4 was observed, due to large volumes of AMD (>80 000 mL) flowing through short coal ash columns. The K decreased to 3 orders of magnitude, from an initial 10-1 m/d to 10-3 m/d, with the AMD iron (>150 mg/L) and sulphate concentration (>2000 mg/L) playing the dominant role in reducing the hydraulic conductivity. From the geochemical leach test results, it was observed that most of the leachate water was of a better quality than the influent AMD water quality. The outflow pH (pH = 11 to pH = 4) was higher than the pH of the inflow AMD (pH = 2.5). Overall EC reduced in discharge compared to inflow AMD (ECinflow: 535 – 545 mS/m versus ECoutflow: 350 – 490 mS/m), although Na and K in the leachate exhibited higher concentrations (10+2 mg/L) compared to the AMD inflow concentrations (10+1 mg/L). However, most of the other chemical elemental concentrations such as Fe (10-2 – 10+1 mg/L), Si (10-2 – 100 mg/L), Al (10-2 – 10+1 mg/L), Mn (10-2 – 10+1 mg/L), Cr (10-3 – 100 g/L) and SO4 (10+2 – 1+3 mg/L) in the discharge showed lower concentrations when compared to the inflow Fe (10+2 mg/L), Si (100 mg/L), Al (10+1 mg/L), Mn (10+1 mg/L), Cr (10-2 mg/L) and SO4 (10+3 mg/L) concentrations. These results show how fly ash backfill may impact on the current coal mining environment. Overall, the laboratory hydraulic conductivity and geochemical testing showed promising results for fly ash backfilling. Based on this research, fly ash can be used to alter the existing coal mining environment as it is currently known in the Witbank area. The topography, hydraulic conductivity and the water table within the backfill can be altered to improve decant water quality of ash backfilled coal mines.
577

Investigating the effect of substituting fractions of imported coals with coke oven tar on coke quality: pilot plant study

Makgato, Seshibe Stanford 23 January 2015 (has links)
In this study, coke oven tar addition over a range of 0 – 8 wt.% was evaluated as a possible substitute for imported coals fractions. Coke oven tar used was collected from coke oven tar decanters of the by-products section of the coke making plant. Moisture content in coke oven tar varied depending on the residence time and water carryover from coke oven tar separators to storage tanks. Therefore, various moisture ranges were considered in order to observe its effect on coal blend, carbonization and coke properties. The optimum moisture content in coke oven tar was found to be 3% with a coke oven tar addition of 6 wt.% in the coal blend. At the same coke oven tar addition of 6 wt.% in the coal blend but with 6% moisture content in coke oven tar, coke properties improved, coke yield showed up to 4% decrease. On the other hand, with 1% moisture content in coke oven tar of 6 wt.% in the coal blend, coke yield increased by 1% and low coke properties such as I40 of 42.9 and Stability of 50.3 were achieved. The latter process was characterized by excessive increased in wall pressure and pushing energy. Both wall pressure and pushing energy increase are less desirable due to their detrimental effect on the physical condition of the oven walls. Furthermore, addition of coke oven tar with 1% moisture content to coal blend can be prohibited by its high viscosity. At 3% moisture content in coke oven tar addition of 6 wt.% in the coal blend, coke properties improved. When the amount of coke oven tar was increased to 8 wt.% at the optimum coke oven addition, coke yield was not affected but low CSR of 57.8 against a target of ³60 was achieved as opposed to CSR of 65.4 at 6 wt.%. Also, coke stability of 52.2 at 8 wt.% as opposed to 56.1 at 6 wt.% was achieved. Moreover, the highest I40 of 50.9 was achieved at 6 wt.% whereas with 8 wt.% coke oven tar, I40 of 47.9 was achieved. However, up to 2% decrease in coke yield was observed. Despite this 2% decrease in coke yield, coke oven tar addition is a positive and viable option based upon economic factors (i.e. this reduces the quantity and cost of imported coals and still achieves improved coke quality which result in improved blast furnace operation and better hot metal quality).
578

The fluidized-bed pyrolysis of coal in both the presence and the absence of dolomitic compounds.

Yeboah, Yaw Duodu January 1979 (has links)
Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: leaves 594-611. / Sc.D.
579

The rise and fall of place the development of a sense of place and community in Colorado's southern coalfields 1890-1930 /

Jacobson, Michael E. January 2006 (has links)
Thesis (Ph. D.)--State University of New York at Binghamton, Anthropology, 2006. / Includes bibliographical references.
580

Sedimentology, Stratigraphy and Petrography of the Permian-Triassic Coal-bearing New Lenton Deposit, Bowen Basin, Australia

Coffin, Lindsay M. 05 April 2013 (has links)
The Bowen Basin is one of the most intensely explored sedimentary basins in Australia and hosts one of the world’s largest coking coal deposits. This study focuses on the Lenton deposit in the north-central part of the Bowen Basin and targets the Rangal Coal Measures, which are the youngest (245 Ma), most areally extensive and least structurally deformed coal measures in the study area. Six lithofacies were identified from detailed bed-by-bed logging of two cores and stratigraphically-upward comprise peatmire deposits of the Permian Blackwater Group overlain unconformably by braided fluvial strata of the Triassic Rewan Group. Coal-bearing strata of the Blackwater Group form a large-scale drying up sequence showing a change from permanent to seasonal waterlogged conditions related to the onset of regional uplift. Sedimentation was then terminated and a regional erosion surface formed by uplift related to the Hunter Bowen Orogeny. This, then, was overlain by braided fluvial strata of the Triassic Rewan Group.

Page generated in 0.0468 seconds