• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 53
  • 4
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 87
  • 87
  • 29
  • 22
  • 16
  • 16
  • 13
  • 10
  • 9
  • 9
  • 9
  • 8
  • 8
  • 8
  • 8
  • 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.
21

Parametric design of a coal mine refuge chamber

Fasouletos, Michael A. January 1900 (has links)
Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains vii, 63 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 52-53).
22

Evaluation of Fungcoal as a bioprocess technology for self-cladding of waste coal dumps

Sekhohola, Lerato M January 2016 (has links)
Low-grade coal, a poor source of energy, has long been regarded as waste material by the coal mining industry. Biological degradation of this coal material by ligninolytic fungal strains presents a viable strategy towards eliminating this unusable fossil fuel. To this end, a novel and patented bioprocess termed Fungcoal was developed. Fungcoal is a biological process utilised in the in situ treatment of waste coal and is based on the mutualistic relationship between the fungus Neosartorya fischeri and the graminaceous species Cynodon dactylon. The process facilitates the rapid conversion of waste coal into soil-like material that stimulates establishment of vegetation for eventual coal dump rehabilitation. While a number of in vitro studies have identified various fungal strains as efficient coal degraders, the mechanisms involved in the Fungcoal-stimulated degradation process have not been fully elucidated. Furthermore, implementation of Fungcoal at both pilot and commercial scale has not been achieved. Thus the objective of this work was to investigate Fungcoal as a bioprocess via examining the role of coal degrading fungi (CDF) and grasses as biocatalysts in coal biodegradation and for the self-cladding of waste coal dumps. Initially, waste coal degradation by N. fischeri, strain ECCN 84, was investigated, specifically focusing on the mechanisms underpinning the process. In vitro studies showed the addition of waste coal induced active fungal colonisation resulting in increased fungal biomass. Increased extracellular laccase (LAC) activity, occuring concomitantly with an increase in hyphal peroxisome proliferation, was also observed in the coal supplied fungal cultures. Analysis of the colonised waste coal revealed a time dependent reduction in the percentage weight of elemental carbon coupled with an increase in elemental oxygen. The results supported metabolism and degradation of waste coal by N. fischeri strain ECCN 84 and involvement of fungal extracellular laccase. The contribution of C. dactylon, a C4 grass species to in situ biodegradation of waste coal in the presence of coal degrading and mycorrhizal fungi (MF) was also investigated. Enhanced degradation of the waste coal into a humic soil-like material was observed within the rhizosphere. Analysis of the resultant substrate revealed an increased concentration of highly oxidised humic-like substances (HS). Fungi remained viable in the rhizosphere up to 47 weeks post-inoculation and cultivation of C. dactylon, indicating the resultant humic substance-rich rhizosphere provided an environment conducive for microbial proliferation and activity. Furthermore, humic substance enrichment of waste coal substrates supported germination and seedling emergence of several agronomic species including Zea mays (corn), Phaseolus vulgaris (bean), Pisum sativum (pea), and Spinacia oleracea (spinach). Use of various cladding materials to support coal biodegradation, by fungus-grass mutualism and rehabilitation of waste dumps was evaluated at commercial scale. While substantial physico-chemical changes were not evident in the absence of cladding or where waste coal was used as cladding material, successful establishment of grass cover and diversity was achieved within three hydrological cycles on dumps cladded with weathered coal. Work presented in this thesis successfully demonstrates the degradation of waste coal by N. fischeri. The biodegradation process included enhanced extracellular LAC activity coupled with increased 3 waste coal oxidation. Increased HS concentration of waste coal substrate supported germination and early seedling establishment of several agronomic species. At commercial scale a co-substrate in the form of carbon-rich weathered coal was essential to support fungus-grass mutualism and Fungcoal-induced rehabilitation. These findings support the developed Fungcoal concept and the underpinning rationale that the phyto-biodegradation of waste coal indeed depends on the mutualistic interactions between grass root exudates and the ligninolytic and mycorrhizal fungi. Taken together, these findings provide practical evidence of the contribution of fungi and grasses as mutualists in the biodegradation of waste coal and sustainable rehabilitation of waste coal dumps
23

Management of the mineral resource risk associated with near-density material in the beneficiation plant at Leeuwpan Coal Mine

Botha, Brendan William 09 February 2009 (has links)
Near-density material is material with similar densities to that of the chosen cut-point density during the separation process of coal into product and discard. The problem is usually classified as a beneficiation problem and not as a reserve problem. To overcome the risk associated with near-density material in the beneficiation process, the constraints of the separators must be merged with the constraints of the coal resource. The problems caused by the presence of near-density material in the beneficiation process of raw coal to a certain percentage ash product, are commonly associated with South African coals. Near-density material is caused by the presence of finely dispersed mineral matter in the coal that can not be separated from the coal by current liberation methods. The mineral matter referred to is directly linked with the original depositional environment of the coal. The depositional environment of coal formation determined the ash, the mineral matter present and the distribution within the coal matrix. A closer look at the ash distribution reveals that all types of coal, irrespective of depositional environment, has intrinsic ash content grouped around a certain percentage and that the amount of near-density material present in the beneficiation process depends on the percentage ash, in the clean coal product, required. As the ash distribution is the controlling factor on near-density material, any external factor that effects the ash distribution will affect the coal’s washability characteristics. There are various methodologies to define a coal’s amenability to being washed to a certain clean coal ash product. All of the methods generate an empirical value of near-density material or the coal’s “difficulty” in being washed. All of these methods have their advantages and disadvantages, but the method used is of no consequence if the information is not applied correctly to the coal resource or reserve. At Leeuwpan Coal Mine a risk matrix is used to relate the values from near-density material calculations to the coal reserves. The risk values from the matrix is incorporated into the mining blocks so that during the mine planning phase the risk of near-density material can be quantified and minimized. At Leeuwpan Coal Mine the application of the risk matrix into the planning and exploitation of the coal seams indicated that through resource/reserve management quality problems, due to near-density material can be minimized and that yield can then be optimized. The optimisation of yield leads to a financial gain that increases the value of the reserves. Therefore by pro-active planning and a good understanding of the resource/reserve the risk associated with near-density material can be managed. / Dissertation (MSc)--University of Pretoria, 2009. / Geology / unrestricted
24

LONG-TERM HIGHWALL STABILITY IN THE NORTHWESTERN POWDER RIVER BASIN, WYOMING AND MONTANA

Smith, William K, Smith, William K January 1980 (has links)
Time-dependent behavior of natural and excavated slopes in sedimentary rocks is a subject that is poorly understood at present but that is now an important consideration in the design, operation, and reclamation of energy-extraction facilities, in part because of the environmental considerations mandated by the Surface Mining Control and Reclamation Act of 1977 (Public Law 95-87). A slide in an abandoned, unreclaimed strip mine northwest of Sheridan, Wyoming, has been analyzed as an example of a long-term slope failure in the region. This slide occurred in early 1975, some 20 years after cessation of mining. This investigation used Spencer's limiting equilibrium method and an elastic-plastic finite element method incorporating the Drucker-Prager yield criterion. This slide was found to fit the model for time-dependent failure proposed by Nelson and Thompson (1977) in which the time to failure is related to Skempton's residual factor. The Nelson-Thompson hypothesis is extended for use with the three-dimensional Drucker-Prager yield criterion. The residual factor (R) may be computed from the factors of safety with respect to peak (F(p)) and residual (Fᵣ) material properties, using either the Mohr-Coulomb or Drucker-Prager criterion, by the relationship R = [(F(p) - 1)/(F(p)-Fᵣ)] At the present time, the Spencer limiting equilibrium analysis is a more usable tool for ordinary slope design than the elastic-plastic finite element analysis because of the speed, simplicity, and ease of including the effects of ground water in the Spencer analysis.
25

The role of living plant roots and cattle manure as a soil amendment in the alleviation of compacted coal mine soils

Mosebi, P.E. (Poloko Emmanuel) 13 August 2010 (has links)
In South Africa, most of the surface coal mines are situated on the Highveld of the Mpumalanga Province. The mining industry plays a vital role and contributes to the economy of the country. Very often the mining activities change the physical nature of the soil which results in soil compaction. In mine soils, compaction is of great importance in plant growth and the environment because its high levels may adversely result in the degradation of soil structure, reduced nutrient distribution and reduced root growth, which eventually decreases plant growth. To ensure a productive vegetation, compacted mine soils has to be ameliorated effectively. A combination of practices is suggested to alleviate soil compaction, but some of them are costly and not ecologically stable particularly the use of conventional methods. Therefore, the challenge is to use the potential practices to ameliorate compacted soils. The proposed investigations, which are envisaged to solve harmful effects of soil compaction on plant growth, include biological activities, achieved through appropriate application of cattle manure and planting of pasture species. A review on literature, some studies indicate that the application of organic manure amendments such as cattle manure may overcome the negative effects of compaction, due to the beneficial effects on soil physical, chemical and biological properties in the zone of incorporation. Other studies has shown that pastures are linked with improvements in soil structure, soil organic matter content, rooting depths, consequently, reductions in bulk density. The focus of this study were to monitor the root biomass of irrigated Tall Fescue (F. arundinacea cv Dovey) and dryland Smuts Fingergrass (D. eriantha cv Irene) on mine soils, and to describe soil bulk density and soil nutrient concentrations in such soils. This study were also determining the effects of incorporating cattle manure into compacted (mine soils) and non compacted (agricultural soils) and evaluating its effects on the seedling growth rate, dry matter and root biomass production of Tall Fescue and Smuts Fingergrass. In addition, the influence of different rates of cattle manure on soil bulk density and nutrient concentration in such compacted soil was also measured. These parameters are relevant to the sustainable rehabilitation of mine soils. Based on the results obtained in this study, it was concluded that the use of two grass species, Tall Fescue and Smuts Fingergrass, with vigorous root systems have extended their roots in compacted mine soil layers over two growing seasons. Other results have demonstrated that application of cattle manure revealed a significant decrease in soil bulk density of compacted mine soils planted to Tall Fescue and Smuts Fingergrass. The bulk density was at a minimum in the 80 tha-1 cattle manure-treated plots and followed by the 40 tha-1 cattle manure treatment, and the maximum bulk density was recorded for the control treatment (0 tha-1). The application of cattle manure resulted in a large input of nutrients to the soil as compared to untreated control and significantly increased Tall Fescue and Smuts Fingergrass growth and production. This research has illustrated that use of plant roots and cattle manure as soil organic amendments to reduce soil compaction may be environmentally and economically beneficial leading to a more sustainable agricultural system. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Plant Production and Soil Science / Unrestricted
26

Resistivity imaging of abandoned minelands at Huntley Hollow, Hocking County, Ohio

Ishankuliev, Murad Allayarovich 24 August 2007 (has links)
No description available.
27

The United Mine Workers and the establishment of coal mine safety regulations

Morton, Charles Anthony January 1954 (has links)
No description available.
28

Bump control design protocol for room-and-pillar retreat mining

Campoli, Alan A. 06 June 2008 (has links)
A stress control design protocol was developed to minimize coal mine bumps, which are the explosive failure of highly stressed pillars. The protocol was developed for room-and-pillar retreat mining conducted with available continuous miner technology. The inability of existing coal pillar equations to accurately represent the wide total extraction pillars required, forced the development of the pseudoductile coal pillar strength model. A confined pillar core is assumed to reach a maximum stress when surrounded by a yielded perimeter. The width of the yielded perimeter is assumed to increase linearly with increased coalbed thickness. The pseudoductile model was employed in the development of supercritical and subcritical width section design criteria. The supercritical design procedure assumes an infinitely long pillar line, composed of uniformly sized pillars, extracted against an infinitely wide gob area. Tributary area theory was combined with a linear shear angle concept to estimate the loads applied to total extraction pillars adjacent to gob areas. The boundary element code MULSIM/NL was utilized in the development and implementation of a systematic subcritical design procedure to apply the stress shield concept to retreat room-and-pillar coal mining, under bump hazard. The complex distribution of gob side abutment load between the side abutment pillars and the chain pillars in the total extraction zone made computer simulation a necessity. Section layouts were determined for the mining of a 6 ft thick coalbed under overburden up to 2,200 ft thick. The sections consist of total extraction areas separated by continuous abutment pillars. A spreadsheet program LAYOUT was created to summarize and provide for efficient utilization of the bump control design protocol. Based on overburden thickness, coalbed thickness, abutment load linear shear angle, and pillar dimensions entered by the user, LAYOUT calculates a stability factor for the first and second pillar row outbye the expanding gob for supercritical width sections. If the overburden and coalbed thickness conditions do not allow a supercritical section design, LAYOUT develops a subcritical design. / Ph. D.
29

Avian population and community dynamics in response to vegetation restoration on reclaimed mine lands in southwest Virginia

Latimer, Chris E. 29 May 2012 (has links)
Coal surface-mining is often implicated for its negative impacts on native flora and fauna. However, some studies suggest that, in reclaiming land after mining, there may be potential to create early successional habitat needed by many avian species currently in decline throughout eastern North America. I evaluated nest-site selection and nest success for on reclaimed mine lands in southwest Virginia during the summers of 2010 and 2011. For this nest-site analysis, I focused on 2 bird species common to reclaimed mine lands in southwest Virginia: field sparrows (Spizella pusillia) and indigo buntings (Passerina cyanea). In addition, I assessed bird community attributes in relation to various surface-mine reclamation regimens over a 5-year period from 2007-2011. For both species, I found estimates of daily nest success to be higher than other estimates reported in the literature; however, empirical estimates of adult and juvenile survival are needed to provide better estimates of population status. For field sparrows, models of avian nest success support the hypothesis that a tradeoff exists between nest concealment and a view of the surroundings for field sparrows. For indigo buntings, year explained the most variation in nest success, with much lower estimates of daily nest survival in 2010, possibly as a result of increased precipitation. I also assessed avian community dynamics in relation to vegetation changes on reclaimed mine sites and observed a total of 96 species throughout the 4 years of sampling. Local species persistence and species turnover were comparable to another continental scale study conducted using breeding bird survey (BBS) data. Observed changes in community vital rates were likely a result of changes in certain habitat attributes over the 5-year period. Lastly, seven species were unique to certain cover types, suggesting the need to consider landscape level processes when developing restoration guidelines for reclaimed coal surface-mines. / Master of Science
30

Demonstration of Direct-on-filter FTIR to Estimate Silica, Kaolinite, and Calcite Mineral Fraction in Respirable Coal Mine Dust Samples

Pokhrel, Nishan 09 September 2021 (has links)
Respirable coal mine dust (RCMD) has long been recognized as an occupational health hazard. In addition to coal, RCMD can contain minerals such as crystalline silica (i.e., most often present as quartz). There has been a resurgence of lung diseases among US coal miners since the late-1990s which has emphasized the need for better quartz monitoring, and better dust characterization in general. Quartz monitoring in coal mines has traditionally used infrared (IR) spectroscopy-based analytical methods such as the MSHA Method P7 that require significant sample preparation and must be performed in a centralized lab. There are generally thus days to weeks between dust sample collection and reporting of results, which can prevent the prompt mitigation efforts to better control dust and reduce exposures. Recently, a rapid analysis method for quartz has been developed by the US National Institute for Occupational Safety and Health (NIOSH) using direct-on-filter (DOF) Fourier Transform Infrared (FTIR) spectroscopy. The method has been demonstrated in a number of NIOSH-led studies using both laboratory and field samples, and the results show very good accuracy relative to the Method P7 reference. However, it has heretofore not been widely used by others or compared to results from other non-IR analytical methods. Moreover, while FTIR can allow the measurement of additional analytes, this has not yet been a focus of DOF FTIR for RCMD analysis. Analytes such as kaolinite and calcite could be of particular interest in the context of RCMD source apportionment. In this thesis, the DOF FTIR method is used to estimate silica, kaolinite, and calcite mineral fraction in RCMD samples collected in 16 coal mines, and in the laboratory using dust source materials from those same mines. The results are compared to results from other dust characterization methods such as mass-based thermogravimetric analysis (TGA) and particle-based scanning electron microscopy with energy dispersive X-ray (SEM-EDX). Results indicate the usefulness of the DOF FTIR method, and comparison suggests the presence of significant non-carbonate minerals other than silica and kaolinite in the coal mine dust. The results also show that SEM-EDX frequently indicates more mineral content (primarily other aluminosilicates), than that is predicted by either FTIR or the TGA. Additionally, by focusing mainly on calcite (generally sourced from limestone-based rock dust used in coal mines to prevent coal dust explosion), the second part of this study explores basic source apportionment by analyzing mine samples and samples of major dust source materials (such as run-of-mine coal, rock strata, and rock dust products). Results show that calcite can serve as a suitable proxy for rock dust in coal mine dust, and the results are consistent with expectations surrounding the contribution of dust from different mine locations and sample sources. Additionally, the DOF FTIR also showed good agreement with the TGA and SEM-EDX. / Master of Science / Respirable dust generated in coal mines has long been recognized as an occupational health hazard. In addition to coal, coal mine dust can contain minerals such as crystalline silica, which is particularly hazardous. Since the mid-1990s, there has been an alarming and unexpected increase in lung diseases in coal miners. Respirable crystalline silica is assumed to be a likely causal factor for this resurgence of lung diseases, and this has emphasized the need for better respirable crystalline silica monitoring and to better understand coal mine dust composition. The standard method of measurement of silica (called the MSHA Method P7) generally takes days to weeks between dust sample collection and reporting of results, which can prevent the mine from taking prompt mitigative efforts to better control dust and reduce exposures. Recently, a rapid analysis method for silica has been developed by the US National Institute for Occupational Safety and Health (NIOSH) called the DOF FTIR (direct-on-filter Fourier Transform Infrared Spectroscopy). This method has been shown to have very good accuracy relative to the standard method (MSHA P7). However, it has heretofore not been widely used by others or compared to results from other analytical methods. Moreover, DOF FTIR can also be used to estimate other minerals of interest such as kaolinite and calcite, which can be important in the context of understanding coal mine dust sources. In this thesis, the DOF FTIR method is used to estimate silica, kaolinite, and calcite mineral fraction in coal mine dust samples collected in 16 coal mines, and in the laboratory using dust source materials from those same mines. The results are compared to results from other dust analysis methods such as mass-based TGA (thermogravimetric analysis) and particle-based SEM-EDX (scanning electron microscopy with energy dispersive X-ray). Results indicate the usefulness of the DOF FTIR method, and comparison suggests the presence of significant non-carbonate minerals other than silica and kaolinite in the coal mine dust. The results also show that SEM-EDX frequently indicates more mineral content than that is predicted by either FTIR or the TGA. Additionally, by focusing mainly on calcite—which is generally sourced from limestone-based rock dust used in coal mines to prevent coal dust explosion—the second part of this study explores the sources of the dust by analysing samples collected in mines, and samples generated in lab from major dust source materials (such as the raw coal, rock strata, and rock dust products obtained from the mines). Results show that calcite can be representative of rock dust in coal mine dust, and the results are consistent with expectations surrounding the contribution of dust from different mine locations and sample sources. Additionally, the DOF FTIR also showed good agreement with the TGA and SEM-EDX.

Page generated in 0.0401 seconds