Supercritical extraction of coal is removal of a select fraction of the coal by a solvent which is slightly above its critical temperature and above its critical pressure. The objective of this dissertation was to understand the mechanism of supercritical extraction, to test some promising solvents, and to explore the design implications of the findings. Supercritical extraction of Wyodak coal was studied by passing various solvents upwards through a 15-gram sample of 12-20 mesh coal. For the high temperature experiments, the coal was heated to 375°C and 425°C in a hot fluidized sand bath. The main solvent used was toluene, while extractions with n-pentane, xylene, methanol, and water were also done. The extract was fractionated into oils, asphaltenes, and asphaltols. Supercritical extraction of coal near pyrolysis temperatures affords an opportunity to remove unstable decomposition products from the reaction environment to avoid repolymerization and pore blinding. Stronger aromatic solvents removed the decomposition products as they were formed. However, product degradation even with the strongest solvents was inevitable during the initial few minutes. For the low temperature experiments (below 95°C), the solvent was carbon dioxide. Effects of liquid entrainers (pre-mixed with the coal), and heat-pretreatment of the coal (at 400°C for 1 hour) were also studied. The major difference between the high and low temperature extractions was that coal reactions occurred at high temperatures simultaneously with solubilization. Extraction of raw coal and heat-pretreated coals with carbon dioxide was negligible. However, extractions as high as 12% were possible when small amounts of liquid entrainers such as pyridine, toluene, and tetralin were pre-mixed with the coal. The entrainers were almost completely recovered with the extract. The process design implications of the supercritical extractions of coal were studied using the method developed by ESCOE (Engineering Societies Commision On Energy Inc.). Preliminary design estimates showed that the following supercritical extraction processes were possible alternatives to present commercialization efforts and deserve further attention: 1. Gasification of the extraction residua; 2. Satellite plants operating in parallel with coal-burning utilities; 3. Entrainer-aided extraction. / Ph. D.

In recent years the Central Appalachian coal industry has suffered from a number of changes in the structure of the coal market. Foremost among these changes have been the collapse of the domestic steel industry and the passage of the Staggers Act. In the past high quality central Appalachian coal was sold mainly as premium coking coal. This market failed, and continues to shrink. Regional coal producers are now looking to the rising demand for steam coal in a nation which is turning away from oil and nuclear power generation. With the possible passage of the Clean Air Act, low sulfur central Appalachian coal may have a promising future, but only if its production can reach this new market. Prior to 1980, regulated rail tariffs gave coal producers access to most consumers, while independent railroads competed for freight. Railroad deregulation greatly improved the position of the railroads, but weakened that of regional coal producers. Central Appalachia and the southern coastal states were left with only two railroads, CSX and NS. These railroads now set their own rates and secretly negotiate contracts with shippers. Due to the configuration of ownership of these tracks, the vast majority of mines and utility plants were left with access to only one carrier. In this situation rail transportation has become the primary concern. Mines unable to originate shipments on the same railroad which is serving the utility plant find themselves locked out of that market unless their mine price is sufficiently low enough to compensate for the increased rail rate. Most of the coal burning plants in Virginia are located on CSX, while the vast majority of southwest Virginia's coal production is served by NS. With a higher mining cost than in eastern Kentucky and southern West Virginia, Virginia producers are having great difficulty in competing in the state's steam coal market. This dissertation is the first effort to quantitatively specify the regional steam coal market. This is done by identifying sources of data which are subsequently used to generate short term forecasts of mine price. These forecasts are used in the cost vector of a Virginia coal Purchasing model which is solved to determine the optimal pattern of coal purchases for Virginia utilities. The structure of the model is based on a detailed market analysis which accounts for the influence of rail rates. / Ph. D.

A typical coal resource characterization study calls for estimating thickness, density, and quality parameters over a block or node simultaneously. Traditionally, estimation has been done for each variable independent of the other variables. The methods range from the well known polygonal and distance weighting methods to the geostatistical method of kriging. None of these methods takes the correlations between the variables into account explicitly. A comprehensive study has been undertaken to determine whether the joint estimation technique of cokriging may be used to utilize intervariable correlations in increasing the accuracy of estimation. Seam thickness, density, ash, calorific value, and sulphur have been studied to determine whether they are cross-correlated. Significant cross-correlations have been found to exist between ash content, density, and calorific value, where the rank of the coal is stable. A survey and a case study indicated that seam thickness may also be cross-correlated with ash content and density. Subsequently, separate kriging and cokriging results have been subjected to comparison via a cross-validation procedure. After normalization, cokriging has provided substantial improvements over kriging in estimating thickness, density, and ash content. Moreover, cokriging performed well in replicating the correlation schemes where kriging occasionally failed. In this study, geostatistical methods have been found to produce results in compliance with their probabilistic premises. A general purpose geostatistics software package has been written to carry out modeling and part of the research on a personal computer. This package has been designed to provide many advantages over the existing costly and black-box type software. / Ph. D.

The Appalachian coal fields contain many contiguously placed seams of coal. Mining in these seams has been active over such an extended period of time that considerable knowledge has been gained in the area of multiple seam mining. It is commonly accepted that the preferred sequence of extracting contiguous seams is in descending order. However, in the past, selection of the mining sequence has been based primarily on seam ownership, availability and economics, not on ground control considerations. One of the major ground control mechanisms that must be considered in mine design, when contiguous seams have not been extracted in descending order, is subsidence. This investigation examines the affects of subsidence not on the surface but on mineable seams of coal lying above the seam that has been extracted. Case studies were collected from the Appalachian region. These studies were analyzed to determine which factors could be correlated with damage. An empirical model was then developed to predict when interaction problems caused by subsidence will noticeably effect mining in an upper seam. / M.S.

M. Tech. (Cost and Management Accounting, Faculty of Management Sciences), Vaal University of Technology / Statistics in South Africa show that the fatality and injury rates within the mining industry have dropped since the end of the apartheid era. Regardless of the drop the fact remains that the mine workers, who are often the breadwinners, are still dying in the country’s mines leaving their families behind without any source of income. If they do not die they may suffer crippling injuries due to mine accidents making it impossible for them to perform their daily duties at work which results in the loss of income, loss of quality of life and this produces a humanitarian and a socio-economic problem. Mining companies incur enormous costs due to fatalities and injuries. Hence a target for zero fatalities was set in the mining industry for 2013. However, the industry has failed to reach this target that it set for itself and it is therefore of the utmost importance to encourage mining companies to invest more than they do currently in safety in order to prevent these fatal and crippling injuries due to mine accidents. The purpose of this study was to determine whether or not the requirements of safety legislation are observed and complied with by a single Colliery in South Africa that was selected for this study. The study also sought to investigate whether or not the employees of this mine observe the safety regulations to ensure safety and to maintain an accident free working environment. An analysis of organizational safety control mechanisms and production cost was conducted through the use of a structured questionnaire, completed by 151 participants. Descriptive statistics, frequency tables, exploratory factor analysis (EFA), one-way analysis of variance (ANOVA) and t-test were utilized to analyse the data. The results indicate that the Colliery was compliant with the safety legislations, a positive employee safety attitude had been cultivated and there was provision of adequate safety facilities through safety investments. Cost reduction due to the application of safety controls was also established, yet it was found necessary for the Colliery to enforce and encourage the application of safety measures to reduce the costs that are still incurred as it is evident that the application of safety controls results in reduced costs. Although the Colliery was considered compliant, with its employees showing a positive attitude towards safety controls, and with safety investments made and cost reduction achieved due to safety measures, ANOVA revealed different perceptions based on the departments in which the employees work, years of experience, English proficiency and qualifications. However, no differences were found in relation to gender and designation.

This study explores the potential extension of occupational health and safety to informal small scale miners in South Africa. It was motivated by an understanding of the integral but much neglected relationship between the quality of work and the goals of poverty reduction and economic development. The study recognises that poor working conditions can reduce productivity and that work-related injury or illness is an unaffordable risk for those working without access to adequate social protection. Further, the protection of labour standards, including work health and safety, is an established basic right in those countries where relevant LLO Conventions have been ratified. Conventional occupational health and safety (OHS) regulation operates through formal employment structures and therefore offers limited or no protection to informal workers. In a country where increasing policy attention is being paid at national and local level to the employment and economic growth potential of the informal economy, this study practically explores within one sector - mining - how the institutional positions of both conventional and identified non-conventional OHS stakeholders work to constrain, or provide opportunities for, the extension of health and safety protection to those working informally. The focus on one kaolin and one clay/coal informal small scale mine site within KwaZulu-Natal and the use of in-depth interviews with workers and a range of identified stakeholders enabled a structured qualitative investigation into the health and safety challenges faced by informal miners; the nature of the support provided to small scale mining by the Department of Minerals and Energy (DME); and the institutional processes acting through national, provincial and local structures that do or could influence workers' access to OHS. The threats presented by each mine to worker and public, as well as environmental health and safety were found to be numerous and severe. There was also evidence of a negative impact of poor working conditions on both the health and economic security of the workers. Despite this, the study identified a vacuum of accountability for the labour protection of informal miners. Conventional mining OHS mechanisms are vertically driven, resource intensive and technocratic. They are both inappropriate for and inflexible towards meeting the challenges presented by informal work. In a minority of cases interdependent links between the responsibil ities of non-conventional OHS stakeholders and work health and safety are understood, but the lack of a worker focus, the institutional boundaries within which people work, their limited OHS knowledge, and the major financial and human resource constraints they face, appear to present significant barriers to any actual OHS intervention. Through the research process it became clear that the management and nature of the DME's small scale mining support strategy itself present fundamental barriers to the extension of OHS. The strategy is a product of a narrow conceptual isation of what is needed to achieve formalisation. This, and the lack of genuine worker representation and accountability within it, means that not only does the strategy fail to attend to OHS and a variety of other worker needs, but that the DME continues unchallenged in its neglect of such issues. With an understanding of the real constraints faced by both workers and the range of identified OHS stakeholders, and in view of the future plans to overhaul the existing national OHS framework in South Africa, the study concludes by outlining some practical opportunities and recommendations that could help to break down existing barriers to the OHS protection of informal workers. Conventional OHS mechanisms could be reoriented to take advantage of cheaper, simpler and more appropriate workerled approaches which could potentially achieve substantial improvements for large numbers of informal workers. Realistic opportunities also exist to more firmly secure the participation of promising non-conventional OHS stakeholders including, in this case, formal mining companies and local government. Finally, there are ways to bridge existing deep divides between social and economic institutional responsibilities that currently serve to obscure potential resource sharing and multiplier impact opportunities of working more collaboratively to improve OHS for the benefit of informal workers. / Thesis (M.Dev. Studies)-University of KwaZulu-Natal, Durban, 2006.

Thesis (MBA)--Stellenbosch University, 2000. / Boschmans Colliery is, as is the case in the rest of the mining industry, heavily reliant on skilled persons in the Engineering discipline to install and maintain the machinery and infrastructure required for the production of a saleable product. Historically, apprentices were recruited from the ranks of school leavers and were given a good, albeit somewhat condensed training to qualify them as artisans. Artisans on their own are however not able to accomplish the tasks at hand and are therefore assisted by artisan assistants. Artisan assistants were historically recruited from the ranks of the unskilled, and in many instances, illiterate masses and were reliant on an unstructured process of on the job training while working under the direct supervision of an artisan. Given the complexities of modern coal mining machinery, the high cost of labour and training, the inherent dangers associated with the mining process and the requirements of the legislative framework, the current approach whereby all the Engineering skills are concentrated in a select few is no longer acceptable. The current system of apprentice training shortcomings are highlighted and a new system of training Engineering employees from the entry level onward is proposed.

Thesis (Ph.D. (Mining Engineering))--University of the Witwatersrand, Faculty of Engineering,1992.

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science in Engineering / Regulation 10.24 of the Minerals Act (1991) of the Republic of South Africa is applied for the purpose of preventing the development and propagation of coal-dust explosions in underground coal mines. ( Abbreviation abstract ) / AC2017

Thesis (M.A.)--University of Tennessee, Knoxville, 2009. / Title from title page screen (viewed on Oct. 22, 2009). Thesis advisor: Sherry Cable. Vita. Includes bibliographical references.