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A reliable estimate of minable coal reserves is essential for long-term planning and for conservation of energy resources. In the majority of the world's coalfields, seams are found on multiple horizons, and coal recovery may be significantly reduced depending upon the magnitude of seam interaction. In order to evaluate the effects of interaction in terms of coal losses, a hazard technique has been developed. The first stage in this technique was to develop an efficient and accurate system to grid spatial geologic and structural information developed from randomly placed boreholes. The second stage was to utilize these gridded values to determine total available coal tonnage and chemical compositions of the seam. Depending on whether over or under mining effects are to be assessed, spatial geologic and structural conditions between the seams, are evaluated to determine if interaction is possible. Where interaction will occur, recoverable reserves are reduced accordingly. To demonstrate application of the hazard approach, potential interaction in a lower seam has been evaluated. To facilitate implementation of this reserve evaluation method under multi-seam conditions, a user-friendly computer design program, HAZARD, has been developed to calculate the recoverable coal reserves in an affected seam. / Master of Science

A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, in fulfilment of the requirements for the degree of Doctor of Philosophy in Electrical Engineering. / Lightning causes electrical shocks to people, the premature ignition of explosives, and the ignition of methane underground in coal mines. This study examines this problem using a theoretical study and the results of an extensive measurement programme that was conducted in several coal mines. The work that has been done, particularly in South Africa, is also reviewed. Two mechanisms are responsible for the penetration of lightning surge currents into the underground workings. A direct strike to the service structures leading into a shaft is one of the two mechanisms, and the second is that resulting from lightning strikes to the strata above the underground workings. The frequency and amplitude with which such surges can be expected is quantified using the theoretical study. This model correlates well with the observed frequencies of the empirical studies. The sensitivity of methane to lightning-type sparks is investigated. Currents as low as 10 rnA have been proved to be capable of igniting methane. The sensitivity of conventional detonators is also investigated. The thesis proposes a generalised test which can be applied to both the low-impedance protection method and a high-impedance protection method. The test methodologies have been generalised to make provision for any new innovative detonators that may be used by the industry. A risk evaluation of mines is developed which allows a mine to be categorised according to the likelihood of lightning causing an accident in a mine. The South African Recommended Practice for avoiding such accidents is also reviewed. / Andrew Chakane 2018

The thesis starts by defining technological change, productivity and safety. Different definitions are discussed and their merits compared. A brief history of coal mining, together with a description of the state of the mining industry at present is given. Technological innovations recently adopted by the industry are discussed. The concept of productivity in relation to the coal industry of the U.K., and the deficiencies of the present measurement technique, are fully explained. Safety in the coal mining industry of the U.K. is investigated. A brief history is given, together with a full discussion of the consequences and costs of accidents. The concept of technical productivity is introduced and its relation to total productivity explained. The total productivity concept is then applied to longwall coal faces. A multi-variable non-linear model is devised which represents mean total productivity of all longwall faces to an accuracy of about J7G. The model is tested and a forecasting method suggested. Total productivity components are analysed and values for the productivity of various inputs during the period 1958-1980 given. Similarly, a model for representing safety, based on costs, is introduced, tested for accuracy and its components analysed. By applying marginal analysis to the total productivity and safety models, the influence of technological change on productivity and safety are quantified. It is concluded that a new method for measuring productivity should be adopted, in which case total productivity would be the most realistic and comprehensive choice. The models introduced can serve as useful tools in planning and forecasting, as well as being used to measure productivity and safety. Since this work has been in progress, work at the NCB has also led to consideration of improved measures of productivity.

Thesis (M.S.)--Northwest Missouri State University, 2006. / The full text of the thesis is included in the pdf file. Title from title screen of full text.pdf file (viewed on January 25, 2008) Includes bibliographical references.

Thesis(M.Eng.)--University of Wollongong, 2006. / Typescript. Includes bibliographical references: leaf 96-99.

Thesis (M.Env.Sc.-Res.)--University of Wollongong, 2007. / Typescript. Includes bibliographical references: leaf 99-104.

Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1939. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed March 25, 2010) Includes bibliographical references (p. 123).