A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering Johannesburg, 1992 / Modern methods of mechanised mining and the necessity for the utilization of total reserves have caused the inclusion of more and more impurities in run of mine coal. This fact, together with the limited supply of naturally clean coal fCI gasification, liquefaction and metallurgical purposes, has made some Iorm l){ beneficiation obligatory at many mines not only in South Africa but also in many other countries. One of the South African Coalfields, Waterherg, contains the continent's largest reserves (approximately 46% of South African known reserves). At the Grootegeluk Coal Mine, approximately 15 m tons of coal per annum are mined by opencast methods. The coal is characterised by containing a high proportion of reactive macerals. The Waterberg Coalfield is currently supplying coal for coke manufacture and middlings for power generation. This coal could also be used for other markets, as Waterberg coal is low in oxygen, contains up to 30% volatile matter. Because it contains 90% vitrinite, it is suitable for direct liquefaction, and possibly coal-water mixtures. However the yield of coal suitable for coking or liquefaction (approx 10% ash) is only 12%, with another 24% of 35% ash coal, currently used for power generation. These yields render mining generally uneconomical if making a simple product. The objective of this project is to ascertain whether the yields of washed coal from the Waterberg Coalfield might be increased by using comminution. Thereafter appropriate beneficiation techniques might be employed on different size fractions. Liberation, float and sink, froth flotation and oil agglomeration processes were examined to identify the best way of treating the coal. Work was carried out on the existing clean coal, middlings and discard fractions. The major objective was to optimise the yield of 10-15% ash coal.The results of the experiment indicate that it is possible to obtain low ash coal from middlings, and middlings from discard for power station. The capital and operating costs for improved new plants are calculated by using available factorised data. The results of experiments on both middlings and discards indicate that yields are significantly higher than those currently obtained, but the cost of obtaining such enhanced yields can be too high for normal commercial application. / MT2017

by Ng Wing-hong. / Abstract also in Chinese / Bibliography: leaf 91 / Thesis (M.B.A.)--Chinese University of Hong Kong, 1983

by Wu Kwok-lai, Peter. / Abstract also in Chinese / Bibliography: leaf 55 / Thesis (M.B.A.)--Chinese University of Hong Kong, 1983

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1999. / Paper copy printed by UMI (University Microfilms International), 1999. Includes bibliographical references (p. 94-99). Original electronic version available via Internet.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1999. / Includes bibliographical references (p. 94-99). Original electronic version available via Internet.

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

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