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
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/22773 |
| Date | January 1992 |
| Creators | Eroglu, Berrin |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | Online resource (162 leaves), application/pdf |
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