Development of a fine coal beneficiation circuit for the Twistdraai Colliery

Master Thesis


Permanent link to this Item
Journal Title
Link to Journal
Journal ISSN
Volume Title

University of Cape Town

The principal aim of this thesis was to develop a fine coal beneficiation circuit for the Twistdraai Colliery capable of achieving.a saleable 10.0% ash (28 MJ/kg CV) product. Gravity circuit testing involved a comparative study of a conventional double-stage Spiral circuit and a Stokes upward-current washer when treating Twistdraai <850J.1m x 106J.1m fine coal. In addition, froth flotation technologies, in the form of the Microcel column and the Jameson cell were also tested in order to ascertain whether they can be suitably applied · to the Twistdraai naturally fine coal to produce a 10.0% ash steam coal export product. In this investigation, the Twistdraai fine coal surface was characterised by size as well as by density. Functional group determination included the measurement of the coals hydroxyl, carboxylic and total acid groups, since these exert the most important influence on the properties of the coal surface. These are supported by contact angle measurements, petrographic analysis and washability measurements in orde:r to determine the oil wettability of the coal fractions prior to flotation testing. The results described and discussed in this thesis show that it was possible to recover the desired quality of product by employing split-stream processing of the (850J.1m x 0) Twistdraai fine coal circuit feed. This was achieved by application of both gravity concentration and froth flotation technologies treating specific particle size ranges.

Bibliography: p. 167-178.