The liberation characteristics of Greenside No. 2 seam coal

Harris, Martin Colquhoun

The liberation characteristics of Greenside No. 2 seam coal

Master Thesis

1987

Publisher

University of Cape Town

Department

Department of Chemical Engineering

Faculty

Faculty of Engineering and the Built Environment

Abstract

In South Africa, ever increasing quantities of fine (-0,5 mm) coal are being produced as a result of the increased use of mechanised mining methods. Very few mines beneficiate the fines; in most cases they are discarded. However the fine size of this material suggests that it should be well liberated, with the potential to produce a low ash product. This thesis forms part of an ongoing research program examining the use of flotation to beneficiate coal fines to produce a low ash product. Coal is a highly heterogeneous material, consisting of a number of both organic (maceral) and inorganic (mineral) components with different physical and technological properties. Therefore in order to evaluate and interpret flotation results, an understanding of the liberation characterist ics of both the organic and inoganic components is required. This thesis presents a liberation study on fine coal from the Greenside Colliery, a typical colliery in the Witbank Coalfield which is the most important source of South African low ash coal. The study was performed by mining a run of mine coal sample to varying degrees of fineness (from 30 % finer than 150 micron to 90 % finer than 150 micron), screening, and assessing the liberation of each size fraction. These results were compared to those obtained from a sample of naturally arising fines (thickener underflow). Liberation was assessed by float and sink analysis, and for this purpose a new technique was developed that enables rapid and accurate float and sink analysis of coal down to a few micron in size. Petrographic analyses were performed to determine the liberation of the organic coal components.