Bibliography: pages 116-119. / 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.

M.Phil. / The study was undertaken at Bosjesspruit, one of the Sasol Collieries, to investigate aspects that contribute to the degradation of coal. Bosjesspruit is penalised with more than nine million rands per year for fine coal that exceeds the set limits. Compliance to quality is the main reason. The cost is directly deducted from the profit. The quality of coal is of importance for the effectiveness of the gasifying process. A feasibility study has indicated that this study is viable. Various factors in the process were studied to identify the system deviations such as: coal bunkers, section and main conveyor belts, geology, production section activities and coal production equipment. A literature study was done and time was spent to become conversant with the coal transport system. The process is described from where the coal is mined, through the handling action up to where it is fed into the Sasol plant gasifiers. Several coal samples of the identified bottleneck areas were taken and analysed. The four main areas that were studied are: Loading actions at East 700 bunker. Incline shaft transfer chute. The horizontal bunker on surface. The South section conveyor chutes. The free-flow technology was researched and developed for an acceptable chute design. The design is now computerised and in use at Sasol Collieries. The current design and its restrictions are compared with the proposed designs to indicate the improvements. A detailed cost analysis was done to determine the expenditures such as: Penalties for fine coal. The cost of adaptability and redesign. - Forecast cost savings after the redesigns are implemented. - Cost to produce coal as well as the income for Bosjesspruit. An economical evaluation indicates that all the suggested solutions are economically justifiable. The results of the study indicate several suggested solutions to overcome the identified bottlenecks. It is further suggested that results of this study are also implemented at the other Sasol mines as well as the mines that are being developed.