Assessment of economic and environmental impact of fines generation at Morupule Mine, Botswana

Abstract

Coal mining causes various problems such as land subsidence, pollution of water sources, fines generation and air pollution. Mining companies spend a lot of money annually to mitigate the impact of fines generation. This study tried to identify the causes of fines generation at Morupule Cola Mine (MCM), estimate the amount of fines generated by the haulage system, and evaluate the economic and environmental impact of fines generation at MCM. Twelve coal samples of 20 kg each were collected from four mining sections and conveyor belts. They were tested for their mechanical and chemical properties to determine the properties that promote fines generation. The drop shatter test results show that the coal from section SM 3/1 is the most friable with 31.25% fines while the coal from SM 4/5 is the least friable with 15.5% fines. Also, the fines generated vary from 3% to 13%. The highest transfer point accounts for about 9% of the fines generation while the fastest conveyor belt and the whole haulage system from the working face to the runoff mine stockpile contribute 8% and 27% fines respectively. About 575 tonnes/shift of coal is lost due to blockages at the tail ends of conveyors. In terms of air quality and health hazard, the environmental impact of fines generation is negligible as the mine employs strict dust control measures. It is recommended that the height of transfer points be reduced, and deflection plates installed at the transfer points to minimise the impact of falling coal during conveying.