Browsing by Author "Animah, Festus Ayinimi"
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- Effects of Dust Controls and Dust Sources on Respirable Coal Mine Dust CharacteristicsAnimah, Festus Ayinimi (Virginia Tech, 2024-10-14)Respirable coal mine dust (RCMD) continues to pose serious health hazards to workers. Over the past few decades, new regulations, monitoring technologies, and improved dust controls have emerged, and all are based on the presumption that limiting RCMD on the basis of mass will effectively mitigate the exposure hazards. Given the latency of exposure outcomes, it will be some time before the full impact of these strategies can be evaluated. In the meantime, there is increasing awareness that RCMD particle characteristics, in addition to mass, might be important. This dissertation comprises four separate studies which explore the effects of primary RCMD sources and/or engineering controls on particle size and constituents. To enable a direct comparison of dust generation from primary dust sources, a field study was conducted to investigate the dust generation and particle characteristics between coal and the rock strata. Results indicated that finer and more dust was generated when mining predominantly into the rock strata versus the coal strata, while the operation of a flooded bed scrubber and an increase in water sprays pressure and volume generally suppressed dust. Prior government research, conducted within the Mining Research Division of the National Institute of Occupational Safety and Health (NIOSH) evaluated the dust mass concentrations removal efficiency of different dust controls (i.e., a dry and wet scrubber, canopy air curtain, and a wet versus dry dust collection boxes). In the second and third studies, preserved samples from these prior NIOSH dust control studies were re-analyzed and evaluated to understand their effects on dust characteristics. Results indicated that the efficiency of dust controls was particle size dependent, as these controls mostly showed no appreciable effects on dust constituents. Generally, the cleaning of dust from a novel wet dust collection box versus a traditional dry dust box led to a reduction in operator exposure to hazardous dust. In the final study, a laboratory prototype flooded bed scrubber was evaluated to understand its efficiency on dust between different particle size bins (i.e., by particle count) ranging from 0.3-10 µm. From the results, removal efficiencies were generally low – and sometimes negative, for dust particles mostly in each of the size bins less than 2 µm. The results presented here highlight the need to holistically evaluate dust controls to understand their efficiency on dust of different particle sizes and constituents, so that informed decisions can be made on the best controls to adopt in mine operations.