Meitan xuebao (Jul 2024)
Relationship between long pressure short extraction dust removal performance and dust source movement path in comprehensive heading face of coal mines
Abstract
Long pressure short extraction ventilation and dust removal method is one of the effective methods for removing high mass concentration dust in the excavation area of coal mine comprehensive heading face. Especially, the local flow field generated by the combination of pressure and suction is conducive to the removal and reduction of respiratory dust. However, the dynamic changes in the location of dust production sources have an unclear impact on the dust removal performance of this method. By considering the movement paths and reciprocating times of the dust source location in both horizontal and vertical directions, four dust source movement paths were designed based on the long pressure short extraction test platform. Combined with the regulation of the parameters of the long pressure short extraction ventilation system, the impact of the dust source on the spatial dust mass concentration, particle size mass concentration, and particle size distribution under different movement conditions was tested and analyzed. The results show that under the same ventilation parameters, the dust mass concentration caused by the horizontal path on the respiratory belt positions of drivers and pedestrians is lower than that caused by the vertical path. In the horizontal path, when the pressure air duct is located on the side near the exhaust duct and the pressure air outlet is located in an area about 1 m in front of the driver, the particle size mass concentrations of PM1, PM2.5 and PM10 at the breathing zone between the driver and pedestrian are the lowest, and the ventilation and dust removal effect is the best. The diffusion of spatial dust is manifested as: particles with a particle size less than 2.5 µm are easily collected and removed by the exhaust flow field at the exhaust port, while the particles with a particle size greater than 10 µm will escape from the dust generation source and exhaust area to the driver and the area behind them, and mainly settle naturally. Based on the optimal dust source movement path and ventilation parameters obtained from preliminary experiments, on-site experiments were conducted on the 2304 fully mechanized heading face of a coal mine in northern Shaanxi. The results show that the total dust mass concentration at the driver's position and pedestrian breathing zone position under the lateral path decreased to 85.6 mg/m3 and 21.9 mg/m3, respectively, with the highest dust reduction rate reaching 76.9%. The mass concentration of respirable dust decreased to 15.3 mg/m3 and 10.5 mg/m3 respectively, with a maximum dust reduction rate of 85.2% and the dust removal performance was significantly improved.
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