Diffusion characteristics of coal dust associated with different ventilation methods in underground excavation tunnel

To further explore the dust diffusion behavior and percentage of different particle sizes under various ventilation methods and perfect the existing research, this work systematically investigated the space-time variation of airflow and dust under three ventilation modes and elaborated on the dust control mechanism and proportion of particle size. The results indicated that using the dust removal fan could reduce the spread of high concentration dust. With the increase in wind volume of the dust removal fan (Qe), dust removal efficiency increased from 34.8% to 74.6%. Meanwhile, the dust of small particle size spread with the airflow towards the rear of the excavation tunnel, but the vortex generated by the larger Qe made it challenge to discharge respiratory dust. The air curtain installation position was determined at 20 m, which restricted the high dust concentration within 10 m so that most of the coal dust was discharged from the exhaust duct. This technology effectively diminished the concentration of dust, resulting in the total dust removal efficiency increased to 89.8% and 98.5%. The results could provide theoretical guidance for dust control and removal strategies of coal mine excavation tunnels.