Research on dust reduction technology of air chamber in fully mechanized mining face

In response to the dust control problem in excavation roadways, the traditional long pressure short suction ventilation dust reduction technology has problems such as large dust diffusion areas and easy blockage of jet holes in the air curtain dust reduction technology. Taking the Balasu Coal Mine fully mechanized mining face as the engineering research background, a mathematical model of dust movement during the excavation process is established. It is found that the key factors to reduce the dust concentration in the fully mechanized mining face are to control the disturbance range of the wind flow field in the excavation roadway and reduce the movement time of dust particles. Based on the above key factors, an air chamber dust reduction technology has been developed on the basis of air curtain dust reduction. By installing air sleeves at the end of the positive pressure air duct and working together with the air curtain, the dust is enclosed in the air chamber area. The dust is extracted by a negative pressure fan to improve dust reduction efficiency. Fluent software is used to simulate and compare the dust reduction of long pressure short suction ventilation, air curtain, and air chamber. The technical parameters of air chamber dust reduction are optimized. The simulation results show that when using the air chamber dust reduction technology, the dust concentration at the breathing zone of the human body in the fully mechanized mining face is 350 mg/m³. It is significantly lower than the 600 mg/m³ when using long pressure and short suction ventilation for dust reduction and the 480 mg/m³ when using air curtain dust reduction. The optimal technical parameters for air chamber dust reduction are a positive pressure air duct 14 meters away from the excavation face and a negative pressure air duct end diameter of 0.6 meters. On site experiments are conducted on the fully mechanized mining face of the second coal seam and second return air roadway in Balasu Coal Mine. The results showed that when using air chamber dust reduction, the minimum dust concentration in the excavation roadway is 118 mg/m³. It is better than the 184 mg/m³ when using long pressure short suction ventilation and 156 mg/m³ when using air curtain dust reduction. The dust reduction efficiency is also improved by an average of 54.8% compared to long pressure short suction ventilation for dust reduction.