An innovative dust suppression device used in underground tunneling

Abstract Dust is one of the main disasters in underground tunneling. This study developed and verified a novel dust suppression device, which was systematically tested in laboratory and field conditions. Based on the basic principle of the Coanda effect, with a small amount of compressed air as power supply, and through a uniform layout of circular hole for high-speed jet to drive the center air movement together thus forming the entrainment effect, the main structure of the new dust removal device was designed. The external dusty air is then drawn in and the dust is removed by water spray. According to laboratory experiments, the optimal structural parameters for the inlet inclination angle θ1, the outlet inclination angle θ2, and the number of the compressed drainage gas nozzle n were determined. It was found that when the inlet angle is 15° and the outlet angle is 5°, the Coanda effect is the most significant, and the suction rate of the dust removal device is the highest. With the increase of the number of gas orifices n, the suction rate firstly increased and then decreased. In addition, through numerical simulation, the optimal position of the spray nozzle is determined. In field tests, compared to that of the original dust removal device, the new device improved respirable dust and total dust suppression efficiencies by 30.5% and 11.5% (A: the motorman position), 56.2% and 24.5% (B: Behind the drilling machine), 69.4% and 21.6% (C: 20 m behind the drilling machine), respectively, thus the new technology effectively improves the atmosphere in the mechanized underground coal mines, creating a safer and healthier working environment.