Abstract: In order to effectively control dust pollution during dry drilling in underground coal mines,this paper presents a newly designed and developed dust removal device. The development of this dust removal device is based on the analysis of dust diffusion characteristics and it combines the benefits of water jet injection and dry mist dust reduction technology. Theoretical analysis and laboratory experiments were conducted to study the specific structure and main performance parameters of each component of the device. Field tests were conducted in the Yangliu Coal Mine Drilling Yard to measure the dust removal rate of the device. According to the results,the new dust removal device comprises a drilling dust collecting device,water jet ejector,and dry mist dust settling device. These three parts respectively have the functions of dust source sealing,dust extraction and dust capture from drilling holes. The water flow rate,suction volume,and ejection coefficient of the water jet ejector increase linearly with increasing water pressure. The optimal operating parameters for a single dry mist nozzle are an air pressure of 0. 70 MPa and a water pressure of 0. 18 MPa. When the dry mist generator is equipped with 15 nozzles and the dry mist dust settling device is positioned 1. 2 m away from the borehole,the resulting mist field effectively covers all the borehole′s leaking points. Upon field application of the new dust removal device,the total dust removal rates were found to be 88. 9% and 87. 5% at distances of 6 m and 20 m respectively from the downwind side of the drilling rig. These results demonstrate a remarkable dust removal effect.

Key words: dry drilling,water jet,negative pressure injection,dry mist,dust removal device