Abstract: In order to implement the strategy of " Healthy China" and solve the practical problems of the severe harm of underground dust in mines and the high energy consumption and low work efficiency of traditional wet-type dust removal means,this paper proposed ejection staging pneumatic spray dust suppression technology and developed an ejection grading pneumatic spray dust suppression device. The inner flow field and velocity field of the ejection grading device were analyzed with numerical simulation. The experimental platform for the ejection grading pneumatic spray dust suppression device was constructed,and both the suction air speed experiment and the dust removal experiment were performed to finally determine the spray nozzle and the ejection structure model. Meanwhile,taking suction air speed and dust-reducing effect in the experiment as a key monitoring index,the feasibility of the ejection grading pneumatic spray dust suppression device was explored. The research results showed that ejecting airflow was formed inside the ejection grading device and the air current at the suction outlet moved towards the spray nozzle;The optimal choice of the ejection grading spray dust suppression device was SV980 spray nozzle together with B-type ejection structure model,the highest air speed in the center of dust absorption port was 1. 27 m / s,and the highest air speed in the side wall of dust absorption port reached up to 1. 53 m / s;And the total dust-reducing efficiency,the first-level dust-reducing efficiency,and the second-level dust-reducing efficiency of the B-type ejection structure model reached 83. 9%,76. 6%,and 7. 4%,respectively,which were better than those of single spray nozzle and A-type ejection structure model. The field experiment revealed that the dust-reducing efficiency of total dust and respirable dust at the location of tunneller drivers was 85. 67% and 81. 02%,respectively,suggesting that the proposed device effectively reduces the dust concentration in mines and safeguards the health of staff.

Key words: dust control,ejection structure,pneumatic spray,suction wind speed,dust concentration