Dynamic and static pressure combined water injection and dust reduction technology in fully mechanized top coal caving face

In order to solve the problem of high dust concentration in fully mechanized top-coal caving face with difficult wetting and high dust production, a combined water injection test of "long period static pressure, alternating dynamic static pressure and static pressure in stress-affected zone" was carried out in Wangjialing Coal Mine with the engineering background of fully mechanized top-coal caving face in 20107 and combined with the previous water injection test and field actual situation. By comparing and studying the wetting and dust-reducing effects of different water injection methods and borehole spacing, the water injection process parameters suitable for this kind of coal seam are obtained. The field practice shows that the wetting radius can be increased to 3 m by the combined water injection process. In the water injection area with 5 m drilling spacing, the total dust removal efficiency can reach 57% and the respirator dust removal efficiency can reach 70%. It can effectively solve the dust hazard problem of the working face, and the effect is re-markable.