Study on technology of fracturing and permeability improved ofcoal seam with high pressure air blasting

In order to solve the inaccurate blasting parameters and abnormal operation procedure problems occurred in the implementation process of the high pressure air blasting technology, a theatrical study and a site experiment combined study method were applied to study the fracturing and permeability improved technology with the high pressure air blasting. The high pressure air blasting parameters mainly with the borehole diameter, blasting pressure, space between the blasting boreholes and blasting impact times were obtained. The fracturing and permeability improved technology was set up, including the six steps of the location selection, drilling operation, system assembly, blasting cartridge placement, borehole sealing and detonation. The processing, integration and standard of the blasting and permeability improved technology were realized. The site experiment results of the seam high pressure air blasting fracturing and permeability improved technology showed that the fracturing and permeability improved technology with the high pressure air blasting could be suitably applied to the underground mine operation, the blasting pressure could be selected as 50 MPa, the diameter of the blasting borehole and the gas drainage borehole could be selected as 94 mm and the blasting times per single borehole was 2～3 times. The fracturing effect was obvious, the permeability of the seam was highly enhanced, the gas emission volume and gas drainage volume of the seam were improved and the seam gas drainage effect was improved.