Research Of CO₂ Fracturing Technique And Application On Coalmine Safety Production

CO2 fracturing technology is a method that transforms the gas phase transformation to fracture coal.It has advantages of no sparking,fissure power controlling,convenient,safety and efficient for storage and transportation and operation,in order to serve the mine production,China Coal Research Institute(Shenyang)tried to explore this technology in coal mines through developing and improving this technology product.In this paper,fracture principle and blasting mechanism of the CO2 cracking technology are analyzed.It is believed that the fracture and displacement are generated by the interaction of high pressure gas and stress wave as the CO2 is transforming.According to the theory of rock mechanics and gas blasting,we tried to use the numerical simulation to analyze the cracks and their effects,and provided theoretical reference for field application.Secondly,the product structure,function,model parameters and process of filling and blasting were systematically introduced through developing and improving CO2 cracking equipment.The characteristics of CO2 cracking and the precautions of deep hole blasting penetration and shallow hole blasting loose crushing were analyzed based on the field application.The application of deep hole presplitting blasting in low permeability coal seam and the rapid excavation of roadway were introduced systematically.In the low permeability coal seam,the gas concentration and purity were improved when the gas flow channel was opened as the obvious cracks were formed by blasting drilling in the coal wall,and this effect is more obvious.In the working face of coal roadway,the gas concentration in the borehole was improved by 2?3 times after blasting.During the blasting,the gas concentration of the return airflow was 0.78%,and the gas concentration of the recirculation flow was 0.28%after blasting,the drainage duration was shortened by more than half.In the application of mine coal(rock)loosening and crushing,including coal,treatment of the bottom drum,face fault,large gangue treatment and other fields,free surface conditions,coal(rock)hardness and joint development,drilling parameters,geological conditions and other factors affect the application.For the coal production,the single-hole blasting coal is 1.5t?3 t,and lump coal rate is about 80%.Rock loose and broken,the free surface of the poor conditions,may be appropriate to adjust the drilling parameters of the free surface structure for the rock loose displacement to provide space.Coal was more easily broken and extended as drilling layout hole spacing is 0.8m?2.5 m,and drilling angle is between 30°and 60°.