关键词: 长焰煤, 孔隙, 裂隙, 氮吸附实验, 比表面积, 分形维数

Abstract: The pore and fissure characteristics of coal have a certain influence on gas migration and surface oxygen absorption capacity. In this paper, experimental methods are used to systematically study the pore and fissure characteristics of No. 2 coal seam with low metamorphic degree in Selian No. 2 Coal Mine. It finds that: level III, level IV and level V fractures are well developed with a width of 3-350μm, usually 7-50μm; the pore volume and specific surface area characteristics of Class II, Class III, Class IV and Class V coals were measured experimentally, and The higher the crushing degree of coal sample is, the greater the total number of micropore and the specific surface area of coal sample are; with the increase of coal fragmentation, the adsorption capacity of coal sample and the width between adsorption curve and desorption curve in adsorption loop increase continuously. With the increase of coal fragmentation, the fractal dimension Dn of pore increases continuously. When Dn<2.6, the transition pore occupies the main position, the gas storage capacity of coal body is stronger, and the seepage capacity is weaker, and when Dn>2.6, the opposite tendency received. The larger the Dn is, the higher the degree of coal fragmentation, the larger the specific surface area, and the stronger the ability to adsorb methane and oxygen. The research results provide a basis for gas extraction and natural combustion prevention and control.