Pore characteristics of tectonic coal based on nitrogen adsorption and SEM
The pore structure characteristics of coal are closely related to gas absorption and transport.Due to damage caused by structural stress,the pore structure characteristics of tectonic coal tend to be complicated.Thus,investigating the development of tectonic coal pores is an important direction for improving the gas treatment level.In this paper,three groups of tectonic coal and a group of intact coal from the Dongyu Coal Mine in the southern part of the Xishan Coalfield were taken as the research object.Besides,the pore characteristics of tectonic coal and intact coal were jointly observed using low-temperature liquid nitrogen adsorption and scanning electron microscopy(SEM).As shown by the research,the nitrogen adsorption amount of the three groups of tectonic coal is 2.04 times,1.49 times,and 2.90 times that of intact coal.The pore volume of the three groups of tectonic coal is 2.08 times,1.53 times and 2.96 times that of intact coal,respectively.The pore volume of the three groups of tectonic coal in micropores and small pores is more than 69.71%.The proportion of micropores in the pore specific surface area of the three groups of structural coal exceeds 79.04%.The micropores and small pores of intact coal provide 89.38% of the pore volume,and the pore specific surface area of micropores accounts for 93.97%.The pore structure of the three groups of tectonic coal is more complex than that of the intact coal and had larger fractal dimension(2.6985 to 2.7106).The fractal dimensions of three groups'tectonic coal(10,000 times)are 1.962,1.979,and 1.947,respectively,greater than that of intact coal.In comparison to intact coal,tectonic coal had more developed pore system;the fractal dimension D1 is directly proportional to the total pore specific surface area and microporous surface area.The volatile content is directly proportional to the total pore surface area,microporous surface area,and small pore surface area within a certain range.
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