Research on Structural Difference for Different Soft and Hard Coal Samples

In order to investigate the microstructural difference of different soft and hard coal, taking Wangzhuang Coal Mine of Shanxi Lu’an Group as the engineering background. Aimed at 6 different soft and hard coal samples, the scanning electron microscopy （ＳＥＭ） was used to analyze the surface morphology features. The pore structural characteristics of these soft and hard coal samples were also studied combined with low temperature liquid nitrogen adsorption method. The comparison of microstructural difference was made among soft and hard coal samples with different metamorphism and deformation degree. The research results show that tectonic deformation has significant influence on surface structure of soft coal. Compared with hard coal, soft coal has more rough surface and contains more complex pore structure. Coalification also has great impact on pore structure. The pore diameter of coal gradually declines with increasing coalification, but the total specific surface area increases. For all the studied samples, micropore occupies more than 60% of the total specific surface area, making it as the main contributor. The average pore diameter of soft coal is always smaller than that of corresponding hard coal, but it is inverse for pore specific surface area. Tectonic deformation complicates the pore structure of coal, and tectonic soft coal has precocious evolution characteristics.