Study on structure characteristics and adsorption features of soft and hard coal

In order to study the relationship between the gas reserves and the pore structure in different soft and hard seams, based on No. 3 seam in Yuwu Mining Area of Shanxi Qinshui basin as the study object, an isotherm adsorption experiment was applied to analyze the gas adsorption characteristics of the different soft and hard coal. A low pressure liquid nitrogen adsorption experiment was applied to study the pore structure characteristics of the different soft and hard coal and to analyze the gas adsorption contral mechanism of different soft and hard coal from a view of the coal microscopic pore structure. The study results showed that the gas adsorptio n capacity of different soft and hard coal samples would be different obviously and the gas adsorption capacity would be increased with the seam failure degree increas ed. The temperature would have an important influence to the gas adsorption capacity of different soft and hard coal. Under the same adsorption pressure, the gas ads orption volume would be negatively correlated to the temperature and the gas adsorption capacity of the seam would be reduced with the temperature increased. From t he in-situ coal to the mylonitic coal, with the seam failure degree increased, coal pore diameter would be reduced, the specific surface area of the pore would be increa sed and the pore structure would be complicated in tendency. The tectonic coal in Yuwu Mining Area was developed, the complicated pore structure in the coal make th e coal reservoir with great gas. Due to the tectonic stress effect, the permeability of the soft coal would be low and would be affected to the coalbed methane developm ent.