| Under the effects of stress, the tectonic coal has low permeability, low intensity, and the pore structure of that is complicated; therefore, it is easy to cause the abnormal gas emission and gas outburst disaster. This thesis is based on the method combining microscopic observation and fluid invasion, studied the specific surface area and the respective specific surface area (specific surface of unit pore volume). As you know, experiments were carried out to compare the adsorption desorption characteristics of coal in the laboratory, meanwhile, pore structure and desorption characteristics were discussed. According to the results, we put forward the linear relation between tectonic coal pore structure and desorption properties. In brief, the research mainly covers the following several parts:(1) Using the method of scanning electron microscopy (SEM), observed the coal sample and got the microscopic observation pictures, then analyzed the SEM scanning images:the pore density found in 1000,5000 and 10000 ratio scanning images of tectonic coal is about 1.25,1.57,1.75 times of that in original coal, respectively.Using Mercury Intrusion Porosimetry (MIP) method and Low-Temperature Nitrogen Adsorption (LTNA) method, we tested the Lu’An mining area 3# coal seam coal pore structural parameters and the results show that micropore and mesopore volume account for the main part of the entrance, and the tectonic coal is about 1.46 times that of the original coal, furthermore, the tectonic coal specific surface area is about 1.17 times of original coal. As a matter of fact, the specific surface area of tectonic coal in Lu’An mining area was about 1.2 times of the original coal, the relative specific surface area is about 1.19 times of original coal.(2) High pressure adsorption experiment was also conducted in the laboratory and found that tectonic coal gas adsorption amount is about 1.16 times that of the original coal; Besides, Adsorption-desorption device was applied to test the desorption speed in the early stage of gas desorption under the condition of different adsorption equilibrium pressure and desorption quantity within 120 minutes, at 0.5 MPa,1.5 MPa,1.5 MPa adsorption equilibrium pressure and the average desorption quantity of tectonic coal is respectively 1.06,1.15,1.17 times of the original coal; in addition, desorption quantity within 1 minute,3-5 minutes is respectively 1.47 and 1.14 times of original coal.(3) Analyzed the relation between pore structure and desorption characteristics and found that with the increasing of relative specific surface area, gas adsorption and desorption quantity have a linear relation; What’s more, the original coal correlation degree is higher than that of tectonic coal, the greater the pressure, the higher the relevance.(4) Field test were performed in Lu’An mining area Guozhuang mine and Gaohe mine3# coal seam, tested the region of tectonic coal and original coal area gas desorption amount within 1 minute and 3-5 minutes, found that the average desorption quantity in tectonic coal region in the corresponding time is 48.6% and 15.9% higher than that of original coal. The test data is consistent with the experimental results. |
