| In this paper,the No.2 coal seam of Dazhong,Hetuo and Longshan coal mine in Anyang coalfield is taken as the research object.The basic physical parameters and surface structure of coal were studied by industrial analysis and scanning electron microscopy(SEM).The molecular structure of coal were studied by X-ray diffraction(XRD),Raman spectroscopy(Raman)and Fourier transform infrared spectroscopy(FTIR)experiment.The adsorption desorption and dynamic diffusion kinetics of coal were studied by gas isothermal adsorption experiment and gas desorption experiment.Besides,taking Dazhong coal mine as an example,the sensitivity index and critical value of outburst in No.2 coal seam were studied.The main conclusions of this paper are as follows:1)The XRD results show that the microcrystalline structure parameters aromaticity(fa),microcrystalline elongation(La)and microcrystalline stacking(Lc)have a positive linear relationship with Ro,max,while layer spacing(d002)has a negative linear relationship with Ro,max.Raman spectral analysis results show that with the increase of Ro,max,the G peak position,the peak potential difference G-D1 has a good negative linear relationship with Ro,max,and the D peak position,the ratio of the strengths of the peaks ID1/IG has a negative linear relationship with Ro,max.FTIR experimental results show that the studied coal sample in Anyang coalfield contains aromatic structure group,aliphatic structure group,oxygen-containing functional group and hydroxyl group.With the increase of Ro,max,the parameter A(CH3)/A(CH2)shows a U-shaped trend of decreasing first and then increasing.2)The adsorption constants a of DZ 1#,DZ 2#,HT 1#,HT 2#,LS 1#and LS 2#are 37.26m3/t,39.95m3/t,41.30m3/t,36.85m3/t,52.36m3/t,51.82m3/t respectively.The gas cumulative desorption capacities in 120 minutes of DZ 1#,DZ 2#,HT 1#,HT 2#,LS 1#and LS 2#coal samples were 12.63m3/t,9.63m3/t,6.20m3/t,7.36m3/t,13.20m3/t and 13.85m3/t,respectively.It is found that the adsorption and desorption abilities of Longshan coal samples are stronger than those of Dazhong and Hetuo coal samples.Besides,there is a good linear relationship between the initial gas desorption amount and the square root of the desorption time in the first 3 minutes.3)The desorption process of coal samples and the dynamic diffusion model have good fitting degree.With the increase of desorption time,the dynamic diffusion coefficient D(t)tends to decrease.Meanwhile,the initial diffusion coefficient D0 decreases first and then increases with the vitirnite reflectance Ro,max.When Ro,max<1.5%,D0 gradually decreases with the increase of Ro,max,when Ro,max>1.5%,D0 gradually increases with the increase of Ro,max,and the minimum value appears when Ro,max=1.5%.In addition,the diffusion coefficient of LS 1#and LS 2#coal samples is obviously greater than that of DZ 1#,DZ 2#,HT 1#and HT 2#coal samples,indicating that the gas desorption/diffusion capacity of No.2 coal seam in Longshan coal mine is stronger than that Dazhong and Hetuo mines.4)In the end,to predicted the outburst risk of No.2 coal seam,the regional predictive sensitivity indicatorsthe gas pressure and gas content of No.2 coal seam in Dazhong coal mine is 0.70MPa and 8.00m3/t,respectively.The critical value of local prediction index of No.2 coal seam in Dazhong coal mine is Ah2 threshold is 210 Pa,the critical value of K1 threshold is 0.40 mL/g·min0.5.The thesis contains 36 figures,30 tables and 121 references. |
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