Study on gas adsorption and diffusion characteristics of intact coal and tectonic coal

In order to study the adsorption-diffusion characteristics of intact coal and tectonic coal, two kinds of coal samples were tested using methane adsorption equipment and desorption equipment.The results show that the maximum methane adsorption capacity of tectonic coal is 1.18 times that of intact coal, and the adsorption capacity of tectonic coal is stronger than that of intact coal under the same methane adsorption pressure.When the equilibrium pressure of methane adsorption is 0.74 MPa and 2 MPa, the constant diffusion coefficient of tectonic coal is 7.3 times and 4.5 times that of intact coal, respectively, indicating that the initial gas diffusion capacity of tectonic coal is much higher than that of intact coal.The time-dependent diffusion coefficients of the two coal samples first decreases rapidly and then tends to be stable with the desorption time.The diffusion attenuation coefficient of tectonic coal reaches 96.6% and 95.8% at the gas equilibrium pressure of 0.74 MPa and 2 MPa respectively.They are much higher than the diffusion coefficients 38.1% and 45.7% of intact coal.