Experimental investigation on the pore and fracture structure of the reconstructed coal and its fractal characteristics

To study the pore and fracture structure in coals, the coal samples reconstructed by the coal powder with different particle sizes were taken as the study subject. The analytical methods based on the fractal theory were introduced and the scale characteristics of coal pore and fracture were analyzed. The results indicate that the fractal curves of the coal pore and fracture from the mercury intrusion porosimetry (MIP) are all divided into the low-pressure part that meets the fractal law and the high-pressure part that violates the fractal law. According to the fractal properties shown by the MIP, the interspace in coals can be divided into the pores and the fractures. The structure parameters of coal fractures can be obtained by the MIP (Low-pressure part) and that of coal pores can be obtained by a physisorption method (N2 and CO2 as the adsorbate). On this basis, the fracture porosity and matrix porosity in coals will be calculated by combining the apparent density of coals. In comparison, the difference between the pore and fracture structure parameters of the reconstructed coal samples and those of the raw coal samples is small, which indicates that the reconstructed coal samples can be used to replace the raw coal samples to study the general law of gas adsorption, desorption and seepage in coals. © 2019, Editorial Board of Journal of CUMT. All right reserved.