Study on pore structure and fractal characteristics of high-rank intact coal and tectonic coal

Abstract

In order to study the pore structure and fractal characteristics of high-rank intact coal and tectonic coal, the selected coal samples were studied by mercury intrusion method and low pressure N2 adsorption method and low pressure CO2 adsorption method. The pore size distribution, pore volume and specific surface area, pore shape and connectivity, and fractal dimension differences between intact coal and tectonic coal were compared. The results show that tectonic coal is dominated by open pores and has better connectivity than intact coal. The sum of their Dubinin-Radushkevic（Ｄ-Ｒ） and micropore specific surface area of both intact coal and tectonic coal accounts for more than 99% of the total specific surface area, thus providing more space for gas adsorption. Moreover, the larger pore volume and specific surface area of tectonic coal result in its high gas content. The seepage pores of tectonic coal are simple, the adsorption pores have low pore structure complexity, and the pore surface is relatively smooth, which improves the gas migration ability in the pores.

Keywords

• intact coal
• tectonic coal
• mercury intrusion method
• low pressure gas adsorption method
• fractal dimension