Study on the influence of coking coal pore structure on methane desorption in Xishan Coalfield

Abstract

In order to investigate the pore characteristic of coking coal in Xishan Coalfield and its influence on methane desorption, cryogenic liquid nitrogen adsorption method was used to analyze the pore structures of six typical coking coal samples. Combining the experimental results with methane desorption, the effect of pore structures on methane desorption characteristics of coking coal was analyzed from the micro level. The results show that both pore volume and pore specific surface area of coking coals are changed in the wide range of 0.017 4-0.081 3 cm3/g and 0.84-2.59 m2/g, respectively. Micropores are most developed among all the pore types in coking coal, and they mainly occupy the pore surface area. However, micropore volume is small, and pore volume is mainly contributed by macropores and mesopores. Pore volume is the main influencing factor of coking coal desorption, simultaneously the increase of pore surface area also contributes to gas desorption. Moisture content in coking coal has great impact on gas desorption. It is easy for water molecules to block the pore-fracture channels, further to inhibit gas desorption, leading to the reduction of total desorption volume.

Keywords

• coking coal
• pore structure
• gas desorption
• xishan coalfield
• influencing mechanism