Experimental Investigation for Pore Structure and CH4 Release Characteristics of Coal during Pulverization Process

Abstract

Qinshui coalfield is the largest coalbed methane and anthracite production base in China. In the process of mine gas prevention and control, there was a larger amount of gas that can be extracted, but even with this, the residual gas pressure is not up to standard. In this paper, in order to analyze its specific reasons, a series of experiments were carried out to investigate the pore structure, particle size distribution, and CH4 release characteristics of anthracite during the pulverization process. Results show that, compared with bituminous coal, anthracite can continuously release a certain concentration of CH4 during the pulverization process. The SEM test exhibits that anthracite possesses more secondary pores while bituminous shows more mineral pores. With the increase of total pulverizing time, the coal particle size is gradually decreased. Furthermore, compared with the pre-pulverized samples, the porosity, pore volume, and surface area of post-pulverized samples are increased, indicating that the closed pores are destroyed to be open pores during the pulverization process. In addition, by combining the gas release concentration and pore volume evolution, it can be inferred that the anthracite may contain more solid solution gas due to the fact that there is a certain amount of gas that can be released when the pore volume tends to be smooth. The research results can provide the theoretical basis for gas extraction in the anthracite mine.