Experimental Investigation on Variation of Physical Properties of Coal Samples Subjected to Microwave Irradiation


The gas drainage rate of low-permeability coal seam is generally less than satisfactory. This leads to the gas disaster of coal mine, and largely restricts the extraction of coalbed methane (CBM), and increases the emission of greenhouse gases in the mining area. Consequently, enhancing the gas drainage rate is an urgent challenge. To solve this problem, a new approach of using microwave irradiation (MWR) as a non-contact physical field excitation method to enhance gas drainage has been attempted. In order to evaluate the feasibility of this method, the methane adsorption, diffusion and penetrability of coal subjected to MWR were experimentally investigated. The variation of methane adsorbed amount, methane diffusion speed and absorption loop for the coal sample before and after MWR were obtained. The findings show that the MWR can change the adsorption property and reduce the methane adsorption capacity of coal. Moreover, the methane diffusion characteristic curves for both the irradiated coal samples and the original coal samples present the same trend. The irradiated coal samples have better methane diffusion ability than the original ones. As the adsorbed methane decreases, the methane diffusion speed increases or remain the same for the sample subjected to MWR. Furthermore, compared to the original coal samples, the area of the absorption loop for irradiated samples increases, especially for the micro-pore and medium-pore stage. This leads to the increase of open pores in the coal, thus improving the gas penetrability of coal. This study provides supports for positive MWR effects on changing the methane adsorption and improving the methane diffusion and the gas penetrability properties of coal samples.


Mining Engineering


This work was supported by the National Natural Science Foundation of China (Grant No. 51774279), Fundamental Research Funds for the Central Universities (Grant No. 2015XKZD04) and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (Grant No. SZBF2011-6-B35).

Keywords and Phrases

Adsorption; Coal; Coal bed methane; Coal deposits; Coal mines; Diffusion; Drainage; Firedamp; Greenhouse gases; Irradiation; Microwave irradiation; Adsorbed amount; Adsorption properties; Experimental investigations; Irradiated samples; Low permeability coal seam; Methane adsorption; Methane adsorption capacity; Methane diffusion; Methane; Absorption; Coalbed methane; Experimental study; Greenhouse gas; Irradiation; Microwave radiation; Physical property; Gas penetrability; Microwave irradiation

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version


File Type





© 2018 Elsevier, All rights reserved.

Publication Date

01 Mar 2018