A novel anti-air-leakage method and an organic polymer material for improving methane drainage performance

Abstract

Abstract Coal mine methane (CMM) drainage is an important method to curb the occurrence of gas disasters and to reduce the amount of greenhouse gas emission, and to make full use of the methane resource. High-grade sealing boreholes is the key factor to achieve efficient drainage of methane. In order to improve the efficiency of CMM drainage as well as to seal in-seam horizontal boreholes and fractures around these boreholes effectively, a dynamic anti-air-leakage method called the dynamic fractures filling technology was presented, and an organic polymer material called the PM sealing material matching with this technology was developed in this paper. Firstly, the destruction of coal body around boreholes because of a roadway and a borehole excavation was analyzed from the view of stresses, and the range of fractures zone caused by roadway excavation was determined, then the sealing technology and sealing principle of the novel technology were analyzed systematically. Moreover, the development process of the PM sealing material was introduced, and the influence of preparation parameters on material properties was investigated. Besides, taking the coal seam in the 39,021 Transportation Lane in the Zhongmacun Mine(China) as the test site of this study, the attenuation law of the methane concentration in drainage boreholes under different sealing depths was investigated via adopting the conventional sealing technology. Finally, the methane-drainage effect of the novel sealing technology and the conventional technology were compared. The results indicate that: (1) Both a roadway excavation and a borehole excavation will cause the redistribution of stresses of the original coal mass, and the coal structure around a drainage borehole has been destroyed in different degrees due to stresses overlapping effect. Moreover, the dynamic developing fractures zone is the main channel of air-leakage during drainage process. (2) The novel technology uses the conventional sealing system and the dynamic sealing system to seal drainage boreholes and dynamic development of fractures around them. (3) When the water-to-material ratio is 7:1 and the treatment temperature is 180\xa0°C for 30\xa0min, the PM material has the best performance. (4) Comparing with the conventional sealing technology, the novel technology has the obvious characteristics of short sealing depth, long efficient continuous drainage time and high drainage amount of methane. and its advantages of methane-drainage effects and economic benefits are remarkable.