低透气性煤层瓦斯预抽技术的探讨与实践

Study and practice on gas predrainage technique in low-permeability coal seam

红阳三矿煤层埋藏深、变质程度高、瓦斯吸附性强,造成煤层透气性低,在采取开钻场先抽后采措施中,预抽时间长、提前掘送巷道增加维护工作量。针对此,提出了在工作面动压影响带采取中深孔抽放瓦斯工艺。在北一1211工作面可行性试验,结果表明,在工作面日产原煤5000t的情况下,回风流最大瓦斯浓度0.8%,一般介于0.5%～0.6%,效果显著。

The coal seam in Hongyang No. 3 metamorphism and great gas adsorption make coal mine is buried deep and its high degree of it be the low-permeability seam. During the process of ＂mining after gas suction＂ in the first drilling field, gas predrainage costs much time and maintenance workload is increased in pre-drilling roadway. Aiming at the above problems, the paper puts forward to adopt the process that performing the gas suction through medium- length hole in the dynamical pressure zone in the working face. The result of the feasibility test in the North No. 1 1211 working face shows that in the case of producing 5000t raw coal per day in the face, the highest gas concentration in the air return is 0.8O//oo, generally ranging from 0.5~ to 0.6 ~/00, and the practice effectiveness is significant.