煤层群首采关键层卸压瓦斯综合治理技术

Comprehensive relieved coal-gas control technology of first mining coal-seam in multiple coal seams

首采煤层群关键层是消除邻近煤层突出危险性行之有效的方法。以淮南新庄孜煤矿66210工作面为例,在综合分析采空区上覆岩层竖向3带以及瓦斯运移基本条件的基础上,将上被保护层所产生的卸压瓦斯运移路径简化为:被保护层→上覆岩层竖向裂隙→采空区→回风巷。为了保障首采保护层工作面的安全回采,提出并实施了卸压瓦斯综合治理技术,对被保护层卸压瓦斯、首采层顶板裂隙发育区富集瓦斯、采空区瓦斯进行强化拦截抽采。采用沿空留巷Y型通风方式消除上隅角瓦斯积聚,降低风排瓦斯量,工作面回风瓦斯体积分数在0.6%以下,实现了高瓦斯煤层群首采工作面的安全高效生产。

Mining key coal seam is an effective measure to reduce outburst risk in adjacent coal seams. The main gas emission source of first working face comes from the protected coal-seam, which can induce the rise of gas concentration. ＂Three vertical bands＂, including caving zone, fracture zone and swelling zone are formed above the gob during mining the key coal seam. The vertical cracks between protective layer and protected coal seam can be connected with the gob and provide many flow paths for the protected coal-seam gas migration. Thus, gases in the protected layer pour into the gob during the mining of first key coal-seam, which make gas control more difficult than single coal-seam mining. Based on the analysis of ＂three vertical bands＂ and the condition of gas migration, the working face 66210 of Xinzhuangzi eoal mine was taken as an example. This paper introduces the comprehensive gas control methods which including relief gas drainage in protected eoal seam, vertical cracks and gob, and Y type ventilation in dealing with the problem of methane accumulation at the upper corner of working-face. Gas migration channels were analysed by extracting the relieved gas as well. The practice effectiveness of working face 66210 of Xinzhuangzi coal mine showed that the concentration of gas in the air-return way was below 0.6%. Thus, a safe and highly efficient comprehensive gas control method of first key coal-seam working face mining in the condition of high-gas content multiple coal seams was successfully developed.