火区下近距离煤层开采有害气体入侵灾害防控技术

Prevention and control technology of harmful gas intrusion in close-up coal seam under fire area

火区下近距离煤层开采容易导致有害气体入侵灾害的产生,严重威胁着工作面的安全回采。陕西煤业化工集团孙家岔煤矿30110工作面上部采空区自然发火严重,虽然采取了注氮、堵漏风技术进行防治,但效果均不明显。针对此问题,利用PFC2D软件建立了火区下近距离煤层开采数值模型,对3号煤层开采过程中的裂隙变化进行动态追踪,结果证明了有害气体入侵灾害的产生并判断了灾害产生的时间节点,为灾害发生前的重点监测工作以及均压通风系统的应用提供了依据。为了防止有害气体的入侵并避免新鲜风流压入火区引发灾害的扩大,对30110工作面进行均压通风技术研究,将上部火区和下部工作面的气压差控制在一个安全的范围内。通过计算确定了均压通风系统试运行期间的安全压差为296 Pa,正常运行期工作面回风风窗压差安全调节区间为(118 Pa,166 Pa)。现场应用结果证明,均压通风技术能够有效地避免有害气体入侵灾害的发生,确保工作面的安全回采。

The mining of the close coal seam under the fire area easily leads to the occurrence of harmful gas intrusion,which seriously threatens the safe mining of the working face.The goaf upon the 30110 mining face of the Sunjiacha coal mine had serious spontaneous combustion problem.Although the nitrogen injection and plugging air technology were taken to control the disaster,the effect was not obvious.To solve this problem,PFC2D was used to build a mining numerical model for dynamically tracking the change of fracture variation.The result shows that the air leakage channel will occur with the collapse of main roof in lower coal seam,which provides the basis for the monitoring work before the disaster and the application of the pressure equalization system.In order to prevent the invasion of harmful gases and avoid fresh air flowing into the fire area causing an explosion,a pressure balancing ventilation method was applied in the 30110 mining face.It can control the air pressure between upper fire area and lower working face in a safe range.The test safety pressure of 296 Pa and the normal safety adjustment interval （118 Pa,166 Pa） were determined by calculation.Application results prove that the pressure balancing ventilation can effectively prevent the occurrence of harmful gas intrusion and ensure the safe mining of the mine.