Jing Zehao, Zhou Xihua, Li Yanchang, Bai Gang, Zhang Siqi
College of Safety Science and Engineering, Liaoning Technical University, Huludao, 125000, Liaoning, China.
Key Laboratory of Mine Thermodynamic Disasters and Control of Ministy of Education, Liaoning Technical University, Huludao, 125000, China.
Sci Rep. 2024 Aug 6;14(1):18205. doi: 10.1038/s41598-024-69297-4.
The implementation of the Gob-Side Entry Retaining Mining Mode with Roof Cutting and Pressure Relief (GERRCPR) results in the gob connecting to the retaining roadway, creating an open space that causes significant air leakage and increases the risk of spontaneous combustion. A study was conducted during the implementation of the GERRCPR in the Xiaonan Coal Mine N1-1502 working face to investigate spontaneous combustion characteristics, along with fire prevention and extinguishing measures. To analyze gob airflow, Computational Fluid Dynamics (CFD) was employed to collect data on airflow conditions, O concentration, and temperature. Based on this, this study focuses on exploring the effects of nitrogen injection treatment under various rates and positions to optimize parameters for buried pipe nitrogen injection. Results indicated that within the GERRCPR, air leakage in the gob increased, leading to an increase in O concentration, expansion of the oxidation zone, and an elevated risk of spontaneous combustion. Air leakage primarily occurred from the retaining roadway and the working face near the intake-air roadway, peaking at a retaining roadway length of 500 m, with a flow rate of 226 m/min. Following nitrogen injection treatment, the oxidation zone was significantly reduced, with optimal treatment achieved at a nitrogen injection depth of 70 m and a rate of 600 m/h. Field monitoring data showed that the inertization measure of using porous long pipes, a nitrogen injection spacing of 30 m, and a nitrogen injection rate of 600 m/h significantly decreased the O concentration within the gob. This reduction meets safety production requirements and outperforms the effectiveness of traditional buried-pipe nitrogen injection methods, thereby validating the simulation accuracy. Understanding the laws governing spontaneous coal combustion in the GERRCPR and enacting preventive measures for nitrogen injection can improve safety standards in mining operations. This proactive approach can effectively prevent spontaneous coal combustion accidents, resulting in substantial social benefits.
采用切顶卸压沿空留巷开采模式（GERRCPR）时，采空区与留巷相连，形成的开放空间导致大量漏风，增加了自燃风险。在小南煤矿N1-1502工作面实施GERRCPR期间，开展了一项研究，以调查自燃特性以及防火灭火措施。为分析采空区风流，采用计算流体动力学（CFD）收集风流状况、氧气浓度和温度数据。基于此，本研究着重探索不同注入速率和位置下注氮处理的效果，以优化埋管注氮参数。结果表明，在GERRCPR模式下，采空区漏风增加，导致氧气浓度升高、氧化带扩大，自燃风险增大。漏风主要发生在留巷以及进风巷附近的工作面，在留巷长度为500 m时达到峰值，流速为226 m/min。注氮处理后，氧化带显著减小，在注氮深度70 m、速率600 m/h时达到最佳处理效果。现场监测数据表明，采用多孔长管、注氮间距30 m、注氮速率600 m/h的惰化措施显著降低了采空区内的氧气浓度。这种降低符合安全生产要求，且优于传统埋管注氮方法的效果，从而验证了模拟的准确性。了解GERRCPR模式下煤炭自燃规律并制定注氮预防措施，可提高采矿作业的安全标准。这种积极主动的方法可有效预防煤炭自燃事故，带来巨大的社会效益。
