article · International Journal of Coal Geology
Deep underground coal mining operations frequently use surface vertical boreholes with narrow spacing and high suction pressure to capture goaf gas and reduce atmospheric emissions. However, intensive drainage risks pulling ventilation air deep into the goaf, potentially generating an explosive gas zone composed of methane and air. Using historical operational data from Australian coal mines, a computational fluid dynamics model was developed to visualise this underground environment. The model output was integrated with Coward's triangle to map hazardous zones. The findings reveal that intensive gas drainage pushes the explosive gas zone away from the active longwall face into a U-shaped formation. Furthermore, drainage design variables such as the number of operational boreholes and borehole completion depth were assessed using the overall size of the explosive gas zone as a safety criterion.
Underground coal mining becomes more hazardous as operations delve deeper, generating large volumes of volatile methane. Extracting this gas is vital for environmental and operational safety, but doing so too aggressively can accidentally pull in oxygen and create explosive mixtures. Visualising and predicting these hidden hazard zones helps mine operators protect workers while continuing to reduce harmful greenhouse gas emissions.
This modelling approach directly serves mine ventilation engineers and safety planners seeking to optimise surface borehole placement and suction strategies. By quantifying how borehole number and depth influence explosion risks, the research provides an applied computational tool that can immediately inform goaf gas drainage designs in active underground coal mines to balance worker safety with methane abatement.
AI-generated from the published abstract. Always read the original work before citing.
Goaf gas drainage is extensively employed in Australian gassy underground coal mines to manage safety and productivity and to mitigate gas emissions. As mining operations reach greater depths and produce higher levels of gas emissions, narrower spacing between adjacent vertical goaf boreholes and higher suction pressure are increasingly being adopted. While this proactive goaf gas drainage design enhances gas extraction efficiency, there is a concern that an increased amount of ventilation air might be drawn back into the deep goaf, potentially resulting in the formation of an explosive gas zone (EGZ) composed of methane-air mixtures. Extensive goaf gas drainage data from various Australian coal mines have undergone detailed analysis in preceding back analysis studies (Wang et al., 2022a, 2023). These findings serve as crucial validation input for a CFD model of the goaf, providing ventilation engineers with visualization of an otherwise inaccessible environment. In this paper, the simulation outcomes of the CFD model were integrated with Coward's triangle to demarcate potential EGZ within the active goaf areas. It indicated that the EGZ was pushed far away from the longwall face under the impact of intensive goaf gas drainage compared to the EGZ without the active goaf boreholes, exhibiting a ‘U-shaped’ distribution. Furthermore, this study delves into the gas drainage factors influencing EGZs in the goaf, emphasising the impact of various gas drainage designs on gas explosion risks within the goaf. Factors such as the number of active boreholes and completion depth are assessed, with the size of EGZ serving as a quantitative evaluation criterion. Therefore, this paper plays a pivotal role in optimising goaf gas drainage efficiency, striving to minimise gas emissions into the atmosphere while upholding the priority of mining and worker safety.
This page summarises published work. The authoritative version sits with the publisher.
DOI: 10.1016/j.coal.2024.104461
Is something wrong with this record? Report it or request removal.
Discussion
Have you built on this work, tried to replicate it, or seen it applied in practice? Share what you know. Verified researchers and MARATTO™ domain experts can open a discussion, and any member can reply. Contributions are reviewed before they appear.
No discussion yet. Open the first thread.
New to MARATTO™? Create a free account.
