Methodology For Predicting Explosion Risk Around Underground Coal Mine Openings Towards Developing Exclusion Zones

The risk of explosions in coal mines is an important subject that requires a comprehensive understanding of explosion dynamics, mining operations, and mining safety. A high level of knowledge is now available in the field of gas emissions, gas, and coal dust explosions in underground mines. However, not sufficient attention has been given to the potential risks associated with explosive forces expelled through the mine opening and resulting in injuries and fatalities to personnel (underground and at the mine portal) and catastrophic infrastructure damage in proximity to the mine opening on the surface. This paper presents a methodology for predicting explosion risk around the coal mine openings (drifts, shafts, boreholes, etc). The proposed methodology is based on establishing an empirical relationship between the parameters of blast overpressure waves emitting from mine entries and the radial distance at an azimuth angle for the various magnitude of methane or coal dust explosions. An Advanced Blast Simulator with the cross-sectional dimensions of 0.3 m x 0.3 m has been manufactured for this study to conduct a series of experiments simulating blast waves exiting a portal entry and propagating over an outside mine site terrain. An array of pressure sensors is placed along the centreline and at several azimuth angles of the blast simulator and along a surface representing a highwall to record the characteristics of blast overpressure waves. Computational Fluid Dynamics modelling of blast wave propagation outside of mine openings is used to correlate the experimental results and scale them up to full-scale dimensions of the coal mine infrastructure and mine sites. A procedure to estimate the lethal ranges of projectiles from mine entries using existing guidelines from a military ammunition storage reference manual is described. The outcome of this research will support the development of scientifically defined exclusion zones around surface mine openings that could be affected by an underground explosion event.