Underground » Ventilation, Gas Drainage and Monitoring
The safety of personnel working in coal mines is a crucial concern that necessitates a comprehensive understanding of explosion dynamics, mining operations, and safety protocols. While there is a considerable body of knowledge about gas emissions and gas/coal dust explosions in underground mines, little attention has been paid to the potential risks associated with explosive forces and projectiles expelled through mine openings. Such hazards can result in injuries and fatalities to personnel underground and at the mine portal, as well as catastrophic damage to infrastructure in the vicinity of the mine opening on the surface.
Recent incidents of spontaneous combustion in New South Wales and Queensland mines have highlighted the importance of defining high risk working zones, mine operational exclusion zones, and public exclusion zones during emergencies. This project aims to establish appropriate exclusion zones for explosion risks around coal mine openings, such as drifts, shafts, and ventilation boreholes.
The methodology involved determining the relationship between the parameters of blast waves emitted from mine entries and the radial distances at an azimuth angle for different magnitudes of methane or coal dust explosions. The project utilised an Advanced Blast Simulator with cross-sectional dimensions of 0.3 m x 0.3 m to simulate blast waves exiting a mine entrance and propagating over an outside mine site terrain. Pressure sensors placed along the centreline and at several azimuth angles of the blast simulator recorded the characteristics of blast wave parameters. The results were used to create blast pressure contour maps that characterise the hazards from propagating blast waves.
The project also developed a procedure to estimate the lethal ranges of projectiles from mine entries using existing military ammunition storage guidelines. This methodology generates exclusion zones that account for the effects of blast waves, blast wind, and lethal projectiles around different types of mine openings.
The report concludes with verification studies that compare the extent of structural damage and injuries/fatalities reported on the surface with the exclusion zones produced using the methodology from this research study. The case studies presented demonstrate the effectiveness of the proposed methodology in defining exclusion zones that can significantly reduce the risk of injuries and fatalities in coal mines.