Mining Project: Exploration of Cross-Sectional Configuration Benefits of an Explosion Apparatus

Research Summary

Traditionally, NIOSH conducted large-scale explosion propagation research in an experimental mine, either the Bruceton Experimental Mine or the Lake Lynn Experimental Mine (LLEM). In the absence of the availability of such a facility, an intermediate-scaled apparatus is necessary to evaluate new explosion prevention technologies. Benchtop testing can test individual properties of a propagating dust explosion, but an intermediate-scaled apparatus could enable researchers to test new technologies while incorporating the dynamic processes of a dust explosion propagation. Such an apparatus would not replace a large-scale facility but could complement and guide future large-scale research by identifying unsuccessful efforts.

This pilot project determined that cross-sectional area configuration, rectangular or circular, can affect results when evaluating explosions. Therefore, depending on the intended outcome, researchers should carefully consider the shape of the apparatus when evaluating explosion propagations and new explosion prevention technologies. This was accomplished through a thorough literature review and consultation with both academic and industry professionals familiar with explosion propagations.

The research used a combination of literature review and site visits to establish the validity and preference for an explosion test apparatus having a rectangular cross-sectional area.  The effects of cross-section shape and construction on the complex and interactive processes, including dust lifting, dust mixing, turbulence, reaction kinetics, and the distribution and role of convective and radiant heat transfer in supporting the propagation of secondary dust explosions, was examined. It was found that limited research has been conducted in which direct comparisons were made on different cross-sectional areas. Most literature was numerical-based and it was concluded that there are differences based on cross-sectional configurations. For example, square or rectangular cross-sections may experience higher temperatures in the corners of the entry, and this may have implications on survivability of cables or structures located in those areas. Flame distances and speeds were reported but a comparison of pressures and pressures histories are lacking.

From this work, strategic direction is given for future NIOSH research. Coal mine operators, rock dust manufacturers, regulatory agencies, explosion modelers, mining organizations, and other industry stakeholders can benefit from the summary of facilities conducting mining explosion research and the identification of any research gap areas.