August 2023
Volume 75    Issue 8

Projectile impact testing of a concrete coal mine seal rated for 120 psi

Steward, Ethan; Perry, Kyle

ABSTRACT:

The mining of underground coal presents several hazards for miners, including the risk of an explosion fueled by methane gas. Methane can continuously leak into old workings and build up through its lower explosive limit. Underground coal mines are required to maintain safe conditions either by ventilating old workings or sealing them off using Mine Safety and Health Administration (MSHA)-approved seals. Mines generally choose to use seals rather than ventilation due to the high cost of ventilating larger and larger areas as the mine progresses. Seals are designed to withstand specific pressures, but high pressure is not the only threat that mine seals may be exposed to. During an underground explosion, pressure waves and gas expansion may propel objects in a mine to a high velocity, generating enough energy to damage mine seals and reduce their strength. Damaged mine seals may fail and allow high-pressure gas to vent through the seal during an explosion or allow gases to leak through the seal later after an explosion has occurred. This study investigated the effects of high-velocity impacts of common mine materials on a reinforced mine seal rated to 120 psi and found that those materials, when propelled to velocities possible during an underground explosion, could generate enough stress to crack or otherwise damage seals even when leaving little visible damage. The results of this study show that mine seals should be evaluated carefully after any impact or high-pressure event to ensure that they maintain their function.

Full-text paper:
Mining, Metallurgy & Exploration, https://doi.org/10.1007/s42461-023-00783-5

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