Exploration of petrographic, elemental, and material properties of dynamic failure-prone coals

The purpose of this study is to explore how the geochemical and petrographic components of coal may impact its physical properties and how these correlate with a history of reportable dynamic failure in coal mines. Dynamic failure events, also termed bumps, bounces, or bursts, are the explosive failures of rock in a mining environment. These events occur suddenly and often with no warning, resulting in worker injury up to and including fatality in greater than 60% of reportable cases through the Mine Safety and Health Administration (MSHA). A database of variables was compiled using publicly available datasets, which includes compositional geographic, strength, and Hardgrove grindability index (HGI) data. Results indicated that bumping coals were less mature, lower in carbon, higher in oxygen, softer, and less well cleated than coals that did not bump. High liptinite content was found to correlate with higher average uniaxial compressive strength (UCS) values. However, no clear and direct correlation between UCS and dynamic failure status was observed. The findings of this study established that differences existed between coals that had versus had not experienced reportable dynamic failure accidents. These differences were inherent to the coal itself and were independent of mining-induced risk factors. Results further illuminated how compositional attribute of coal influenced physical properties and began to clarify potential links between geochemistry and dynamic failure status. Only through the better understanding of risk can more effective mitigating strategies be enacted.