Intake belt air safety by the numbers

Abstract

Due to prior major accidents in the United States underground coal mines, regulations concerning use of intake belt air were changed in 2008. Several safety requirements were introduced to combat the most acknowledged risk of using belt air; conveyor belt flammability. However, use of belt air increases airflow at the face area, which results in improved methane control. A definitive connection between belt air use and accident occurrence has not been established. Also, the frequency of belt air ventilation violations and their relation to other ventilation violations is not known, so reliable weighing of the benefits and risks is difficult.Based on data from 98 reports on underground belt entry fires the relationship among belt fires, ignitions, explosions, fatalities, and injury information was analyzed. Ignitions and explosions due to lack of ventilating air are much more common than belt fires. The number of injuries and fatalities resulting from these incidents far outnumbers those related to belt fires.Belt air related issues were further studied by researching an MSHA violations database. The number of belt air standard violations was expected to be significant enough to show the need to restrict its use. However, this was not found.It was concluded that because methane explosions and ignitions result in a much larger number of accidents, injuries, and fatalities, the benefit of additional air supplied to the face surpasses the risk of belt fires. Also, data showed that mines using belt air were not at greater risk than mines not using belt air.