| Description |
Mine fires and explosions associated with spontaneous combustion (sponcom) can be the cause of mines closings temporarily or permanently. The risk of fatalities and production losses are also associated with the hazards of sponcom. Over the last 175 years, nearly 13,000 deaths have been recorded and are attributed to mine fires or explosions in the United States coal mines. Some of these fires could have been prevented with proper ventilation precautions. Ventilation is a primary tool used to prevent fires and explosions in an underground mining environment. Removing contaminants with proper air flow rate is the general method for preventing fires and explosions. Another method for fire prevention is pressure balancing. Pressure balancing is a technique of redistribution of the air pressure in areas where there is potential for sponcom. The implementation of passive and dynamic pressure balancing methods can be used to reduce the risk of spontaneous combustions and accumulation of explosive gas mixtures in confined areas. These methods have been applied in mines outside of the United States, mostly practiced in Australia, India, and some European countries. Pressure balancing, when applied correctly, may reduce or eliminate the flow of air through caved areas, thus reducing the possibility of self-heating of coal in critical areas where sponcom is more prevalent. Each mine in the United States will have different ventilation designs that are either classified as Bleeder or Bleederless with multiple variations in design. Passive and active pressure balancing designs were engineered for two underground longwall mines, one ventilated by a bleeder system and the other by a bleederless system. The study includes pressure quantity surveys in these coal mines, computer simulation exercises, and laboratory tests performed at the University of Utah. The simulations of surveyed coal mine models have been compared with field data and model data to produce results of potential pressure balancing implementations. The results have been analyzed and compared to each other, and used to develop strategies to prevent spontaneous combustion, create safe working conditions, and minimize ventilation requirements |
