Mining Topic: Fire Fighting

Fire fighters in training to fight a mine belt fire.

What is the health and safety problem?

Mine fires occur every year due to equipment malfunction, spontaneous combustion, frictional ignition, cutting and welding, lightning, and other causes. Misaligned or damaged conveyor belts are often the source of frictional heating that leads to fires. Further, fire suppression systems do not always function as intended. Many mines conduct regular firefighting training for their workforce and some mines support specially equipped fire brigades. When a fire occurs, mine workers not engaged in extinguishing it must evacuate the area inby the fire, sometimes under significantly impaired visibility from smoke or difficult environmental conditions.

The spontaneous heating of coal in mines often occurs in gob areas and may not be easily detected. The risk of an explosion ignited by a spontaneous combustion fire is also present in mines with appreciable levels of accumulated methane. A project is being conducted to develop new methods to prevent, detect, control, and suppress spontaneous heating in western coal mines.

What is the extent of the problem?

Since 2000, more than 20 mine fires have occurred in the United States. In fact, three of the mine fires since 2000 resulted in subsequent methane explosions. Two mine workers were fatally injured as a result of an underground mine conveyor belt fire in 2006 in West Virginia. During the same time period, 25 spontaneous combustion fires have been reported in underground coal mines. Generally there are over 50 face ignitions reported to the Mine Safety and Health Administration (MSHA) every year.

How is OMSHR addressing this problem?

Section 11 of the MINER Act of 2006 required that a Technical Study Panel be formed to provide recommendations on the use of belt air and new technology that may be available for increasing the fire resistance properties of conveyor belts used in underground coal mines. The Office of Mine Safety and Health Research (OMSHR) is currently working on research to reduce the hazards of underground coal mine fires. This research focuses on applying recent technological advances in the areas of fire-resistant and fireproof belt materials, belt fire suppression systems, atmospheric monitoring systems, and computer codes for predicting and assessing, in real time, the impact of fire on the mine ventilation system and the spread of fire contaminants throughout the mine.

OMSHR completed a long-running emergency response research program that included interacting with 440 fire fighters and 3,200 mine rescuers, identifying methods to improve skills that are now incorporated in expanded mine rescue training events. Currently, the Mine Rescue and Escape Training Laboratory is being used to determine optimal use of virtual reality (VR) technologies for training and assessing mine emergency responders. Responders include specially trained individuals, such as mine rescue or fire brigade team members, and also managers and mine workers who may be called upon to respond to an emergency situation.

Computational fluid dynamics modeling techniques are being used to simulate the spontaneous heating of coal in longwall gob areas. These simulations may be used to evaluate spontaneous combustion control methods and to determine nitrogen injection strategies to prevent/suppress the spontaneous heating in longwall gob areas.

What are the significant findings?

The number of conveyor belt fires and injuries/fatalities due to fire can be significantly reduced by fire-resistant and fireproof belt materials, well-designed belt fire suppression systems, and atmospheric monitoring systems to detect incipient heating. Real-time prediction of the impact of fire on the mine ventilation system and the spread of fire contaminants throughout the mine is possible with new software.

What are the next steps?

OMSHR will continue both laboratory and field evaluations of novel and emerging technologies to keep mine fires from starting, control fires after they become large enough to detect and suppress, and train and equip human fire fighting efforts. Plans are also in the works to incorporate firefighting modules into the Mine Rescue and Escape Training Laboratory to develop innovative training methods based on VR technologies for use in mine safety and health training classes.

Noteworthy Publications & Products

• A Global Inventory of Mine Rescue Training Facilities: Compendium of Ideas to Improve U.S. Coal Mine Rescue Training (2012-08)
  This paper presents a summary of domestic and international coal mine rescue training facilities and identifies those that provide unique, real-life, and/or state-of-the-art training.
• Development of a Gas Monitor Simulator and Mine Rescue Contest Field Trials (2012-08)
  NIOSH researchers completed field trials during coal mine rescue contests using simulated gas detectors in place of placards, and demonstrated that the newly developed GMS device may be used with no adverse impact on team contest performance.
• Effect of Air Velocity on Conveyor Belt Fire Suppression Systems (2012-08)
  Researchers evaluated four different types of fire suppression systems to study the effect of air velocity on extinguishing conveyor belt fires. Details are presented on the large-scale fire test set-up and arrangement of fire suppression systems.
• Effect of Longwall Face Advance on Spontaneous Heating in Longwall Gob Areas (2010-06)
  In this paper, Computational Fluid Dynamics modeling of the effect of longwall face advance on the spontaneous heating of coals in a two-panel gob area using a bleeder ventilation system is presented.
• Effects of Ventilation and Gob Characteristics on Spontaneous Heating in Longwall Gob Areas (2012-08)
  The results of field tests to understand how ventilation and gob characteristics affect the spontaneous heating process causing spontaneous combustion fires in longwall or worked-out gob areas are presented.
• Evaluation of Smoke Detectors for Use in Underground Mines (2012-08)
  This report describes experiments and their results in determining the responses of a prototype smoke detector and a commercially available photoelectric smoke detector to smoke particles generated from various combustion sources.
• Final Report of the Technical Study Panel on the Utilization of Belt Air and the Composition and Fire Retardant Properties of Belt Materials in Underground Coal Mining (2012-09)
  This final report was prepared by the Technical Study Panel on the Utilization of Belt Air and the Composition and Fire Retardant Properties of Belt Materials in Underground Coal Mining. It provides a review and recommendations concerning the utilizatio...
• Fire Response Preparedness for Underground Mines (2010-07)
  This report deals with the preparedness of miners to respond to underground fires. It is intended to aid the mining industry in understanding the various roles of emergency responders and the training techniques used to increase their skill levels. The ...
• In-Mine Study of High-Expansion Firefighting Foam (2012-08)
  This paper describes the production of high-expansion firefighting foam and discusses the in-mine experimental tests and results.
• Reducing the Fire and Explosion Hazards of Flame-Cutting and Welding in Underground Coal Mines (2010-12)
  This paper provides a summary of work done in a study on fires and explosions in underground U.S. coal mines that were caused by flame cutting and welding operations to determine the root causes of these types of fires and explosions.