Throughout history, coal-mining explosions have accounted for the deaths of thousands of workers as a result of the combustion of either methane gas or coal dust within the mine.
A significant amount of progress has been made in understanding the causes to these disasters, however these explosions remain a life-threatening aspect of a coal miner’s daily life.
In 1942, the most devastating coalmine explosion in history occurred in Benxihu Colliery in China, which claimed the lives of a staggering 1,549 coalmine workers. Additionally, in 1907 the worst coalmine explosion to ever occur within the United States killed 362 miners in Monongah, West Virginia. While this tragedy occurred over a century ago, fatality rates associated with underground coalmine explosions in 2010 accounted for an average of 23.5-80.4% fatalities among coal workers in the United States1.
Methane and Coal Dust
Methane, which is the primary component of natural gas, is often a byproduct of the rocks that are stripped from the walls of a mine as coal is being extracted. Without proper ventilation in a coalmine, the released methane gas could potentially come into contact with a heat source, causing this highly combustible gas to ignite.
Mixtures of methane in the air can also become explosive at concentrations of 5% to 15%, with 9.5% being its most dangerous concentration, as its ability to react with oxygen within the mine allows for the massive production of heat that will induce an explosion2.
It is estimated that an average coal mine within the United States will contain anywhere between 100 to 600 cubic feet of methane, which only increases the likelihood of this explosion to occur.
Explosions in coal mines as a result of coal dust accumulation is not as common as that which is associated with methane combustion, as a very high concentration of coal dust must be suspended within the air. Methane-coal dust hybrid mixture explosions, can also occur with more severe characteristics as compared to either explosion alone.
To prevent coal dust explosions and limit the amount of inhaled dust particles to reduce injury, limestone powder is sprayed along the walls of mines on a regular basis. In the event of an explosion, the surface limestone layer absorbs heat that is generated from the explosion to reduce its intensity.
Certain preventative measures can also be taken to reduce methane explosions within a mine, some of which include installing large fans to circulate the air within the mines and provide adequate ventilation for workers.
By constantly circulating the air, these fans are able to dilute any methane gas present within the air to levels that are below the explosive ranges. Mining machines can also be equipped with monitors that alert workers when methane concentrations within a given area reach 1%, thereby allowing excessive methane to be removed before an accident occurs.
Maintaining the Safety of Mines through Products and Maintenance
Several companies over the last several years have also focused on developing equipment and other materials that are explosion proof. Such equipment includes switchgears, surveillance and monitoring systems, material handling systems, cable glands, power generation and distribution systems, lifting apparatuses and much more.
Worksite Lighting and Power Solutions, for example, offer a number of versatile mining lighting products that are lightweight and completely explosion proof3. Similarly, Cooper Industries offers durable, corrosion-resistant and explosion proof products for both underground and aboveground projects.
Cooper’s explosion proof products include fittings, glands, circuit breakers, control stations, frequency drives, lighting products and several others4.
Government-run organizations, such as the National Institute for Occupational Safety and Health (NIOSH), must also remain committed to preventing coalmine explosions by continuously monitoring methane levels and coal dust accumulation within mines and conducting research on effective intervention methods.
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- “Mining Feature: Coal Mine Explosion Prevention” – Centers for Disease Control and Prevention
- “Methane from Coal” – Pennsylvania Department of Conservation and Natural Resources
- “Mining Lighting” – Worksite
- “Mining – Industrial and Explosionproof” – Cooper Industries