The problem is that methane is unavoidable. When you mine coal, you expose fissures and pores in the coal bed in which methane is lying. Therefore, you cannot help but release into a confined area a gas that is not only highly flammable with the potential to violently explode in a ball of flame but one that is also an asphyxiant, capable of driving out oxygen and causing death by suffocation. A build up of hazardous gas in a mine is known as a damp.  Methane build-ups are called “fire damps”.

Carbon monoxide accumulation, also called “white damp” adds to these dangers. When methane combusts, this highly toxic and flammable gas is generated as a by-product and spreads through a mine’s labyrinth of tunnels and shafts.

Coal dust also reacts badly to a methane explosion. As part of a violent chain reaction, it can burst into flames in a series of secondary explosions throughout a mine.

You Can Not Predict Methane Risk
The properties of methane make it as difficult to detect in a mine as elsewhere. It is colorless, odorless and non-toxic, so there are no obvious physical signs such as coughing or streaming eyes to warn of its proximity (although, as mentioned above, it will cause suffocation if it builds up in a badly ventilated space). Furthermore, it is difficult to assess how much methane is likely to be freed from a particular coal bed – factors such as coal type, the depth of the mine and the geologic age of the coal strata all play a part.

Mining Activity Adds to Methane Explosion Risk
Once present in the atmosphere of the mine, methane can be easily ignited. Modern mining equipment includes electric arcs, hammers and cutters that can all generate sparks and open flames – the very things that detonate a pocket of methane gas. This is why American federal standards stipulate that if there is 1.0 percent or more of methane in the working area, miners must immediately shut down all electrically powered tools and other mechanized equipment.

Because of these environmental and working conditions, the risks of a methane gas explosion and the possibility of fatalities are greater in a coal mine than anywhere else. The testimony to this is the number of coal mining accidents throughout history and the amount of lives that have been lost in countries such as Canada, China, Japan, Poland, Russia, the United Kingdom, and the United States.  2007 statistics for fatal occupational injuries in the mining industry from the U.S. Bureau of Labor Statistics unit of the United States Department of Labor indicate mining to have the second highest percentage of fatality per employee.  This is second to a group consisting of agriculture, forestry, fishing and hunting.

Tragedies Can Be Prevented by Detecting Methane Gas Danger

• The worst Chinese disaster occurred on 26 April 1942 in the Benxihu Colliery when an explosion killed 1,549 miners.
• In Japan, on 9 November 1963, an explosion at the Miike coal mine killed 20 miners, and a further 438 died from carbon monoxide poisoning.
• Since 1880 in Poland, there have been 24 recorded coal mining accidents, the final 12 of which happened in the last twenty years.
• In the Russian coal mine of Ulyanovskaya at Kemerovo Oblast, 108 died in a methane explosion on 19 March 2007.

Methane’s perilous nature is clear from this short list taken from the hundreds of recorded coal mining accidents that have blighted the industry over the last two centuries and more. In the United States, one of the most recent in a long line of methane coal mine blasts took place just a short while ago.

2006 Coal Mine Explosion Killed 12 Miners
The coal mine in question was the Sago Mine, West Virginia, where at around 6.00 am on 2 January 2006, two carts of miners entered a shaft to commence work after the New Year holiday weekend. About 30 minutes later there was an explosion somewhere between the two carts. The miners on the second cart managed to escape but the 13 miners on the first cart were trapped thousands of feet below ground. After two days of frantic efforts, rescuers managed to bring just one survivor to the surface.

Theories Explaining Ignition of Methane Gas
Everyone agreed that the cause of the explosion was methane gas but there was debate about the source of ignition. The initial feeling was that one of two cloud-to-ground lightning strikes near the mine had hit and sparked a methane well. Such wells are drilled from the mine shafts to the surface to draw out methane from the working areas.

A further theory speculated that there had been a change in barometric pressure that caused the density of the air to drop, in turn allowing the methane gas to build to an explosive concentration.

Yet another suggestion was that a spark from electrical machinery may have ignited a large pocket of methane that had developed during the closure of the mine for the holiday weekend.

Rescue Effort Complications
Whatever the cause, rescue efforts were hampered by high levels of carbon monoxide and the concern that additional fresh air introduced into the mine might react with any remaining methane and lead to a further explosion.

Such accidents as the Sago Mine disaster are shocking reminders of our defenselessness when faced with methane’s lethal characteristics. And although safety standards increase and the awareness of danger continues to grow, methane gas remains notoriously difficult to manage.