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Coal mine safety

Dear Control Engineering: Aren’t there sensors and other safety devices that could make coal mining less hazardous?

June 22, 2010

Dear Control Engineering: Aren’t there sensors and other safety devices that could make coal mining less hazardous?

While 2010 has been a difficult year with 27 mine-related fatalities so far, coal mining is not nearly as hazardous an occupation as it used to be. Prior to 1930, people were practically a consumable item with 2,000 and more fatalities a year. Once we got through WWII, deaths continued a downward trend and by 1950 they were typically below 500, and half that by 1970. Still, mines continue to be dangerous places, and it is difficult to imagine the turmoil people around Montcoal, WV, are experiencing as they await news of who may have perished below the ground.

Methane is frequently trapped in coal seams, and coal dust is highly explosive if airborne, so there are many potentially life-threatening elements. Technologies to measure these problems are common. There are devices to monitor oxygen, carbon dioxide, carbon monoxide, and methane. There are personnel locating devices that use GPS technology to indicate who is where. Some mines tie sensors together using Ethernet, just like any other potentially dangerous process manufacturing environment.

The problem is that such technologies have to be deployed and used properly. One report from the current Upper Big Branch mine rescue says that the mine owner had not put the equipment in the part of the mine that suffered the explosion. This is in spite of a 2006 federal law requiring its use. Miners have been known to bend safety rules to increase production. Regulations require that mines must be evacuated if methane concentrations exceed 1%. (It becomes explosive with concentrations as low as 5% and is especially dangerous around 9 to 10%.) Heavy equipment is supposed to shut down automatically if it reaches 1.5%, but such regulations have been ignored to maintain production levels. Coal dust can be even more explosive, but equipment usually uses water sprays to capture it.

As is often the case with industrial disasters, the main issues don’t relate to a lack of relevant technology as much as the way technology is (or isn’t) used, and how well people are trained. The mine owner in this case, Massey Energy, has been criticized for its record on safety operations. Such was also the case brought against BP in the Texas City refinery explosion in 2005. After the dust settles in West Virginia, there will be much to sift through.

Posted by Ask Control Engineering on April 10, 2010