Tools Exist For Safer Coal Mines
Fatal disasters might be averted if existing tech was more fully deployed.
In the days after a mining disaster killed 29 coal miners in West Virginia and another accident killed at least 35 in China’s Shanxi province, experts are saying that existing technology could make coal mining significantly safer–if only it was used.
While it’s still too early to determine exactly what led to the disasters, improved monitoring of dangerous gases and coal dust could help reduce the risk of explosions like the one that occurred at the Upper Big Branch Mine in West Virginia. The sort of flooding that trapped miners in China could potentially be avoided with relatively simple approaches, such as drilling ahead to probe for water. Rescue efforts could be aided by improved mine assessment tools (including computer models) that can help rescuers pinpoint the location of collapsed mine areas and other problem areas.
“I strongly believe that the technology is available, and in many cases in use, for preventing mine disasters and individual fatalities,” says John Grubb, a professor of mining and earth systems engineering at the Colorado School of Mines who has 40 years’ experience in the coal-mining industry.
One way new technology is not likely to help, at least in the near future, is by replacing coal miners entirely with automated machines, although in some mines it may be possible to operate machinery remotely. Some of the latest mining machinery allows operators to program them to do repetitive tasks, such as cycling back and forth across the face of a predictable mine seam. But in complex mines, it’s still essential to have a human operator present to quickly react to changing situations, says Jerry Tien, a professor of mining engineering at Missouri University of Science and Technology.
However, sensors that can continuously monitor the levels of dangerous gases, such as methane and carbon monoxide, as well as the pressure and flow rates in ventilation systems, already exist and are used in some mines. But in most coal mines in the United States, monitoring is done only a few times a day using handheld detectors, and not continuously via a network of sensors throughout an entire mine. According to the Mine Safety and Health Administration, the Upper Big Branch Mine used handheld detectors rather than a network of continuous methane sensors.
What’s more, areas of a mine where mining is finished and have been sealed off, but which still contain significant amounts of coal, coal dust, and methane, are often not monitored directly. These areas can be particularly dangerous because, unlike many pristine coal seams, the coal here has been exposed to oxygen, and so is vulnerable to combustion. Because of these dangers, electronic sensors aren’t allowed in sealed areas–they could cause a spark that sets off an explosion. But techniques have been developed to monitor inside sealed areas continuously by sampling gas levels via tubes that run to the surface–a practice used in Australia, but not much in the U.S., Grubb says.
The best way to avoid flooding is to probe ahead of the mining face, says Jeff Kohler, the mine safety research director at the National Institute for Occupational Safety and Health. His conclusion came after studying an incident at Quecreek Mine in Pennsylvania, where nine miners were trapped by water in 2002.
Researchers at Virginia Tech are developing a system that uses multiple trace gases to probe the complex ventilation systems of mines. They’re working to identify safe gases that can be injected at different entry points to the mine, and then measured at exists and ventilation shafts. Based on the relative concentrations of the gases, the amount of time it takes them to move from entrances to exits, and measurements of the ventilation system before an accident, it could prove possible to use computer models to locate obstructions, which could help rescuers, says Kray Luxbacher, professor of mining and minerals engineering at Virginia Tech.
Improving communications to locate miners will be difficult. In existing systems, wireless mesh networks can allow mine operators to track the location of miners, but these rely on wires to relay the signal out of the mine. In a disaster, such communications are often cut.
Experts emphasize, however, that new technology isn’t necessary to avoiding mining disasters– just following current regulations consistently could make a big improvement in mine safety. “Technology is wonderful, but it’s merely a tool. It still takes people to make it work, or not work,” Tien says.
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June 11-12, 2019