Coal industry hopes to strengthen seals

A carbon fiber material called BlastSeal shows promise, experts said.
CHARLESTON, W.Va. (AP) -- The coal mining industry has high hopes for a new material that may harden underground seals that don't meet federal strength standards.
Regulators say as many as 13,000 foam block seals in mines across the country don't meet the new strength requirement the Mine Safety and Health Administration set in July. MSHA upped the strength requirement after methane gas explosions behind seals killed 17 miners in separate accidents in West Virginia and Kentucky this year.
Alternative seals must be built to withstand explosive forces of 50 pounds per square inch to meet the new rule. The old standard was 20 psi, but West Virginia regulators suspect the explosion at the Sago Mine on Jan. 2 unleashed at least 95 psi and shattered the seals. Twelve miners died as a result.
Figuring out how to strengthen those seals has been a puzzle for regulators and mine operators ever since. How they solve that puzzle is considered critical to making the nation's 600 or so underground coal mines safer. And it will affect coal companies that do much of their business in Appalachia, such as Richmond, Va.-based Massey Energy and Pittsburgh's Consol Energy.
Possible solution
One answer may be a carbon fiber material called BlastSeal.
"It seems to have a lot of promise," said National Mining Association lobbyist Bruce Watzman. "They believe that it would be at least 50 psi. It may be far in excess of that. We just don't know."
Regulators hope to find out by testing foam block seals treated with BlastSeal at the federal government's Lake Lynn Experimental Mine in southwestern Pennsylvania next year.
BlastSeal's developer, First Defense LLC in Tucson, Ariz., says walls treated with the material could survive blasts as high as 180 psi. Vice president Jim Butler said a concrete block wall treated with a similar material withstood a 180-psi explosion in tests for the U.S. Department of Defense in 2003. An untreated wall failed.
The way Butler explains it, BlastSeal works by adding high tensile strength carbon fiber sheets to the side of a wall opposite the source of an explosion. When the blast hits, the material, which is 10 times stronger than steel, deflects the blast, preventing the wall from blowing apart or over. Then it dissipates the energy by moving back and forth much like a plucked guitar string.
In the DOD test, the treated wall survived the blast, then shifted no more than 2 inches as it oscillated, Butler said.
Here's the concern
One sticking point might be whether BlastSeal adheres to foam block material.
Butler knows it sticks to concrete and wood, but he says the material's adhesive strength might not be enough to harden a foam wall sufficiently. "That's what we need to test."
Regulators also are working on other answers to the seal question.
The West Virginia Office of Miners' Health, Safety and Training, for instance, hopes to test a new seal design at Lake Lynn next year. And former acting director James Dean is gathering information on possible solutions for the state's Mine Safety Technology Task Force.
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