The mine, near Keen Mountain, Virginia, is known to be one the gassiest underground coalmines in the US.

The goaf fall created a large air pressure wave that disrupted ventilation and caused the methane gas ignition that in turn caused the fire. Employees working underground at the time were immediately evacuated, without serious injury, and mining was suspended.

CONSOL Energy management, in conjunction with the Mine Safety and Health Administration, and the Virginia Division of Mines, Minerals and Energy, monitored gas readings from the mine. Analysis of the samples suggested that a fire existed in a localized area adjacent to the longwall mining system. The mine is being sealed to reduce oxygen and render the mine atmosphere inert.

Once the mine shafts are sealed, the company plans to drill several boreholes from the surface into the area of the mine where the problem is believed to be located. Nitrogen foam and water will be pumped into the boreholes to accelerate the mine inertization process. Each borehole is expected to take approximately four days to complete.

"Sealing the mine is the safest and most expeditious way to return Buchanan Mine to normal production," said chief operating officer (coal) Peter B Lilly.

The mine is currently idle and will not produce coal while it is sealed. The company expects, however, to be able to continue to ship coal from its inventories on the surface.

The mine employs more than 400 and produced 4.4 million tons of coal in 2004. Buchanan mines the Pocahontas #3 coal seam, with three continuous mining machines and one longwall.