Don L. Blankenship, chairman and chief executive officer of Massey Energy Company (left), watches as protesters disrupt a luncheon at the National Press Club, where he spoke on Thursday. Wayne Huang/NPR hide caption

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Methane monitors are mounted on 30-foot-long continuous miners like this one, and other mining machines, to warn coal miners about dangerous levels of explosive methane gas. File photo hide caption

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Methane monitors are mounted on 30-foot-long continuous miners like this one because methane gas collects in pockets near the roofs of mines. File photo hide caption

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Clay Mullins (left), brother of mine disaster victim Rex Mullins, listens as Upper Big Branch miner Stanley "Goose" Stewart tells the House Education and Labor Committee that the mine "was a ticking time bomb" because of problems with ventilation and explosive methane and coal dust. Jon C. Hancock/AP hide caption

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Mine workers stand at the entrance of the Upper Big Branch coal mine on April 9, a few days after an explosion killed 29 men. Matt Sullivan/Getty Images hide caption

itoggle caption Matt Sullivan/Getty Images