By Kim Murphy, Los Angeles Times
SEATTLE — Seven miners have been pulled safely from an Idaho mine after a sudden rock burst left them injured more than a mile below the surface.
The accident Wednesday night was the third one this year at the Lucky Friday Mine in Mullen, where two workers have died — one of them a month ago — and the Mine Safety and Health Administration already has issued a series of enforcement orders.
The mine was ordered closed again pending an investigation into the latest incident, which officials at Hecla Limited said did not appear to be connected to blasting activity in the underground shaft.
Hecla Vice President Melanie Hennessey said the miners were installing a safety system to contain rock bursts when precisely the kind of burst the company was seeking to protect against occurred. Such a burst, a spontaneous fracture in the rock, can be triggered by blasting in deep mines, or by “seismic activity,” she said in an interview.
“In the case of last night’s rock burst, we had not done any blasting in the previous 24 hours, and therefore the cause of the burst is not mining related,” she said. “We’re currently doing an investigation into the seismic activity and compiling all the data to be able to have a proper understanding of what occurred, and what caused it to occur.”
About 25 workers were down in the silver, lead and zinc mine when the fracture occurred shortly after 7:30 p.m., and other miners were able to come to the injured workers’ aid and evacuate them to the surface. All were transported to the hospital, with most suffering cuts and bruises. Three were kept overnight; the most seriously injured had a broken arm and required stitches.
“We are thankful that all employees are out of the mine and have been accounted for, and that those injured have been treated. The safety of our employees is our primary concern,” Hecla President Phil Baker said in a statement.
On Nov. 17, two workers employed by a contractor were injured, one of them fatally, when rock started collapsing below their feet, much like an hourglass. Though they were wearing fall arrest equipment, the devices are designed to trigger from sudden jolts, much like a car seat belt, and one of them failed to engage, Hennessey said.
The worker was transported to the hospital but died of his injuries.
In April, a miner was crushed by a 90-foot-long rock fall. Rescuers, including the miner’s brother, worked frantically to reach him but his body wasn’t recovered until nine days later.
In that case, the federal mining agency issued a critical report concluding that Hecla management had failed to conduct a proper engineering analysis to determine the structural integrity of that area of the mine. The report said management had also failed to install a support system — apparently of the kind Hecla was trying to install this week — to control the ground where miners work and travel.
Hennessey said the workers injured Wednesday night were in the process of installing a support system similar to those used in road tunnel construction. The three accidents this year were unrelated, she said.
Amy Louviere, a spokeswoman for the federal mining agency, said no fines have been assessed against Hecla in connection with the previous accidents.
©2011 the Los Angeles Times