Two workers were killed and 12 injured on July 31 when a fire set off a methane gas explosion at the Willow Creek underground coal mine, about 160km south-east of Salt Lake City.

 

The fire started in the area where coal was being mined, about 600m beneath the surface. Four miners escaped uninjured from the blaze.

 

The fire was caused by a “normal” roof fall behind the longwall shields, which caused hydrocarbons on the mine floor to ignite. While the crew was attempting to extinguish the flame an explosion occurred.

 

Roof falls of this nature were a normal part of the mining operation, according to Ron Spangler, a spokesman for mine owner RAG Coal International of Essen, Germany.

 

The roof collapse apparently created sparks that started a fire and ignited a secondary explosion that may have been fueled by a pocket of methane gas, Spangler said.

 

The dead workers were Cory Nielson and Shane Stansfield. Of the 12 injured workers, one was in a critical condition and another was in a serious condition.

 

Tom Bingham, president of the Utah Mining Association, said air monitoring in coal mines has become so precise that fires are often detected even before flames can erupt. For a fire to catch so many people unaware it must have been very sudden, he said.

 

“That particular mine is what they would refer to as a ‘gassy’ mine,” Bingham said. “There is a lot of methane in that particular area, and that would probably have something to do with it.”

 

On August 7, the Mine Safety and Health Administration (MSHA) said the mine remains sealed at the portals.

 

The MSHA reported that mine air sampling from tubes installed through the earthen seals, at the fan housing and at two boreholes was continuing.

 

The mine atmosphere remained in the explosive range near the portals, the MSHA said. No means of sampling the mine atmosphere at the longwall face was available. Sealing of the fan housing and belt structure in portal number four was improved in an effort to minimise air leakage.

 

Meanwhile, MSHA gas analysis personnel are on site around the clock monitoring the mine atmosphere behind the seals. Mine personnel have started flooding the longwall gob area in an effort to cool the area where fire was originally observed. This process will take many days to complete, the MSHA said.

 

The mine employs about 340 people and can produce 5.1 million tonnes of coal a year.