Coal mine bump
Encyclopedia
A coal mine bump is a term used to describe a seismic jolt occurring within a mine. The term refers to the explosive collapse of a wall or one or more support pillars, sometimes called a rock burst
. These pillars are left in place during room and pillar mining
, where an original narrow passage is dug and then substantially widened as ore is removed, creating open rooms with support pillars left in place. As the coal is extracted, the pressure is redistributed onto the pillars and can increase to the extent that the pillar explodes like a hand grenade, shooting coal and rock at lethal speeds.
In eastern United States coalfields, bumps are more likely when the overburden
is at least 500 feet (152 m); where a strong, overlying stratum
, such as sandstone, occurs near the coalbed; and with a strong, inflexible floor. In the United States, the number of deaths from bumps had dropped off dramatically since the early 1990s, but fatalities are more common in the West where mines often run deeper. Bumps are three times more likely in room-and-pillar mines, and are even more common in mines that do retreat mining
, in which the pillars are removed as the miners retreat towards the mine entrance with the intent of allowing an orderly collapse of the mine.
refers to a bump which occurred in Springhill, Nova Scotia
, Canada
on October 23, 1958.
Debate over the cause of the August 6, 2007, Crandall Canyon Mine
disaster, which took place 1,800 feet beneath the surface, raised public awareness about coal mine bumps. Seismologists at the University of Utah and the University of California, Berkeley concluded that an associated 3.9 magnitude temblor was likely caused not by an earthquake, but by the collapse itself. The mine's owner, Robert E. Murray
, adamantly disagreed.
Rock burst
A rock burst is a spontaneous, violent fracture of rock that can occur in deep mines. The opening of a mine shaft relieves neighboring rocks of tremendous pressure, which can literally cause the rock to explode as it attempts to re-establish equilibrium...
. These pillars are left in place during room and pillar mining
Room and pillar
Room and pillar is a mining system in which the mined material is extracted across a horizontal plane while leaving "pillars" of untouched material to support the roof overburden leaving open areas or "rooms" underground...
, where an original narrow passage is dug and then substantially widened as ore is removed, creating open rooms with support pillars left in place. As the coal is extracted, the pressure is redistributed onto the pillars and can increase to the extent that the pillar explodes like a hand grenade, shooting coal and rock at lethal speeds.
In eastern United States coalfields, bumps are more likely when the overburden
Overburden
Overburden is the material that lies above an area of economic or scientific interest in mining and archaeology; most commonly the rock, soil, and ecosystem that lies above a coal seam or ore body. It is also known as 'waste' or 'spoil'...
is at least 500 feet (152 m); where a strong, overlying stratum
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...
, such as sandstone, occurs near the coalbed; and with a strong, inflexible floor. In the United States, the number of deaths from bumps had dropped off dramatically since the early 1990s, but fatalities are more common in the West where mines often run deeper. Bumps are three times more likely in room-and-pillar mines, and are even more common in mines that do retreat mining
Retreat mining
Retreat mining is a term used to reference the final phase of an underground mining technique known as room and pillar mining. This involves excavating a room or chamber while leaving behind pillars of material for support. This excavation is carried out in a pattern advancing away from the...
, in which the pillars are removed as the miners retreat towards the mine entrance with the intent of allowing an orderly collapse of the mine.
Incidents
The Springhill Mining DisasterSpringhill mining disaster
The term Springhill mining disaster can refer to any of three separate Canadian mining disasters which occurred in 1891, 1956, and 1958 in different mines within the Springhill coalfield, near the town of Springhill in Cumberland County, Nova Scotia....
refers to a bump which occurred in Springhill, Nova Scotia
Springhill, Nova Scotia
-Coal mining:The first industrial coal mining in the area took place in the 1870s after a rail connection was built by the Springhill and Parrsboro Coal and Railway Company to the newly completed Intercolonial Railway at neighbouring Springhill Junction....
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
on October 23, 1958.
Debate over the cause of the August 6, 2007, Crandall Canyon Mine
Crandall Canyon Mine
The Crandall Canyon Mine, formerly Genwal Mine, was an underground bituminous coal mine in northwestern Emery County, Utah.The mine made headline news when six miners were trapped by a collapse in August 2007. Ten days later, three rescue workers were killed by a subsequent collapse...
disaster, which took place 1,800 feet beneath the surface, raised public awareness about coal mine bumps. Seismologists at the University of Utah and the University of California, Berkeley concluded that an associated 3.9 magnitude temblor was likely caused not by an earthquake, but by the collapse itself. The mine's owner, Robert E. Murray
Robert E. Murray
Robert E. Murray is an American CEO of Murray Energy Corporation, a mining corporation based in Pepper Pike, Ohio, near Cleveland. He is one of the largest independent operators of coal mines in the United States.-Personal details:...
, adamantly disagreed.