Coal mine bump

A coal mine bump (also called a bump, a mine bump, or a mountain bump) is a seismic jolt occurring within a mine, often due 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 the eastern United States' coalfields, bumps are more likely when the overburden is at least 500 feet (150 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.

Coal mining

The goal of coal mining is to obtain coal from the ground. Coal is valued for its energy content, and, since the 1880s, has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United States, United Kingdom, and South Africa, a coal mine and its structures are a colliery. In Australia, "colliery" generally refers to an underground coal mine.

Coal mining has had many developments over the recent years, from the early days of men tunneling, digging and manually extracting the coal on carts, to large open cut and long wall mines. Mining at this scale requires the use of draglines, trucks, conveyors, jacks and shearers.

History

Small scale mining of surface deposits dates back thousands of years. For example, in Roman Britain, the Romans were exploiting all major coalfields (save those of North and South Staffordshire) by the late 2nd century AD. While much of its use remained local, a lively trade developed along the North Sea coast supplying coal to Yorkshire and London.