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Longwall mining is a form of underground coal mining where a long wall of coal is mined in a single slice (typically 0.6–6.0 m (2 ft 0 in – 19 ft 8 in) thick). The section of rock that is being mined, known as the longwall panel, is typically 3–4 km (1.9–2.5 mi) long, but can be up to 7.5 km (4.7 mi) long and 250–400 m (820–1,310 ft) wide.
Shortwall mining – A coal mining method that accounts for less than 1% of deep coal production, shortwall involves the use of a continuous mining machine with moveable roof supports, similar to longwall. The continuous miner shears coal panels 150–200 feet wide and more than a half-mile long, depending on other things like the strata of the ...
Underground longwall mining. Mining techniques can be divided into two common excavation types: surface mining and sub-surface (underground) mining. Today, surface mining is much more common, and produces, for example, 85% of minerals (excluding petroleum and natural gas) in the United States, including 98% of metallic ores. [45]
Longwall face. A longwall face is a coal face of considerable length between the gates from which the coal is removed. ... used particularly when collapsing the roof ...
Longwall systems have their own hydraulic roof supports which advance with the machine as mining progresses. As the longwall mining equipment moves forward, overlying rock that is no longer supported by coal is allowed to fall behind the operation in a controlled manner. The supports make possible high levels of production and safety.
When the ore body is more or less horizontal, various forms of room and pillar stoping, cut and fill, [4] or longwall mining can take place. In steeply-dipping ore bodies, such as lodes of tin, the stopes become long narrow near-vertical spaces, which, if one reaches the surface is known as a gunnis or goffen. [1]
Specifically with regards to Appalachia, Tunnel Ridge had reduced shipments as unfavorable mining conditions repeatedly impacted longwall advance causing production to be 466,000 tons below our ...
The longwall mining operations at the mine began in 1998. [2] Extraction occurs roughly 200 metres below the surface. Operations are expected to continue until around 2033. [3] The mine is owned by Anglo American Australia and several joint partners. [2] Methane gas extracted from the mine powers the Moranbah North Power Station. [4]