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An outburst is the sudden and violent ejection of coal, rock, and gas from a coal face and surrounding strata in an underground coal mine. Outbursts can be a very serious events, possibly even resulting in fatalities.
Outbursts may range in severity from being barely noticeable, to causing the destruction of an entire mining panel, and throwing pieces of machinery weighing tens of tonnes several metres. An outburst at Tahmoor Colliery, in New South Wales, Australia, in June 1985 ejected 350 tonnes of coal and rock and over 3000 cubic metres of gas, killing one miner. [1] An outburst at the nearby South Bulli Colliery in 1991 killed three miners. An outburst at Westcliff Colliery in January 1994 ejected 300 tonnes of coal and rock and killed one miner.
Several factors predispose certain coal seams to being outburst-prone. These include:
The statistical results show that the primary factor in coal and gas outbursts is crustal stress (P), followed by sturdiness coefficient (f). The coal seam gas content (W) affect affects coal and gas outbursts as the least important factor. [2]
Outburst management primarily focuses on the prevention of outbursts by pre-draining the gas from coal seams prior to mining. The aim of gas drainage is to lower the gas content of the seam below a certain threshold value, at which time it is considered safe to mine the seam. [3] These threshold values should vary depending on the coal seam and coal measure being mined. Since the introduction of threshold values, not a single fatality due to an outburst has been recorded in Australia.
Gas drainage is achieved by drilling boreholes into the seam in advance of mining. Gas liberated from the seam into the boreholes is transported out of the mine via a pipe range.
Where standard gas drainage techniques are ineffectual, mine operators have a number of options. These may include:
Mining under "bomb squad" or outburst conditions is no longer considered acceptable, since this method still presents a fatal risk to at least one miner. "Bomb squad" is a special set of operating conditions that used to be adopted when it was anticipated that an outburst could occur. Under "bomb squad" conditions, the following working methods would apply:
Coal mining is the process of extracting coal from the ground or from a mine. 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 Kingdom and South Africa, a coal mine and its structures are a colliery, a coal mine is called a 'pit', and the above-ground structures are a 'pit head'. In Australia, "colliery" generally refers to an underground coal mine.
Coalbed methane, coalbed gas, or coal seam gas (CSG) is a form of natural gas extracted from coal beds. In recent decades it has become an important source of energy in United States, Canada, Australia, and other countries.
A mining accident is an accident that occurs during the process of mining minerals or metals. Thousands of miners die from mining accidents each year, especially from underground coal mining, although accidents also occur in hard rock mining. Coal mining is considered much more hazardous than hard rock mining due to flat-lying rock strata, generally incompetent rock, the presence of methane gas, and coal dust. Most of the deaths these days occur in developing countries, and rural parts of developed countries where safety measures are not practiced as fully. A mining disaster is an incident where there are five or more fatalities.
Longwall mining is a form of underground coal mining where a long wall of coal is mined in a single slice. 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.
Drift mining is either the mining of an ore deposit by underground methods, or the working of coal seams accessed by adits driven into the surface outcrop of the coal bed. A drift mine is an underground mine in which the entry or access is above water level and generally on the slope of a hill, driven horizontally into the ore seam.
The Maltby Main Colliery was a coal mine located 7 miles (11 km) east of Rotherham on the eastern edge of Maltby, South Yorkshire, England. The mine was closed in 2013.
Kellingley Colliery, known affectionately as the 'Big K', was a deep coal mine in North Yorkshire, England, 3.6 miles (5.8 km) east of Ferrybridge power station. It was owned and operated by UK Coal.
In mining, a windblast is a sudden rush of air or gas due to the collapse of a void.
The South Yorkshire Coalfield is so named from its position within Yorkshire. It covers most of South Yorkshire, West Yorkshire and a small part of North Yorkshire. The exposed coalfield outcrops in the Pennine foothills and dips under Permian rocks in the east. Its most famous coal seam is the Barnsley Bed. Coal has been mined from shallow seams and outcrops since medieval times and possibly earlier.
The South Waratah Colliery was a coal mine located at Charlestown, in New South Wales Australia.
Pentremawr Colliery was a coal mine, located in the Gwendraeth valley in Carmarthenshire, South Wales.
The Tarenni Colliery and its associated workings, are a series of coal mines and pits located between the villages of Godre'r Graig and Cilybebyll located in the valley of the River Tawe, in Neath Port Talbot county borough, South Wales.
Haig Colliery was a coal mine in Whitehaven, Cumbria, in north-west England. The mine was in operation for almost 70 years and produced anthracitic coal which is most useful for coking coal. Situated on the coast, the underground workings of the mine spread westwards out under the Irish Sea and mining was undertaken at over 4 miles (6.4 km) out underneath the sea bed.
Wheldale Colliery was a coal mine located in Castleford, Yorkshire, England which produced coal for 117 years. It was accessed from Wheldon Road.
This is a partial glossary of coal mining terminology commonly used in the coalfields of the United Kingdom. Some words were in use throughout the coalfields, some are historic and some are local to the different British coalfields.
Mine safety is a broad term referring to the practice of controlling and managing a wide range of hazards associated with the life cycle of mining-related activities. Mine safety practice involves the implementation of recognised hazard controls and/or reduction of risks associated with mining activities to legally, socially and morally acceptable levels. While the fundamental principle of mine safety is to remove health and safety risks to mine workers, mining safety practice may also focus on the reduction of risks to plant (machinery) together with the structure and orebody of the mine.
Hapton Valley Colliery was a coal mine on the edge of Hapton near Burnley in Lancashire, England. Its first shafts were sunk in the early 1850s and it had a life of almost 130 years, surviving to be the last deep mine operating on the Burnley Coalfield.
Bentley Colliery was a coal mine in Bentley, near Doncaster in South Yorkshire, England, that operated between 1906 and 1993. In common with many other mines, it suffered disasters and accidents. The worst Bentley disaster was in 1931 when 45 miners were killed after a gas explosion. The site of the mine has been converted into a woodland.
Tahmoor Colliery is an underground coal mine at Tahmoor in the Southern Highlands region of New South Wales, Australia. It operates in the Bulli coal seam. Most of the mine product is hard coking coal used for steel making. A small quantity of steaming blend coal used for power generation is also produced. Both products are exported to Europe and Asia.
Western Jharia Area is one of the 12 operational areas of BCCL located in Dhanbad Sadar subdivision of Dhanbad district in the state of Jharkhand, India.
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