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Coal dust suspended in air is explosive—coal dust has far more surface area per unit weight than lumps of coal, and is more susceptible to spontaneous combustion. However, five elements are needed for an explosion to occur: oxygen, an ignition source, coal dust, dispersion of the coal dust, and confinement of the dust. [ 4 ]
In the coal mining industry, a methane explosion can initiate a coal dust explosion, which can then engulf an entire mine pit. As a precaution, incombustible stone dust may be spread along mine roadways, or stored in trays hanging from the roof, to dilute the coal dust stirred up by a shockwave to the point where it cannot burn. Mines may also ...
Pyroclastic flows exited the northern breach and covered avalanche debris, lahars, and other pyroclastic flows deposited by the May 18 eruption. [51] At 7:05 pm on June 12, a plume of ash billowed 2.5 mi (4.0 km) above the volcano. At 9:09 pm, a much stronger explosion sent an ash column about 10 mi (16 km) skyward. [57]
Ideally, coal slurry consists only of crushed coal and water, which can be efficiently separated. In practice, the separation is significantly costly due to the large amounts of water needed and wastewater generated by the process. [8] Furthermore, the slurry consists also of very fine coal dust that results in a waste called blackwater.
Damp is the collective name given to all gases (other than air) found in coal mines in Great Britain and North America. [1]As well as firedamp, other damps include blackdamp (nonbreathable mixture of carbon dioxide, water vapour and other gases); whitedamp (carbon monoxide and other gases produced by combustion); poisonous, explosive stinkdamp (hydrogen sulfide), with its characteristic rotten ...
[c] Collectors designed to reduce airborne dust account for more than 40 percent of all dust explosions. [24] Other important processes are grinding and pulverizing, transporting powders, filing silos and containers (which produces powder), and the mixing and blending of powders. [25] Investigation of 200 dust explosions and fires, between 1980 ...
The mining and processing of coal causes air and water pollution. [124] Coal-powered plants emit nitrogen oxides, sulfur dioxide, particulate pollution, and heavy metals, which adversely affect human health. [124] Coal bed methane extraction is important to avoid mining accidents. The deadly London smog was caused primarily by the heavy use of ...
The mixing of coal dust with air, creating a potentially explosive mixture The overpressure wave can throw objects into people, knock people over (and potentially throw people into stationary objects or even into automated machinery), knock miners' helmets off, pepper the flesh with gravel or small rocks, stop or alter the normal ventilation of ...