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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 ...
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.
[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 ...
Surface water in MTM regions has higher concentrations of arsenic, selenium, lead, magnesium, calcium, aluminum, manganese, sulfates and hydrogen sulfide from overburden. Wastewater from the coal cleaning process contains surfactants, flocculants, coal fines, benzene and toluene, sulfur, silica, iron oxide, sodium, trace metals and other chemicals.
Areas where the earth has been disturbed (e.g. construction sites or highway construction) may create acid rock drainage. In many localities, the liquid that drains from coal stocks, coal handling facilities, coal washeries, and coal waste tips can be highly acidic, and in such cases it is treated as acid rock drainage. These, combined with ...
A coal fire in China Open-cast mining continues near a fire at Jharia coalfield in India. A coal-seam fire is a burning of an outcrop or underground coal seam. Most coal-seam fires exhibit smouldering combustion, [1] particularly underground coal-seam fires, because of limited atmospheric oxygen availability. Coal-seam fire instances on Earth ...
The production of coal-water slurry fuel involves the crushing of coal or coal sludge to particles between 10 and 65 micrometers diameter (standard crushers can be used); wet milling and homogenisation (with additives as required). The resulting product (coal slurry) is then prepared for intermediate storage or transport. [2] Large particle ...