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COAL
Coal mining
has been carried out for over a thousand years, but only on a large-scale
since the 18th Century. Coal is mined by two main methods – surface or
‘strip’ mining and underground or ‘deep’ mining.The choice of method is
largely determined by the geology of the coal deposit. Almost two-thirds
of hard coal production worldwide comes from underground mines, but in
certain important coal producing countries, such as the USA and Australia,
this proportion is significantly lower.
In Colombia
surface mining is economic because the coal seam is generally found near
the surface. this method recovers a higher proportion of the coal deposit
than underground methods.The equipment used includes: draglines, which
remove the overburden (the term given to the strata between the coal seams
and the surface); power shovels; large trucks, which transport overburden
and coal; bucket wheel excavators; and high capacity conveyors.
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