In the late 20th century coal mining went through enormous technological advancements, with machinery getting bigger, safer and more precise. The technology expanded through a whole section of the mining industry from seismic surveys to find the coal, coal bores to find the depths of the seam, then it had to be decided on which methods of mining would be suitable for what they had found in the survey, whether it be surface mining, mountain top removal, longwall mining or continuous mining. Ventilation plays a huge role in mining today; we first looked at how, by placing a fire at the bottom of a shaft that drew fresh air in through the mine. Today it is done by running a complex set of huge cables that bring in fresh and cool air and another set for diluting and removing stale and toxic air. Transportation of coal has also undergone radical changes with the developments in the sea, rail and road industries.
Surface mining is when a coal seam is found quite near to the surface, where they would strip away the top layer of soil until the coal seam is exposed, the coal would then be removed and replaced with the originally removed top soil after stripping the coal, the reclaimed soil is then moved from one side to the other, so that the action can be repeated on the next piece of excavation (see figure 8). Mountain top removal is a form of surface mining, where they would take the summit off and proceed with surface mining.
Underground mining includes two methods; ‘longwall' and ‘continuous' mining. ‘Longwall' mining (see figures 9 & 11), ‘continuous' mining(see figures 10 & 12) or ‘room and pillar' are both still mined the same way but has radically improved with technological advances of machinery used.
To put all of the above in context we must look at some figures down through the last 70 years; for example, surface mining 50 years ago were limited to excavation with a bucket measuring less than 1 cubic metre, while today with the advancements there are machines that can excavate with buckets measuring in range from 10 - 27 cubic metres, an example of this would be the modern day dragline machines which is pictured above (see figure 13). Having said that, we also need to look at the depth of the excavation, in 1948 the deepest excavation was 30 metres while today the machines can dig deeper, to depths of 80 metres and above if necessary. (Figures taken from UK Coal. Community & Environment. Education. Coal in Britain.10/12/09. http://www.ukcoal.com/coal-in-britain)
Another example would be underground mining, where in 1947; the average coal output for each man employed was at just over 1 tonne per shift, today it is more than ten times as much if not more, with all this in mind, the coal miners used to use shovels, picks, explosives and wooden structures. The wooden structures were used to prop up the mine roof. Nowadays, we have few men operating machinery that can eat away at the coal face, electric conveyor belts that move the coal, powered roof supports that consist of steel beams on hydraulic legs. (Figures taken from UK Coal. Community & Environment. Education. Down a modern mine.10/12/09. http://www.ukcoal.com/down-a-modern-mine)
In terms of production figures (see table), last year it is estimated that the total global hard coal production was 5845Mt (2008e), this figure compared with previous years shows a still steady growth in coal production.
(These figures were taken from the World Coal Institute, Resources, Coal Statistics. Documents. Coal Facts 2005 and 2008. 11/12/09. http://www.worldcoal.org/resources/coal-statistics/)
The coal industry is still advancing with development of new technologies, but this time the damages caused to the environment are very much to the forefronts of our minds. Although the industry has reduced in size in recent years, it is still a very dependable source, as coal still supplies some of the world's energy and heat used. This reduction is also linked with the quick excavation of the mines that is now possible with the advancements in the machines. This also does not include the by-products of coal we rely on in many industries varying from road surfaces, plastics, paints and fertilisers.