COAL MINING
- Created by: HannahCaviel
- Created on: 23-02-17 12:17
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- COAL MINING
- UNDERGROUND MINING
- Pillar and Stall
- Where pillars of coal are left un-mined to support the mine underneath an area of importance
- e.g underneath a town
- Pillars are stacks of coal whilst stalls are the spaces where coal is mined
- Prevents subsidence and cave-ins underneath an area of importance
- Where pillars of coal are left un-mined to support the mine underneath an area of importance
- Longwall Mining
- access tunnels are placed into the area of extraction
- the access tunnels are then supported by steel hoops
- the access tunnels are linked by a working face
- the roof of the working face is then supported by hydraulic jacks
- the coal cutter is put into place and this extracts a section of coal
- the jacks are moved back to allow the coal face to collapse to form goaf
- the machine then cuts another section of the coal face and this process is repeated until the main road is reached
- ADVANTAGES
- Does not disrupt the appearance of the area unlike opencast mining
- less pollution created than opencast mining
- can be used to mine under the sea
- waste can be backfilled into the mine
- can be used in concealed coalfields where removal of overburden would be expensive
- DISADVANTAGES
- High technology use so would be expensive
- noise and dust pollution created
- rock is inflexible so cannot protect the mine against water and faulting
- risk of gases such as methane, CO2 and carbon monoxide
- risk of roof collapse and cave-ins
- Pillar and Stall
- OPENCAST MINING
- overlying soil is extracted and put to one side
- overburden (overlying rock) is extracted and put onto a waste pile
- coal is extracted, with thinner seams being taken out one at a time until the bottom wall is reached
- overburden for another section is backfilled into the hole left by the coal extracted
- when all of the coal is extracted, the hole is completely backfilled and overlying soil is replaced.
- ADVANTAGES
- low use of technology so inexpensive
- is flexible and can mine around problems
- any harmful gases are not trapped, they are released into the atmosphere
- water is not a problem as it can easily be pumped out of the extraction area
- no risk of roof collapse or cave-ins
- DISADVANTAGES
- can be an eyesore to the environment
- can cause noise and dust pollution and is a nuisance for inhabitants
- cannot reach deep coal seams
- can disrupt groundwater operations
- UNDERGROUND MINING
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