There are five methods of
underground mining. These methods include drift mining, shaft mining, room
& pillar mining, continuous mining, and longwall mining.
1) Drift Mining
Drift mining is possible where the coal seam intersects the surface- the mine then enters the seam in a horizontal direction following the coal. This type of mining is done when mineral or rock is on the side of a hill. It is a much cheaper, more efficient method compared to most others. But, it can also be very dangerous. Many tunnels can cave in- collapsing and killing miners.
2) Shaft Mining
Next we have shaft mining. Shaft mining is a pretty common method. This mining method accesses a coal seam in which elevators provide access to mines. In WV, it is not rare to see a shaft coal mine deeper than 1000 feet below the surface. Shaft mines are much faster and conventional than most regular mines. While that's one advantage, another can be that there is safer breathing: due to the moving air that vents the gases that are naturally underground. The one negative thing about this way of mining could be that often times tunnels are deepended and the mine is made larger until there isn't any ore left, or the cost of removal is too high.
3) Room & pillar mining
The third method is room & pillar mining. In this method, nearly half of the coal is left behind to support the roof of the mine. Pillars can “squeeze” which puts pressure on pillars, which can ultimately lead to roof collapse. Roof falls are a constant danger, which is a disadvantage. An advantage of this type of mining could be that it can be alot faster than other types.
4) Continuous mining
The fourth method is called continuous mining. The machines for continuous mining can be used with drift or room & pillar mines. A miner can operate this machine to a rotating steel drum with tungsten carbide teeth to mine 5 tons of coal per minute. (WV Coal Project) This method/ machine has been in use since the 1940s. These machines are paired with conveyor systems to transport the coal from the mine as it is mined. The biggest advantage to this would definitely be how time efficient it is. It can make as much as five tons of coal a minute- which is more than a mine without technology in the 1920s could produce in an entire day. 45% of coal production comes from continous mining. A disadvantage, once again, can be that there is not much roof support, which could cause a roof to collapse.
5) Longwall mining
Last but not least, we have longwall mining. This method is “highly efficient.” Huge mining machines support the roof with hydraulics as it removes coal. Once the coal is removed, the machine retreats allowing the roof to fall behind it. Longwall mines extract much more of the coal than room & pillar mines, which is why it’s known to be highly efficient. This accounts for about 50% of the underground production of coal. Longwall systems have their own "hydraulic" roof supports. As the mining equipment moves forward, the overlying rock that no longer has the support of coal falls behind the equipment. This makes for a very safe work enviroment. After about 75% of the coal is removed, the roof collapses in a safe, controlled manner. While this all sounds great, the collapse afterwards can really damage rivers, which is a disadvantage.
Source
1) Drift Mining
Drift mining is possible where the coal seam intersects the surface- the mine then enters the seam in a horizontal direction following the coal. This type of mining is done when mineral or rock is on the side of a hill. It is a much cheaper, more efficient method compared to most others. But, it can also be very dangerous. Many tunnels can cave in- collapsing and killing miners.
2) Shaft Mining
Next we have shaft mining. Shaft mining is a pretty common method. This mining method accesses a coal seam in which elevators provide access to mines. In WV, it is not rare to see a shaft coal mine deeper than 1000 feet below the surface. Shaft mines are much faster and conventional than most regular mines. While that's one advantage, another can be that there is safer breathing: due to the moving air that vents the gases that are naturally underground. The one negative thing about this way of mining could be that often times tunnels are deepended and the mine is made larger until there isn't any ore left, or the cost of removal is too high.
3) Room & pillar mining
The third method is room & pillar mining. In this method, nearly half of the coal is left behind to support the roof of the mine. Pillars can “squeeze” which puts pressure on pillars, which can ultimately lead to roof collapse. Roof falls are a constant danger, which is a disadvantage. An advantage of this type of mining could be that it can be alot faster than other types.
4) Continuous mining
The fourth method is called continuous mining. The machines for continuous mining can be used with drift or room & pillar mines. A miner can operate this machine to a rotating steel drum with tungsten carbide teeth to mine 5 tons of coal per minute. (WV Coal Project) This method/ machine has been in use since the 1940s. These machines are paired with conveyor systems to transport the coal from the mine as it is mined. The biggest advantage to this would definitely be how time efficient it is. It can make as much as five tons of coal a minute- which is more than a mine without technology in the 1920s could produce in an entire day. 45% of coal production comes from continous mining. A disadvantage, once again, can be that there is not much roof support, which could cause a roof to collapse.
5) Longwall mining
Last but not least, we have longwall mining. This method is “highly efficient.” Huge mining machines support the roof with hydraulics as it removes coal. Once the coal is removed, the machine retreats allowing the roof to fall behind it. Longwall mines extract much more of the coal than room & pillar mines, which is why it’s known to be highly efficient. This accounts for about 50% of the underground production of coal. Longwall systems have their own "hydraulic" roof supports. As the mining equipment moves forward, the overlying rock that no longer has the support of coal falls behind the equipment. This makes for a very safe work enviroment. After about 75% of the coal is removed, the roof collapses in a safe, controlled manner. While this all sounds great, the collapse afterwards can really damage rivers, which is a disadvantage.
Source
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