What are underground and open-pit mines?
According to the World Coal Institute, there are two types of underground mines and just one type of open pit mines. In underground mining, Room and Pillar style mining allows a maximum extraction of 40% of coal in the seam. The other approach is Longwall Mining, which uses mechanical shearers to fully extract coal from a section of the seam. A longwall face requires careful planning to ensure favourable geology exists throughout the section before development work begins. Over 75% of the coal in the deposit can be extracted from panels of coal that can extend 3km through the coal seam. Geologists say the highest possible coal production from an underground mine, anywhere around the world, is 5 million tons a year. There are very few Longwall underground mines around the world, because this kind of mine is possible in a very limited geological situation. The World Coal Institute says that open cut or surface mining is only economic when the coal seam is near the surface. This method re
