| The coal mining industry segment produces coal, a | | | | where the coal is located. Depending on where |
| fossil fuel that is used primarily for electric power | | | | the coal seam is in relation to the surface, tunnels |
| generation and in the production of steel. Like oil, | | | | may be vertical, horizontal, or sloping. Entries are |
| coal is formed over millions of years from plant | | | | constructed so that miners can get themselves |
| and animal matter, but unlike oil, coal is a solid, and | | | | and their equipment to the ore and carry it out, |
| therefore miners must go into the earth to | | | | while allowing fresh air to enter the mine. Once |
| recover it. Many coal seams are located close to | | | | dug to the proper depth, a mine’s tunnels |
| the surface, however, which makes the | | | | interconnect with a network of passageways |
| extraction of this resource easier. | | | | going in many directions. Using the room-and-pillar |
| Surface mining of coal typically uses the method | | | | method, miners remove sections of the coal as |
| known as strip mining, which is usually more | | | | they work the coal seam from the tunnel |
| cost-effective than underground mining and | | | | entrance to the edge of the mine property, |
| requires fewer workers to produce the same | | | | leaving columns of coal in place to help support |
| quantity of coal. In strip mining, workers use huge | | | | the ceiling together with long steel bolts. This |
| earthmoving equipment, such as power shovels or | | | | process is then reversed, and the remainder of |
| draglines, to scoop off the layers of soil and rock | | | | the ore is extracted, as the miners work their |
| covering the coal seam. Once the coal is exposed, | | | | way back out. In the case of longwall mining of |
| it is broken up by using explosives, and then | | | | coal, self-advancing roof supports, made of |
| smaller shovels lift it from the ground and load it | | | | hydraulic jacks and metal plates, cover the area |
| into trucks. Mining companies are required by | | | | being mined. As coal is removed, the entire |
| Federal, State, and local laws to restore the mined | | | | apparatus advances, allowing the ceiling in the |
| land after surface mining is completed; as a result, | | | | mined area to cave in as the miners work back |
| the overburden and topsoil are stored after | | | | towards the tunnel entrance. Underground mining |
| removal so that they can be replaced and native | | | | does not require as extensive a reclamation |
| vegetation replanted. | | | | process as surface mining; however, mine |
| Underground mining is used when the coal deposit | | | | operators and environmental engineers still must |
| lies deep below the surface of the earth. When | | | | ensure that ground water remains |
| developing an underground mine, miners first must | | | | uncontaminated and that abandoned mines do not |
| dig tunnels deep into the earth near the place | | | | collapse. |