Coal miners use large machines to remove coal from the ground. Many U.S. coal beds are near the surface, and about two-thirds of U.S. coal production comes from surface mines. Modern mining methods allow coal miners to easily reach most of the nation's coal reserves. Advances in mining technology enable today's coal miners to produce about three times the amount of coal in one hour than they produced in 1978.
Coal miners use two primary methods to remove coal:
Surface mining is used to produce most of the coal in the United States because the method is less expensive than underground mining. Surface mining can be used when the coal is less than 200 feet underground. In surface mining, large machines remove the top soil and layers of rock known as overburden to expose the coal seam. Mountaintop removal is a form of surface mining where the tops of mountains are dynamited and removed to access coal seams. After the mining is finished, the disturbed area is covered with topsoil, and the area is replanted.
Underground mining, sometimes called deep mining, is used when the coal is several hundred feet below the surface. Some underground mines are 1,000 feet deep, and extend for miles. Miners ride elevators down deep mine shafts and travel on small trains in long tunnels to get to the coal. The miners use large machines that dig out the coal.
After coal is removed from the ground, it may go to a preparation plant located near the mining site. The plant cleans and processes coal to remove rocks and dirt, ash, sulfur, and other unwanted materials. This process increases the heating value of the coal.
After coal is mined and processed, it is transported to market, which can be more expensive than the cost of mining it.
Nearly 70% of coal delivered in the United States is transported, for at least part of its trip to market, by train. Coal can also be transported by barge, ship, truck, and even by pipeline.
It is often cheaper to transport coal on river barges, but barges are unable to take coal everywhere it's needed. If the coal is used near the coal mine, it can be moved by trucks and conveyors. Coal can also be crushed, mixed with water, and sent through a slurry pipeline. Sometimes, coal-fired electric power plants are built near coal mines to lower transportation costs.