How is underground coal mined?
There are two basic types of underground mining methods: the first is called “room and pillar” and the second is called “longwall.” In room and pillar mines, coal is removed by cutting rooms, or large tunnels, in the solid coal. Pillars of coal are left standing to support the roof. In longwall mining, miners remove successive slices of coal from the entire length of a long working face, or wall. In the United States, almost all of the coal recovered by underground mining is by room and pillar method. In other parts of the world, such as Great Britain, the longwall method is more popular. The thickness of coal deposits in the United States ranges from a thin film to over 50 feet (15 meters). The thickest coalbeds are in the western states, ranging from 10 feet (3 meters) in Utah and New Mexico to 50 feet (15 meters) in Wyoming. Source: Cuff, David J. The United…
