Arch Resources Inc. mines, processes, and markets bituminous and sub-bituminous coal with low sulfur content in the U.S. Arch Resources is the second-largest supplier of coal in the country. It operates 32 active mines and controls approximately 5.5 billion tons of proven and probable coal reserves and sells its coal to electric power utilities, steel producers, and industrial facilities. Formerly known as Arch Coal, Arch Resources was formed in 1997 and is headquartered in St. Louis, MO.