Arch Coal is an American coal mining and processing company. The company mines, processes, and markets bituminous and sub-bituminous coal with low sulfur content in the United States. Arch Coal is the second largest supplier of coal in the U.S. behind Peabody Energy. The company supplies 15% of the domestic market. Demand comes mainly from generators of electricity.Arch Coal operates 32 active mines and controls approximately 5.5 billion tons of proven and probable coal reserves, located in Central Appalachia, the Powder River Basin, Illinois basin and the Western Bituminous regions. The company operates mines in Colorado, Illinois, Kentucky, Utah, Virginia, West Virginia and Wyoming, and is headquartered in St. Louis, Missouri. The company sells a substantial amount of its coal to producers of electric power, steel producers and industrial facilities.