North Antelope Rochelle Coal Mine, Wyoming

The North Antelope Rochelle coal mine in Wyoming, USA, is the world’s biggest coal mine by reserves. Image courtesy of Alexrk2.

North Antelope Rochelle coal mine produced 107.7Mt of thermal coal in 2012. Image courtesy of Peabody Energy.

North Antelope Rochelle mine supplies coal to more than 40 electricity generating companies in the US.

The North Antelope Rochelle coal mine (NARM) is owned and operated by Peabody Energy in the Powder River Basin of Wyoming, US, is the world’s biggest coal mine by reserves.

NARM is a surface coal mining operation that has been in production since 1983. The mine employs approximately 1,300 people, including 300 contract employees. It has produced more than 1.8 billion tonnes of coal since its inception. Coal produced at the mine is delivered to more than 40 electricity generating customers who operate over 80 power plants across the country.

History of the North Antelope Rochelle mine

The North Antelope Rochelle mine comprises of two mines namely North Antelope and Rochelle. Mining operations at the North Antelope mine began in 1983 whereas the Rochelle mine commenced production in 1985.

The two coal mines were combined into a single operation in 1999 and the North Antelope/Rochelle Complex was renamed as North Antelope Rochelle Mine in 2003.

Powder River Basin geology and coal reserves

The Powder River Basin is a major coal-bearing geologic structure underlying south-east Montana and north-east Wyoming. The coal beds of the basin are believed to have formed around 60 million years ago.

The basin spans 190km from east to west and 320km from north to south, accounting for more than 40% of the country’s coal reserves. The Powder River Basin coal is categorised as sub-bituminous coal that contains 8,800 British thermal units per pound (Btu/lb) and has sulphur content as low as 0.2%.

The North Antelope Rochelle mine lies within the Wyodak-Anderson coal zone of Powder River Basin, about 65 miles south of Gillette in the Wyoming province. The coal seams of the mine are 60ft to 80ft thick and located 100ft to 400ft below the surface.

The recoverable coal reserves at the North Antelope Rochelle mine were estimated to be more than 2.3 billion tonnes, as of December 2012.

Mining at North Antelope Rochelle mine

Conventional surface mining method is employed at the North Antelope Rochelle coal mine. Three draglines and five truck-and-shovel fleets are used for overburden removal.

Coal mined from three pits at the mine site is hauled to one of the four hoppers via trucks, where it is crushed and conveyed to the silos before transportation by trains from the load outs.

The mine is connected with Burlington Northern Santa Fe and Union Pacific railroads’ joint trackage through two concentric loop tracks, each capable of handling 150 cars per unit train. The loading facility comprises two load outs, each capable of handling 10,000t of coal an hour.

Coal production in Wyoming

The North Antelope Rochelle mine produced 107.7 million tonnes (Mt) of thermal coal in the year ending in December 2012, compared to 109.1Mt during 2011. North Antelope Rochelle became the biggest coal producing mine in the US, followed by the Black Thunder coal mine, which is also located in the Powder River Basin in Wyoming.