The Black Thunder coal mining complex (43°41'54.98"N, 105°17'31.16"W) is the largest surface coal operation in the world, and it has produced more coal to date than any other mine in the world.¹ Located in Campbell County, Wyoming, the mining complex produces about 93 million tons of coal per year, equivalent to about 8% of U.S. coal output. That is used in about 100 power plants to generate about 5% of the nation's electricity. The energy content of the annual energy output of the mine is about 1.6 x 10¹⁸ joules, equivalent to almost 2% of the nation's total primary energy use. In 2004, Black Thunder became the first coal mine in the world to ship a cumulative one billion tons of coal since its first shipment on December 14, 1977.

The mine produces high quality, low-sulfur, sub-bituminous coal that is suitable for power station fuel without any preparation except crushing. Black Thunder coal has a heating value of 20.3MJ/kg, a sulfur content of 0.5-0.7 lbs. SO₂/mmBtu, an ash content of about 5%, and a moisture content of 25-30%.

The scale of everything at Black Thunder is colossal. The mine complex is located on approximately 24,300 acres and has six active pit areas. Its fleet of five draglines includes Ursa Major, a Bucyrus-Erie 2570WS model, one of largest draglines in the world. It weighs 14.7 million pounds, is 238 feet tall, and its 110m-long boom carries a 122m³ bucket. The machine can dig the equivalent of an Olympic-sized swimming pool in just 25 minutes. Draglines of this size are assembled on site and never leave.

The draglines remove 15-75m of overburden after the topsoil has been removed and stored for use during reclamation. Black Thunder relies heavily on cast blasting to move between 20 and 30% of the overburden to its final position directly. The remainder is removed by the draglines. The coal is also blasted before loading.

Eleven massive electric shovels, each of which can dig up to 80 tons in a single bucket, load the material into one of 60 haul trucks of between 218 and 360 ton capacity. The coal is haled to crushers that can take lumps of coal up to 5 feet thick and turn them into two-inch pieces, processing a 240-ton haul truckload in about five minutes. From the crushers, the coal is moved on conveyor belts that load it onto trains. All of the production is shipped via the Burlington Northern and Union Pacific railroads. On average, each 120 to 150-car train carries more than 14,000 tons of coal. The loadout facilities are capable of loading a 14,500-ton unit train in two to three hours On an average day, Black Thunder loads more than 25 miles of rail cars. Black Thunder's coal is shipped to more than 20 states and 2 foreign countries, where most of it is to generate electricity.

The Black Thunder coal mining operation extracts coal from Wyodak-Anderson coal zone of the Powder River Basin of Wyoming and Montana, which is among the most prolific coal resources in the world. The USGS estimates that the total coal resource of the Wyodak-Anderson coal zone is about 550 billion tons of coal. By way of comparison, the USGS estimates that the identified coal resources of U.S. are about 1,700 billion tons. The total resource (identified plus undiscovered) base is estimated at 4,000 billion tons.

^[1] China is the world's largest coal producer, and has a number of large mines, especially in the Shanxi-Datong Mining District. However, there is a scarcity of reliable data on the attributes of Chinese coal mines. This article relies on the best information available at the time of writing (16 August 2007).

Sources

• Arch Coal, Inc., Black Thunder Coal Mine, Accessed August 16 2007.
• Mining technolgy.com, Black Thunder Coal Mine, WY, USA, Accessed August 16 2007.
• U.S. Bureau of Land Management, Final Environmental Assessment of the West Black Thunder Coal Lease Application as applied for by Thunder Basin Coal Company, Accessed August 16 2007.