It produces two tons of coal a second and was the first mine in the US to ship 500 million tons!!43 31 40.46N
105 16 04.13W.
The Black Thunder thermal coal mine, located in the Southern Powder River Basin of Wyoming, opened in 1977 and for many years was the largest single coal operation in the US. Having been relegated to second-largest, after Peabody's North Antelope-Rochelle operation, also in the Powder River Basin, in 2004 Black Thunder once again became the nation's leading coal-producer following Arch Coal's acquisition of the neighbouring North Rochelle mine from Triton Coal Co. The combined operation is now producing coal at a rate of around 91Mt/y, equivalent to about 10% of total US coal production. In 2004, Black Thunder became the first coal mine in the US to ship a cumulative 1,000Mst (907Mt) over its 27-year life to date.
Construction began at Black Thunder in 1976 with the installation of crushing, conveying, sampling and high-speed train-loading systems. Today, all plant processes are computer controlled, including the precision loadout systems and the hi-tech, near-pit crushing and conveying system installed in 1989.
Until 1998, Black Thunder was owned and operated by ARCO Coal, part of the Atlantic Richfield group. It is now owned by Arch Coal, the second-largest coal miner in the US, which bought the property following ARCO's withdrawal from the coal market.
GEOLOGY AND RESERVES
Black Thunder works coal reserves in the Wyodak seam. Hosted in the palaeocene Fort Union formation, which covers vast areas of Wyoming, Montana and the Dakotas, the seam at Black Thunder is gently dipping, 22m thick and locally splits into the Anderson and Canyon beds separated by up to 18m of waste. In 2004, Arch successfully bid $611m for the rights to mine the neighbouring Little Thunder reserves, which contain some 650Mt of recoverable coal, increasing the property’s reserves to 1,370Mt-plus.
COAL QUALITY
The mine produces low-sulphur, sub-bituminous coal suitable for power station fuel without any preparation except crushing. Black Thunder coal has a heating value of 20.3MJ/kg, and the ash contents are around 5% while as-received moisture is 25–30%. The moisture content of some Powder River Basin coals increases their reactivity to the extent that spontaneous combustion can be a problem if they are not properly handled.
MINING AND SHIPMENT
"At the beginning of 2006, Arch Coal and Peabody Energy undertook a swap of reserve and infrastructure assets that would enable both companies to optimise their future operations."
Black Thunder operates several individual open pits within its enlarged concession area, using five large draglines for overburden handling. The dragline fleet includes Ursa Major, the largest of the three, a Bucyrus-Erie (B-E) 2570WS model weighing some 6,700t. The third-largest dragline ever built, it was assembled on site over a three-year period at a cost of US$50m. Its 110m-long boom carries a 122m³ bucket. Of the other draglines, Thor, a B-E 1570W, has a 97.5m boom and a 69m³ bucket, while Walking Stick is a B-E 1300W with a 92m boom and a 34m³ bucket. Originally built at Coal Creek, another Arch Coal property where production was halted in 2000, it was tramped across the prairie to Black Thunder late 1991.
Arch planned to resume production at Coal Creek in 2006 in response to increased market demand, at a cost of some US$50m, including the re-assembly of a dragline that had been moved from one of the company’s other operations in the Western USA.
15–75m of overburden has to be stripped after the topsoil has been stored for use during restoration. Black Thunder relies heavily on cast blasting to move between 20 and 30% of the overburden to its final position directly. The remainder is handled by the draglines. The coal is also blasted before loading.
The coaling fleet consists of five P&H 2800 electric mining shovels and one Marion 351-M. Coal haulage is carried out by a fleet of Liebherr T-262 (218t-capacity) and Komatsu 930E (290t) haul trucks, and the mine has had both Liebherr T-282 (360t-capacity) and TI-272 (290t) trucks under evaluation. Coal is hauled to a near-pit dump and crusher station, which feeds a 3.5km-long overland conveyor to the coal storage and loadout silos.
Black Thunder's two 12,700t silos and 82,000t slot storage system feed twin rail loadouts with capacities of 4,100t/h and 10,800t/h. Both the Burlington Northern and Union Pacific rail systems service the operation.
At the beginning of 2006, Arch Coal and Peabody Energy undertook a swap of reserve and infrastructure assets that would enable both companies to optimise their future operations. In Arch’s case, this resulted in the sale of a rail spur and loadout facility, with the company using the proceeds to build a new rail spur and loadout close to its Little Thunder Creek reserves, where future operations will be focused.
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The past is a foreign country: they do things differently there.