Equipment Specs

Twentymile Coal Mine

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The Twentymile Coal Mine is one of the most successful coal production mines in the world. Based just outside of Steamboat Springs in the northwest region of Colorado, the mine employs more than 240 miners and staff. The mine is owned by Peabody Energy and produces coal based on the demands of its customers. It employs a longwall mining system as its primary mining method.


[edit] Construction History

Upon the opening of the mine in 1983, operation began with a small room and a pillar. Miners had to contend with an 8.5- to 9.5-foot (2.6- to 2.9-m) thick Wadge seam that was layered beneath 984 to 1,312 feet (300 to 400 m) of overburden rock.

The mine comprises two panel units to be stripped, each with a Joy 12CM12 continuous miner, two Fletcher roof bolters, Joy Shuttle_car, and a Stamler feeder-breaker to facilitate the entire process. Typical in longwall mining, miners divide the mine into blocks in which layers or strips of longwall are extracted for coal. Longwall mining is used in a majority of underground coal mining applications.

[edit] Longwall Panels

Twentymile miners began developing a longwall system in 1987 and the first face was completed in 1989. The longwall panels underwent an extraction phase between 1989 and 1996 in the western block where nine panels were extracted. The final eight longwalls were removed in 2001. The completion of longwall mining in the western block quickly shifted activity to the northern block where 15 panels were extracted. The face length, which was initially 639 feet (195 m) thick on the eastern faces, was mined using an 853-foot (260-m) face that was lengthened to an additional 1,000 feet (305 m) by 1999.

Peabody Energy experimented with panels as long as 18,044 feet (5,500 m) on the faces of the two eastern blocks. The length of the panel was then reduced to its current state of 2.24 to 2.8 miles (3.6 to 4.5 km).

[edit] Equipment, Process, and Output

Mining equipment responsible for stripping the faces of the mine’s blocks includes a Long Airdox Electra 3000 double-drum shearer with a capacity of 174 face supports. Other equipment involved are an armored face conveyor and a stage loader made by Deutsche Bergbau Technik. Once the coal is stripped away, it is loaded onto a conveyor system capable of handling 5,000 metric tons of coal per hour.

Shearing equipment is used to cut along the face of the panel, in this case, at 40 meters per minute, cutting 35.4 inches (90 cm) of coal each time it the shear passes the face. Each shift typically completes as much as two production cycles, accounting for a daily output as high as 46,340 tons mined. The shearing equipment is monitored by a computerized system that shuts down when the face output has reached its maximum rating. The shut down prevents the conveyor system from experiencing potential malfunctions brought on by overloading the system.

The geology of the mine calls for rock to be extracted along with the coal. Although not conventionally done, this prevents the rock-coal mixture from infusing with the coal. A specially designed conveyor system and chute was constructed to facilitate this process.[1]

When the materials are conveyed out of the mine, some are shipped directly to customers and others undergo a washing and screening process. Approximately 95 percent of the output is crushed to -1.96 inches (-50 mm) by primary crusher equipment. Once crushed, it is loaded onto unit trains and transported to customers.

The mine broke records with an output of 8.7 metric tons of power station fuel in 2005, a production considerably higher than that of previous years, which amounted to 7.3 metric tons of coal.

Since the beginning of the mine’s production, it has produced more than 100 metric tons of coal.[2]

[edit] Equipment Used

[edit] Refurbishment/Recent Projects/Renovations

A new longwall system was built in response to customers' higher demand for coal. Previously, Peabody was content to extract coal from the reserves of 65 metric tons that had been completed by the closing of 2005. The higher-capacity longwall system installation will result in the mine being depleted sooner than previously anticipated. The longwall system was completed in 2006 in attempt to help the mine reach its target of 10.9 metric tons by 2008.

[edit] References

  1. Federal Mine Safety and Health Review Commission v. Twentymile Coal Company, August, 2004. (accessed: 2008-09-25)
  2. Twentymile Coal Mine, CO, USA., 2008-09-25.