State Alaska Production 349,729 Active 1996-present Company Kinross Gold | Country United States Financial year 2010 Address Fort Knox, AK 40121, USA Opened 1996 | |
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Location Fairbanks mining district, Fairbanks North Star Borough, near Steele Creek, Alaska | ||
Alaska fort knox gold mine
The Fort Knox Gold Mine is an open pit gold mine in the Fairbanks mining district of Alaska. It is owned and operated by Toronto based Kinross Gold. Originally staked in 1913, the property sat idle until being restaked in 1980, and purchased by Amax Gold, who brought the mine into production. Ownership transferred to Kinross Gold following its 1998 merger with Amax.
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Alaska alaska fort knox gold mine
History
The land that the Fort Knox mine sits on was originally staked in 1913 with no mining taking place. There was no activity in the area (typically placer mining takes place in the area), until the area was restaked in 1980 by two prospectors, and leased to various mining companies. In 1992 Amax Gold purchased the property and ran it under a subsidiary company. Construction began 1995 with the first gold pour at the end of 1996. In 1998 Kinross Gold merged with Amax.
Geology
The Fort Knox gold is hosted by a late-Cretaceous granite pluton that intruded into the surrounding Fairbanks Schist. The pluton is described as "a light gray, fine grained granodiorite, medium grained biotite granite, and coarse grained, biotite granite porphyry, which form blocky bedrock exposures". Gold, bismuth and tellurium mineral deposits occur in pegmatite and quartz veins and fractures within the pluton. The sulfide content is very low (<0.1%).
Description
The Fort Knox Gold Mine operates a single large pit. From 2001 - 2004 the True North Mine, a small satellite deposit was operated and the ore was processed through the Fort Knox mill. Production from Fort Knox is up to 45,000 tonnes (50,000 short tons) per day of low grade ore (1 gram per tonne), with two mineral processing streams (carbon in pulp for higher grade ore and heap leaching for lower grade ore). The mine is located 42 kilometres (26 mi) from the city of Fairbanks via a combination of paved and unpaved roads. Surpassing 6 million ounces in 2011, Fort Knox is the single largest producer of gold in the history of the state of Alaska.
Mining & milling
In 2003 the mine was scheduled to excavate up to 130,000 tonnes (140,000 short tons) per day with a 2.3:1 stripping ratio, operating seven days per week twelve months per year. Waste rock from Fort Knox does not contribute to acid mine drainage. Ore from the mine is processed at the Fort Knox mill, with a capacity of 2,800 tonnes (3,100 short tons) per hour. The mill consists of a semi-autogenous grinding mill, then sent through gravity separation in a Knelson concentrator. Gold not recovered via the Knelson concentrator is sent through the carbon in pulp circuit.
In 2009 a valley-fill heap leaching operation came on line. Lower grade material is trucked to the facility from the mine.