The Fort Knox Gold Mine is an open pit gold mine , 9 mi (14 km) east of Fox in the Fairbanks mining district of Alaska . It is owned and operated by Toronto -based Kinross Gold . Originally staked in 1913, after very minor mining at the location the property sat idle until being restaked in 1980. Following the initial exploration discovery in 1987, in 1992 the project was purchased by Amax Gold , which brought the mine to production. Amax Gold merged with Kinross Gold in 1998.
22-489: The land that the Fort Knox mine sits on was originally staked in 1913 when a bismuth-bearing, gold-quartz vein was located. Minor mining occurred with a small shaft and a three-head stamp mill . There had been placer mining in the area as early as 1903 and in 1980 local prospectors Joe Taylor and George Johnson worked the placer deposits. In 1986, the property was leased to various mining companies. In 1992, Amax Gold purchased
44-505: A capacity of 36,000 tonnes (40,000 short tons) per day. The mill consists of a gyratory crusher , a 34' x 15' semi-autogenous grinding mill , two 20' x 30' ball mills , and a gravity separation circuit with a Knelson concentrator . Gold not recovered by the Knelson concentrator is sent through the CIL circuit. In 2009, a valley-fill heap leaching operation came on line. Lower grade ore is trucked to
66-421: A mining claim. The traditional methods of prospecting involved combing through the countryside, often through creek beds and along ridgelines and hilltops, often on hands and knees looking for signs of mineralization in the outcrop. In the case of gold, all streams in an area would be panned at the appropriate trap sites looking for a show of 'colour' or gold in the river trail. Once a small occurrence or show
88-404: A triangular head, with a very sharp point. The introduction of modern gravity and magnetic surveying methods has greatly facilitated the prospecting process. Airborne gravimeters and magnetometers can collect data from vast areas and highlight anomalous geologic features. Three-dimensional inversions of audio-magnetotellurics (AMT) is used to find conductive materials up to a few kilometers into
110-515: Is a common and inexpensive metal , as opposed to a precious metal such as gold or silver . In numismatics , coins often derived their value from the precious metal content; however, base metals have also been used in coins in the past and today. In contrast to noble metals , base metals may be distinguished by oxidizing or corroding relatively easily and reacting variably with diluted hydrochloric acid (HCl) to form hydrogen . Examples include iron , nickel , lead and zinc . Copper
132-798: Is also considered a base metal because it oxidizes relatively easily, although it does not react with HCl. In mining and economics , the term base metals refers to industrial non-ferrous metals excluding precious metals . These include copper , lead , nickel and zinc . The U.S. Customs and Border Protection agency is more inclusive in its definition of commercial base metals. Its list includes—in addition to copper, lead, nickel, and zinc—the following metals: iron and steel (an alloy), aluminium , tin , tungsten , molybdenum , tantalum , cobalt , bismuth , cadmium , titanium , zirconium , antimony , manganese , beryllium , chromium , germanium , vanadium , gallium , hafnium , indium , niobium , rhenium , and thallium , and their alloys. In
154-477: Is the largest producer of gold in the history of the state of Alaska. The mine's life is expected to extend to 2027 following a $ 100 million expansion investment announced in 2018, increasing life-of-mine production by about 1.5 million gold equivalent ounces. In 2024 Fort Knox began processing ore from the Manh Choh mine near Tetlin, Alaska and poured the first gold ingot from Manh Choh ore on July 8, 2024. In 2003,
176-573: Is used for a variety of prospecting, but can mainly be for finding conductive materials. So far these low frequency EM techniques have been proven for geothermal exploration as well as for coal bed methane analysis. Geochemical prospecting involves analyzing the chemical properties of rock samples, drainage sediments, soils, surface and ground waters, mineral separates, atmospheric gases and particulates, and even plants and animals. Properties such as trace element abundances are analyzed systematically to locate anomalies. Base metal A base metal
198-463: The 19th and early 20th century, it was very unlikely that a prospector would retire rich even if he was the one who found the greatest of lodes. For instance Patrick (Paddy) Hannan , who discovered the Golden Mile, Kalgoorlie , died without receiving anywhere near a fraction of the value of the gold contained in the lodes. The same story repeated at Bendigo, Ballarat, Klondike and California . In
220-491: The Earth, which has been helpful to locate kimberlite pipes, as well as tungsten and copper. Another relatively new prospecting technique is using low frequency electromagnetic (EM) waves for 'sounding' into the Earth's crust. These low frequency waves will respond differently based on the material they pass through, allowing for analysts to create three-dimensional images of potential ore bodies or volcanic intrusions. This technique
242-619: The United States and Canada, prospectors were lured by the promise of gold , silver , and other precious metals . They traveled across the mountains of the American West , carrying picks, shovels and gold pans . The majority of early prospectors had no training and relied mainly on luck to discover deposits. Other gold rushes occurred in Papua New Guinea, Australia at least four times, Fiji, South Africa and South America. In all cases,
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#1732887654746264-543: The city of Fairbanks , operates as a single large open pit. From 2001 to 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-leach (CIL) for higher grade ore, and heap leaching for lower grade ore). Surpassing 7 million ounces in 2016, Fort Knox
286-414: The facility from the mine. Prospecting Prospecting is the first stage of the geological analysis (followed by exploration ) of a territory. It is the search for minerals , fossils , precious metals, or mineral specimens. It is also known as fossicking . Traditionally prospecting relied on direct observation of mineralization in rock outcrops or in sediments. Modern prospecting also includes
308-462: The gold rush was sparked by idle prospecting for gold and minerals which, when the prospector was successful, generated 'gold fever' and saw a wave of prospectors comb the countryside. Modern prospectors today rely on training, the study of geology, and prospecting technology. Knowledge of previous prospecting in an area helps in determining location of new prospective areas. Prospecting includes geological mapping , rock assay analysis, and sometimes
330-435: The intuition of the prospector. Prospecting of minerals found in mobile fluids, as is often the case of lithium , adds a "temporal element" to be considered. Metal detectors are invaluable for gold prospectors, as they are quite effective at detecting gold nuggets within the soil down to around 1 metre (3 feet), depending on the acuity of the operator's hearing and skill. Magnetic separators may be useful in separating
352-464: The magnetic fraction of a heavy mineral sand from the nonmagnetic fraction, which may assist in the panning or sieving of gold from the soil or stream. Prospecting pickaxes are used to scrape at rocks and minerals , obtaining small samples that can be tested for trace amounts of ore . Modern prospecting pickaxes are also sometimes equipped with magnets , to aid in the gathering of ferromagnetic ores. Prospecting pickaxes are usually equipped with
374-432: 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. Due to its very low sulfide content, waste rock from Fort Knox does not produce acid mine drainage . Ore from the mine is processed at the Fort Knox mill, a conventional crushing, grinding, CIL leaching, carbon stripping and electrolytic recovery process, with
396-471: The pluton. The sulfide content is very low (<0.1%). The Fort Knox gold deposit had pre-production Proven and Probable Reserves in 1996 of 158.3 million tonnes @ 0.83 g/t gold with a 0.39 g/t gold cut-off for 4.2 million ounces. After the production of over 7.5 million ounces, at 31 December 2019 Proven and Probable Reserves were 255.8 million tonnes @ 0.3 g/t gold for 2.80 million ounces. The Fort Knox Gold Mine, located 15 mi (24 km) northeast of
418-539: The property. Construction began 1995 with the first gold pour at the end of 1996. In 1998, Amax Gold merged with Kinross Gold. 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 minerals occur in pegmatite and quartz veins and fractures within
440-432: The prospector to move onwards to the next and hopefully bigger and better show. Occasionally, the prospector would strike it rich and be joined by other prospectors to develop a larger-scale mining operation. Although these are thought of as "old" prospecting methods, these techniques are still used today, but usually coupled with more advanced techniques such as geophysical magnetic or gravity surveys. In most countries in
462-553: The use of geologic, geophysical , and geochemical tools to search for anomalies which can narrow the search area. Once an anomaly has been identified and interpreted to be a potential prospect direct observation can then be focused on this area. In some areas a prospector must also stake a claim, meaning they must erect posts with the appropriate placards on all four corners of a desired land they wish to prospect and register this claim before they may take samples. In other areas publicly held lands are open to prospecting without staking
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#1732887654746484-489: Was found, it was then necessary to intensively work the area with pick and shovel, and often via the addition of some simple machinery such as a sluice box, races and winnows, to work the loose soil and rock looking for the appropriate materials (in this case, gold). For most base metal shows, the rock would have been mined by hand and crushed on site, the ore separated from the gangue by hand. These shows were commonly short-lived, exhausted and abandoned quite soon, requiring
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