Bingham Canyon Mine

For the former city at this location, see Bingham Canyon, Utah.

Bingham Canyon Open Pit Copper Mine
U.S. National Register of Historic Places
U.S. National Historic Landmark
Bingham Canyon Mine, April 2005
Location:	Salt Lake County, Utah
Nearest city:	Salt Lake City, Utah
Coordinates:	40.523°N 112.151°W / 40.523; -112.151
Built:	1904
Governing body:	Private
NRHP Reference#:	66000736
Significant dates
Added to NRHP:	November 13, 1966
Designated NHL:	November 13, 1966

The Bingham Canyon Mine, also known as the Kennecott Copper Mine, is an open-pit mining operation extracting a large porphyry copper deposit southwest of Salt Lake City, Utah, USA, in the Oquirrh Mountains. It is the deepest open-pit mine in the world. The mine is owned by Rio Tinto Group, an international mining and exploration company headquartered in the United Kingdom. The copper operations at Bingham Canyon Mine are managed through Kennecott Utah Copper Corporation which operates the mine, a concentrator plant, a smelter, and a refinery. The mine has been in production since 1906, and has resulted in the creation of a pit over 0.75 miles (1.2 km) deep, 2.5 miles (4 km) wide, and covering 1,900 acres (7.7 km²). According to Kennecott, it is the world's largest man-made excavation. It was designated a National Historic Landmark in 1966 under the name Bingham Canyon Open Pit Copper Mine.

History

Minerals, in the form of copper ore, were first discovered in Bingham Canyon in 1848 by two brothers, Sanford and Thomas Bingham, sons of Erastus Bingham, Mormon pioneers of September 1847, who grazed their family's and other's cattle and horses there. They reported their find to their leader, Brigham Young, who advised against pursuing mining operations because the survival and establishment of settlements was of paramount importance at that time. The brothers applied themselves to that purpose as directed and did not stake a claim. In 1850, the Bingham family went to settle what is now Weber County, leaving the canyon still today known by their name.

Bingham Canyon Mine, November 1942. Carr Fork Canyon as seen from "G" bridge. A train in the background carries material to the dump.

It was not until 1863 that extraction of ore began and the potential of the canyon's mineral resources began to be widely recognized. At first, mining was difficult due to the area's rugged terrain, but a railroad reached the canyon in 1873, prompting greatly increased mining activity and accompanying settlement. The canyon's nineteenth-century mines were relatively small, however, and it was not until 1898 that plans for very large-scale exploitation of the canyon's ore bodies began to develop. That year, Samuel Newhouse and Thomas Weir formed the Boston Consolidated Mining Company, intending to increase mine development in the canyon.

A more significant development took place in 1903, when Daniel C. Jackling and Enos A. Wall organized the Utah Copper Company. Utah Copper immediately began construction of a pilot mill at Copperton, just beyond the mouth of the canyon, and the company actually started mining in 1906. The success of Utah Copper in mining the huge but low-grade porphyry copper type orebody at Bingham Canyon revolutionized the copper industry, and set the pattern for the large open-pit porphyry copper mines that today dominate the copper industry worldwide. Utah Copper and Boston Consolidated merged in 1910. The Kennecott Copper Corporation, established in 1903 to operate mines in Kennecott, Alaska, purchased a financial interest in Utah Copper in 1915 and fully acquired the company in 1936.

Bingham's Canyon mine expanded rapidly, and by the 1920s the region was a beehive of activity. Some 15,000 people of widely-varying ethnicity lived in the canyon, in large residential communities constructed on the steep canyon walls. The population declined rapidly as mining techniques improved, however, and several of the mining camps began to be swallowed up by the ever-expanding mine. By 1980, when Lark was dismantled, only Copperton, at the mouth of Bingham Canyon and with a population of 800, remained. Today, mining operations continue at full-swing in the mine. For years, the largest open-pit mine in the world, it is still the largest copper mine and among the world's largest open-pit mines. Work to expand the mine 600 feet (180 m) east began in 2005, continuing to increase its size, growth, and capabilities.

Geology

Cross-section through open pit, showing ore zonation, USGS.

The Bingham Canyon orebody is a porphyry copper deposit, formed by a quartz monzonite porphyry intruded into sedimentary rocks. It has the concentric alteration pattern and mineralogic zonation typical of porphyry copper deposits.

The oldest rocks at Bingham Canyon--sandstones, quartzites and limestones--were originally deposited as sediment by the shallow seas that covered the region 300 million years ago (in the late Paleozoic Era). Much later, between 60 and 135 million years ago, extensive folding and faulting of the sediments created the Oquirrh Mountains.

Geologic map showing bedrock geology and alteration zones, USGS.

Thirty to 40 million years ago, massive igneous intrusions initiated the process of mineralization. Extreme pressure forced superheated, mineral-rich solutions into fractured intrusive and adjacent sedimentary rock. Upon cooling, the mineralized solutions deposited enormous quantities of metals throughout a broad section of igneous and sedimentary rock that is now known as the Bingham Stock.^{[citation needed]}

Bingham Canyon is not presently a source of notable mineral specimens. The Bingham Stock is a porphyry deposit, meaning that copper minerals—primarily chalcopyrite--are present in very low grades and disseminated throughout the granite-like host rock as tiny grains, seams and fracture coatings.

Recovery process

The extracted ore is run through a concentrator, where huge grinding mills reduce it to the consistency of face powder. Flotation then separates the gangue from the metalliferous particles, which float off as a 28-percent concentrate of copper along with lesser amounts of silver, gold, lead, molybdenum, platinum and palladium. A selective flotation step separates the molybdenite (molybdenum disulfide) from the chalcopyrite.

The filtered concentrate slurry is piped 17 miles (27 km) to the smelter, where it is dried, and then injected along with oxygen into a flash smelting furnace to oxidize the iron and sulfur. The oxidized iron is skimmed off, while the sulfur dioxide gas is captured and sent to an on-site acid plant for conversion to valuable sulfuric acid - a million tons of it each year.

Left behind is a molten copper sulfide called matte. The 70-percent-copper matte is water-quenched to form a sand-like solid, then injected, with oxygen, into a flash-converting furnace that produces molten, 98.6-percent-pure copper. This copper is then cast into 700 pounds (320 kg) anode plates and shipped by rail to the refinery.

At the refinery, the anode plates are pressed flat and interleaved with stainless steel cathode blanks. Automated robotic vehicles place the prepared anodes in cells containing an acidic electrolyte. When the cells are electrified, the anodes slowly dissolve, freeing copper ions that are deposited on the cathode as 99.9-percent-pure copper.

Impurities and precious metals settle to the bottom of the electrolytic cells as "slimes." A chlorination leaching process recovers the gold and silver, which is melted in induction furnaces.

Production

Over its life, Bingham Canyon has proven to be one of the world's most productive mines. As of 2004, ore from the mine has yielded more than 17 million tons (15.4 Mt) of copper, 23 million ounces (715 t) of gold, 190 million ounces (5,900 t) of silver, and 850 million pounds (386 kt) of molybdenum. The value of the resources extracted from the Bingham Canyon Mine is greater than the Comstock Lode, Klondike, and California gold rush mining regions combined. Cumulatively, Bingham Canyon has produced more copper than any other mine in the USA, and is the second in the world after Chuquicamata in Chile. Mines in Chile, Indonesia, Arizona, and New Mexico now exceed Bingham Canyon's annual production rate. High molybdenum prices in 2005 made the molybdenum produced at Bingham Canyon in that year worth even more than the copper. The value of metals produced in 2006 at Bingham Canyon was US$1.8 billion dollars.

Operations

Utah Copper Co. Mill, Bingham Canyon, circa 1910

Employing 1,800 employees and hundreds of contractors, 450,000 tons (408 kt) of material are removed from the mine daily. Electric shovels can carry up to 56 cubic yards (43 m³) or 98 tons (89 t) of ore in a single scoop. Ore is loaded into a fleet of 64 large dump trucks which each carry 255 tons (231 t) of ore at a time; the trucks themselves cost about $3 million US each. There is a five mile (8 km) series of conveyors that take ore to the Copperton concentrator and flotation plant. The longest conveyor is 3 miles (4.8 km) long.

As of 2010, Kennecott Utah Copper is the second largest copper producer in the United States and provides about 13-18% percent of the U.S.'s copper needs. Kennecott’s Bingham Canyon Mine is the largest man-made excavation in the world, and is visible with the naked eye from space. It is one of the top producing copper mines in the world with production at more than 18.7 million tons. Every year, Kennecott produces approximately 300,000 tons of copper, along with 400,000 ounces of gold, 4 million ounces of silver, about 20 million pounds of molybdenum, and about 1 million tons of sulfuric acid, a by-product of the smelting process. Rio Tinto purchased Kennecott Utah Copper in 1989 and has invested about $2 billion in the modernization of KUC’s operations. KUCC has also spent more than $350 million on the cleanup of historic mining waste and $100 million on groundwater cleanup.

The current mine plan will expire in 2019. Rio Tinto is currently studying a plan to extend the open pit 1,000 feet southward, which would extend the life of the mine into the mid-2030s. The plan is contingent on approval by the Rio Tinto board of directors and approximately 25 required environmental permits.

See also

• Mir mine

References

• Kennecott Utah Copper Mine brochure (distributed to visitors), dated September 2004.

External links

• Kennecott's Home Page
• 2005 Expansions
• To Move A Mountain: A History of Mining and Railroads in Bingham Canyon
• Photo gallery
• Geology, mining and ore processing at Bingham
• Kennecott Copper Mine Utah Teacher Guide
• Visiting the mine
• Panoramic View of the Bingham Canyon Mine