División El Teniente ("The Lieutenant") is an underground

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

mine located in the

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

above mean sea level Height above mean sea level is a measure of a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero level ...

. It is in the commune of Machalí in Cachapoal Province, Libertador General Bernardo O'Higgins Region, near the

company town A company town is a place where all or most of the stores and housing in the town are owned by the same company that is also the main employer. Company towns are often planned with a suite of amenities such as stores, houses of worship, schoo ...

of Sewell. This was established for the workers and their families. Mining at El Teniente is reported to have started as early as 1819. In the early 20th century, two men from New York, United States set up a mining operation there, starting operations in 1906. Kennecott Copper Corporation, based in

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

, United States, later operated the mine through their subsidiary company. The Chilean government bought a 51% interest in the mine in 1967. Some 15,000 people lived in Sewell at its height as a company town. In 1971 Chile nationalized copper production under President

Salvador Allende Salvador Guillermo Allende Gossens (26 June 1908 – 11 September 1973) was a Chilean socialist politician who served as the 28th president of Chile from 1970 until Death of Salvador Allende, his death in 1973 Chilean coup d'état, 1973. As a ...

and formed the

state-owned State ownership, also called public ownership or government ownership, is the ownership of an industry, asset, property, or enterprise by the national government of a country or state, or a public body representing a community, as opposed to ...

copper mining company Codelco. This company still operates the mine. Workers began to live in other areas. With over of underground drifts, El Teniente is reportedly "the world's biggest underground copper mine", and is the largest of Codelco's operations. Typically more than 5,000 workers were involved in production.''Emol,'' June 20, 2005
''"La Tragedia del Humo":'' A 60 años del peor accidente minero en Chile
(in Spanish) Since 2011, a structural project called New Mine Level (NML) has been underway at El Teniente. It consists of expanding the mine deeper into the hill at 1,880 meters above sea level. The project is being carried out without interrupting the operation of El Teniente Division.

History

According to legend, the El Teniente mine was discovered in the 1800s by a fugitive Spanish official. Exploitation of the resource began in 1819. The best ore was mined manually in what would be called the Fortuna sector, and transported out of the mine by

pack animal A pack animal, also known as a sumpter animal or beast of burden, is a working animal used to transport goods or materials by carrying them, usually on its back. Domestic animals of many species are used in this way, among them alpacas, Bact ...

s, such as ponies and mules. It was worked until 1897, when the high-grade ore was exhausted. In 1904 William Braden (an

engineer Engineers, as practitioners of engineering, are professionals who Invention, invent, design, build, maintain and test machines, complex systems, structures, gadgets and materials. They aim to fulfill functional objectives and requirements while ...

from

New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

, United States) and E.W. Nash formed the Braden Copper Company. They built a road for carts and a concentrating plant, which was in operation by 1906. In June 1910, Guggenheim Exploration took control of the mine and provided financing. In 1916 Braden became a subsidiary company of Kennecott Copper Corporation, which was based in

. Chileans have referred to such large-scale copper mining operations as ''La Gran Minería del Cobre'' (a major copper mine). Before nationalization, these operations generated a large proportion of the foreign currency which the country received. In 1945 there was a disaster at El Teniente mine, resulting in the deaths of 355 men and injury to 747 more. It was the largest mining accident in Chilean and has the highest death toll in world history associated with metal extraction. Some 1,000 miners were down in the pits when the fire started in a nearby warehouse. Dense smoke spread in the underground tunnels. Most of the dead and injured suffered

carbon monoxide poisoning Carbon monoxide poisoning typically occurs from breathing in carbon monoxide (CO) at excessive levels. Symptoms are often described as " flu-like" and commonly include headache, dizziness, weakness, vomiting, chest pain, and confusion. Large ...

. Emergency exits were not well marked. In Chile, this incident is known locally as the Smoke Tragedy (). In 1967 the Chilean government bought a 51% stake in the mine and founded Sociedad Minería El Teniente. Under this agreement Kennecott built a new concentrator, and the mine expanded production to per day. On July 11, 1971,

President President most commonly refers to: *President (corporate title) * President (education), a leader of a college or university *President (government title) President may also refer to: Arts and entertainment Film and television *'' Præsident ...

ordered the Chilean nationalization of copper, in an effort for the country to gain more benefit from the mines. Corporación Nacional del Cobre de Chile (known as Codelco) was formed, and El Teniente became a state-owned operation. The Chilean government paid Kennecott $92.9-million for the property. The mine increased production to of ore per day, and in 2006 the mine produced over of copper. The

Vancouver, British Columbia Vancouver is a major city in Western Canada, located in the Lower Mainland region of British Columbia. As the List of cities in British Columbia, most populous city in the province, the 2021 Canadian census recorded 662,248 people in the cit ...

-based,

Canadian Canadians () are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of their being ''C ...

company Amerigo produces both a copper and

molybdenum Molybdenum is a chemical element; it has Symbol (chemistry), symbol Mo (from Neo-Latin ''molybdaenum'') and atomic number 42. The name derived from Ancient Greek ', meaning lead, since its ores were confused with lead ores. Molybdenum minerals hav ...

concentrate from El Teniente's

tailings In mining, tailings or tails are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Tailings are different from overburden, which is the waste rock or other material ...

. It has been granted the right also to treat higher grade tailings from a large, abandoned tailings impoundment near the El Teniente property.

Geology

The copper

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

deposits are those of a typical copper porphyry and associated alteration-mineralization. These altered zones include

chalcopyrite Chalcopyrite ( ) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a Mohs scale, hardness of 3.5 to 4 ...

pyrite The mineral pyrite ( ), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue ...

, bornite and

molybdenite Molybdenite is a mineral of molybdenum disulfide, Mo S2. Similar in appearance and feel to graphite, molybdenite has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of molybdenum at ...

hypogene In ore deposit geology, hypogene processes occur deep below the Earth's surface, and tend to form deposits of primary minerals, as opposed to supergene processes that occur at or near the surface, and tend to form secondary minerals. At great d ...

minerals and chalcocite as a supergene mineral. The ore body surrounds the Braden Pipe in a continuous ring with a width of 2000 feet. The pipe is a geologic structure in the shape of an inverted cone, having a surface diameter of 4000 feet, and consisting of post-pipe

breccia Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language ...

called the Braden Formation. The boundary of the pipe is marked by this post-pipe breccia and a pre-pipe breccia forming a belt up to 200 feet wide. "The Braden Pipe was a center of strong mineralization and structural weakness before the pipe was formed." Copper mineralization and pipe formation occurred in the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

or in andesitic flow breccia adjacent to the pre-pipe breccia." Mineralization at El Teniente is thought to be indebted to its position at the intersection of two large fault systems. This favoured the rise of magma and the subsequent circulation of mineral-rich fluids.

Labour disruptions

As of 2007 Codelco employed 17,000 direct-hire company employees and 28,000 contract employees across all their operations. There have been multiple labour disruptions at the El Teniente mine, where about 5,000 workers produce the ore.

1983

In 1983 El Teniente and two other Codelco mines closed when approximately 13,000 workers voted to strike "indefinitely" in protest of a union leader's arrest for calling for an end to military rule in Chile. In total among the three mines, at least 3,300 workers and 37 labour leaders were fired for participating in the strike.

2008

Contract workers went on strike at Codelco mines in 2008. El Teniente and two other Codelco mines were closed, El Teniente for the shortest length. Company employees continued to work; however, striking workers closed access to the mines and threw stones at buses transporting employees from the mine to the town of Rancagua. At least one employee was injured; he was hit by a metal object thrown by a protester on the highway leading to the mine.

References