the encyclopedic entry of Codelco

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History

Codelco's history begins with Law 11,828, of May 5, 1955, that created the Copper Office (Departamento del Cobre) of the Chilean government, approved under President Carlos Ibáñez del Campo. During the administration of President Eduardo Frei Montalva, Congress sanctioned Law 16,425, on January 25, 1966, and transformed the Copper Office into the Copper Corporation of Chile (Codelco).

With the constitutional reform that nationalized copper (Law 17,450 of July 11, 1971), during President Salvador Allende's government, full ownership of all copper mines and copper fields in the country were transferred to Codelco. The creation of the Corporación Nacional del Cobre de Chile, as it is currently known, was formalized by decree of April 1, 1976, under the Augusto Pinochet administration. A study by Goldman Sachs of January 2006 estimated the current value of the company between US $24.5 and $27.5 billion.

Codelco's symbol is based on the alchemical symbol for copper.

The Company

Codelco consists of the usual head office facilities with extensive research, exploration, acquisition and development departments. It has five principal operating divisions, Codelco Norte, Salvador, Andina, Las Ventanas and El Teniente, and a 49% interest in the El Abra Mine. It has several other potential mining operations under exploration and development including the Alejandro Hales, Gaby/Gabriela Mistral, the Toki Cluster, Mocha, and Casualidad projects. These operating divisions will be dealt with in more detail below.

Sales in 2007 fell from 1.783 million tonnes of copper to 1.664 million tonnes and sales revenue fell to US$16.99 billion from US$17.08 billion the previous year and pretax profit was US$8.45 billion v US$9.22 billion before the Law 13,196 payments (a 10% tax on foreign currency from sales abroad which goes to the armed forces) despite a higher copper price. The Corporation had several problems last year including lower grades and tonnes mined, a breakage of the bucketwheel excavator at Radomiro Tomic and conflict with contractors. The total paid to the Chilean Treasury, including income tax, dividends and Law 13,196 was US$7.94 billion. Codelco has negotiated a 7 year US$3.0 billion syndicated loan which, with the US$1.96 billion in cash and cash equivalent at the end of 2007 leaves the corporation well placed to finance the several new projects that it is investigating.

Codelco Norte

This is situated some 240 km northeast of Antofagasta in Region II and is the largest division in terms of copper production (896,308 tonnes copper and 19,065 tonnes molybdenum in 2007). It was formed in August 2002 by the merger of the Chuquicamata and Radomiro Tomic divisions. It has effectively four producing operations, the origial Chuquicamata pit, the Radomiro Tomic pit, the northern expansion of Mina Sur (formerly the Exótica mine) which is the heap leaching of ore from the paleochannel (an ancient gravel deposit) between the main pit and Mina Sur, and leaching of the Secondary Waste Leach Dump. Individual outputs are no longer available but for 2006 Cochilco gave Chuquicamata 634,000 tonnes (which would have included the leaching projects) and Radomiro Tomic 306,600 tonnes. The leaching of the paleochannel material is expected to produce 129,000 tonnes p.a and the Secondary Waste Leach about 26,000 tonnes p.a.

Chuquicamata

Copper has been mined for centuries at Chuquicamata as was shown by the discovery in 1898 of "Copper Man", a mummy dated at about 550 A.D. which was found trapped in an ancient mine shaft by a fall of rock. . However mining on any scale did not start until the later years of the XIX Century and these early operations mined the high grade veins (10-15% copper) and disregarded the low grade disseminated ore. . One attempt was made to process the low grade ore in 1899-1900 by Norman Walker, a partner in La Compañia de Cobres de Antofagasta, but it failed leaving the comany deeply in debt..

The modern era started when the American engineer Bradley finally developed a method of working low grade oxidised copper ores. In 1910 he approached the lawyer and industrialist Albert C Burrage who sent engineers to examine Chuquicamata. Their reports were good and in April 1911 he started to buy up mines and claims, mainly from the larger mining companies in Antofagasta, in association with Duncan Fox y Cia., an English entrepreneur. Unfortumately Burrage did not have the capital to develop a mine so he approached the Guggenheim Brothers. They examined his claims and estimated reserves at 690 million tonnes grading 2.58% copper. The Guggenheims also had a process for treating the low grade ores developed by E A Capellen Smith and were immediately interested, organised the Chile Exploration Company (Chilex)in January 1912 and eventully bought bought out Burrage for US$25 million in Chilex stock.

The Modern Mine

Chilex then went ahead wih the development and construction of a mine on the eastern section of the Chuquicamata field (It acquired the remainder gradually over the next 15 years) and a 10,000 tons per day leaching plant which was planned to produce 50,000 tons of electrolytic copper annually. Amongst the equipment purchased were steam shovels from the Panama Canal A port and oil fired power plant were built at Tocopilla, 90 miles to the west and an aquaduct was constructed to bring water in from the Andes Production started on May 18th 1915. Actual production rose from 4345 tonnes in the first year to 50,400 tonnes in 1920 and 135,890 tonnes in 1929 before the Depression hit and demand fell. The Guggenheims gave up control of the mine in 1923 when they sold 51% to Anaconda, who acquired most of the remainder in 1929. Anaconda ran the mine until the 1960's when the Chilean state acquired a 51% holding in the "Chilenization" of the copper industry. In 1971 the mine was nationalised and in 1976 was incorporated into Codelco (Corporacion Nacional del Cobre de Chile). It is now the major part of the Codelco Norte division

Production from the capping of oxidised minerals, which required mere leaching in sulphuric acid to dissolve the copper and the recovery of the copper by electrolysis was the sole means of production until the 1950's. However their gradual depletion forced the construction of a mill and flotation plant in 1961 to treat the underlying secondary sulphides. These have been steadily expanded until recently the pit was producing over 600,000 tonnes of copper annually, though this has now fallen with the lower grades as the richer secondary mineralisation is also depleted in the three porphyries that make up the orebody.

The present mine is a conventional truck and shovel operation, with a large proportion of the ore crushed in-pit and transported by underground conveyors to the mill bins. The 182,000 tonnes p.a. concentrator is also conventional and is primary crushing followed by SAG mills and ball mills with cyclone classification. The flotation section produces both copper and molybdenum concentrates using Outokumpu TankCell 160 system which has increased both copper and molybdenum recoveries. The 1.65 million tonnes p.a. of concentrate are smelted in one Outokumpu flash smelter and one Teniente convertor with electric furnace and cylindrical slag cleaning followed by four Pierce Smith convertors. The blister copper goes to six anode furnaces which feed three anode casting wheels. The anodes go on to the 855,000 tonnes p.a. electrolytic refinery.

The Future of Chuquicamata

Plans to go underground and mine the rest of the Chuquicamata orebody by block caving are now fairly well advanced though these may be being revised in the light of the current high copper price. At the SIMIN conference in 2007 in Santiago Codelco engineers detailed a possible future mining plan. The open pit, with one barren side because it is against the Falla Oeste (West Fault, a feature which extends hundreds of kms. down Chile and is associated with most of the major porphyry copper deposits) is becoming gradually uneconomic and it was estimated that mining would slow down and stop by 2020. In the meantime the mill will be kept up to its 182,000 tonnes per day capacity with sulphides from Radomiro Tomic and Alejandro Hales. The underground mine will start up in 2018 and when it reaches full capacity of 120,000 tonnes per day in 2030, the balance of the tonnage will come from the Alejandro Tomic underground mine. It is estimated that extractable underground reserves below the present pit total 1,150 million tonnes of ore gradeing 0.76% copper and 0.052% molybdenum.

This may seem an overlong description of Chuquicamata but it is one of the most remarkable mines the world has seen. The largest annual copper producing mine until recently overtaken by Escondida and one of the largest ever copper mining excavations, it retains its crown as having produced far more metal, over 29 million tonnes, than any other copper mine

Radomiro Tomic

The Radomiro Tomic deposit, 5 km north of the main pit, was discovered in 1952 when Anaconda conducted an extensive churn drilling programme to explore for oxidised ore for ten miles to the north of the Chuquicamata pit. It was named Chuqui Norte but they did not develop it, largely because the technology had not been developed, particularly SX/EW. Two smaller areas of interest were found and the overall results showed that the Chuquicamata complex of mineralised porphyries is no less than 14 km long

The deposit is covered with some 100 metres of alluvium and in 1993/94 Codelco estimated a resource base for the operation of 802 million tonnes of oxide ore grading 0.59% copper and 1,600 million tonnes of refractory ore. The deposit covers an area of 5 km x 1.5 km.

Mining started in 1997 and is again a conventional truck and shovel operation followed by crushing, pre treatment and stacking before acid leaching. Copper is extracted by SX/EW. Leached ore is removed by bucket wheel excavator followed by secondary leaching. It is likely that the 'refractory' sulphide ore will be mined and used to keep the Chuquicamata mill full during the changeover to underground mining. The last published production by Radomiro Tomic, from Cochilco, was 306,600 tonnes in 2006.

Northern Expansion of Mina Sur

Between the main pit and Mina Sur there remains a substantial tonnage of so-called exotic copper in the channel of paleogravels (ancient gravels) between the two and which were mined in Mina Sur. The minerals, thought to be deposited by colloidal copper solutions leached from the main deposit, included manganese bearing copper pitch and copper wad, along with other impurities which made the ore difficult to leach in the original vats and produced a substandard cathode. The 'exotic' ore is now being heap leached and the copper extracted by SX/EW which leaves the impurities behind in the leach solution. It is expected that this operation will produce 129,000 tonnes of good quality copper cathode annually.

Seconday Waste Dump Leach

This is the leaching of certain copper bearing waste dumps and is expected to produce 26,000 tonnes of copper annually.

Ministro Alejandro Hales (formerly Mansa Mina)

This is a major discovery that was made between Chuquicamata and Calama. It was initially estimated to have reserves of over 500 million tonnes grading over 1% copper but was found to be geologically complex and have a high arsenic content and work was stopped on it for some years. Work resumed in 2000, as a result of the development of a process to treat high arsenic ores, the need for sulphide ore feed to the mill when Chuquicamata's mining goes underground and to test bioleaching technology. It is also possible that it may enable an expansion of the sulphide mill's capacity

Pollution

For many years Chuquicamata, particularly its smelter, was a byword for pollution. The black smoke from the smelter smokestacks could be seen many miles away and the inhabitants of the Chuquicamata camp and Calama had serious amounts of arsenic in their blood. This has changed drastically. The camp at Chuquicamata has been closed and the inhabitants moved to Calama, away from the dust and general pollution close to the mine.

The off gasses from the flash smelter, Teniente convertor and Pierce-Smith convertors have a high enough sulphur dioxide content to allow sulphuric acid production in a single absorption sulphuric acid plant which has improved shlphur capture to 98%. The Corporation also planned some years ago to reduce arsenic emisssions by 97% but there have been no recent reports. Pollution of the River Loa, which flows through Calama is a problem which is being addressed but little has been reported.

Salvador

Situated some 100km east of the port of Chañaral, the Salvador division is the smallest of Codelco's divisions and has only a short life remaining. Its history starts with the Potrerillos mine. A known mining area since the early XIX Century, two Chileans formed the Compania Minera de Potrerillos but had great difficulty in operating it. In 1913 it was bought by William Braden (of El Teniente fame) who in turn sold his rights to Anaconda's Andes Copper Mining Company. Starting up the mine involved the construction of the entire infrastructure, compounded by fuel shortage and the cessation of work for some years and it was not until 1927 that mining started.

By the early 1950s production had fallen drastically and in a search for more reserves, exploration was concentrated on a small copper occurance known as Indio Muerto (Dead Indian). Early drilling was disappointing but finally some very good values were found and by 1957 a reserve of 375 million tonnes grading 1.5% copper had been estimated. Construction of an underground mine started immediately, and production started in 1959 using the Potrerillos smelter and electrolytic refinery. Eventually open pit mining of oxide ore and heap leaching were undertaken. The name mine was named Salvador or Saviour because it was effectively the saviour of the Andes Copper Mining Company, as it was at that time.

However, time is running out. Reserves were only 63 million tonnes grading 0.61% copper at the end of 2007 and production in that year was only 63,883 tonnes of copper and 1,204 tonnes molybdenum compared with 97,100 tonnes in 1987 In its 2007 Annual Report, Codelco stated that the oxide operations would close in 2010 and the sulphide operations the following year. The smelter, which was equipped recently with a Teniente convertor and acid plant, will undoubtedly continue to operate, treating concentrates from othe Codelco mines.

Andina

Situated some 50 km northeast of the capital, Santiago, the Andina mine was discovered in 1920 but production did not start until 1970. It consists of the Rio Blanco underground (block cave) mine and the Sur Sur open pit and an underground concentrator. Unlike other Codelco mines, it does not have its own smelter. Geologically it consists of about half the Los Bronces-Rio Blanco complex of mineralised breccias, the other half being owned and mined by the Los Bronces mine of Compania Minera Disputada de la Condes which is in turn owned by Anglo American.

Originally owned by the American Cerro De Pasco Corporation, who brought the mine to production, it has been gradually built up by Codelco and is now the subject of a major expansion scheme. At the end of 2007, reserves and resources in the mining plan totalled 5,698 million tonnes grading 0.78% copper containing 44.3 million tonnes of metal and additional identified resources of 11,342 tonnes grading 0.52% copper containing 59.6 million tonnes of metal.

The orebodies are at considerable heights, between 3,000 and 4,200 metres and operations can be severely affected by the weather. Originally the mine was only the underground block cave and an underground concentrator with an 'hotel'/bunkhouse where the workers live when the Rio Blanco vally is impassable in the winter. Now the Sur Sur and Don Luis breccias above and to the south of the underground mine are being worked as open pits. Production in 2007 was 218,322 tonnes of extractable copper and 2,525 tonnes molybdenum in concentrate from the 72,000 tonnes per day concentrator.

Work is now under way on the Andina Phase I Development Project which aims to raise mill capacity to 92,000 tonnes per day and is expected to be complete by November 2009. Pre feasibility studies on raising mill capacity to over 200,000 tonnes per day by 2014 should be complete this year. Deep drilling to prove up resources to sustain such a production rate continue. No estimates of the likely copper output at a milling rate of 200,000 tonnes per day have been given and cannot be until the deep drilling campaign is complete.

One of the mysteries of Andina is why it did not buy Compania Minera Disputada de las Condes when Peñarroya was prepared to sell it for a very low price in 1972. It went to Enami who subsequently sold it for a handsome profit to Exxon Minerals for US$97 million. It would have given Codelco complete control of the district. When Exxon finally did decide to sell in 2002, Codelco expressed interest but were not prepared to match the US$1.3 billion that Anglo American were prepared to give for it

El Teniente

Situated 44 km east of Rancagua and 75 km south of the capital, Santiago, El Teniente claims to be the largest underground copper mine in the world (see below). The El Teniente orebody has been known and worked on a small scale for many years. In the XVI Century it became the property of the Jesuits as it was located on their Hacienda de la Compañia de Jesús. They operated a small mine known as the Socavón de los Jesuitas. Following their expulsion, the hacienda was acquired in 1768 by Don Mateo de Toro y Zambrano y Ureta. Between 1819 and 1823 his heirs restarted and enlarged the workings, bringing in a mining engineer to help. However, these and subsequent attempts to establish anything more than a small scale mine failed for lack of capital and the property was eventually bought by the American, William Braden, for approximately US$100,000. The same year Braden formed Rancagua Mines, which became the Braden Copper Company, in association with old colleagues from ASARCO, including Barton Sewell.

Work started on establishing a mine in 1905 after Government permission had been acquired but progress was slow because of difficulty of access and a hard winter climate. A small gravity plant was soon erected but it was not until 1912 that a flotation plant was erected at Sewell . Control passed to Kennecott in 1915 and it ran the mine until nationalisation in 1971.

The Present Mine

The porphyry orebody consists of a stockwork (a network of narrow veins) of mineralised veinlets, mainly in andesitic lavas and tonalite, superimposed by a leached zone and a substantial zone of secondary enrichment, both of very variable thickness. It surrounds a narrow, almost circular ring of tourmaline breccia which in turn surrounds the Braden Chimney, an inverted cone of breccia which was emplaced after the main mineralisation. Reserves and resources are substantial. At the end of 2007 reserves and resources in the mining plan totalled 4,204 million tonnes grading 0.91% copper or 38.3 millionn tonnes of contained copper. In addition the mine has identified additional resourcesof 15,827 million tonnes grading 0.46% copper or nearly 73 million tonnes of contained copper though there is no indication how much of this may prove economic. Production in 2007 was 404,728 tonnes copper and 5,053 tonnes molybdenum.

Mining is gradually moving lower and removing the ore between the barren country rock and the Braden Chimney. Access is through adits (horizontal tunnels) to shafts and other services cut in the Braden Chimney. Mining methods include panel caving, panel caving with pre-undercut, and block caving, which have been adapted to overcome the serious rockburst problem which stopped mining some years ago on level 6 and threatened the future of the mine. A new level, Level 8, is now in operation and another, lower, level is being studied which will give access to 1.5 billion tonnes of ore grading 0.96% copper and extend the life of the mine by many years.

All ore is now treated in the lower Colón mill, the original Sewell mill being closed. Capacity is now 130,000 tonnes daily, split equally between SAG and conventional milling, followed by flotation, thickening and filtration. The recent increase in mill capacity has been necessary to compensate for the gradual move of mining into the lower grade primary ore zone. The concentrate goes to the Caletones smelter further down the valley. This is equipped with two Teniente convertors with slag furnaces, three Pierce Smith convertors and six anode furnaces feeding two anode and one fire refined casting wheels. Tailings are flumed down the vally to dams on flatter ground. An independent company, Minera Valle Central, retreats old and current El Teniente tailings and extracts some 12,000 tonnes p.a. of copper in concentrate.

Sewell

Sewell, the original mine camp and known as the 'city of stairs' because it looked as though it had been poured down the mountain, has becom a UNESCO World Heritage Site. It was founded in 1906 by William Braden to house his mine workers and had a population of around 15,000 at its peak. It was closed down in the late 1980's as all the workers moved down to Rancagua.

The Biggest Underground Copper Mine?

Any claim to be the biggest mine immediately runs into the question of how one defines biggest. Is it the total production, annual production, extent of the underground workings, individual mine, mines on the same orebody and so on. El Teniente has a rival here, namely KGHM, the Polish copper miner. Its operations are all underground, it produces more than El Teniente, 533,000 tonnes in 2007, but from three adjacent mines on the same orebody, the Kupferschiefer, but they have not produced the total that El Teniente has but they cover a far larger area. Take your pick. El Teniente wins on the individual mine basis so its claim valid.

Las Ventanas

Las Ventanas is a smelter situated on the coast 35 km north of Valparaiso. It was transferred from ENAMI in May 2005. It processes concentrates and anodes from Andina and El Teniente, amongst other producers, and makes Codelco increasingly self-sufficient. The 'New Ventanas Project' is investigating the feasibility of converting it into a large scale smelting and refining complex.

The plant consists of a Teniente convertor with electric furnace slag cleaning, three Pierce Smith convertors, a rotary anode furnace and two reverbatory refining furnaces and two anode casting wheels. Capacity is 450,000 tonnes p.a. concentrate to produce 110,000 tonnes copper annually. Off gasses go to a Hugo Petersen sulphuric acid plant. The refinery produces cathode copper, and gold, silver and selenium are produced from the anode slime left over from the refining process.

El Abra (49% owned)

Codelco sold a 51% interest in its El Abra deposit in 1994 to Cyprus-Amax (now part of Freeport McMoRan Copper and Gold) who then developed it. Production started in 1996. It is a porphyry copper with an extensive capping of leachable oxide and sulphide mineralisation. Production over the next three years is expected to be in the 152,000 to 168,000 tonnes copper p.a. from the 227,000 tonnes p.a.capacity SX/EW plant. It is planned to exploit the underlying sulphides starting in 2010 which should extend the mine life by over 10 years

Other Projects

The Gabriela Mistral (Gaby) Project is an oxide copper project located 120 km south of Calama. Reserves are estimated at 580 million tonnes of oxide ore grading 1.41% copper and there is underlying sulphide mineralisation but this is not being considered at present. A 14 year open pit leaching and SX/EW operation producing about 150,000 tonnes of copper annually is planned. Startup is expected in 2008. Leaching of tailings with the potential to produce and additional 30,000 to 50,000 tonnes p.a. between 2011 and 2014 is being investigated, as is wind power. An 'exotic copper' orebody, Vicky has also been found in the Gabriela Mistral area with potential estimated resources of 80 million tons of oxide ore with a copper grade of 0.6%.

The Toki Cluster is a group of porphryies that is now included in the Codelco Norte division. In 2004 the resources in the four porphyries found to date was estimated at 18 million tonnes of copper. Since then a fifth, Miranda, has been found containing estimated resources of 2.5 millionn tonnes of copper.. Other recent discoveries include Casualidad and Mocha.