Escondida is the world's largest source of copper and one of the lowest cost producers. Escondida ore is produced from two open pits producing 370 million tonnes of material per year. Production began in 1990, and since October 2005 Minera Escondida also operates Escondida Norte, which is a second open pit located 5 km from the main pit.
Escondida produces copper concentrate by means of the sulphide ore flotation process, and also produces copper cathodes using the oxide ore leaching and low-grade sulphide bio-leaching processes. Escondida moves around 360 million tonnes of mineral annually.
The mineral deposit has reserves of 4,157 million tonnes ore containing 31.567 million tonnes copper, and mineral resources amounting to 4,650 million tonnes (2009). Planning for the mine considered the utilization of 662 million tonnes with an average copper grade of 2.12 percent.
Escondida employs more than 2,300 people directly and another 1,900 permanent jobs through contractors. After successive phases of expansion, total investment in Escondida approaches US$ 4 billion (2005).
The mine plays a significant role in Chile's economy with 2.5 percent of Chile's gross domestic product. It is one of the ten largest companies in the country.
The mine is owned by BHP (57.5 percent), Río Tinto (30 percent), Jeco of Japan lead by Mitsubishi (10 percent) and the International Finance Corporation (2.5 percent).
The mining operation is located in northern Chile in the Atacama Desert, 170 kilometers southeast of the city of Antofagasta.
Geology and Mineralization
The Escondida district hosts two of the world's largest porphyry copper deposits systems with superimposed supergene-enriched deposits: Escondida and Escondida Norte. Escondida Norte is located 5 kilometres from Escondida. The porphyry deposit was weathered to form a high-grade secondary Cu zone above the hypogene mineralization.
The main copper bearing sulphide minerals are chalcocite, covellite and chalcopyrite. Local oxidation of the sulphide ore has resulted in the formation of "oxide ore" from the convertion of the sulphide minerals into copper sulphates mainly brochantite and antlerite.
Beneficiation of the high-grade sulphide and green copper mineralisation is through in-pit crushing, sharing a common processing plant complex.
Escondida produces copper concentrate by means of the sulphide ore flotation process, and also produces copper cathodes using the oxide ore leaching and low-grade sulphide bio-leaching processes. The Company moves around 360 million tonnes of mineral annually. The infrastructure consists of two open pit mines (Escondida and Escondida Norte, which is located 5 kilometres from Escondida), two concentrator plants (Laguna Seca and Los Colorados), an electro-winning plant to produce cathodes from oxide and sulphide ore, and two pipelines that transport copper concentrate from the mine to the filter plant, which is also owned by the Company and is located at the Port of Coloso, in the far south area of the city of Antofagasta. A seawater desalinisation plant was recently built in that same area to supply part of the operation's water consumption.
The infrastructure of the company consists of two open pit mines, two concentrator plants, an oxide plant for cathode production (SX-EW), two pulp ducts to transport copper concentrate to the port of Coloso, where there is a filtering plant and port facilities where the product is shipped to its final destination.
The sulphide concentrator employs crushing, milling and flotation circuits. 12m-high, 4m-square column cells are used for cleaning the bulk sulphide concentrate.
Production levels are in the order of 1,000,000 tonnes per day total movement, including 130,000 tonnes per day of sulphide ore fed to the concentrator. Beneficiation involves in-pit crushing, semi autogeneous and ball milling with conventional flotation to produce a high-grade concentrate.
Nominal production capacity is 3.2 mtpa of copper concentrate and 330,000 tonnes per annum of copper cathode.
A variety of products are produced: copper concentrates, copper blister and copper anodes, refined copper, semi-manufactured and manufactured products, and copper scrap.
Copper cathodes are produced in the SX-EW plant, sent by rail to the port of Antofagasta. Copper concentrate is shipped from Punta Coloso. Major customers are in Japan, Germany, Canada, China, Sweden, Brazil, South Korea, and France.
Environment and Community
Escondida actively works with public and private institutions and community organisations, directing its contributions to various cultural, educational and social initiatives that are oriented towards improving the quality of life of the inhabitants of the Antofagasta region.
In 1996 the Company created the Minera Escondida Foundation. The Foundation maintains permanent cooperative relationships with indigenous people, especially with the Atacamenian communities, through an office in the San Pedro de Atacama community, where the work is mainly focused on educational issues. Also, and as an expression of its Community Social Responsibility, Minera Escondida created the Centro de Entrenamiento Industrial y Minero (CEIM) (Industrial and Mining Training Centre), the objective of which is to form and develop the labour skills of mining industry workers, as well as workers from other productive sectors.