Anglo American delivered copper production on schedule from its Los Bronces expansion project in central Chile. The expansion of Los Bronces is expected to more than double (on average over the first three years of full production) the mine’s existing production of 221,000 metric tons per year (mt/y) and is the second of Anglo American’s four major strategic growth projects to begin production during 2011.
“We have delivered this major expansion of Los Bronces on schedule, thanks to the admirable hard work and dedication of the entire team of up to 16,000 people who have been working on the project over the last three years,” said John Mackenzie, CEO, Anglo American’s copper business. “We have a 12-month ramp up period ahead until we reach full production, during which time we will be increasing processing plant throughput from 61,000 mt to 148,000 mt of ore per day.”
“The commissioning of the Los Bronces expansion marks the second major new project that we have delivered on schedule this year,” said Cynthia Carroll, CEO, Anglo American. “At peak production levels, Los Bronces is expected to be the fifth largest copper mine in the world, with reserves and resources that support a mine life of over 30 years and with further expansion potential. We are driving volume growth across the most attractive commodities with a continued focus on long life assets with low cash operating costs. Our long term growth pipeline presents significant opportunities and optionality. Looking at our copper business in particular, we have existing projects spanning Chile, Peru and the United States, and exploration activities under way in several other geographies.”
Los Bronces is an open-cut copper and molybdenum mine located 65-km northeast of Santiago, Chile, at an altitude of 4,000 m above sea level. The ore is extracted, crushed and transported down a 56-km slurry pipeline to the Las Tórtolas flotation plant, where copper and molybdenum concentrates are produced. The mine also produces copper cathodes.
The Los Bronces expansion project involved several sub-projects that spanned various geographical areas. A new primary crusher was installed near the Los Bronces open-pit, with crushed ore being fed by conveyer through a 4.4-km tunnel to the grinding plant at an area known as Confluencia. At Confluencia, a new stockpile, a grinding building (with one SAG mill and two ball mills), thickeners and other associated equipment were installed to produce the slurry. The slurry is then transported through a 56-km pipeline from the Confluencia grinding plant to a new copper and molybdenum concentrator plant (flotation) built next to the existing concentrator at the Las Tórtolas complex some 45 km from Santiago at about 750 m above sea level.
Due to the more than 3,000-m difference in elevation between Confluencia and Las Tortolas, the pipeline system also required the construction of five choke stations to control the gravitational force of the descending slurry, and five pump stations to return water from Las Tortolas to Confluencia.
The project also called for the construction of new 220-kV electric power lines to satisfy increased energy requirements, in addition to improvements to the operation’s tailings dam, fresh water supply and water recirculation systems.