Minera Atacocha ------
The deposits are located in the central mountain range of Peru, 15 km to the northeast of Cerro de Pasco.
The concentrating plant, the Marcopampa Hydro Plant, the General Superintendence and the administrative offices are located in the Chicrín Camp, at 3,500 meters above sea level and 324 km from Lima on the Central Highway.
The Atacocha camp, at 4,000 meters above sea level, houses the facilities for the mine. Access from Chicrín is by a 5-kilometer transitable trail or by a 24-kilometer paved road.
The Chaprín Hydro Plan is on Kilometer 340 of the Central Highway.
The main office is located in Av. Javier Prado Oeste N° 980 - San Isidro, Lima.
The Atacocha Mine consists of two deposits clearly differentiated both as to their origin and as to mineralization: Atacocha and Santa Bárbara.
The Atacocha deposit is polymetallic, of hydrothermal and epigenetic origin, formed by replacement and refilling of fractures, which have originated ore bodies and veins with economic mineralization, consisting mainly of Pb, Zn and Cu sulfides, with Ag contents and, in lesser amounts, Au and Bi.
In the last 5 years, ore body 17, located in the crevice of the Atacocha Fault, midway between Atacocha and Santa Bárbara, has been surveyed and is being mined since 2001. Its mineralization is similar to that of Atacocha, but with higher values of Pb and Ag. This important area is considered to be a part of Atacocha.
The Santa Bárbara deposit was formed by contact metasomatism in the limestone adjacent to the intrusive igneous rocks, resulting in bodies with economic mineralization of Zn and Cu sulfides and, in lesser amounts, Pb, Ag, Au and Bi content.
During the mine's 68 years in operation, more than 270 km in horizontal and vertical passages have been opened to explore, develop and extract over 26 million metric tons of ore, in an area of approximately 300 hectares (741 acres), with a vertical extent of over 1000 meters, with more than 18 levels of crosscuts and drifts.
Proven and probable reserves as of 12/31/2003 are estimated at 7.3 million metric tons and an approximate potential of 10 million tons of ore is believed to exist.
Mining equipment consists of compressors, pumps, lifting winches, fans, pneumatic drills, electro-hydraulic jumbos, electric and diesel scooptrams, low profile loaders, locomotives, mining trucks, etc. This new technology equipment is in good condition and in sufficient number for exploration, mining and extraction of 1,250,000 dry metric tons/year.
The production process begins in the underground mine, with exploration and development of mineralized bodies, which, once recognized and evaluated, are prepared for extraction.
The mechanized cut-and-fill stoping technique is used, using hydraulic filling made up of the thickest part of the tailings from the concentrating plant, which are then pumped back to the mine. Mining operations consist of drilling, blasting, haulage, transportation and extraction of the ore to the concentrating plant. All mining operations use trackless equipment on wheels; extraction through the 3-kilometer Level 3600 Tunnel is carried out with locomotives and mining trucks on tracks to the coarse-ore bin at the concentrating plant.
Ore from the mine is processed at the concentrating plant using the selective flotation method to obtain Zn, Pb and Cu concentrates, with Ag and Au values, which are the products marketed by Atacocha.
The first concentrating plant installed at the mining unit was Concentrator N° 1, in 1937, with a capacity of 100 dry metric tons/day, which was later expanded to 250 dry metric tons/day.
In 1950, the current Concentrator N° 2 was put into operation, with a capacity of 375 dry metric tons/day, which was progressively expanded to reach 1,500 dry metric tons/day in 1968, allowing for deactivation of Concentrator N° 1.
In the year 1979, the stowage plant was put into operation, where tailings from the concentrating plant are classified and the coarsest half is pumped back to the mine to fill voids left by mining operations.
Concentrator N° 2 was successively expanded and updated as more reserves were identified and volume was calculated. In 1985, new facilities for the crushing and flotation sections were put into operation. Later, the tertiary and primary crushers were changed and the flotation and grinding section was expanded with three new and three refurbished grinders, reaching a capacity of 3,500 dry metric tons/day by the year 2001.
At present, with the recent installation of a regrinding mill for Zn flotation and additional flotation cells, we have a capacity of 3,650 dry metric tons/day, allowing us to process 1,250,000 dry metric tons this year.
In keeping with Atacocha's continuous improvement policy to have the most modern and efficient technology and equipment in its operations, a Courier Outokumpu online continuous chemical analyzer was installed in the concentrating plant to obtain analytic reports in real time on 12 process points, which allow for better and faster metallurgy control, as well as lower use of reagents.
Atacocha has two hydroelectric plants with an installed capacity of 6.6 megawatts.
The Marcopampa Hydro Plant began its operations in 1938, was later expanded and, in 1984, the generator was changed to reach 1.2 megawatts. The Chaprín Hydro Plant was put into service in 1953 with two generating units. Since 1955, it operates with three units and has a capacity of 5.4 megawatts.
These hydro plants cover approximately 75% of total demand and are interconnected by our own high-voltage lines to the National Electric System, from whom the remaining demand is purchased to fully cover our needs.
Supplementary services include a hospital, elementary and secondary schools and churches.
There are also hotels for administrative staff, retailers and markets managed by licensees.
