Chile’s El Teniente deposit is the largest known porphyry Cu-Mo orebody (>70 Mt Cu), and is genetically related to Late Miocene–Early Pliocene igneous activity on the western slopes of the Andean Cordillera (cf. Howell and Molloy, 1960, Camus, 1975, Cuadra, 1986, Skewes and Stern, 1995). The deposit is 2700 m long by 1000 to 1700 m wide and is elongated in a N-S direction, with a recognized vertical extent of about 1800 m. Approximately 80% of the copper at El Teniente is distributed within a stockwork of mineralized veinlets and minor hydrothermal breccias within pervasively altered andesites, basalts and gabbros that are part of the Upper Miocene country rocks. Two intrusive bodies occur within the deposit, the Sewell Diorite (actually a tonalite) in the southeast part of the orebody and the dacitic Teniente Porphyry in its northern part. The Teniente Porphyry occurs as a north-south trending dike 1500 m long and 200 m wide. Minor quartz-diorite or tonalite intrusions known as the Central Diorite and the Northern Diorite occur along the eastern side of the deposit. Hydrothermal breccias commonly occur along the contacts of intrusive bodies with the country rocks. The Braden Breccia is a conspicuous diatreme in the center of the deposit that forms a pipe 1200 m in diameter at the surface, narrowing to 600 m at a depth of 1800 m. The Braden diatreme pipe is poorly mineralized (~0.3% Cu), but it is surrounded by the copper-rich Marginal Breccia, a discontinuous rim of tourmalinematrix hydrothermal breccia.

Latite dikes intrude El Teniente, some forming altered ring dikes that encircle the Braden breccia pipe. After mineralization had ceased, the southern section of the deposit was cut by a 3.8 ± 0.3 Ma lamprophyre dyke, marking the end of igneous activity (Cuadra, 1986). Biotitedominated K-silicate alteration is widespread within the orebody. In contrast, pervasive phyllic alteration is restricted to ‘diorite’ intrusions, and to the Braden and Marginal breccias. Phyllic alteration primarily occurs as quartz-sericite haloes of quartz–sulfidesulfate veinlets within the perimeter of the orebody, and slightly overprints potassic alteration. Propylitic alteration occurs largely peripheral to ore-grade rock. The relatively restricted development of phyllic alteration and the occurrence of the central breccia conflict with the classic porphyry copper model of Lowell and Gilbert (1970), but El Teniente may be regarded as a “variation on a theme” of the classic model, as suggested by Gustafson and Hunt (1975).

A typical level model used at El Teniente mine: block caving, production, ventilation, transport and crushing.

Grinding process in El Teniente concentrator is divided in three plants:

Sewell plant: With a processing capacity of 12,000 tpd (tons per day), is the oldest plant in El Teniente. Its crushing section feeds 22 primary bars and 30 secondary ball mills. The pulp is conducted through a channel to the conventional flotation plant in Colón Bajo, distant 9,3 Km.

Colón plant: Located in Colón Bajo, has a nominal processing capacity of 58,000 tpd and is composed by a secondary/terciary crushing section and 13 ball mills. The product is processed in the same colective conventional flotation plant as Sewell production.

SAG plant: Also located in Colón Bajo, has a nominal processing capacity of 70,000 tpd. In its two SAG lines (one SAG, two ball mills for each line), process the mineral crushed in the primary crushing plant. Pebbles generated by both SAG lines are processed in a centralized crushing plant. The product of both SAG lines is processed in its own fl ........