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.

(Translated from Spanish)
Teniente Projects Portfolio consists of the following projects: Andes Norte Nuevo Nivel Mina (NNM), Diamante and Andesita, formerly Nuevo Nivel Mina, the original project, and which will extend the division operations by 50 years. We started mining Teniente Level 9, the deepest level compared to other areas currently in production.

In November 2022, Codelco launched the first 100% electric underground LHD (Load, Haul, Dump) mining loader in South America, which began its pilot test in the El Teniente Division. Developed by Epiroc, it can load up to 14 tons of material without generating direct greenhouse gas emissions into the atmosphere.

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Concentration
During the concentration process, which takes place in the industrial areas of the Colón and Sewell Divisions, the ore is reduced in size through the use of crushers and mills, where it is converted into a fine powder that is mixed with water and chemical reagents to form a slurry that enters the flotation stage. Here, a foam is produced to which copper and molybdenum particles adhere, separating them from the rest of the sterile material.

Smelting
In the smelter, the concentrate goes to a plant that extracts the humidity and, through a pneumatic transport system, it arrives at the Teniente Converters for the melting process. The main product of these converters is a white metal, which contains 75% copper. This white metal is then poured into the Pierce Smith converters, where the conversion process begins that gives rise to blister copper and from which fire-refined copper or RAF and anodic copper are finally obtained.

Current El Teniente pyrometallurgical process for copper concentrate was commissioned at Caletones Smelter during the period 1988–1991, following an intensive R&D program that led to several improvements to the original process developed during the seventies.

Current process involves four main stages to transform copper sulphide concentrate into blister copper, as follows:
- Wet concentrate drying down to 0.2 wt.% moisture;
- Smelting bone dried concentrate and partial converting to white metal;
- White metal converting to blister copper;
- Slag cleaning directed to recover copper from the slag produced during the smelting and partial converting steps.

The El Teniente converter process involves the smelting and partial converting of bone dried copper concentrate in a thermally autogeneous operation. This operation mode takes into account an improvement to the El Teniente converter original process. The bone dried concentrate is directly injecting to the molten bath, with a mixture of oxygen-enriched air up to 34 vol.% O2 through specially designed tuyeres. Siliceous flux and reverts are fed into the reactor through a garr-gun feeder. The products of smelting and oxidizing of copper concentrate with flux are two separate molten phases, the high grade matte or ‘white metal’ with the degree of oxidation being controlled so as to yield white metal with about 75 wt.% Cu and a slag that contains 7–10 wt.% Cu and 12–16 % Fe3O4. These molten phases are intermittently tapped in a countercurrent flow pattern, white metal at 1220°C and slag at 1240°C, through especially designed water cooled tapholes located at each side of the endplates. White metal is poured into ladles and transferred to the Peirce-Smith Converters, where final blowing to blister copper takes place. Normally three Peirce-Smith Converters are operating while another unit remains on stand-by or under maintenance. Slag produced is transferred by ladles or directly by launder, to the El Teniente slag cleaning furnaces for decoppering.

The El Teniente slag cleaning furnace process is based on an intensive reduction of magnetite and copper content in molten slag produced at the El Teniente converter, by injection of a solid, liquid or gaseous reductant directly in to the molten slag through specially designed tuyeres followed by sedimentation stage. The reduction of magnetite decreases the slag viscosity and enhances the settling of copper enriched phase. The molten products obtained after the settling stage are, a discard slag with a copper content less than 1 wt.% Cu, and a high grade copper matte with 60–70 wt.% Cu. The decoppered slag is poured into ladles, and then transported to dump by potcarriers. The high-grade copper matte is tapped into ladles and then recycled to the Peirce-Smith converters.

Sulphur dioxide and other gases produced inside the El Teniente reactors, continuously exhausted through the offgas mouths, are cooled, dedusted and used for sulphuric acid production.