The Ccalla and Azulccacca zones of the Cotabambas deposit are considered to be examples of porphyry copper deposits. The two host porphyries cover an area about 2.5 km long and 1.5 km wide.

Mineralization occurs in hypogene, supergene enrichment and oxide zones. A welldeveloped leached cap hosts the oxide mineralization. Sulphide mineralization occurs below the base of the leached cap. This zonation is considered to be typical of porphyrystyle copper and porphyry-style copper–gold deposits.

Hypogene mineralization in the Project area has been intersected at depths from approximately 20 m from surface to depths of over 500 m from surface.

Hypogene copper–gold–silver mineralization is best developed with pyrite mineralization in quartz–sericite-altered quartz monzonite porphyry dykes running parallel to the north north-east trending structural corridors at Ccalla and Azulccacca. Mineralization occurs as disseminated chalcopyrite and pyrite, pyrite-chalcopyrite stringers or veinlets and quartz chalcopyrite pyrite veinlets. Local patches of hypogene mineralization are developed in diorite, peripheral to the quartz monzonite porphyry, where the north–northeast-trending structural system passes within 10 to 20 m of the diorite–porphyry contact. Chalcopyrite mineralization intensity decreases and disseminated pyrite mineralization increases distal to the higher grade parts of the hypogene zone.

Sulphide mineralization consists of chalcopyrite and pyrite and gold grades are strongly correlated to copper grades in the hypogene zone. Some occurrences of bornite have been noted in deeper portions of the hypogene zones. Silver grades are not as strongly correlated to copper grades as they are to gold grades, but are generally elevated where copper–gold mineralization is present.

Zones of high-grade chalcocite mineralization with lesser covellite and chalcopyrite occur at the top of the hypogene sulphide mineralization, and at the base of the leached cap. Supergene zones occur at Ccalla and Azulccacca and are characterized by high chalcocite content, correspondingly high cyanide-soluble copper assay grades and total copper grades that are generally >1%.

Oxide mineralization occurs in the leached cap of the Ccalla and Azulccacca deposits. Iron oxides and oxy-hydroxides replace pyrite, and oxide copper–gold mineralization occurs as patches of green copper oxides, typically chrysoscolla, malachite and broncanthite. Copper oxides occur as coatings on disseminated chalcopyrite grains and as fill in fractures and veinlets.

Lenses of oxide copper–gold mineralization having lateral extents of 100 to 200 m and thicknesses of 10 to 50 m have been mapped in outcrop and intersected in core drill holes.

Oxide gold mineralization has been defined in a lens in the Azulccacca area, but has also been intersected in short, isolated 1 to 5 m intervals in other parts of the leached cap of the deposit. Oxide gold mineralization is associated with limonite and occurs near major structures cutting the hypogene sulphide zone that are associated with the quartz monzonite porphyry.

A PEA open pit mine plan is developed for the Cotabambas project.

The PEA mine plan is based on a subset of the Mineral Resources. No mining dilution was incorporated in the plan. The assumed mill feed throughput is 80,000 t/d (29.3 Mt/a)

Two open pits will be mined, in seven pit phases, utilizing 12 m high benches. Cotabambas has a projected life of mine of 18 years, considering one year of prestripping and 17 years of feed to the plant.

A WRF with a maximum capacity of 369 Mm3 will be located in Guaclle Creek. Waste will be transported by truck

The operating fleet will consist of a conventional diesel fleet. Equipment requirements were estimated using first principle calculations

Haulage requirements are based on measured annual haulage profiles from the two pits. The average haulage distance for mineralized material to the primary crusher is 3.3 km. The average haulage distance for waste by trucks is between 3 and 4 km.

The mine plan assume that Cotabambas will operate seven days a week, twentyfour hours per day with four crews rotating to fill the mine roster of 12 hours per shift.

Mine infrastructure includes shops, warehouse, washing and welding bays, fuel stations, explosives magazine and administrative offices.

Main consumables for mine operations include diesel fuel, ANFO, emulsion and tires.

The plant design consists of a plant with a nominal processing capacity of 80,000 t/d and it includes crushing, grinding, flotation, concentrate dewatering and tailings disposal.

Mineralized material will be processed in a conventional copper porphyry flotation concentrator plant to produce a copper, gold and silver concentrate, with copper as the main payable metal in the concentrate and gold and silver providing important economic by-product credits.

The process considers a primary crusher, a SAG mill and a ball mill prior to the flotation plant consisting of rougher flotation, regrinding and three cleaner stages. Flotation tailings will be thickened and pumped to a tailings storage facility for disposal and final product concentrate is dewatered for storage and transport to port by trucks.

The selection of the conventional SAG/ball grinding circuit and equipment is based on a typical process flowsheet for this type of mineralization and scale of the Project. However a comminution trade-off study and further testing needs to be done.

Milled feed will be processed in a conventional rougher, regrind and cleaner copper flotation plant to produce about 270,000 t/a of copper concentrate with a grade of 27.0% Cu and 11.5 g/t Au. Concentrate will be dewatered to about 8% moisture, and tailings will be pumped to a TSF at 62 wt% solids for disposal.

About 80% of process water in the plant flotation tailings stream will be recovered and recycled to the process from tailings thickeners (75%) located at the plant site and as reclaim from the thickened tailings storage facility (5%). Water make-up requirements for the plant are estimated to be about 364 L/s.