The Vizcachitas mineral deposit has similar characteristics to other Andean-style porphyry copper and molybdenum mineral deposits. This type of mineralized deposit contains large masses of hydrothermally altered rocks, sulphide-bearing small veins, disseminated sulphides, quartz veins and stockworks that may cover several square kilometres. These altered areas are commonly coincident with shallow intrusives, hydrothermal breccias and intrusion breccia.

The mineralized system of Vizcachitas comprises complex porphyries and breccias with copper and molybdenum mineralization, which intrudes andesitic volcanic rocks. The earliest intrusive rocks are porphyries of diorite composition. The petrographic work identifies this unit as a diorite with biotitized mafics (phlogopite) with deformed quartz veins and others of hyaline quartz/anhydrite veins. This is associated with abundant chalcopyrite and development of sericite haloes where the pyrite is greater than chalcopyrite. This phase has the highest primary grades for both copper and molybdenum.

Hydrothermal breccias have various matrix including: siliceous, silica-K feldspar, silica-sericite, silica-anhydrite, silica- sulphides and silica-tourmaline. These are genetically related to each igneous event. The hydrothermal breccias are normally associated with higher copper grades than their related intrusive phase.

The first inter-mineral intrusive phase is of a tonalitic composition and is followed ........

An open pit mining method has been selected for the Vizcachitas deposit mainly owing to the copper and molybdenum grades and the continuous mineralization occurring near the surface, which is a considerable benefit in relation to the waste/mineral ratio for open pit mining.

Previous engineering studies have discarded an underground mining option owing to the lack of grades to support such an option.

The mine has been scheduled to operate 360 days per year. The plan contemplates two 12-hour shifts per day. Mining operations include drilling, blasting, loading, hauling and support services.

The annual operation period defined for the mine considers minimal snow-related downtime. The deposit is located at an average elevation of 2000 masl, with potentially minor snow events. The roads and working areas may be promptly cleared by using support equipment considered in the operation.

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Copper-Molybdenum Flotation Circuit Design
The flow sheet selected shown in Figure 17.2 consists of rougher flotation, rougher concentrate regrind, three stages of cleaner flotation and three stages of scavenger flotation. The mineralized material will require a fine regrind of the rougher concentrate to a P80 of 45 µm to achieve adequate recovery. After regrinding, conventional flotation will be used to enable the production of commercial grade concentrates.

Rougher concentrate, as well as first and second scavenger concentrate, will report to the regrind cyclone pump box. The regrind cyclones will target an overflow size of P80 at 45 µm, which will be achieved with a cluster of cyclones operating in reverse closed circuit. The cyclones overflow will report to the first cleaner flotation while the underflow will feed the vertical mill. The vertical mill discharge will recirculate back into the cyclone pump box.

The first cleaner stage will be composed of con ........