Constancia mine include the Constancia and Pampacancha deposits

CONSTANCIA
The Constancia deposit is a porphyry copper-molybdenum system which includes copper-bearing skarn mineralization. Multiple phases of monzonites and monzonite porphyry have intruded a sequence of sandstones, mudstones and micritic limestone of Cretaceous age.

The majority of the mineralization is associated with potassic alteration and quartz veining, occurring as chalcopyrite-(bornite)-molybdenite-pyrite mineralization in “A” and “B” type veinlets, and replacing ferromagnesian minerals or filling fractures. Copper grades are highest where fracture-filling style copper mineralization is superimposed on earlier disseminated copper mineralization. The higher-grade hypogene copper mineralization is hosted by a dense A-veinlet stockwork developed in an early porphyry phase. The pyrite/chalcopyrite ratio is typically below 2:1. Molybdenite commonly increases with depth in association to “B” veinlets. Bornite occurs sporadically especially at deeper levels, sometimes associated with some gold values.

Propylitic alteration is transitional to the potassic alteration and extends more than one kilometre from the porphyry intrusive contacts. The propylitic alteration mineral assemblage includes epidote-chlorite-calcitepyrite-rhodochrosite. Subordinate chalcopyrite is also present, filling fractures or replacing mafic minerals. Sphalerite-galena veinlets and veins are distributed as a halo to the copper-molybdenum mineralization within the propylitic alteration zone up to 3 km away from the porphyry copper system.

Phyllic alteration forms a pervasive carapace surrounding and sometimes overprinting potassic alteration. The phyllic alteration accompanies almost complete destruction of primary rock textures; the mineral assemblage includes sericite-quartz-pyrite, limited amounts of chalcopyrite and associated occasional “D” veins and veinlets.

At the contact between intrusions and limestones, a magnetite garnet skarn develops, while a pyroxene– diopside (garnet–epidote) association is more common in calcareous sandstones and arkoses of the Chilloroya formation. Skarn mineralization is volumetrically much smaller, but grades are normally higher.

Structural deformation has played a significant role in concentrating the hydrothermal alteration and the copper-molybdenum-silver-gold mineralization, including skarn formation. Major inter and post mineral fracture systems in the deposit area strike northeast and include the Barite fault system. This is represented by a number of nearly parallel vein-faults carrying base metal sulphides and barite which have been exploited by artisanal workings throughout the property. A second important system strikes northsouth. It appears to be more recent than the Barite system and controls part of mineralization and most of the silicified breccias (sometimes mineralized) in the system.

PAMPACANCHA
The Pampacancha deposit is a porphyry Cu-Mo-Au related Skarn system. Oligocene unmineralized basement diorite is intruded by the diorite porphyry cited as the source for skarn mineralization. This in turn is cut by intra-mineral monzonite intrusions which provide minor local increases in Cu-Au and also locally replaces skarn Cu-Au mineralization which is most developed at the upper and lower margins of the limestone body. Magnetite-chalcopyrite-pyrite skarn ranges to marginal less well mineralized garnet and pyroxene skarn, locally overprinted by epidote-bearing retrograde skarn.

Epithermal mineralization as low sulphidation quartz-sulphide Au + Cu style accounts for common supergene enriched Au anomalies along with other features such as hydrothermal alteration and veins typical of near porphyry locations.

The Constancia mine is an open pit mining operation relying on conventional trucks and shovels. The Constancia ultimate pit design will measure approximately 1.6 km east to west, 1.7 km north to south, and have a maximum depth of around 705 m. The Pampacancha ultimate pit design will measure approximately 0.6 km east to west, 1 km north to south, and have a maximum depth of about 300 m. A primary waste rock facility (WRF), which is located to the south and east of the Constancia pit, is intended to be used for both deposits.

The processing facility is located approximately 1 km west of the Constancia Pit. The NAG waste rock is deposited south of the Constancia pit, while the tailings management facility (TMF) is located 3.5 km southwest of the Constancia pit.

DESIGN CRITERIA
Constancia is mined in nine stages and a two stage pit is planned at Pampacancha. The minimum mining width for each phase is 60 meters; this will allow a shovel, trucks (in two lines) and a drill to work safely and simultaneously.

The haul roads at Constancia and Pampacancha have been designed with a 10% grade and 32 m width for double lane haul roads and 24 m for single lane haul roads.

The final design for waste rock facilyty facility incorporates 20 m high benches with 1.4H:1V (36°) of bench slopes and 32 m wide benches. The overall slope of the stockpile will be about 3.0H:1V (18°). The current remaining capacity of the WRF is estimated at 413 Mt.

The Constancia mine is planned to have four operational stockpiles, which will segregate the ROM material by ore type and grade range. The lift height of these stockpiles ranges between 12 and 20 meters.

The Tailings Management Facility (TMF) area is where mill tailings are placed behind waste rock containment buttresses. The buttresses' material will come throughout the life of the mine, from mining operations and quarries. The TMF area is located southwest of the mining facilities area. The design for the TMF includes ramps access to the lower and upper levels for the regular mining fleet (240 tonnes trucks) and a smaller fleet called HCW, which has been used since October 2015 to send NAG material from the Constancia pit to the TMF area.

MINE PHASES AND ULTIMATE PIT
The extraction sequence is defined by nine mining phases at Constancia and two mining phases at Pampacancha. In parallel, seven pushbacks are planned for ore exposure purposes and optimal sequencing at Constancia with one pushback for waste and construction purposes. The phase development strategy consists of extracting the highest metal grades along with minimum strip ratios during the initial years to maximize the economic benefits while enabling smooth transitions in wastestripping throughout the life of the mine to ensure sufficient ore exposure.

MINE OPERATIONS
Open pit mining at the Constancia operation is based on conventional open pit mining techniques. The Constancia operation consists of two pits, Constancia and Pampacancha. The Constancia pit operation started in 2014.

In early April 2021, the company finalized the remaining land user agreement for Pampacancha and gained full access to the site to complete pit development activities. Blasting began in mid-April and first production from Pampacancha was achieved at the end of April

The mine production plan contains 569.4 Mt of waste and 532.5 Mt of ore (from pit and stockpiles), yielding a stripping ratio (waste/ore) of 1.1 to 1. An average yearly mining rate of 77.0 Mtpy, through the first 13 years, with a maximum of 81 Mtpy, is required to provide a nominal ore process feed rate of 31.3 Mtpy based on a variable throughput by ore type (90 to 94ktpd and 94% available). LOM average grades are 0.311% Cu, 0.009% Mo, 0.065 g/t Au and 3.04 g/t Ag, where the mine's life is 17 years.

For primary drilling production, single-pass 270 mm diameter (or 10 5/8”) drills are used. After evaluating equipment dimensioning, three drill rigs PV-271 were selected to achieve the production rate. The drilling ratio of the drill rig is approximately 45 m/h. Pre-split drilling is done with a Smart Rock D65 drill (downhole). Equipment used to improve the stability of the slopes and optimize the design of the phases.

For wet holes, Heavy ANFO 73 (70% of Emulsion and 30% of ANFO) and dry hole, Heavy ANFO 55 (50% emulsion and 50% of ANFO) is used. Based on the evaluation of productivity, powder factors are estimated to be about 0.40 Kg/t for ore and 0.30 Kg/t for waste.

Two 27 m3 (Hitachi EX5600-6) shovels and a 19 m3 (CAT 994H) loader are used to excavate blasted materials. The loader provides flexibility for blending purposes. Pampacancha is expected to enter into production in 2019, and will require a loader at the start of the mining activities.

All phases have been designed to achieve high productivity, taking advantage of double-side loading and working at faces around ~60 meters in width.

For life of mine, ore and waste will be transported by 240-tonne capacity haul trucks (CAT 793F). The use of this class of trucks minimizes road congestion, labor requirements, and operating costs. 240-tonne trucks require a minimum haulage road width of 32 meters.

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GENERAL
The processing plant has been laid out in accordance with established industry best practices for traditional grinding and flotation plants. The major objective was to make the best possible use of the natural ground contours to minimize pumping requirements by using gravity flows and to reduce the height of steel structures.

To optimize the cost of the major footings for the SAG mill, the height of the SAG mill above grade was minimized by situating the cyclone feed sump as low as possible. The mill cyclones have been located so that the cyclone overflow can gravitate into the rougher conditioning tank.

At the tailing end of the flotation bank, the copper tailings thickener has also been situated to facilitate gravity flow and eliminate the requirement for another large set of pumps.

Due consideration has been given to the layout of the molybdenum plant to facilitate good housekeeping and occupational health and safety requirements. ........