The copper-gold sulphide mineralization present at the Candelaria Copper Mining Complex is generally referred to as iron oxide copper gold (“IOCG”). Depending on lithology and the structural setting, the polymetallic sulphide mineralization can occur as veins, hydrothermal breccias, replacement mantos, and calcic skarns.

Calcareous, sedimentary, and volcaniclastic rock of the Abundancia and Punta del Cobre formations are exposed within the open pit of the Candelaria mine. Due to the closer proximity to the Coastal Batholith, rocks in the open pit of the Candelaria mine show stronger metasomatism and metamorphism than in other sulphide deposits of the Punta del Cobre district.

The lowermost unit in the Candelaria mine and Candelaria Underground is the Lower Andesite, a compact succession of porphyritic to massive andesite and volcaniclastic breccias with intense biotite-quartz-magnetite-albite alteration. The Lower Andesite is overlain by a succession of stratified volcaniclastic rocks including tuffs, which are further sub-divided by alteration and mineralisation into pink garnet skarn and magnetite breccia. The Upper Andesite of the Punta de Cobre Formation consists of a homogenous succession of undifferentiated volcaniclastic and andesitic rock. The biotite-bearing andesite exhibits alteration varying from quartz-pyroxene hornfels to pyroxene-scapolite-garnet skarns.

At the Candelaria mine a low angle shear zone, located at the confluence of ductile to brittle highangle faults, marks synplutonic brittle-to-ductile extensional deformation.

The main mineralized body at the Candelaria mine is hosted in rocks of the Punta del Cobre Formation. Specifically, the host rocks are massive andesite and andesite breccias of the Lower Andesite, and volcanic tuffs and volcaniclastic rocks comprising the base of the Upper Andesite. In the metasedimentary rock unit, the mineralization is confined to a few isolated layers (mantos).

The mineralized body is up to 400 metres thick in its central part and thins towards the edges. In east-west sections, the mineralization has a lenticular, downward concave shape with a steep eastern limb and a shallowly dipping western limb. The shape of the mineralized body in north south section is irregular. In plan view, the extent of the mineralization is approximately 1,400 metres by 2,400 metres. The mineralized body was folded after its formation. The north-northeast trending fold axis corresponds to the Tierra Amarilla Anticline.

The mineralization assemblage in the Candelaria mine consists of chalcopyrite, magnetite, pyrite, pyrrhotite, and sphalerite. Biotite, calc-silicate minerals, and potassium feldspar constitute the gangue minerals. Pervasive potassic alteration is associated with the mineralization.

Dominant copper mineralization styles are mantos, veins, breccia bodies, and veinlets along foliation planes. Gold occurs within chalcopyrite grains and along fractures surface in pyrite. Chalcopyrite and pyrite also occur in secondary northwest and north-northwest-striking faults.

Minera Candelaria consists of the Candelaria Open Pit and the Candelaria Underground mines.

The open pits will operate with an overall mining rate of approximately 310,000 tonnes per day for the next ten years. As the final Candelaria Phase 13 waste stripping is completed the overall mining rate will decline. A stockpile strategy has been developed to maximize the grade of material going to the processing facility.

TThe Candelaria open pit was designed to be mined in several phases of development. As of June 2018, five phases of development remain in the LOM plan.

The primary components for the open pit slope design include bench geometry, inter-ramp, and overall slope angles (Figure 28). The current pit dimensions are 2,200 metres by 1,400 metres with a depth of 700 metres. Current inter-ramp slope angles range from 45 to 52 degrees in the west wall and from 52 to 57 degrees in the east wall. Bench face angles range from 65 to 72 degrees.

The Candelaria Open Pit is relatively dry owing to its location in an arid region. The northeast wall appears to be receiving some seepage from the toe of the tailings dam. Horizontal drain holes have been drilled up to 200 metres into the wall to reduce pore pressures in the area of the Lar fault.

SRK is of the opinion that the stopes that support the proposed LOM plan for the Candelaria, Alcaparrosa and Santos underground mines can be mined as expected. The three underground mines utilize a sublevel open stoping mining method for ore extraction. This method is ideal for relatively large, vertical, thick deposits with favourable (stable) host rock.

Stope excavations can typically be up to 180 metres high with sublevels at 20 to 60 metre intervals. The length of the stopes ranges from 40 to 100 metres, with widths varying between 20 to 30 metres. A Redbore RB50 or down-the-hole (DTH) drill is used to create a slot at one end of the stope, which will provide the relief necessary when blasting commences. Stope blastholes are drilled downwards from the sublevel drilling drifts as benches, using 114- to 140-millimetre diameter holes. The holes are loaded and blasted in vertical slices towards the open face created by the slot blasting. The blasted ore gravitates to the bottom of the stope and is collected in draw points at the production level below. This lower level also consists of the haulage (transport) drift.

Run-of-mine ore is trucked to a primary gyratory crusher. The crushed product is transported using an overland conveyor belt to a coarse ore stockpile with a combined live and dead capacity of 500,000 tonnes. Semi-autogenous grinding (SAG) mills are followed by pebble crushing, with separate grinding of a portion of the crushed pebbles and the remainder brought back to the SAG mills. This circuit is followed by closed-circuit ball milling with hydrocyclones to classify the flotation feed size.

The Candelaria processing plant receives ore from the Candelaria Open Pit and the Candelaria Underground (North Sector) and Alcaparrosa underground mines. It has a nameplate capacity of 75,000 tonnes per day. The Pedro Aguirre Cerda (PAC) processing plant receives ore from the Santos underground mine and has a design capacity of 3,800 tonnes per day.

The historical processing performance of Minera Candelaria from 2000 to mid-2017 averaged 25.6 million tonnes per year, equivalent to approximately 70,000 tonnes per day with a utilization of 93 percent. During this period, metallurgical recovery averaged 94 percent for copper, 75 percent for gold, and 83 percent for silver.

The Candelaria processing plant flowsheet is conventional, comprising two parallel process lines for grinding and flotation, reclaimed process water from a conventional tailings dam, final concentrate filtration, and shipping of bulk copper concentrates. A multi-stage flotation circuit using an ar ........