The New Afton deposit is a copper-gold, alkalic porphyry system situated within the Iron Mask batholith complex. The Iron Mask complex is part of the Paleozoic age island-arc assemblage known as the Quesnel Terrane. Regional-scale fault zones are believed to be the principal control to intrusion of the batholithic rocks and related copper and gold mineralization in the New Afton area.

Mineralization is characterized by discontinuous copper sulphide veinlets and disseminations (principally chalcopyrite and minor bornite) at brecciated margins between altered porphyry intrusives and volcanic rocks of the Triassic Nicola Formation. The copper sulphides are replaced by tennantite-tetrahedrite locally and along faults that transect the mineralized body. Native copper with accessory chalcocite occurs in minor amounts within highly oxidized near-surface portions of the deposit. Gold and silver generally occur as electrum grains within the chalcopyrite and bornite.

The bulk of the New Afton deposit forms a tabular, nearly vertical, southwest-plunging zone of continuous mineralization measuring 1.4 kilometres long by approximately 100 metres wide, with a down-plunge extent of over 1.5 kilometres. The deposit plunges toward the southwest where it remains open at depth.

Mineralization results from late stage hydrothermal activity driven by remnant heat from the porphyry intrusion. Thermal gradients within these systems give rise to broadly concentric, although often complexly intermingled, zones of alteration and mineralization. The distribution of alteration and mineral facies are largely influenced by dikes, veins, and fracture systems which concentrate and control fluid flow.

The principal host rock for the New Afton deposit comprises crystalline and polymictic fragmental volcanics belonging to the Triassic Nicola Formation and lesser monolithic intrusive breccias. These rocks have been altered and mineralized by a monzonite intrusive consisting of a fault controlled elongated stock and related dike swarm. The monzonite is generally weakly mineralized to unmineralized and is interpreted as the causative intrusive phase that is less susceptible to the introduction of sulphide mineralization. Its geometry is best described as a narrow, elongated stock that remains open at depth and pinches down plunge to the west.

The primary mine site host lithologies are described by New Afton geologists as follows:
Polymictic Fragmental Volcanic Breccia: Comprising poorly sorted, variably coloured, massive to phyric, angular to sub-rounded, lapilli to block sized clasts of porphyritic diorite, andesite, basalt, picrite, and aphyric volcanics within coarse-grained crystal-rich matrix. Clast rock types are commonly porphyritic diorite, andesitic flows, mafic volcanics, picrite and aphyric volcanics within ash to coarse grained crystal dominated matrices.

Monomictic Volcanic Breccia: Contains subangular crystal-rich clasts of diorite or monzonite or Nicola Group volcanic rocks and are commonly located on the margins of intrusive bodies.

Crystalline Volcanic Rocks: Crystal tuffs and andesite flows dominated by very fine and fine to medium grained subhedral to anhedral, broken and or embayed phenocrysts of plagioclase ± pyroxene ± hornblende. Contains less than five percent by volume of coarse ash to lapilli sized lithic fragments within a variably altered fine grained to ash matrix.

Copper-gold-silver mineralization occurs as disseminations and fracture-filling sulphide grains occurring in three roughly tabular east-west striking, steeply dipping bodies. The Main Zone, as its name suggests, is the principal zone of mineralization. Present mining operations are located within the Main Zone. It is flanked to the east and south by two smaller bodies called the HW Zones.

The mineralization at New Afton is grouped into three broad categories: hypogene, secondary hypogene, and supergene. The term describing secondary hypogene mineralization has changed over time from mesogene to secondary hypogene and is now thought of as late hypogene/epithermal assemblage. Secondary hypogene has been retained for consistency in order to minimize confusion. Hypogene was originally ascribed to primary copper sulphide mineralization that had not undergone significant oxidation. Presently, hypogene refers to chalcopyrite and accessory bornite mineralization which forms the core of the deposit and is dominated by biotite alteration. This is noted to typically occur along the northern margins of the monzonite stock in the Main Zone and discontinuous monzonite dykes in the HW Zones. For logging purposes, hypogene mineralization is defined as having greater than 1% sulphides, or 0.5% sulphides in bornite-dominant zones.

Secondary hypogene is a later overprint of mineralization upon primary sulphide mineralization by tennantite-enargite + tetrahedrite with possible bornite and chalcocite. The secondary overprint is associated with pervasive kaolinite-rich argillic alteration localized along narrow fault zones and is responsible for the introduction of the deleterious elements: arsenic, antimony, and mercury. It is thought to be related to late-stage, lower temperature low-pH fluids that ascended along high-angle structures and remobilized copper from primary sulphides to form sulphosalts and high-sulphidation state sulphide minerals. Secondary hypogene mineralization appears as sooty steel grey to bluish grey reaction rims on chalcopyrite blebs and stringer fractures. The distribution of secondary hypogene mineralization is very narrow and discontinuous and commonly restricted to faults such as the HW, J, E and D faults, particularly where they intersect.

The supergene mineralization type consists of native copper and chalcocite that formed through oxidation of primary sulfides within the uppermost portion of the deposit that were exposed to weathering and erosion during the Eocene to Quaternary. The domain is roughly conical in shape and centered below the New Afton pit, limited to the east by the M fault. The supergene domain is defined for logging purposes as having 0.5% or greater native copper, or, in the absence of native copper, intervals of strong oxidation with a threshold assay of 0.2% Cu.

The mineralized zone, as it is delineated to date, is a sub-vertically dipping, generally continuous, tabular body extending downwards from the base of the existing pit. The body plunges to the southwest at an angle of 50°, extending 1,570 m from surface to the lowest drill hole intercept. The Main Zone measures approximately 220 m across strike at its widest point, and it tapers with depth and along strike. Two smaller satellite bodies are located on the hanging wall side of the Main Zone, bringing the maximum width of mineralization subtended by all bodies to just over 470 m.

The New Afton Mine is a block cave mining operation. Other mining methods, including open pit mining and sublevel caving, were considered but block caving was chosen for the New Afton deposit because this method starts from the bottom and is conducive to large-scale low-cost mining. Ore is transported from the drawpoints, on the extraction level, by a load haul dump loader (“LHD”) to an ore pass. The ore is then re-handled on the haulage level by an LHD and loaded into a haul truck. The haul truck transports the ore to the underground gyratory crusher and the crushed ore is conveyed to surface.

There are three general zones at the mine, located beneath and to the south west of the historic Afton open pit – Lift 1 (B1 & B2), B3 and C-Zone. Lift 1, including the Recovery Level program, was closed in the second quarter of 2022. Primary ore is being extracted from the B3 zone until such time as production from the C-Zone commences.

In the B3 block cave, located 160 m below and immediately to the west of Lift 1, ore will be hauled by truck to the existing gyratory crusher. In the C-Zone block cave, located 550 m below and to the west of Lift 1, ore will be hauled by LHD from the drawpoints to the ore passes and then to a new gyratory crusher. The ore will then be conveyed from the crusher to a junction with the existing conveyor for movement to surface.

The operation is planned to produce 4 to 6 Mtpa of copper-gold ore for processing over the life of mine. Waste mined as part of development activities is transported to surface by conveyor and deposited in an area apart from the ore via a belt plow. The waste is then trucked to an area on the edge of the historic Afton mine pit. Less than 5% of the mined rock is treated in this manner.

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The process plant has been in operation since 2012. Throughput in the process plant has been averaging above the nameplate of 11,000 tpd since early 2013. A mill expansion was completed in 2015 to add a tertiary stage of grinding and additional flotation cleaning capacity. This allowed throughput to increase to a peak average of 16,420 tpd in 2017. Throughput for 2022 averaged approximately 9,100 tpd. The surface stockpiles used to supplement the lower tonnes mined in 2022 were exhausted by the third quarter of 2022. For 2023, the throughput is expected to be maintained throughout the year at approximately 8,100 tonnes per day.

To process supergene ore, which commenced in 2019, gravity recovery capacity was added to the ball mill circuit and increased in each of the tertiary and regrind circuits. In the ball mill circuit, two inline pressure jigs (one rougher and one cleaner) were installed along with a magnetic separator for removal of magnetite and a portion of the hematite from the cleaner jig concentrate. The jigs were selected for the ball mill circuit primarily due to their ability to process a coarse feed compared to flotation or centrifugal concentrators.

The flowsheet changes were made primarily to recover native copper; however, the jigs have also recovered native gold associated with the supergene ore. With supergene ore being completed during the third quarter of 2022, the gravity circuit operation will be adjusted in 2023 to focus on gold rather than native copper recovery. Life-of-mine recoveries are expected to average 90% for copper and 87% for gold. Recoveries in 2023 are expected to be 85%-92% for copper and 80% - 87% for gold.

FLOTATION
The tertiary grinding cyclone overflow flows by gravity into the rougher flotation circuit, which consists of two staged flotation reactor (SFR) cells in series followed by six 100 m3 flotation tank cells in series. The two SFRs were commissioned in Q2 2017. The concentrate from the rougher flotation cells is collected in launders and flows by gravity to the regrind circuit; the tailings from the final rougher cell is discharged into the tailings pumpbox.

The regrind circuit grinds the rougher flotation concentrate, to decrease the particle size to 80% passing 35 µm to 40 µm, prior to it being processed in the cleaner flotation cells. The regrind circuit consists of a 932 kW Vertimill in closed circuit with the regrind cyclopac. The underflow stream from two of the operating regrind cyclones is processed through two XD-40 Knelson concentrators to recover liberated gold and native copper from the regrind circuit. The Knelson concentrate discharges to the 3rd cleaner concentrate pumpbox, where it is pumped to the concentrate thickener. The Knelson concentrator tailings are discharged back to the regrind cyclone feed pumpbox. The regrind cyclone overflow discharges into the cleaner flotation circuit and the tailings flow to cleaner scavenger flotation. Cleaner scavenger tailings report to the tailings pumpbox. Three SFR cells were added to the head of cleaner flotation as part of the mill expansion project in 2015 to increase cleaner flotation capacity. The concentrate from these three cells is combined with the inline pressure jig final concentrate, 3rd cleaner concentrate, and regrind Knelson concentrates to produce the final copper concentrate for dewatering.

DEWATERING
The final concentrate is pumped to the concentrate thickener, where the solids achieve an underflow slurry density of approximately 55% solids. The slurry is pumped to an agitated tank and subsequently pumped into one of the two filter presses, where the concentrate is dewatered to less than 9% moisture. The dewatered concentrate is discharged from the filter presses directly into the concentrate storage shed, before being loaded onto trucks and transported to the Port of Vancouver for shipping.

TAILINGS
Currently, tailings streams from the rougher flotation and cleaner-scavenger flotation circuits are discharged into the tailings pump box and pumped to the tailings storage facility (TSF). The tailings are cycloned at the TSF for use in internal tailings dam construction.

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