Overview

Deposit type

• Porphyry
• Vein / narrow vein

Summary:

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.

Mining Methods

• Block caving

Summary:

The underground mine consists of four block caves: East Cave, West Cave, B3 Cave and C-Zone Cave. East Cave and West Cave, together referred to as Lift 1, with an extraction level approximately 600 metres below surface, were mined from 2011 to 2022 and are now depleted. The B3 cave extraction level is approximately 760 metres below surface and has been in production since 2021. C-Zone cave, with an extraction level approximately 1,150 metres below surface, is in the production ramp-up phase, with commercial production expected in the second half of 2024.

The New Afton Mine is a block cave mining operation, which involves development of a footprint at the base of the cave including an undercut level, for initiating the cave, and the extraction level from which ore will be mucked from drawpoints for the life of the cave. Block caving requires upfront capital investment in development and footprint construction, followed by a production period with minimal capex and the lowest unit mining costs of all the underground mining methods. Other benefits of block caving include high production rates and a low environmental impact.

In the B3 cave, ore is transported from the drawpoints on the extraction level to an ore pass. The ore is then loaded into a haul truck and transported to the underground gyratory crusher at the base of Lift 1. Crushed ore is then conveyed to surface.

For C-Zone, development of the dual ramps from B3 commenced in the first quarter of 2019, reaching the C-Zone footprint in the second quarter of 2022. In October 2023, the New Gold announced the completion of the first draw bell at C-Zone which is significant because it is the transition point at which the block cave gradually ramps up ore production. Additional draw bells will continue to be constructed until the cave reaches hydraulic radius to achieve steady state self-cave propagation (considered commercial production for C-Zone), after which the extraction rate can be accelerated. Relative to other block caves, New Afton ore caves well, with Lift 1 and B3 achieving hydraulic radius as expected without any preconditioning required. C-Zone is expected to achieve hydraulic radius in the second half of 2024.

A second gyratory crusher will be installed and connected by conveyors to the existing Lift 1 conveyor system to surface, eliminating the cost of truck haulage. Of the three additional main conveyor legs, two are already installed and operational. Excavation of the crusher chamber is complete and has been handed over to the construction crew with commissioning expected in the second half of 2024 to align with the increased extraction rate.

The Lift 1 extraction level at New Afton employs straight-through drawpoints. The extraction level consists of a west and east cave with six and five strike drives respectively separated by a central pillar. Ore is mucked from the drawpoints with 6 yd3 LHDs and dumped down ore passes to the haulage level.

The haulage level consists of four main legs below the extraction level connecting to the ore passes. LHDs load from the ore passes and fill 45 t haul trucks which haul the material to a centralized crusher. From the crusher, the material is conveyed to surface onto an ore feed stockpile. Intermediate grade material is plowed off the conveyor at surface and stockpiled to be milled later in the mine life.

Comminution

Crushers and Mills

Summary:

Run-of-mine (ROM) ore is crushed to minus 150 mm through a 1,100 mm x 1,800 mm FLSmidth gyratory crusher located at the cave extraction level. The ore is then transported to surface via five conveyor belts. The final conveyor belt has a plow, which allows waste and low-grade ore to be diverted from the mill feed. The remaining ore discharges onto a 120,000 wet metric tonne (wmt) live capacity stockpile. Underneath this stockpile, two 1.8 m x 11 m apron feeders regulate the flow of ore onto the SAG mill feed conveyor. The SAG mill is an 8.5 m diameter x 4 m long Farnell-Thompson mill, driven by a 5,220 kW GE motor with a variable speed drive. The SAG mill discharge is screened over a 2.4 m x 6.1 m Deister doubledeck screen with 6 mm x 28 mm apertures on the lower deck. The screen-deck was upgraded from single to double deck in 2015 to allow for an increased milling rate. Both the upper and lower deck oversize are recycled to the SAG mill feed conveyor, with the option of crushing this recycle stream using an FLSmidth XL600 Raptor cone crusher.

Secondary grinding is accomplished using a 5.5 m diameter x 9.8 m long Farnell-Thompson fixed speed ball mill, driven by a 5,220 kW motor, in closed circuit with seven (five operating) Krebs GMax-26 hydrocyclones. Approximately 7% of the cyclone feed is diverted to a Gekko inline pressure jig and magnetic separation circuit for native copper and gold recovery and magnetite rejection, with concentrate reporting to the concentrate thickener. Approximately 15% of the secondary underflow feeds an Outotec Skim-Air 500 flash flotation cell with concentrate reporting to the rougher concentrate regrind circuit, and the tails reporting to the ball mill feed. The cyclone overflow reports to the tertiary circuit.

The tertiary grinding circuit was added as part of the 2015 mill expansion project. Prior to this, the ball mill cyclone overflow reported directly to rougher flotation. Tertiary grinding is accomplished using a Metso Vertimill 3000 in closed circuit with seven (five or six operating) Krebs GMax-26 hydrocyclones. The tertiary cyclone overflow reports to the rougher flotation cells. Approximately 15% of the tertiary cyclone underflow reports to a continuous CVD42 Knelson concentrator for native copper and gold recovery with concentrate reporting to the cleaner inline pressure jig feed. Both the SAG and ball mill circuit control is supported with an expert control system.

Installation of the C-Zone gyratory crusher was completed in October.

Processing

• Gravity separation
• Inline Pressure Jig
• Centrifugal concentrator
• Crush & Screen plant
• Flotation
• Magnetic separation
• Dewatering
• Filter press

Summary:

The processing flowsheet at the New Afton Mine consists of conventional crushing and grinding circuits, a flotation circuit and gravity circuit. Run-of-mine ore is crushed at the underground gyratory crusher and transported via conveyor belts to the crushed ore stockpile on surface. Ore is reclaimed from the stockpile using two apron feeders and transported to the grinding circuit, consisting of a SAG mill and ball mill.

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. 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.

With supergene ore being completed during the third quarter of 2022, the gravity circuit operation was adjusted in 2023 to focus on gold rather than native copper recovery. The concentrate from the flotation and gravity circuits produce the final copper concentrate for dewatering.

The processing plant throughput is currently limited by mine production and, with C-Zone ramping up in the next few years, the New Afton Mine intends to take advantage of the existing processing capacity at the mill to process up to 16,000 tpd.

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.

Pipelines and Water Supply

Summary:

A water pipeline approximately four kilometres in length can deliver fresh water from Kamloops Lake to the mine site. New Gold purchased the pipeline and pump house facilities from Teck as part of the purchase agreement in 2007. New Gold has a water permit to withdraw water from Kamloops Lake for mining and milling operations.

Kamloops Lake is the source of freshwater primarily used for ore processing make-up water, road dust suppressant, vehicle wash-down, fire control, and drilling. Three water licences authorize a maximum freshwater withdrawal of approximately 292.5 m3/hr from Kamloops Lake as follows:
• 2010 authorization (123886) for 139 m3/hr, plus 50 m3/day (2.1 m3/hr) for potable water purposes
• 2011 authorization (126715, with date of precedence extending back to 1973) for 0.38 m3/hr for use at DL2017
• 2015 authorization (132319) for 151 m3/hr

New Afton is working towards implementing an on-demand water strategy with the installation of a tailings thickener. The thickener overflow will recycle water to supply the majority of water required to support operations, however, make-up water is necessary to supplement the water needs. In the short term, an increase to water withdrawal from Kamloops Lake is being sought for a period of two years to a rate of 360 m3/hr to address current shortfalls in water supply needs. A permanent water licence is also being developed to increase the rate to 420 m3/hr.

Production

Operational metrics

Personnel

Job Title	Name	Profile	Ref. Date
Environmental & Permitting Manager	Luke Holdstock		Jun 11, 2024
General Manager	Jeffrey LaMarsh		Jun 11, 2024
Health & Safety Manager	Justin Clark		Jun 7, 2024
Maintenance Superintendent	Bryan Madsen		Jun 11, 2024
Mine Operations Superintendent	Tyler Roberts		Jun 15, 2023
Process Manager	Martin Froehling		Jun 11, 2024
Supply Chain Manager	Brian Gagné		Jun 11, 2024