The Mount Milligan deposits are categorized as silica-saturated alkalic Cu-Au porphyry deposits (Lang et al., 1995; Panteleyev, 1995) associated with alkaline monzodioritic-to-syenitic igneous rocks and are recognized in only a few mineral provinces worldwide (Deyell and Tosdal, 2004). Mineralization at the Mount Milligan deposit consists of two styles, early-stage porphyry gold-copper (Au-Cu) and late-stage high-gold low-copper (HGLC). The early-stage porphyry Au-Cu mineralization comprises mainly chalcopyrite and pyrite, occurs with potassic alteration and early-stage vein types and is spatially associated with composite monzonite porphyry stocks (especially at their hanging-wall and footwall margins), hydrothermal breccia, and narrow dyke and breccia complexes. Late-stage, structurally controlled pyritic HGLC style mineralization is associated with carbonate-phyllic alteration and intermediate- to late-stage vein types, and is spatially associated with faults, fault breccias and faulted lithological contacts (i.e. faulted monzonite porphyry dyke margins). It crosscuts and overprints the earlier stage porphyry Au-Cu mineralization. Porphyry style Au-Cu mineralization occurs in the hanging-wall and footwall zones of the MBX, Saddle, Southern Star, and Goldmark stocks. Disseminated and vein/veinlet-hosted mineralization is associated with the composite monzonite stocks, their brecciated margins and variably altered volcanic host rocks. Core zones of auriferous chalcopyrit ........

The mining operation is a conventional shovel and truck open pit mine feeding a 60,000 tpd (permitted throughput on an annualised basis) processing plant. The planned mine life is just over 11 years (2022 – 2033). The pit has been planned as a series of seven discrete pushbacks and scheduled to maximize the production of ore. Total ore and waste will be mined at a rate of 54.3 Mt/a in 2023, 51.9 Mt/a in 2024 and decreasing to 19.6 Mt/a by 2032 with the last reclaim of 1.9 Mt from the stockpile in 2033. This yields an overall LOM waste:ore ratio of 0.88:1.0. The mining sequence has been developed to allow for provision of suitable waste material for annual TSF construction requirements.

Pit slope designs are based on double-benching 15 m high benches and consider haulage ramp positioning, safety berms and other geotechnical features required to maintain safe inter-ramp angles (IRA) and overall slope angles.

Equipment sizing for ramps and working benches is based on the use of 229 t rigid-frame haul trucks. The operating width used for the truck is 8.3 m. This means that double lane widths are 34 m (three times the operating width plus berm and ditch). Ramp gradients are 10% in the pit.

MINE SCHEDULE
The 2022 LOM mine schedule considers pit mining from 2023 onward and stockpile reclaim (and includes a forecast stockpile balance at the end of 2022 of 2.7 Mt), delivers 220.9 Mt of mill feed grading 0.37 g/t gold and 0.18 % copper from 2023 – ........

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