All of the PGE-Cu-Ni mineralization documented on the Lac des Iles mine property is classified as magmatic sulphide mineralization. Conventional magmatic sulphide deposits are defined as disseminated to massive sulphide deposits hosted by ultramafic or mafic rocks that contain economic concentrations of base metals and/or precious metals (PGE, Au, Ag). These deposits can occur in intrusions or lava flows.

The Lac des Iles mine property captures the known extents of two discrete intrusive complexes, including the South Lac des Iles Intrusive Comlex (IC) comprising the former Mine block, South Lac des Iles and Camp Lake intrusions, and the North Lac des Iles IC. The North Lac des Iles IC is a polyphase intrusive body consisting of nested to locally crosscutting intrusions.

Intrusive contacts between the two bodies suggest that the southern part of the North Lac des Iles IC was younger than the northern margin of the South Lac des Iles IC.

Most of the North Lac des Iles IC consists of layered ultramafic rocks distributed within two types of cyclic units, including an orthopyroxene-bearing cyclic unit and an orthopyroxene-free cyclic unit. Historical surface prospecting, mapping and limited trenching and diamond drilling have identified several areas in the North Lac des Iles IC hosting PGE occurrences exceeding 1.0g/t of combined Pd+Pt+Au. These PGE occurrences are interpreted to represent stratiform or reef-type magmatic PGM mineralisation.

All past and current mineral resources described on the Property are located in the northwestern part of the South LDI Complex. PGE and Au mineralization in the South LDI Complex is most commonly associated with 1% to 2% of fine- to medium-grained disseminated iron-copper-nickel sulphides within broadly stratabound zones of PGE and gold enrichment. A majority of the known PGE-rich sulphide mineralization consists of approximately 50% pyrrhotite, 25% pentlandite and 25% chalcopyrite. In some mineralized zones, pyrite is the dominant iron sulphide mineral but these areas tend to have low PGE + gold grades (e.g., less than 1 ppm combined). Minor millerite is locally present in the PGE-rich mineral zones. Sulphides occur as polycrystalline aggregates that generally reflect the grain sizes and shapes of adjacent silicate minerals. The coarsest sulphide blebs observed at LDI are up to several centimetres long but typical sulphide aggregate sizes are less than two centimetres. Rare massive sulphide occurrences up to approximately one metre thick are also reported from the Property (Duran et al., 2016). Primary sulphide textures were commonly destroyed during late magmatic hydrous alteration such that the schistose PYXTE unit contains very fine-grained disseminated sulphides that are difficult to observe without the aid of a hand lens.

Nearly all of the known mineralized zones in the South LDI Complex occur at or adjacent to the boundary between breccia and norite series rocks. Most of the past and present mineral resources are contained in the semi-contiguous Roby and Offset zones. These two zones are considered to have been part of a single, vertically-oriented, disseminated magmatic sulphide deposit that was subsequently affected by post-magmatic displacement along the east-northeast striking and north dipping Offset Fault. Displacement on this fault appears to have involved dextral lateral movement and, possibly, normal vertical movement such that the Roby block moved down and to the right of the Offset block. However, there is conflicting evidence of the magnitude and sense of displacement of various geological markers along the Offset Fault including some mineral zones that show no apparent displacement.

Mine production at Lac des Iles occurs from three areas: the Offset Zone, the Roby Zone and the Open Pit. These areas are broken down further by mining method and mineralisation zone and/or spatial location. For the Offset Zone, except for the near-surface Sheriff South Zone, the ore is typically hoisted to the surface through the shaft. Ore tonnes from the Roby Zone are transported via haul truck through a ramp and the lower portal; a new replacement portal and ramp to the surface were completed during FY2021.

The majority of the planned production for the Roby Zone involves sub-level caving (SLC) targeting ore below and southwest of the current dormant pit. Production from these near-surface zones will involve a gradual ramping up of the caving operations culminating in steady-state production in FY2022. Production from the Offset Zone includes production by the open hole stoping (OHS) and sub-level shrinkage (SLS) methods. The SLS production represents the bulk of the Offset Zone production. Production from each of the lower mine zones will remain relatively constant over the LoM.

Sub-Level Shrinkage (SLS) and Sub-Level Caving (SLC)
The SLC mining method and the modified version called SLS are modern, highly mechanized, high tonnage, low operating cost mining methods. Sub-level shrinkage is sub-level caving with waste rock added on top of the broken ore blanket to fill the air gap between the top of the cave and the ore blanket in zones where the rock will not cave reliably. The introduced backfill serves to provide some confinement to the cave walls for stability.

Typically, SLC-style mines begin underground mining beneath an existing open pit, which is the case for the planned mining of the Roby Central Zone.

The SLS mining method was introduced at LDI for the Lower Offset zone.

The Roby Central and Offset Central domains are well suited to this type of mining method because of their massive disseminated halo of mineralization. The ore body is also steeply dipping and has strong, competent rock with few major geological structures or weak/altered materials.

Open Hole Stoping (OHS)
OHS mining methods are generally used in areas where caving methods are not suitable. Transverse or longitudinal open stope designs are applied to zones with dips steeper than 60° and with good geometric continuity depending on width of ore zone. These mining zones include Roby NW, Sheriff South, Roby NE, Roby South, B2, Upper Offset, and some areas of the Roby Central and Lower Offset.

The OHS stopes included in the LOM plan are of many different designs in order to fit the requirements of individual zones. Generally, the design parameters are as follows:
• Sub-level spacing from 25m up to a maximum of 75m (floor to floor).
• Typical strike length of 20m to 60m.
• Roby South zone has 100m strike length and is expected to experience progressive failure which is why it is scheduled to be mined at the end of mine life.
• Mining width is generally 10m wide for longitudinal stopes.
• Transverse stopes can be 15m to 50m wide.
• Transverse stopes generally have drawpoints established on a 12m to 20m spacing.
• Drilling can be up-holes only, down holes only or a combination of up-holes and down-holes.

Hybrid Blasthole/Caving Method
The Roby SW Floor zone has been designed to use a hybrid blasthole/caving method due to the proximity of the Roby open pit. This zone mines out a portion of the pit’s southern wall and floor, which is expected to cause the open pit benches above this area to cave on top of the blanket of blasted ore. Due to the low-grade nature of this near-surface zone, a typical SLC mining method was deemed too capital intensive. Consequently, a hybrid method utilizing extraction trenches and mass blasting was selected.

The basic premise of this hybrid method is that, similar to SLC, it creates a blanket of broken to arrest any material soughing off the open pit benches located above. Mining progresses in a top down sequence underneath this ore blanket, which will also act to buttress the vertical south wall created by mining this zone, thereby slowing down failure of this wall and the open pit benches above. An adequate draw control strategy is critical to the success of this method.

The main disadvantage of this mining method is the requirement for more widely-spaced sub-levels which may make the drilling, blasting and draw control more challenging. More oversize is expected with a coarser overall particle size distribution for the blasted material.

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The Lac des Iles mill has a nominal capacity of 13 500t per day. The run-of-mine (RoM) ore feed is crushed before reporting to the milling circuit. High-grade polymetallic sulphide concentrate is produced and shipped via trucks to its final destination. The concentrate’s principal value is generated from palladium, with lesser values from platinum, gold, copper, silver, nickel and cobalt.

The rougher conditioning tank receives feed from the primary hydrocyclone overflow. The conditioner is configured to feed two flotation lines, each with a rougher flotation cell having a capacity of 50m3. The concentrate from the rougher flotation cells (cell 1 in line 1 and cell 2 in line 2), report to the 1.7m rougher column cleaner cell (column cell C). The tailings from rougher flotation move forward to a series of scavenger flotation cells having a capacity of 130m3 each (cells 1B to 1G on line 1 and 2B to 2G on line 2). Tailings from scavenger flotation are final tailings and are pum ........