All of the PGE-Cu-Ni mineralization documented on the 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 (Naldrett, 2004). Recent advances in the understanding of the relationships between the geology, structure, alteration intensity, metal grades, geochemistry and geophysical characteristics at LDI show that the majority of the known mineral zones can be explained by physical sorting of dense sulphide liquid droplets and high-temperature orthopyroxene crystals from aluminum- and volatilerich residual magma. Increasingly, the importance of pre-magmatic structures in directing the pward flow of magma into the host intrusive complex and in determining the physical location of
metal-rich sulphide trap sites is being recognized.

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.

LDI historically used open pit and a top down open hole stoping (OHS) mining methods to mine the Roby block and also began mining the Upper Offset using OHS. LDI transitioned to a sub-level shrinkage (SLS) mining method for the Lower Offset Central zone in 2016 and will continue to use this method for the bulk of the Lower Offset Central zone. LDI continues to use the OHS method around the periphery of the SLS, for pillar recovery and otherwise as appropriate.

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.

The run-of-mine (ROM) ore feed is crushed prior to reporting to the milling circuit. The crushing circuit begins with all the ore being crushed through a primary 54” x 75” gyratory crusher driven by a 447kW (600 hp) motor. The gyratory discharge is conveyed to a live stockpile. Apron pan feeders feed the conveyor between the stockpile and the main grinding circuit, with the capability of diverting a variable proportion of the coarse ore to the secondary crusher. The proportion fed to the secondary crushing circuit is regulated by the operator to maximize throughput in the grinding circuit. Secondary crushing is accomplished with a cone crusher (standard HP800), which discharges back on the mill feed conveyor producing a finer feed for the grinding circuit.

The grinding circuit consists of a SAG mill, ball mill and pebble crusher. The SAG mill, which can be operated in autogenous or semi-autogenous configurations, has dimensions of 9.14m in diameter by 4.27m equivalent grinding length (EGL), and is driven by a 6,400kW (8,500 hp) motor. The mill output is passed over a vibrating screen where oversized particles are directed by conveyor to the pebble crusher (short head cone HP800). The pebble crusher product is then returned to the grinding mill. The pebble circuit is configured to allow oversized particles to bypass the pebble crusher and return directly to the SAG mill feed.

Undersized particles from the SAG mill output are directed by the vibrating screen to the ball mill diverter box, which splits the stream to feed between two ball mills. The two ball mills each have dimensions of 6.10m in diameter by 10.36m EGL and are also each fitted with 6,400kW (8,500 hp) motors. Each ball mill is in closed circuit with a hydrocyclone cluster. The underflows from the hydrocyclones report back to the ball mills and the overflows report to a collection tank. The primary hydrocyclones were upgraded to GMAX 20” and the ball mill media was reduced to 1” high chrome balls in order to produce the current P80 of 55µm.

The LDI mill has a capacity to process 4,470,000 tonnes per annum of ore to a final particle size of 55µm. The plant operates at 555 tonnes per hour at a 92% availability.

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 pumped to the tailings management facility (TMF) for impoundment. Scavenger concentrates from cells 1A, 2A, 1B, 2B, 1C, and 2C are combined and pumped to the cleaner A feed bank of flotation cells. The scavenger concentrates ........