The Curaçá valley deposits are complex with features that do not conform to conventional deposit models (this section is modified from Desrochers et al., 2020). The strong spatial association of mineralization in the Curaçá valley deposits with mafic-ultramafic bodies, dominated by orthopyroxenite, and the common occurrence of some of the sulphide interstitial (“intercumulus”) to orthopyroxene, led several researchers to conclude that mineralization formed through orthomagmatic processes (e.g., Maier and Barnes, 1996), and hence invoked a modified magmatic sulphide model. A number of features, however, are unusual for magmatic sulphide deposits including the high Cu/Ni ratio (virtual absence of Ni in many deposits); significant amounts of bornite in many deposits; significant amounts of magnetite, most of which contains elevated Al, Cr, V, Ni and Zn; the abundance of phlogopite in the orthpyroxenite and wall rocks locally associated with sulphides and in some cases also containing concentrations of apatite and zircon; as well as the low S/Se ratio in sulphides. Maier and Barnes (1996) suggest various mechanisms to explain some of these features including sulfur loss resulting in the abundance of magnetite and the low S/Se ratio.

The Pilar Mine is located in the southern part of the MCSA Mining Complex within the Curaçá Valley. The geology of the mine consists of a high-grade metamorphic terrain, composed of gneiss and migmatite of the Caraíba Complex that were in ........

Mining operations were assumed to be the same as for the Deepening Inferred Project, using a combination of transverse stoping and longitudinal stoping mining method. Dilution was set to 1.0m, comprised of 0.5m for the hanging wall, 0.5m for the footwall and a maximum waste percentage of 75%.

In support of the Deepening Inferred Project, an additional 15km of horizontal development is required when compared to the Deepening Extension Project. In support of the Deepening Inferred Project, an additional 554 m of vertical development is required when compared to the Deepening Extension Project.

Extraction of mined material from the Deepening Inferred Project required the addition of two new panels below -1381L, as the production panels and supporting infrastructure to be built from level -1069 to -1381 are shared by the Deepening Extension Project. The primary ramp continues at depth beyond the Deepening Extension Project and is designed to follow the mineralization to the north. The bottom of the new external hoisting shaft that will be built in support of the Deepening Extension Project will be completed to the -1075 Level. Two new panels with 4 production levels each are designed below -1381 Level in support of the Deepening Inferred Project.

For the Deepening Extension Project the same mining method will be employed as the rest of the Pilar UG Mine. A panel height reduction from 35m to 26m will be applied to improve mining recovery and reduce ........

All ore is transported for treatment at the Caraíba Mill.

The Deepening Inferred Project is expected to utilize the same infrastructure that will be built in support of the Deepening Extension Project, including a new external shaft.

The expansion to increase capacity to 4.2Mtpa of annual mill throughput requires the installation of quaternary crushing, additional increase in screening capacity, upgrades to the flotation circuit to ensure residence time is not impacted, and an increase in concentrate filtration capacity. While there are a number of options available for quaternary crushing, the characteristics of the Caraíba ore make it amenable to High Pressure Grinding Roll (“HPGR”) crushing. Additional laboratory testwork is planned to confirm the HPGR sizing and design route and has been included in the capital cost estimates.

As a result of increased demands for the quality and delivery of paste associated with the Deepening Extension Project, modi ........