In the most general sense, deposits in the District are orogenic, polymetallic veins with lesser disseminated mineralization emanating from the principal veins.

Mineralization at Bunker Hill falls in four categories, described below from oldest to youngest events:

- Bluebird Veins (“BB”): W--NW striking, SW-dipping, variable ratio of sphalerite-pyrite-siderite mineralization. Thick, tabular cores with gradational margins bleeding out along bedding and fractures;

- Stringer/Disseminated Zones: Disseminated, fracture controlled and bedding controlled blebs and stringer mineralization associated with Bluebird Structures, commonly as halos to vein-like bodies or as isolated areas where brecciated quartzite beds are intersected by the W-NW structure and fold fabrics;

- Galena-Quartz Veins (“GQ”): E to NE striking, S to SE dipping, quartz-argentiferous galena +/-siderite-sphalerite-chalcopyrite-tertahedrite veins, sinuous-planar with sharp margins, cross-cut Bluebird Veins;

- Hybrid Zones: Formed at intersections where GQ veins cut BB veins, with open space deposition of sulfides and quartz in the vein refraction in quartzite beds, and replacement of siderite in the BB vein structure by argentiferous galena from the GQ Vein.

The four types of mineral zones listed above are truly only two separate structural events: the NW trending Bluebird Veins and the E-NE trending Galena-Quartz Veining. Initial 3D modeling (Rangefront Technical Services 2020) and structural + mineral zonation analysis (Juras and Duff, 2020) has indicated the various vein segments are likely post- mineral offsets of two vein systems that initially comprised four distinct Bluebird Veins and three to five Galena- Quartz Veins.

Although the mineralogy of the two veins types is distinct, and there are significant differences in vein textures and structures that are not germane to this Technical Report, the physical mechanism of both types of mineralization is sulfide minerals filling open spaces (Duff, personal communication, 2020). The creation of intra-bed open space by differential movement of a folded rock package leading to a structurally prepared host rock, is one of the main theories regarding the origins of mineralization along these structures (Juras and Duff, 2020).

Quartzite is the primary host to mineralization in all vein types, deposited in open-space caused by refraction of the vein structure as it passes from softer siltite argillite packages into quartzite units. The vein deflects to cross the quartzite unit more orthogonally, bending to normal with the bedding plane, in essence decreasing the length of quartzite that needs to fracture to continue propagation. Mineralizing fluids ascending the vein structure deposited sulfides in the open-spaces and pressure shadow created by these refractions. Although the veins are commonly mineralized to some degree along their entire length, economic ore shoots in historic mining operations were largely hosted in these dilated zones in quartzite beds, with the shoot plunging up and down at an orientation defined by the intersection between the vein and bedding (Juras and Duff, 2020).

Both vein sets at Bunker Hill exhibit textures typical of orogenic veins, with no boiling textures or sharp textural differences from pressure-temperature changes, nor any significant wallrock alteration other than disseminations of the vein minerals. The huge vertical extent (3000-600ft+) of mineralization typical of all the vein types in the District strongly indicates that all mineralization was emplaced at moderate to deep crustal levels. Juras and Duff note examples of open-space-filling textures in sulfide minerals in veins in their 2020 report, and classify all of the veins at Bunker Hill as open space fissure veins. If all of these observations hold true, an active fold system is one of the few ways to geologically explain the spaces and pressure shadows necessary to form those open-space cavityfill textures under the pressures and temperatures present at the time of vein emplacement.

Long-hole stoping with fill (LHOS), cut-and-fill and possibly room-and-pillar mining with fill are the only methods viable for sustained operations today. LHOS is the preferred mining method with limited cut-and-fill mining at Bunker HIll. Room-and-pillar mining is not in the current plan.

LONG-HOLE OPEN STOPING WITH HYDRAULIC FILL
Long-hole open stoping (LHOS) is employed with engineered hydraulic fill. Bench is extracted utilizing the top cut as drilling and loading access and the lower cut for mucking access. LHOS are typically mucked with remote control equipment for safety. Stope centerlines are laid out and designated as alternating primary and secondary excavations. The primary stopes are taken first with native rock on all sides. As they are mined-out, they are filled with an engineered hydraulic backfill. The secondary stopes are then mined out adjacent to the primary backfill. The fill strength requirements for secondary stopes are typically much less as they are the last excavations taken in an area. Secondary stopes are typically filled with development material and low or zero cement content hydraulic fill. The LHOS areas are accessed through existing Bunker Hill excavations rehabilitated to modern mining standards in addition to new development ramps as required.

OVERHAND CUT-AND-FILL MINING
Overhand cut-and-fill mining is a selective method that can maintain grade and minimize dilution. Rubber tire access ramps have replaced raises, slusher and rail car haulage systems and provide greater production efficiencies. Even greater efficiencies are now possible with the relatively new development of viable battery electric vehicles (BEV’s) which greatly mitigates mine ventilation air quality and heat demands. Overhand mining is a bottom-up method to mine successive stope cuts between main mining levels. Typical cut dimensions are estimated at 12 ft by 14 ft. Ground support is installed as required during each cut. As each cut is completed, it is filled with an engineered hydraulic fill. Then the next stope cut is taken on top of the placed fill and the process repeated until the mining panel between main mine levels is extracted.

The cut and fill stopes are accessed via an inclined ramp developed between levels. The ramp provides ventilation, utilities, and secondary escapeway as well as connecting the mine levels with rubber tire access.

MINE PLANNING AND SCHEDULING
Backfill is provided via an underground hydraulic backfill plant and distribution system located on the 5-level above a majority of the workings to allow for gravity placement of thickened fill to the greatest extent possible. The plant will produce engineered geotechnical hydraulic fill for the mining operations and a thickened tailing byproduct to be placed in existing open stopes and select secondary stopes. Delineation drilling in advance of mining will be used to confirm final stope geometries and identify historically non-filled stopes which will be appropriately backfilled prior to new mining advancements.

Production commences six months following the start of construction, targeting 200 tons/day (tpd) ramping up to 1,500 tpd over a 14-month period. The scheduled ramp-up allows for infrastructure components to be completed and commissioned and to ensure the mine is adequately developed to maintain consistent production. Initially, production will be targeted above the 9-level as the hoists and first sections of shaft rehabilitation are completed. The mine plan is developed to allow sequential water draw-down and shaft rehabilitation between levels as new production horizons are required. This sequencing is continued to the 26-level.

As the mine matures and progresses deeper, the resource transitions from primarily zinc to primarily lead mineralization in Year 9. In Year 8, the mine plan also transitions away from cut and fill production to LHOS for the remainder of the mine life.

The existing #1 and #2 Shafts are inclined at 50-degrees and 40-degrees respectively and provide skipping, personnel
and materials handling capabilities to the lower levels of the Mine. The headworks, hoist rooms, shops, switchgear,
motor control centers, power distribution and dump bins are located on the 9-level about 9,500 feet to the southsouthwest of the KT portal. Access is via the rail system in the KT. Power and other services are also routed through
the KT.

The #1 Shaft and #2 Shafts will require rehabilitation of the tracks and rollers to facilitate access and future hoisting capabilities. Two small hydraulic single drum hoists, one for each shaft. The existing dump bins and chutes appear to be in good condition and should require a minimum effort to restore to proper working condition. This will permit the hoisting of mill feed and waste as needed at 1500-2000 tpd. A new hoist will be installed for the #1 shaft with a line pull of 18,000 lbs. and an installed electrical requirement of 700 nominal horsepower.

New conveyances will be constructed and modifications to the dump to use a more conventional dumping method vs the Kimberly style dump on the existing skips. A modular track system is envisioned to replace the timber and rail system currently in the shaft.

The processing flowsheet and metallurgical assumptions as envisaged in the June PEA remain unchanged, with a crushing and milling plant to be centrally located on the 9-level, and milled material to be pumped in slurry to the flotation and paste plant on the 5-level. The flotation plant will generate concentrates which will be transported to surface for shipment. The paste plant will generate paste for geotechnical fill and tailings disposal in open drifts and stopes in the mine. This approach optimizes material transport costs while eliminating the need for surface tailings disposal.

The process flowsheets consist of two-stage crushing to produce a feed of P80 of 0.5 inch for the milling circuit. The mill feed will be ground in a ball mill to P80 of 150 mesh (104 micrometers) with sodium cyanide and zinc sulfate. The ground slurry will be subjected to rougher flotation of lead and silver minerals using xanthate and MIBC. Concentrates may be reground and cleaned up to three ........