The East Kemptville deposit is a greisen-hosted Sn-Cu-Zn-Ag-In deposit with the alteration and mineralization predominantly affecting the East Kemptville leucogranite (EKL). Three major lithologies (besides overburden) are recognized for the East Kemptville deposit. They are:
1. Leucogranite (EKL) intrusive which is primary host of the mineralization.
2. Within the Baby Zone, a contact zone which is a mineralized igneous breccia containing both metasediment and granite clasts.
3. Metasedimentary rock consisting of interbedded psammites and pelites.

Tin and base metal (Zn-Cu-Ag-W) mineralization within the deposit is primarily fine to medium-grained and is associated with northeast-trending, sub-vertical and zoned, quartztopaz, sulphide-bearing greisens, veins, and stockworks that occur primarily in the sericitesilica-topaz altered portions of the leucogranite meet the roof zone in contact with surrounding metasediments.

In many respects, the geometry of the mineralization over the areal extent of the deposit appears akin to a series of closely spaced jellyfish where the bodies represent wider zones of 51 intense fracturing and coalescing greisens near the top of the intrusion and where the tentacles represent narrower, higher-grade feeders or root zones. A structural control on the emplacement of the mineralization may help explain why some thicker (20-40 m) portions of the deposit occur at greater depths and why some thinner zones (2-5 m) occur at higher levels (i.e., northern portion of Main Pit). In general, the zones below the current pit appear to be thinning and are of higher grade.

The overall gross dimensions of the original potential economic mineralization at the Main and Baby Zones based on a cut-off grade of approximately 0.05% Sn are in the order of 1,500 m long, 350 m wide and 75 m to 150 m deep. Most of this volume is represented by the larger, Main Zone, which has been further subdivided into three subzones termed the Western Flank and South and North Extension Zones. The smaller and discrete Baby Zone occurs a few hundred metres southwest of the Main Zone within what is believed to be a structurally controlled, satellite intrusion. The intrusion hosting the Baby Zone is in the order of 250 m long and 50 m to 75 m wide, but may be continuous with that of the Main Zone at depth through the South Extension Zone.

Higher grade, thicker, mineralization in the Baby Zone is focused along its structurally controlled, southeastern contact with the metasediments and along an interpreted fault that continues northeastward through the Main Zone. Here, potentially economic mineralization reaches tens of metres in thickness and grades appear to average over 0.20% Sn, 0.30% Zn and 0.10% Cu.

The Main Zone mineralization is closely associated with ductile zones and greisens are predominantly restricted to fractures whereas the Baby Zone displays brittle deformation and has pervasive greisens below the wallrock contact.

Mineralization between the Main Zone and the Baby Pit is referred to as the Southwestern Extension of the Main Zone and is not exposed at surface but intersected in drilling.

The mining will re-start as a continuation of the historic open pit operation using a conventional drill and blast process and conventional truck and shovel methods for material movement. Mill feed will be hauled to a small (24 h) stockpile and then reclaimed into the crusher rock box by a front-end loader. The mill treatment rate is set at 2,208 t/d (806,000 t/y) starting initially using only stockpiled material, which will then be supplemented by new feed mined from the Baby Zone Pit during production Years 2 and 3. Thereafter, mining will take place from the southern portion of the Main Zone Pit in Years 3 through 7, followed by production from two pits located in the northern portion of the Main Pit Zone in Years 7 through 14, after which the operation will be fed with the remainder of the legacy stockpile through Years 15 to 19. During Years 2 through 14 when the majority of mill feed is sourced from the pits, approximately 6 weeks’ worth of material will be scheduled from the legacy pile in order to (a) incrementally reduce the environmental liability and (b) maintain mill productivity in the event significant operational delays are encountered in the mine.

Two rotated resource block models were prepared by Avalon at different block resolutions (6 m x 6 m x 6 m for the Baby Zone, and 24 m x 24 m x 12 m for the Main Zone). The two models were merged to create a single functional model suitable for mine planning and pit optimization at a resolution of 6 m x 6 m x 6 m.

Key milestones for the conceptual Project development are described below:

Year -1: Dewatering of the Baby Pit and Main Pit begins, along with site preparation for construction of plant.

Year 1: Final dewatering and removal of sludge in the Baby Pit takes place during Q1 and Q2. Shipment from the legacy stockpile begins in Q3, with process tailings directed to the TMF. Dewatering of the Main Pit continues and will carry over into the first month of Year 2.

Year 2: Mine operations in the Baby Pit begin supplemented by feed from the legacy stockpile. Waste rock is shipped to its final destination to the west of Main Pit South and tailings are directed to the TMF. Any overburden material suitable for use in future revegetation work will be set aside.

Year 3: Baby Pit production ceases and Main Pit South mining begins, supplemented with legacy stockpile feed. Waste rock from both pits is shipped to Waste Zone A and process tailings are sent to the TMF.

Year 4-6: Production feed is sourced from Main Pit South, supplemented with the RAL legacy stockpile. Waste rock is shipped to Waste Zone A. Once the TMF capacity is reached in the last quarter of Year 4, tailings will be directed to the Baby Pit. Beginning in Year 6, mill feed from the Main Pit will be processed through a sulphide flotation circuit to produce clean tailings to cap the TMF.

Year 7: Main Pit South production ceases and Main Pit West mining begins, supplemented with legacy stockpile feed. A portion of the waste rock from Main Pit West will be temporarily staged as required to create a fill ramp in Year 9 to haul mill feed excavated from the lower benches. Sulphide tailings are directed to the Baby Pit, with low-sulphide tailings directed to capping operations.

Year 8-10: Production feed sourced from Main Pit West is supplemented with the RAL legacy stockpile. Stockpiled waste rock from the upper benches of Main Pit West is used to construct a fill ramp needed to haul mill feed from the lower benches in year 9 and 10. Remaining waste in is shipped to the final lift of Waste Zone A and the first lift (70 m elevation) of Waste Zone C. Low-sulphide tailings are directed to capping operations and sulphide tailings are deposited in the Main Pit South repository.

Year 11-14: Production feed is sourced from Main Pit North, supplemented with the RAL legacy stockpile. Waste rock is shipped to Waste Zone C and D. Sulphide tailings continue to be directed to Main Pit South, with Year 11 being the final year of lowsulphide tailings production used for surface capping of the TMF. In Year 12, additional capacity in Main Pit South becomes available that will be sufficient for tailings deposition through Year 13. In Year 14, tailings deposition will be directed to the Main Pit West area.

Year 15-19: Mill production comes from the RAL stockpile for the remainder of the Project life. Tailings deposition continues in Main Pit West and Main Pit South areas through Year 16. Beginning in Year 17, tailings are directed to the Main Pit North pit area, after which tailings will continue to be deposited in the Main Pit for the remainder of the schedule. If evenly distributed, the estimated tailings volume in the Main Pit will approach an elevation of 87.5 m, leaving approximately 0.9 Mm3 of additional capacity that may be used to reach the final allowable fill elevation of 90.5 m.

The 100 tonne per hour operation to treat the mineral resources at East Kemptville consists of several conventional processes to produce a tin concentrate. The plant feed undergoes crushing in a three staged crushing circuit, milling and classification, and is then put through a series of gravity circuits using high-speed centrifugal concentrators (HSCCs), magnetic separation and flotation to remove the metal sulphide before going through a series of shaking tables.

Crushing Circuit.
The crushing circuit consists of a three staged crushing circuit and a series of screens for classification and magnets for tramp iron removal. Run-of-mine (ROM) material is fed at a rate of 200 t/h to a vibrating grizzly feeder (with 50 mm openings) by a front-end loader. Material greater than 400 mm is retained ahead of this feeder by a static grizzly screen and broken with a hydraulic rock breaker.

Material coarser than 50 mm is fed to a jaw crusher and then combined with feeder undersize before being classified at 50 mm by a vibrating primary screen. Primary screen oversized material is further crushed in a secondary cone crusher the product from which is combined with primary screen undersize and then screened at 8 mm by a secondary screen. Oversize (+8 mm) reports to a tertiary cone crusher before being recycled back to the secondary screen. The -8 mm product from the secondary screen is conveyed and stored in the fine crushed ore bin.

Milling and Classification Circuit.
The grinding and classification circuit consists of a ball mill, a coarse screen and 6 “stacks” of fine screens (80 µm). The ball mill discharge is pumped to the coarse classification screen to remove +0.5 mm material which is recycled to the mill. The - 0.5 mm material is pumped to a 4-way distributor, 2 outlets of which feed continuous primary HSCC concentrators (space will be provided for installation of up to a further 2 concentrators in the future if necessary). Tailings from the primary HSCC concentrators are combined with the other 2 outlets from the distributor, along with recycled gravity table tails 207 and cleaner 1 and 2 HSCC concentrate tails and pumped to the stack of -80 µm fine screens. Screen oversize is recycled to the ball mill while screen undersize is feeds the main HSCC gravity circuit.

Gravity Circuit.
Screen underflow from the milling circuit feeds a 2-way distributor with each outlet feeding continuous rougher HSCC concentrators in the gravity circuit. Tailings from the rougher concentrators are pumped to tailings. Concentrates from the rougher concentrators are combined with primary HSCC concentrates and fed to a primary cleaner HSCC concentrator. Primary cleaner concentrate feeds a secondary cleaner concentrator, the concentrate from which is pumped to a sulphide removal circuit. Tailings from cleaner concentrators are combined and recycled to the fine screens in the milling circuit.

Sulphide Removal Circuit.
The gravity concentrate sulphide removal circuit comprises a low intensity magnetic separation (LIMS) unit and a small flotation circuit to remove the entrained sulphides in the centrifugal concentrate. Gravity concentrate feeds a rougher LIMS, to scavenge entrained tin.

Non-magnetics from both magnetic separators are combined and sent to a small, sulphide flotation circuit where sulphide flotation reagents, such as Copper Sulphate, Xanthate and MIBC, will be added during a two-stage conditioning process. Flotation rougher concentrate is pumped to a small cleaner circuit to remove entrained tin with the final sulphide concentrate then being combined with the magnetics stream and pumped to the final tailings facility where they will be contained under water to prevent oxidation.

Tin Shaking Tables Circuit.
The non-sulphide material is pumped to the tin shaking table circuit which consists of a dewatering cyclone and a series of 4 shaking tables used to produce a final tin concentrate containing ±55% tin. The dewatering cyclone thickens the slurry to ±40% solids which feeds a four-way distributor ahead of 4 shaking tables operating in parallel. Final concentrates from the four shaking tables are combined and fed into a holding tank before being pumped to filters for final dewatering. Table middlings are recycled back to the table feed whilst table tailings are recycled back to the milling/classification circuit. The dewatered tin concentrate filter cake will contain approximately 10% moisture and will be collected in large one tonne super-sacs before being containerized and shipped to potential customers.

Bulk Sulphide Flotation.
The circuit is designed to maximize sulphide removal in order to achieve the targeted <0.05% S in the final tailings. The tailings after sulphide removal will be filtered and the cake transported by truck to the tailings facility where it will be used for capping as part of the tailings facility remediation process.

Tailings and Sulphide Concentrates Storage.
The tailings treatment circuit consists of a holding tank and a series of pumps. There are two sections to tailings and sulphide concentrate treatment, the first processes the tin tailings and the second handles the sulphide concentrate from the sulphide removal circuits.

Tailings from the gravity circuit will initially be pumped to the existing tailings facility and distributed appropriately across the facility (and below the current water line). Once the existing facility is filled, the material will be deposited inside one of the existing, mined out pits.

Metallurgical accounting.
Mechanical weightometers will be installed on the conveyors to the jaw crusher feed as well as the feed to the ball mill to both measure and control feed rates onto the conveyors.

Mass flow systems and/or sampler facilities will be installed on the following process streams:
• Jaw crusher product conveyor (weightometer).
• Crushed material to the ball mill (weightometer).
• Manual sampling of feed.
• Mill circuit product (automatic sampler).
• Final plant tailings (flowmeter, densitometer and automatic sampler).
• Feed to sulphide removal circuit (access for manual sample).
• Sulphide concentrate (access for manual sample).
• Tin shaking table concentrate (automatic sampler).
• Tin shaking table tailings (automatic sampler).