Processing Plant: The FS incorporates a planned upgrade to the comminution circuit to include a new, single-stage SAG mill and pebble crusher. The expansion also includes primary crushing upgrades and an ore blending area, along with other circuit modifications intended to provide increased flotation, thickening, filtration and pumping capacity to achieve the target throughput of 1.3 Mtpa. The upgrade will also include several flowsheet modifications aimed at improving both the concentrate grade and metal recoveries.

Underground Development and Infrastructure: A dedicated portal and decline to the WF3 deposit will be constructed to support the increase in mine production levels and to reduce operating costs. The planned trucking decline is 3.9 km in length, excluding level access and stockpiles. The trucking decline will act as an additional fresh air intake within the ventilation network and will enable direct ore haulage from the WF3 zone to a new surface primary crusher station utilizing large-scale (60 tonne) trucks. Ore sourced from other areas (EOF, SF3, SOF, and BME) will be transported to the existing underground crushing system using the existing 30 tonne truck fleet and conveyed to surface via the existing conveying system.

Paste Fill Plant: A paste fill plant designed to operate at both the current 0.7 Mtpa and the 1.3 Mtpa targeted throughput rate has been included. Paste filling the stopes rather than leaving them void is expected to improve ground stability, increase ore recovery, and reduce dilution, and also to reduce surface tailings as a portion of new tailings will be redirected underground to be used as paste fill. A water treatment plant has been added to the paste fill plant system which is expected to significantly reduce water consumption. The system in conjunction with the paste fill plant system is anticipated to reduce the water intensity of the Rosh Pinah operation from 1.54 m³/t to 0.65 m³/t of ore.

Mobile Equipment: The existing, small-scale underground trucks and load-haul dump (LHD) fleet will continue to be used primarily in the current mining areas. As mining extends deeper and average haulage distances increase in WF3, new large-scale trucks and LHDs are planned to be purchased for the more efficient transportation of material to surface which is expected to reduce costs over the life-of-mine.

Renewable Solar Energy Power Purchase Agreement: Trevali has entered into a fifteen-year Power Purchase Agreement (the "PPA") with Emerging Markets Energy Services Company ("EMESCO"). The PPA with EMESCO is anticipated to deliver 30% of Rosh Pinah's power requirements during the life of the agreement. EMESCO will be responsible for the design, permitting, financing and implementation of a solar energy system on a neighbouring property at no cost to Trevali. EMESCO will sell the power generated to Trevali at a fixed rate that is expected to reduce energy costs by 8% over the fifteen-year term of the agreement.

Onsite Operating Costs: Once the project is commissioned, onsite operating costs are expected to reduce by approximately 26% on a per tonne milled basis. Mining costs per tonne milled are expected to be reduced due to the planned change in the mining method to include paste fill allowing for increased ore recovery and reduced mining dilution. Mining costs are also expected to benefit from the dedicated underground decline to the WF3 deposit which should allow for more efficient material handling and reduced cycle times. The processing unit costs are expected to decrease as a result of treating increased tonnages following the upgrade. Fixed on site costs on a per tonne milled basis are also expected to decrease as the mine ramps up from 0.7 Mtpa to the FS target of 1.3 Mtpa as a function of higher annual throughput.

Rosh Pinah Mineral Reserves as at March 31, 2021^{(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)}

Notes

1. CIM Definition Standards for Mineral Resources and Mineral Reserves (2014) were used for reporting of Mineral Reserves.
2. Mineral Reserves were estimated at a full breakeven NSR cut-off value of US$50 per tonne.
3. NSR values were calculated based on average metal prices of US$1.17/lb Zn, US$0.96/lb Pb, and US$24.47/oz Ag.
4. The average processing recoveries used were 88.8% for zinc, 68.5% for lead, and 45.0% for silver.
5. Average payable values used were 85% for zinc, 95% for lead, and 95% for silver.
6. Dilution (Inferred and unclassified material set to zero grade) assumed as a minimum of 1.0 m on each hangingwall and 0.5 m on each footwall.
7. Mining recovery factors assumed as a minimum of 60%, ranging to 95%, with a weighted average of 93%.
8. Mineral Reserves are reported based on mined ore delivered to the plant as mill feed.
9. The average exchange rate used was N$14.90 = US$1.00.
10. Effective date of Mineral Reserves is March 31, 2021.
11. The Qualified Person for the Mineral Reserve estimate is Mr Andrew Hall, MAusIMM (CP), of AMC.
12. Totals may not compute exactly due to rounding.
13. Mineral Reserves are stated on a 100% ownership basis.