Highland Copper Completes Phase 1 Engineering and Announces Positive Results from Trade-Off Studies at Its Copperwood Project

Executive Summary

• Highland Copper completed Phase 1 detailed engineering for the Copperwood Project, delivering significant process‑plant redesigns that raise copper recovery to 87.6% and cut operating costs by ~US$1/tonne milled.
• Mine‑engineering studies identified a hybrid drift‑and‑fill / room‑and‑pillar approach that could boost mine recoveries from 69% to ~94%, extend mine life, and reduce tailings footprint.
• Phase 2 engineering (≈35‑40% complete) will refine capital & operating cost estimates, update the mine plan, and support a construction decision and financing target in 2026.

Key Details

• Phase 1 Scope: Comprehensive re‑evaluation of process plant, mine design, water balance, and tailings disposal; led by internal team under Project Director Dr. Wynand van Dyk with engineering partners DRA Americas (process & mine), Foth Infrastructure & Environment (water balance), and Tetra Tech (tailings).
• Process Plant Redesign:
• Expected copper recovery = 87.6% at 25 % Cu concentrate grade.
• Operating cost reduction ≈ US$1.00 per tonne milled via optimized reagent scheme.
• Adoption of MF2 circuit, coarser primary grind, de‑sliming stage, ISAMill regrind – lowers power demand and fine particle loss.
• Integration of Jameson‑cell ultrafine flotation reduces plant footprint & capital cost; improves ESG profile.
• New larger ore storage silo, enhanced pump redundancy, PLC/SCADA control system for reliability.
• Mine Engineering Highlights:
• Evaluated drift‑and‑fill (D&F) in high‑grade zones – potential recovery increase to ~94% and tailings reduction via paste backfill; hybrid D&F (west) / R&P (east) option pending Phase 2 testing.
• Reviewed roadheader productivity vs. conventional drill‑and‑blast; further assessment planned for Phase 2.
• Preferred underground ore handling: conveyors over truck haulage – lower OPEX, reduced ventilation, scalable to battery‑electric vehicles.
• Tailings & Water Management:
• Tailings thickener raises solids to ~50 % mass, cutting handling costs and shrinking surface TDF footprint; >80 % of process water recycled directly to plant.
• Underground storage potential: ~7.9 M m³ thickened tailings → ~40 % reduction in surface TDF area; to be studied further in Phase 2.
• Water balance modeling confirms robust supply across climate scenarios, enhancing ESG performance.
• Phase 2 Considerations:
• Updated labor cost survey to reflect Michigan market and impact on unit mining costs.
• Integrated mine‑plan update incorporating revised cut‑off grade, labor inputs, potential D&F adoption, ground support design, and copper price/cost index assumptions.
• Potential permit amendments for optimized process flow sheet, tailings thickener, power source, and mining method; could shift targeted construction decision from Q2 2026 to H2 2026.
• Qualified Person: Dr. Wynand van Dyk (qualified under NI 43‑101) reviewed and approved technical content.

Notable Quotes

“Phase 1 engineering has delivered meaningful improvements to both the process plant and mine, strengthening the overall project, improving its environmental footprint and advancing Copperwood toward Phase 2.” – Barry O’Shea, CEO, Highland Copper Company

Materiality Assessment: Material – Positive (the engineering advances materially improve project economics, reduce risk, and move the project closer to a construction decision and financing).