Kanmantoo underground for Hillgrove: 2026 mine plan and cost lens for engineers
Reviewed by Joe Ashwell

First reported on Australian Mining
30 Second Briefing
Hillgrove Resources’ Kanmantoo underground copper mine in South Australia has driven a sharp profit increase in 2025 on the back of higher copper production and improved unit costs as the operation ramps up. The mine is transitioning from its former open-pit to a fully underground layout targeting the Nugent and deeper Kanmantoo orebodies, with stoping and development ore feeding an upgraded on-site concentrator. Management is positioning Kanmantoo for a strong 2026, signalling further throughput increases and longer mine life, which will influence regional processing, power and tailings planning.
Technical Brief
- Transition from open-pit to underground reduces surface disturbance footprint and changes haulage and backfill logistics.
- Mine planning now focuses on deeper extensions, requiring longer decline development and revised ventilation circuits.
- Regional infrastructure planning must account for higher electrical load profiles from underground pumping and hoisting.
- Tailings strategy is being revisited to align with extended mine life and higher milling throughput.
- Similar Australian copper conversions from open-pit to underground are increasingly leveraging existing plants to defer capex.
Our Take
Copper items in our database increasingly feature Australian underground restarts rather than greenfield builds, suggesting Hillgrove Resources’ Kanmantoo underground strategy in South Australia is aligned with a lower-capex, faster-to-cashflow model that lenders and offtakers currently favour.
Within the 272 copper‑tagged pieces in our coverage, South Australia appears less frequently than Western Australia or Queensland, which may give Kanmantoo outsized visibility with state agencies and infrastructure planners as they look to anchor regional copper supply heading into 2026.
A 2025 profit uplift feeding into a ‘strong 2026 entry’ signals that Hillgrove could time Kanmantoo underground ramp‑up into a window when several higher‑cost copper operations in our database are facing grade decline, potentially improving pricing leverage for a well‑positioned Australian producer.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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