Southern Copper’s $680M Cuajone mine expansion: throughput and tailings lens for engineers
Reviewed by Tom Sullivan

First reported on MINING.com
30 Second Briefing
Southern Copper is evaluating a $680 million expansion of the Cuajone open-pit in southern Peru to lift milling capacity by 33% from 90,000 to 120,000 tonnes per day, targeting an extra 55,000 t/y of copper and 1,400 t/y of molybdenum, with a further option to reach 150,000 t/d. Cuajone produced nearly 163,000 tonnes of fine copper in 2025 and, together with Toquepala, holds The Copper Mark accreditation covering tailings management. The project sits within a >$15 billion decade-long capex pipeline, including the $1.8 billion Tia Maria build, now 49.6% complete and aiming for 120,000 t/y of cathode from 2028.
Technical Brief
- Expansion is explicitly framed as a response to declining ore grades at Cuajone’s existing pits.
- Southern Copper has not yet issued a final investment decision or schedule, keeping expansion timing uncertain.
- Company copper output dropped 2.9% to 693,602 t in the first nine months of 2026, mainly from lower Peruvian grades.
- Cuajone and nearby Toquepala both hold The Copper Mark, including compliance with accredited tailings management requirements.
- Southern Copper forecasts 911,400 t copper in 2026 and about 900,000 t in 2027, down from 954,270 t in 2025.
- Long‑term corporate plan targets 1.6 Mt/y copper by 2033 from projects across Peru and Mexico.
- Tia Maria is 49.6% complete, with US$884.3M spent and a further US$1.1B already contractually committed.
- Los Chancas is aimed for first production in 2031 and Michiquillay in 2032, feeding a >US$15B decade capex pipeline.
- Analysts at BNEF project a 3 Mt (8%) copper deficit by 2035, widening to 20 Mt (44%) by 2050 if new mines lag.
Our Take
Southern Copper features repeatedly in recent copper price coverage, including August–September 2026 pieces where Comex copper traded around $14,500–$14,800/t, so a 33% milling capacity lift at Cuajone positions the company to lock in leverage to any renewed price spikes highlighted in those market reports.
With more than $10.3 billion of potential capital earmarked for Peru alongside projects like Tia Maria, Los Chancas and Michiquillay, Southern Copper is concentrating country risk in a jurisdiction where our database also flags artisanal and small‑scale mining interference as a material operational risk for the company.
The long‑term output target of 1.6 Mt/y by 2033 aligns with BNEF and Wood Mackenzie projections in this piece of multi‑million‑tonne copper deficits by 2035 and 2050, implying that even full delivery of Southern Copper’s Peruvian pipeline would address only a slice of the structural shortfall rather than saturating the market.
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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