Orla’s South Railroad gold project: capex, flowsheet and schedule lens for engineers
Reviewed by Joe Ashwell
First reported on MINING.com
30 Second Briefing
Orla Mining will start full construction of the South Railroad gold project on Nevada’s Carlin Trend by mid-2026 after an updated feasibility study doubled initial capex to US$395 million, driven by inflation plus added two-stage crushing and water management systems. The heap-leach operation is planned to process 66.6 million tonnes of reserves grading 0.71 g/t Au and 5.1 g/t Ag, targeting average output of 104,000 oz. Au per year over 10 years at US$1,505/oz. AISC, with first production expected in 2028. The study gives an after-tax NPV5 of US$783 million and 48% IRR at US$3,100/oz. gold, rising to US$1.7 billion and 95% IRR at US$4,500/oz.
Technical Brief
- Updated feasibility adds two-stage crushing plus enhanced water management as key new plant systems.
- Initial capex jumped from US$190 million (2022) to US$395 million, explicitly attributed to inflation and flowsheet upgrades.
- Life-of-mine sustaining capital is estimated at US$202 million, separate from initial build costs.
- South Railroad lies ~700 km north-east of Las Vegas within Orla’s 250 sq. km South Carlin Complex.
- Proven and probable reserves contain 1.52 Moz Au and 6.2 Moz Ag in 66.6 Mt ore.
- Since 2022, measured and indicated resources increased by 206 koz oxide and 469 koz sulphide gold.
- Exploration drilling totalled 57,800 m over three years, including 18,000 m completed in the last year alone.
- Federal and state permits are expected around mid‑2026, following detailed engineering and board construction approval.
- Orla plans “aggressive” exploration in 2026, signalling continued step-out and infill drilling around the planned pits.
- South Railroad is central to Orla’s strategy to build towards 500,000 oz/year group gold production capacity.
Our Take
Within our 623 Mining stories, very few Nevada gold items show such a large step-change in capital cost estimates as South Railroad’s move from $190 million to $395 million, which signals how quickly inflation and scope creep are repricing heap-leach style projects on the Carlin Trend.
At a 5% discount rate and a 10-year mine life, the after-tax NPV of $783 million against roughly $597 million in initial plus sustaining capital suggests South Railroad sits in the upper tier of North American gold project economics in our database, even though its reserve grade of 0.71 g/t is firmly in the low-grade camp.
The presence of BMW AG’s i Ventures and Breakthrough Energy LLC alongside Mangrove Water Technologies and Canada Growth Fund in the same fact set underlines how gold and silver projects like South Railroad are increasingly being evaluated in a capital market that is simultaneously funding low-carbon and lithium-related technologies, which can influence competition for project finance windows around 2026–2028.
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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