Sixty North Mon mine restart: design, safety and economics lens for engineers
Reviewed by Tom Sullivan
First reported on MINING.com
30 Second Briefing
Sixty North Gold Mining plans to restart the past-producing Mon gold mine in the Northwest Territories by midyear, installing a 100-tonne-per-day mill on site about 40 km from Yellowknife. CEO David Webb targets production of roughly 100 oz. gold per day from new development 17 metres beneath historical stopes in a belt that previously yielded about 15 million oz. at 16 g/t. The restart is proceeding without a formal economic study or compliant resources/reserves, with Webb opting to validate the orebody directly through mining.
Technical Brief
- Restart plan omits NI 43-101-compliant resources/reserves and formal economic study, increasing reliance on operational controls.
- Webb explicitly rejects spending on technical reports, preferring to validate ore continuity via direct production.
- New ramp will be driven beneath historical stopes, introducing interaction risks with old voids and legacy ground conditions.
- Mining below old workings demands rigorous void detection, backfill verification and ground support re-assessment against historic designs.
- Onsite 100 t/d mill delivery targeted for March fixes a tight commissioning window before midyear restart.
- Project lies ~40 km from Yellowknife, so emergency response, medevac and supply chains must accommodate remote-access constraints.
- Historical belt production of ~15 Moz at 16 g/t implies narrow, high-grade structures requiring precise drilling and blasting control.
- Proceeding to production without conventional de-risking studies will test how regulators and insurers view safety assurance based mainly on operating practice.
Our Take
With a planned 100 tonnes-per-day mill and a target of 100 oz. of gold per day, Mon sits at the small, high-grade end of the gold operations spectrum in our database, which usually signals a focus on selective mining and tight cost control rather than bulk tonnage.
Historical grades around 16 g/t gold place the Mon gold mine among the higher-grade assets in our recent gold coverage, implying that even modest throughput can generate meaningful cash flow if dilution and ground-control risks are well managed.
Northwest Territories projects in our coverage often flag logistics and winter access as key constraints, so a restart only 40 km from Yellowknife gives Sixty North Gold Mining a relative advantage on supply, workforce access, and emergency response compared with more remote northern camps.
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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