The Diavik mine – one of Canada’s biggest diamond mines – has completed the development and construction of Phase 1 of the A21 underground mine, now moving the mine into commercial production.

Building on the success of the first phase, Rio Tinto earlier this year approved Phase 2 of the A21 underground project with an additional investment of $17-million. The project will enable Diavik to maximise the value from its known resources through to closure.

The construction of the A21 underground mine involved the development of more than 1 800 m of underground tunnels to access the orebody and begin underground production.

Rio Tinto reports that it completed the 20-month project without any lost-time injuries, with 100 000 labour hours worked.

Diavik COO Matt Breen said the A21 underground operation is positive news for employees, partners, suppliers and local communities in the Northwest Territories, as it will enable operations to continue through to closure.

“Rio Tinto’s decision to proceed with Phase 2 is a testament to the excellent performance of our Diavik team in successfully developing the underground mine beneath the previously mined A21 openpit.”

Rio Tinto is also continuing its investment in preparing for the closure and remediation of Diavik mine site, focusing on progressive reclamation activities such as earthworks, site clean-up, equipment procurement, and other closure-readiness efforts. 

Earlier this year, Rio Tinto installed a 3.5 MW solar plant at Diavik, which is the largest off-grid solar plant across Canada’s territories.

The solar power plant will provide up to 25% of Diavik’s electricity during closure work, with commercial production at the mine expected to end in 2026 and closure to run until 2029.

The solar project complements a wind power plant at Diavik, which has been operating since 2012 and is the largest wind power installation in Canada’s North, having generated over 195-million kilowatt-hours of electricity since activation.