Rio Tinto announced on Thursday that it has successfully completed Phase 1 of the A21 underground expansion at its Diavik diamond mine in Canada’s Northwest Territories and has entered commercial production. This expansion is expected to significantly extend the mine's operational life through at least early 2026.
The Australian mining giant had previously committed $40 million to transform the existing A21 open pit into an underground operation. Phase 1 aims to produce an additional 1.4 million carats, while Phase 2, recently approved with an extra investment of $17 million, is projected to yield another 800,000 carats.
The construction of the A21 underground mine involved developing over 1,800 meters of tunnels to access the orebody. Impressively, there were no lost time injuries recorded during the project, which involved over 100,000 labor hours over 20 months.
“The A21 underground operation is great news for our employees, partners, suppliers, and local communities in the Northwest Territories, as it ensures continued operations until closure,” said Matt Breen, Diavik mine chief operating officer. He also highlighted that the decision to proceed with Phase 2 reflects the Diavik team’s exceptional performance in developing the underground mine beneath the previously mined open pit.
Additionally, Rio Tinto is focused on preparing for the closure and remediation of the Diavik mine site, emphasizing progressive reclamation activities such as earthworks, site clean-up, and equipment procurement. Since mining began in 2003, Diavik has produced over 144 million carats of rough diamonds, making it one of Canada’s largest diamond mines by volume.
