The project aims to extend the operational life of the mine to at least early 2026.
Under the approved first phase of the expansion, the miner will expand the diamond extraction underground, below the existing A21 open pit. Mining recently concluded at the pit, which was opened in 2018.
Phase one below A21 is expected to produce additional 1.4 million carats (Mct) while the second phase would produce a further 800,000ct of rough diamonds.
In a statement, Rio Tinto said: “Based on the updated mine plan and production schedule, including the A154N and A154S pipes, and subject to the approval of the second phase of the A21 underground project, Diavik is now expected to end commercial production in the first quarter of 2026.”
With an annual production of 6Mct-7Mct of rough diamond, the Diavik mine is claimed to be Canada’s largest of its kind by production.
Rio Tinto Minerals CEO Sinead Kaufman said: “Rio Tinto’s decision to support the underground development of the A21 pipe was prefaced on compelling industry fundamentals, our proven capacity to safely develop diamond mines in extreme conditions and a track record in competing successfully in the global diamond industry.”