Global mining giant Rio Tinto has approved a $40-million investment to proceed with underground mining of Diavik’s A21 pipe, below the existing A21 open pit.

During the first phase of underground mining of Diavik’s A21 pipe, an additional 1.4 million carats of rough diamonds are expected to be delivered.

The updated mine plan and production schedule — including the A154N and A154S pipes, and subject to approval of the second phase of the A21 underground project — shows that Diavik is now expected to end commercial production in the first quarter of 2026.

Current employees and contractors will be transitioned from other areas of the mine for both the construction and production phases of the project.

Construction of the A21 open pit commenced in 2015. It was finished ahead of time to commence commercial production in 2018.

Phase two of the A21 underground project is not approved at the time, but Diavik expects to seek approval in the first half of 2024. Phase two is expected to deliver an additional 0.8 million carats of rough diamonds.

“Rio Tinto’s decision to support the underground development of the A21 pipe was prefaced on compelling industry fundamentals,” stated Sinead Kaufman, chief executive of Rio Tinto’s minerals portfolio. ”Our proven capacity to safely develop diamond mines in extreme conditions and a track record in competing successfully in the global diamond industry. This is good news for our employees, partners, suppliers and local communities in the Northwest Territories.”

Located 300 km northeast of Yellowknife, the Diavik mine, 100 per cent owned and operated by Rio Tinto, is Canada’s largest diamond mine in terms of production with six to seven million carats of rough diamonds produced each year. Since mining began at the site in 2003, Diavik has produced more than 100 million carats of diamonds.

Kaicheng Xin

Kaicheng Xin is a Multimedia Journalist with NNSL Media. You can reach him at

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