Rio Tinto Developing Diavik’s A21 Pipe

Development will proceed on a fourth pipe at the Diavik diamond mine, with initial production expected in late 2018.
Output from the $350 million project is needed to support the mine’s existing production level.
Rio Tinto has approved development of a fourth pipe, known as A21, at the Diavik diamond mine in Canada’s Northwest Territories. Rio Tinto is operator of the Diavik Joint Venture, which is owned 60% by Rio Tinto and 40% by Dominion Diamond. Development of the A21 pipe has been in the Diavik mine plan since the start of production in 2003. Development will cost an estimated $350 million over four years. A 2015 works program has been approved, and production from the pipe is planned for late 2018.

The Diavik mine is located 300 km northeast of Yellowknife, the capital of the Northwest Territories. The mine produces 6 million to 7 million carats/year of predominantly large, white gem-quality diamonds destined for use in high-end jewelry. The A21 pipe is being developed as an important source of incremental supply to ensure continuation of existing production levels.

The A21 pipe is located just south of Diavik’s existing mining operations. Development will require rock-fill dike construction to encircle the orebody, which is located just offshore of existing mining operations at Lac de Gras. The project will utilize the same technologies that were used to construct two other dikes to enable mining of pipes below the lake surface.

First equipment and supplies for A21 pipe development are scheduled to be transported to the mine site in early 2015 on the seasonal winter ice road. Planning calls for four years of dike construction and pre-stripping (2015-2018) to be followed by approximately five years of open-pit mining.

As of year-end 2013, the A21 pipe had an estimated 3.6 million metric tons (mt) of measured resources at a grade of 2.8 carats/ mt and 0.4 million mt of indicated resources at a grade of 2.6 carats/mt. Resources and reserves are scheduled for updating in the first quarter of 2015. The current mine plan calls for production to end in 2023.

As featured in Womp 2015 Vol 01 -