Name: Gahcho Kué mine.

Location: The mine is located at Kennady Lake, abouty 280 km north-east of Yellowknife and 80 km south-east of De Beers’ Snap Lake mine, in Canada’s Northwest Territories.

Controlling Company: The Gahcho Kué mine is a joint venture between De Beers Canada (51%) and Mountain Province Diamonds (49%).

Brief Description: Gahcho Kué is an openpit operation, mining three kimberlite pipes in sequence: 5034, Hearne and Tuzo. Gahcho Kué has a 12-year life-of-mine (LoM).

Brief History: In the early 1990s, Gahcho Kué, previously known as the Kennady Lake project, was staked by Mountain Province Diamonds. Canamera Geological was contracted to conduct the original exploration, which led to the discovery of the 5034 kimberlite pipe in January 1995.

In 2002, a joint venture agreement was entered into between Mountain Province (44.1%), De Beers Canada (51%) and Camphor Ventures (4.9%). In 2007, Mountain Province acquired 100% of Camphor Ventures, thereby increasing its interest in Gahcho Kué to 49%. A feasibility study on the project was completed in 2010, with Ministerial approval for the project awarded in 2013 and construction starting in the same year.

The mine began the ramp-up of production in early August 2016. The project cost an estimated $1-billion to develop.

Products: Diamonds.

Geology/Mineralisation: The Kennady Lake kimberlite cluster is in the south-east Slave Craton. The area was glaciated repeatedly during the Pleistocene, most recently by the Laurentide ice sheet. The Laurentide ice sheet began to recede about 18 000 years ago and the ice retreated past the Kennady Lake project area between 9 000 and 9 500 years ago. The Kennady Lake kimberlite cluster comprises 5034, Hearne, Tuzo and Telsa.

The 5034 kimberlite is an irregular hypabyssal root zone. Hearne and Tesla are transitional diatremes and root zones, and Tuzo is the deeper part of a diatremes zone.

Telsa is currently not included in the Gahcho Kué mineable resource because of its smaller size (0.4 ha). However, it may be exploited towards the end of the project life. The shapes and internal geology of each of the kimberlite pipes has been based on the logging of the available drill core. The external shapes and internal geology of each body was modelled in three dimensions using GEMCOM. Both internal and external models were updated after drilling programmes conducted between 2001 and 2011. All the pipes remain open to depth.

Reserves: Reserves as at December 31, 2015, were estimated at 33.8-million tonnes, grading 153.8 carats per hundred tonnes (cpht).

Resources: Measured and indicated resources as at December 31, 2015, were estimated at 2.3-million tonnes, grading 137.1 cpht. Inferred resources were estimated at 12.9-million tonnes, grading 140.6 cpht.

Mining Method: Conventional truck/shovel.
Major Infrastructure and Equipment: Mining will be undertaken using 29 m3 bucket diesel hydraulic front shovels, a 17 m3 front-end loader and 218 t class haulage trucks. This large fleet is augmented by 12 m3 bucket front-end loaders and excavators, and 90 t haul trucks.

Prospects: Under the current LoM plan, the 5034 kimberlite will be mined until the fourth quarter of 2021, with mining having started in the third quarter of 2016. Prestripping of the Hearne kimberlite will start in the first quarter of 2019 and mining will continue until the end of 2024. Prestripping of the Tuzo pit will start in the first quarter of 2020 and mining will continue until the end 2028.

Contact Person: De Beers head of external and corporate affairs Tom Ormsby.

Contact Details:
De Beers Canada,
tel +403 930 0991 ext 2703,
email tom.ormsby@debeersgroup.com, and
website http://www.debeersgroup.com.