The Ekati property covers 344,000 hectares, with the land lease area being 10,960 hectares and is located in Northwest Territories, Canada.
Ekati Diamond Mine opened in 1998 and produces nearly three per cent of current world rough diamond production by weight and five per cent by value. It is Canada's first surface and underground diamond mine.
Diamonds are sent from the mine to Yellowknife for cleaning and preparation for valuation before being exported from Canada. Approximately 80 percent of total production is of gem quality. Diamonds are found in kimberlite pipe deposits thought to be Mesozoic or Cenozoic in age. Ekati produces nearly 3% of current world rough diamond production.
The mine operator is BHP Billiton Diamonds Inc. It is a joint venture between BHP Billiton Diamonds Inc. (80%) and the explorers that discovered the diamond pipes: geologists Charles Fipke and Dr. Stewart Blusson.
The mine is located approximately 300 kilometres northeast of Yellowknife and 200 kilometres south of the Arctic Circle in the Lac de Gras area of the MacKenzie Mining District in the Northwest Territories, Canada. The mine site can be reached by means of a 400 km ice road during the winter or by air.
There is a solid layer of ice and snow on the ground for more than eight months of the year. The summers, while short, are pleasantly warm. Temperatures in this region fall below zero degrees Celsius for seven months of the year, October through to April. Extreme temperatures such as minus 57 degrees Celsius have been recorded, but this is rare.
In Yellowknife, the average daily temperature from November to March is minus 22 degrees Celsius. The average temperature in Yellowknife during June, July and August is 14 degrees Celsius.
A short growing season is offset by long hours of daylight. There are 20 hours of daylight in June in the southern Mackenzie and the area averages eight hours of bright sunshine a day throughout the summer. The "land of the midnight sun" has 23 hours of sunlight or more through much of June and July. Dogsledding and viewing the aurora borealis are top winter activities.
For 8 to 12 weeks in winter there is a 475 kilometre ice road to supply the mine. The only other transport is by air from Yellowknife.
Geology and Mineralization
The property is composed of approximately 388,416 hectares in the Lac de Gras area of the MacKenzie Mining District of the NWT. Diamonds occur in kimberlite pipe deposits. Kimberlites on the property are thought to be Mesozoic or Cenozoic in age. The kimberlites have been emplaced into Archean rocks of the Slave tectonic province. BHP Billiton has discovered 150 kimberlite pipes on its claim block.
Though much younger, formed 52 million years ago, the Lac de Gras kimberlites are similar to those found in Russia and South Africa. Their younger age also means that they are less eroded which indicates that less diamond bearing material has been carried away from the minesite by surface waters.
The kimberlite pipes themselves are usually covered by small, shallow (10m-30m) lakes. The mine plan for the property is based on multiple pipe development with each starting as an open pit operation which will progress to underground development as conditions and reserves permit.
Mining & Operations
The current mining plan is focusing on open-pit mining from the Panda, Koala, Fox, Beartooth, Pigeon, Sable and Misery orebodies, and underground mining of the Panda pipe which commenced in June 2005. The project is expected to have a life of 25 years or beyond.
Open-pit mining started on the Panda pipe and Koala, Misery and Fox have subsequently been developed sequentially. Each lake is being drained and shovel-and-truck, open-pit mining developed, with some 35 - 40Mt/y of waste rock being excavated from the pits. The ore feeds a central 18,000t/d-capacity processing plant. The 3.4km Panda Diversion Channel diverts water around the Panda and Koala Lakes into Kodiak Lake.
Panda open pit mining operations commenced in August 1998 and continued through June 2003. Underground production began in early 2005 and it was estimated to last for another 4 years. Ore is brought to surface by a 2.4km long conveyor system.
Koala open pit mining was completed in April 2006. Underground operations were designed as a 3,300 tonnes per day sublevel caving mine. The project will recover 6.5 million carats of high-quality diamonds over 11 year mine life. First production was expected by the end of calendar 2007.
A number of frozen core dams stop water from flowing into mining area. Termosyphons, or liquid CO2 pipes are used to freeze up the ground.
Major mining equipment includes four Driltech D90KS blasthole drills, two Demag H655SP diesel hydraulic shovels, ten Caterpillar D10R dozers, one Caterpillar 994 loader, one Caterpillar 5130 hydraulic excavator, four Caterpillar 992 loaders, two Komatsu PL 1800 hydraulic excavators and other support equipment. Carrying waste rock and ore from the open pits are thirteen 240-ton Caterpillar, three 170-ton Caterpillar 793 haul trucks and 11 x 100-ton Caterpillar 777D haul trucks. Well over 90 pieces of surface support equipment are used in mine operations. That includes mine production equipment from loaders and backhoes to buses and a fire truck. Also, approximately 100 diesel pickup trucks are used on site.
The processing plant has a nameplate capacity of 12,000 tonnes of ore per day for on average 15,000 carats of diamonds a day.
A gyratory primary crusher reduces ore to minus 300mm, coarse ore being stockpiled in a 20,000t-capacity storage building. A hot water-flushed cone crusher reduces the ore to 75mm before a high pressure roll crusher reduces it to minus 25mm. Primary and secondary scrubbers and degritting and sanding sections remove fine waste material for disposal. Heavy-medium separation (HMS) using slurried water and ground ferrosilicon separates a diamond concentrate from the crushed ore. Finally, X-ray fluorescence sorters are used to extract the diamonds from the HMS concentrate.
Diamond production increased by 26% in 2007 due to processing of higher grade ore containing lower value diamonds. Over 4 million carats of diamonds have been produced in the financial year ended June 30, 2009.
Environment and community
The mine site is located in sub-arctic tundra with the closest community approximately 180km southwest of the Ekati.
The environmental management plan continuously monitors the effects that mining operations have on wildlife and aquatic life.
In 1996 BHP Billiton Diamonds Inc. signed a Socio-Economic Agreement with the Government of the territory. Hiring preference is given to Aboriginal northerners and other NWT residents. The company's hiring target is 62% for northerners and 31% for northern Aboriginals.