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PHASE THREE: MINING
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What is kimberlite?
According to the Geological Survey of Canada, kimberlites are rock formations where diamonds can be found. Diamonds form at a depth greater than 150 kilometres within the earth. After their formation, diamonds are carried to the surface of the earth by strong volcanic activity. This mixture of magma, transported rock and diamonds forms pipes called kimberlites as it reaches the surface. The name kimberlite comes from the town of Kimberly, in South Africa, considered, last century, as the world centre for diamond mining. |
Underground mining methods will be used to mine the kimberlite dyke, which is about 2.7 metres thick and dips an average of 15 degrees from the northwest shore down under Snap Lake.
The primary entrance to the mine is five metres wide by 4.5 metres high. Low profile trackless mining equipment is used at Snap Lake as this allows for access to areas of low overhead clearance and small spaces.
De Beers received 49 pieces of heavy equipment on the 2007 winter road, including jumbo drills, mechanized roof bolters, scoops and light vehicles.
The ore is mined using a modified room and pillar method. Segments of kimberlite will be extracted in excavations that are separated by pillars of ore.
Kimberlite will be hauled underground to a crusher. Crushed ore will be loaded onto a conveyor to the process plant on site.
Some of the processed kimberlite will be dewatered, mixed with cement and piped underground to fill voids left, after ore is mined out.
The remaining processed kimberlite will be deposited in bermed processed kimberlite containment area, known as the North Pile.
Diamonds extracted in the process plant are sorted and then sent to De Beers’ valuation facility in Yellowknife. Once valued for royalty purposes, they will be exported to the Diamond Trading Company in London for sorting and sale.
De Beers signed an agreement in May 2004 with the Government of the NWT to make available 10% of Snap Lake’s diamond production, by value, in economically cuttable categories to support the NWT secondary industry. Snap Lake diamonds made available for sale under this arrangement will be made available to those local cutting and polishing factories in the NWT that are GNWT approved manufacturers and that successfully fulfill the Diamond Trading Company’s (DTC’s) client selection criteria. The DTC is the sales and distribution arm of De Beers.
The mine is on target to attain its average planned production rate of 3,150 tonnes per day by mid-2008. First diamonds were recovered on the first day the process plant began commissioning, August 22, 2007.
The Snap Lake Mine is expected to be in production for approximately 20 years.
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