The Diavik diamond project in the Northwest Territories is one step closer to development, following a draft report by the federal government which indicates that environmental or socio-economic problems are not expected to be significant.
The draft, which remains subject to revision, has been placed on public record in Yellowknife. The final report is to be released later this month for a 30-day public review period. After considering the report and any public comments, the federal environment minister, Christine Stewart, will issue a decision as to whether the project should proceed to the permitting phase.
The Diavik project is 300 km north of Yellowknife and 35 km southeast of the producing Ekati diamond mine. Diavik Diamond Mines (DDMI), a division of London-based
A feasibility study has been delayed until Stewart has issued her decision. The partners hope to have gained a better understanding of the project’s permitting, regulatory and fiscal requirements before completing the feasibility. Provided the study is favourable and all permits are issued, construction could start in January 2000, with startup projected for mid-2002.
The proposed mine centres on the development of four kimberlite pipes — A-154 South, A-154 North, A-418 and A-21 — that lie just offshore of the 20-sq.-km East Island in Lac de Gras. The pipes boast a resource of 133 million carats contained in 37 million tonnes averaging a grade of 3.6 carats per tonne. A diluted minable reserve is estimated at 26 million tonnes grading 3.9 carats per tonne, representing 102 million carats at an average value of US$56 per carat.
DDMI intends to dam off the pipes with water retention dykes and mine, by open-pit methods, all four pipes to depths of between 250 and 300 metres, followed by underground mining on the A-154 South and A-418 pipes to a depth of 400 metres.
The feasibility study is examining a production rate of 1.5-1.9 million tonnes of kimberlite per year, which would yield 6-8 million carats of diamonds annually during the full open-pit mining phase. The project has a mine life of up to 22 years, with capital costs estimated at $875 million.
During a winter exploration program, seven delineation holes and two mini-bulk sample holes tested the A-841 (or Piranha) kimberlite pipe, which lies in Lac de Gras about 250 metres northeast of the A-154 North pipe. The A-841 straddles the property boundary between the Diavik project and the Buffer zone claims. Ownership of the Buffer zone block is held 51% by BHP Diamonds, a division of
The A-841 pipe was discovered in 1997 by the Diavik joint venture. Drilling to date suggests that the kimberlite is smaller than A-154 South and that about 30% of the pipe lies on the Diavik property.
The first four holes that tested A-841, including two 1997 holes, have yielded 384 macrodiamonds and 1,032 micros from 867.8 kg of drill core (a macro is defined here as exceeding 0.5 mm in at least one dimension). Aber says the ratio of 1.63 diamonds per kg is similar to early results from the A-154 South pipe. Further results from A-841 will be available later this summer.
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