TORONTO (miningweekly.com) – Canadian precious gem miner Dominion Diamond on Monday said it had promoted new material found at the Ekati mine’s Misery pit, in Canada’s Northwest Territories, to the inferred resource category, adding five-million carats of rough diamonds to the mine’s existing compliant resources.

The TSX- and NYSE-listed miner said diamond grade and value estimates for the Misery satellite pipes had been validated by drilling, mining and processing activities, and the inferred resource now totalled 3.9-million tonnes, grading 1.3 ct/t for five-million carats.

After analysing this winter's drilling programme, Dominion said it would by the end of the year prepare an updated technical report on the mineral resources and reserves at the Ekati mine that would include more details on the Misery satellite resources as well as updates to some other pipes.

Dominion, which last year bought out diversified miner BHP Billiton’s stake in Ekati for C$553-million, earlier this month agreed to buy multimillionaire Canadian diamond magnate Charles ‘Chuck’ Fipke’s remaining 10% stake in the mine for C$67-million.

The Canadian miner, which also operates the Diavik mine in the Northwest Territories, also on Monday updated its mine plan for Ekati, saying it expected to produce 19.18-million carats from the mine between 2015 and 2020. The new plan would see Ekati's output ramp up from 2017 to a peak of 6.33-million carats in 2019. Pending permitting of the Jay deposit, the mine would close in 2020.

The plan assumed production from the Misery, Pigeon and Lynx openpits, and the Koala and Koala North underground operations. Mining of the Fox pit was completed this year.

Koala North was currently in production as a sublevel retreat underground operation and was scheduled to finish later this year. Koala was currently in production as a sublevel/inclined cave underground operation and was scheduled to finish in fiscal 2020.

Waste stripping was in progress at the Misery openpit, where Dominion expected to achieve the first full year of output in fiscal 2016. The deposit would be depleted by 2018.

Waste stripping from the Pigeon openpit was scheduled to start this year with kimberlite mining starting in fiscal 2016 and finishing in fiscal 2020.

The base scenario also included developing and mining the Lynx pipe from 2017. The deposit currently held an indicated resource.

Dominion noted that the reserves and resources planned for processing still did not fully use the Ekati processing plant's capacity of about 4.35-million tonnes a year, prompting the company to use the spare capacity to process additional material from Koala North, Misery Northeast, and coarse ore reject stockpiles. These sources of material were not included in the mine plan.

Dominion last week said during the second quarter ended June 30, processing volumes at the 40%-owned Diavik mine rose 17% year-on-year owing to improvements in mining rates as the underground ramp-up progressed throughout 2013 to full production from all three kimberlite pipes, and improvements in the availability and use of the processing plant. The Diavik mine is operated by Diavik Diamond Mines, a Rio Tinto company.

The diamond output from the mine rose 38% to 2.15-million carats in the period, a combination of higher realised grades in all three orebodies and a higher volume of ore processed.