(submitted photo/Star Diamond)

By Glenn Hicks

DIAMOND MINING

Core and sonic drilling completed at diamond site

Apr 17, 2019 | 5:13 PM

Rio Tinto has completed some of the most detailed drilling yet on the site as efforts continue to deduce the make-up of the diamond deposits at Fort à la Corne, east of Prince Albert.

Star Diamond Corp, which owns the land rights, announced this week that the mining giant — which has an option on up to 60 per cent of the deposits — had concluded core drilling and sonic measurements in a total of 24 holes across the Star and Orion South kimberlite areas.

Most of the core holes drilled were in the region of 250 metres but one of them went as deep as 560 metres, although Star Diamond said that was not necessarily how deep the open pit mine would be.

“While we know the kimberlite continues at depth we don’t fully understand the diamond grade information – in other words how many carats per ton – there are at those depths,” Senior Vice President George Read told paNOW. “Our bulk sampling we do with the trench cutter will only go 200 metres below the surface.”

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That massive trench cutting work is set to begin within weeks according to Read, and the series of drilling holes that have been made will guide the bulk sampling process as Rio Tinto establishes if there are enough quality diamonds to make a go of the proposed 30-plus year mining project.

According to Read, the drilling work by Rio Tinto has confirmed earlier analysis by Star Diamond geologists on the depth of the kimberlites. The sonic drilling however gave a very high quality and degree of accuracy on the depth of the overburden on top of those kimberlites. That rock and debris runs to about 100 metres below the surface, which Read suggested was not an insurmountable issue.

“It certainly is a mining challenge to remove the overburden but with a bucket wheel excavator we can remove it and it becomes economical with that sort of equipment,” he said.

From an environmental perspective, where would all that excavated material go? Read said part of their environmental plan showed the waste would be piled into a small hill.

“It would not be an eyesore and would ultimately be re-vegetated to look like the forest; it would not be inconsistent [with the landscape] because we know already there is [topographical] relief in that part of the Fort à la Corne,” he explained.

As Rio Tinto gears up for the large scale trench cutting and the assembly of an on-site processing plant for the bulk sampling, Read said the amount of people working on the project is increasing.

“There has been a camp established for 90 persons that’s now being expanded for 150 persons and I believe that is close to being full already,” he said.

Rio Tinto has an option agreement with Star Diamond to conduct four phases of work in total and the mining giant has committed to spend $18 million on exploration activity. If the proposed mine were to happen, it would employ up to 700 people over a period exceeding 30 years.

A final decision on whether the venture is feasible is likely still years away.

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glenn.hicks@jpbg.ca

On Twitter:@princealbertnow