SOMBA K'E/YELLOWKNIFE - With its December production shutdown cancelled, Diavik Diamond Mines Inc. is now focusing on the mine's transition to underground mining.

System analyst Arnold Enge poses in front of a tunnel leading to the underground workings of the Diavik Diamond Mine. Underground mining at Diavik is slated to begin in the first quarter of next year, after an investment of $787 million by partners Rio Tinto (which owns mine operator Diavik Diamond Mines Inc.) and Harry Winston. - NNSL file photo

Rio Tinto - owner of Diavik Diamond Mines Inc. - and its partner Harry Winston have invested $787 million into underground mining infrastructure at Diavik. That's compared to the $1.3 billion it cost to build the original Diavik mine.

The start date of commercial production from the underground mine has been pushed back more than once, as Rio Tinto contended with the reduced demand for rough diamonds caused by the global economic slowdown. Production at the mine was shut down for six weeks this past summer.

Underground mining is now slated to begin in the first quarter of next year, said Doug Ashbury, spokesperson for Diavik Diamond Mines Inc.

"We have completed enough of the underground infrastructure to commence production," he said. "Specifically, the north inlet water treatment plant expansion, the fresh air and return air raises, the underground pump station, the crusher and (second) powerhouse are now complete.

"We are still working on infrastructure required in due course such as the paste backfill plant, additional permanent accommodations, the permanent underground mine dry (change room) and the underground maintenance workshop.

"In terms of the underground tunnels, or what are known as the preproduction tunnels, these are virtually complete. Keep in mind, we can mine in one area underground while we build in another."

In the first half of 2009, Diavik averaged 812 employees, 65 per cent of whom were from the North.

The company is now recruiting for underground staff.

"We have recently commenced hiring our permanent underground workforce (and) are looking to fill about 150 positions with both internal and external applicants in this first wave of recruitment," said Ashbury.

From early next year to 2012, both underground and open pit mining will take place, resulting in a larger-than-normal contingent of workers on site. But that won't last. Some time in 2012, open pit mining will cease and Diavik, like De Beers Canada's Snap Lake diamond mine, will become a fully underground mine.

There was much talk at last week's 1st Annual Strategic Northern Infrastructure Symposium about the remaining life of both Diavik and BHP Billiton's Ekati Diamond Mine.

Diavik's feasibility 1999 study - which predicted the mine would last past 2020 - still holds, said Ashbury.

"In feasibility, back before the initial mine construction phase, we were projecting a total mine life of 16 to 22 years," said Ashbury.

"With surface production starting back in January 2003, we are approaching the end of year seven. The underground phase is expected to take us past 2020, so that 16-22 range remains accurate."