Pretium steps up exploration, development

Pretium Resources Inc. Feb. 26 said it is ramping up underground development and exploration at Brucejack, a high-grade gold mine in British Columbia's Golden Triangle.

The company reached commercial production at Brucejack in mid-2017 and the operation produced 152,484 ounces of gold during the first six months of operation. This roughly 305,000-oz-per-year pace is despite the fact that lower grade was fed into the mill early on.

While the mill has outperformed its 2,700-metric-ton-per-day capacity, the gold grades being fed into it have been lower than expected.

Pretium attributes some of the lower than modelled gold grades being fed into the mill last year to ore that was mined from an area that "had a lower drill density than stopes on other levels of the mine."

As the mining moves into areas more thoroughly drilled, the company expects the ore reaching the mill to be closer to the grades expected.

Pretium said access to the broadest possible range of stopes will maximize stope blending and is expected to improve the management of production grades.

To improve access and build stope inventory the rate of underground development has been increased to 700 meters per month, up from 420 meters originally envisioned in the feasibility study for Brucejack.

The company plans to have 10 to 12 stopes with a range of grades available by mid-year.

This inventory, which includes multiple higher grade stopes, is expected to improve the management of production grades as the ramp-up continues.

Another component of the grade control program, reverse circulation drilling to optimize stope definition, is currently being carried out on a trial basis.

If effective, the RC drilling will provide a larger sample per meter and is expected to be faster and more cost effective than core drilling, which has been used for infill drilling to date.

In addition to better defining the reserves, Pretium has launched an underground exploration drill program to test for a porphyry source and evaluate the potential extension of the Valley of the Kings deposit at Brucejack to the east.

The drill program will follow-up on a 2015 regional grassroots drill program that cut high-grade gold at Flow Dome, a prospective zone about 500 meters east of the Brucejack Mine.

Pretium said the mineralization drilled at Flow Dome confirms the presence of either a new mineralized zone or an extension of the Valley of the Kings deposit.

Two holes drilled from the 1,200-meter level of the Valley of the Kings, each 1,600 meters long, will provide a continuum of information from Valley of the Kings to Flow Dome. The drilling will also test below Flow Dome, where structural geology combined with a geophysical anomaly suggests a potential porphyry source.

–SHANE LASLEY