Pretium Advances Engineering Work on Brucejack Gold

Pretium will initially develop the Valley of the Kings deposit—one of two identified at its Brucejack property in
British Columbia—before turning to the lower-grade West Zone deposit. Ore in Valley of the Kings probable
reserves is reported at 13.6 grams per metric ton. (Photo courtesy of Pretium Resources)

Pretium Resources has reported the results of a positive, NI 43-101-compliant feasibility study of the high-grade gold and silver resources identified to date at its 100%-owned Brucejack project in northern British Columbia. The feasibility study was prepared by Tetra Tech.

Pretium also noted it is continuing to advance engineering for the Brucejack project in support of the ongoing permitting process and anticipates filing its application for an Environmental Assessment Certificate later in 2013. After obtaining permits and subject to a production decision, Pretium anticipates starting construction of the mine in the second half of 2014.

Brucejack is planned as an underground mining operation using a long-hole stoping mining method and cemented paste backfill. The Valley of the Kings deposit—the higher-grade, primary targeted deposit—will be developed first. The lower-grade West Zone will be developed during the second half of the project’s 22-year mine life.

The Brucejack project is planned to operate at a processing rate of 2,700 mt/d, producing a total of 7.073 million oz of gold and 31.641 million oz of silver over the mine life. Average annual gold production during the first 10 years of production is planned at 425,000 oz/y.

The base case for the Brucejack feasibility study assumes $1,350/oz gold and $20/oz silver prices and a one-to-one US$:C$ exchange rate. Project capital cost, including contingencies, is estimated at $663.5 million. All-in sustaining cash costs per ounce of gold produced are estimated at $508/oz, net of silver credits. Internal rate of return is estimated at 42.9%, and payback is estimated at 2.1 years.

Valley of the Kings probable mineral reserves currently stand at 6.6 million oz of gold in 15.1 million mt grading 13.6 g/mt gold. West Zone’s proven and probable mineral reserves currently stand at 700,000 oz of gold in 3.8 million mt grading 5.8 g/mt gold.

The Brucejack mineral processing plant is planned to use conventional sulphide flotation and gravity concentration and to produce both gold-silver doré and gold-silver flotation concentrate. Metallurgical recoveries are estimated at 96.7% for gold and 84.8% for silver for the Valley of the Kings deposit and 94.7% for gold and 90.4% for silver for the West Zone deposit.

The estimated capital cost for the Brucejack project includes $49.9 million for a 50-km-long transmission line. An evaluation of the cost benefits of alternatively entering into a build-own-maintain agreement for the construction and operation of the transmission line is now under way. The capital cost associated with plant construction is also being evaluated for potential savings in optimizing the site layout.

As featured in Womp 2013 Vol 07 -