ONTARIO Vancouver’s NORTHGATE MINERALS has released a NI 43-101 preliminary assessment report for its Young-Davidson project in Matachewan. The report indicates that that the mine could be reopened and has resources sufficient for a 12-year life.
Using a gold price of US$635/oz, the report estimates inferred resources recoverable both from open pit and underground to be 15.7 million tonnes grading 3.31 g/t Au or 1.7 million contained ounces. The inferred resource for both recovery methods totals 4.0 million tonnes at 3.34 g/t Au or 433,000 contained ounces. An initial capital cost of $306 million is needed. Annual production would be 158,000 oz of gold at a net cash cost of $405/oz.
Northgate plans to develop a small open pit to feed the mill for the first three years. The pit will employ 50-t haul trucks and a stripping ratio of 2.9:1.
Production from underground will ramp up as the pit winds down, and the mill will treat underground ore exclusively for the remaining nine years of the project. The underground deposit is currently located approximately between 210 m to 1,300 m below surface. A new 6-m-diameter, 1,390-m-deep shaft will be sunk in the footwall with three main levels. The mine will be developed for sublevel open stoping. Plans call for using 17-t load-haul-dumpers and 18-t skips.
Initial mining capital costs are estimated to be $103.2 million for the completion of the new production shaft, completion of the ramp with initial lateral development, ventilation raises, a paste backfill plant and the purchase of underground mobile equipment to complete these activities.
A 5,000-t/d processing plant with autogenous grinding has been selected. The plant will include gravity recovery, flotation and carbon-in-leach (CIL) circuits. The mill will cost $69.3 million to build.
Additional costs include $18.1 million to upgrade existing power lines and establish a new 7-km line. A price tag of $7.7 million has been put on creating a tailings management area that incorporates and remediates the historic tailings area. Indirect costs such as engineering, procurement and construction management (EPCM), freight, start-up/commissioning, vendor support, first fills/capital spares, and owners’ costs are estimated at $50.9 million. An additional $45.6 million are estimated as contingency.
The complete Young-Davidson technical report is posted at www.NorthgateMinerals.com.