In its latest updated technical report filed April 23, Pretivm Resources has some interesting updates on its mining operation plans at its Brucejack high-grade gold underground mine located in northwestern British Columbia, approximately 65 km north of Stewart. Notably it includes the active consideration of using battery electric mining equpiment in conjunction with the mine’s contractor, Procon, which handles production mining using longhole drill/blast/muck methods, backfill, as well as sustaining development. Procon supplies the bulk of the heavy equipment, with the exception of supplemental long-hole drills for production and sampling and some auxiliary vehicles.
Regarding mucking, on site Procon has three 10 yd3 LHDs and five 8 yd3 LHDs for production and development. This fleet is sufficient for the 3,800 t/d operation of the mine. The mine says it is now also evaluating battery electric LHDs as an alternative to diesel LHDs. On the haulage side, Procon has twelve 30 t trucks on site to support the development required to maintain current production. Later when the majority of ore hauled to the crusher is from the lower levels or the West Zone, one additional truck maybe required to support operations. Pretivm says the need for additional haulage capacity may be counteracted by the reduction of development needs at that same time, depending on the LOM schedule. The mine is researching the use of electric haul trucks on a trial basis and initially to be used as supplemental units until the evaluation is completed, stating: “The battery trucks could replace the diesel trucks providing benefits in costs, environmental health,and safety.”
The updated underground mine design in the report supports the extraction of 3,800t/d of ore through a combination of transverse and longitudinal long hole open stoping (LHOS). Closely matching the previously stated plan disclosed in the 2014 FS (Ireland et al 2014) and the 2019 FS Update (Tetra Tech), paste backfill and trackless mobile equipment will be employed in the majority of mining activities. Access to the mine is via the Valley of the Kings decline, situated near the concentrator. The Valley of the Kings decline is also utilised as a conveyor way, with two conveyors installed at a combined length of 800 m. The existing West Zone portal provides the main access for large underground equipment and waste haulage.
Development initiated during the two pre-production years of the LOM continues, with the mine operating at a rate of 2,700t/d since commercial production began in July 2017. The ramp-up period to a maximum output of 3,800t/d is complete, with production averaging 1.3 Mt annually. The Brucejack gold mine uses conventional gravity concentration and sulphide flotation to produce gold (Au)-silver (Ag) doré and gold-silver flotation concentrate.