Feasibility Study and Technical Report - Pretivm

• three development headings advancing• two production levels with stope mucking and truck loading• two production levels with drilling/charging/servicing activities.Airflow allocations, based on the steady state production and development scenario, aresummarized in Table 16.14.Table 16.14Total Airflow RequirementsAreasFlow(m 3 /s) NumberTotal(m 3 /s)Development 38 3 114ProductionStope Mucking and Loading 24 2 48Drilling/Charging/Services 13 2 26Crusher Chamber 24 1 24InfrastructureWorkshop/Magazine 20 1 24Fuel Bay Loop 24 1 24Sacrificial Level 20 1 20Leakage and Balancing 15% - - 45Total (rounded) 32016.8.2 AUXILIARY VENTILATIONAll work areas in the mine not supplied with a split of fresh air must be ventilated usingauxiliary systems. The most effective means for providing airflow to areas withoutprimary airflow is typically with small diameter (up to 1,400 mm) axial fans combinedwith low leakage and flexible ducting.DEVELOPMENT VENTILATIONDuring access and level development, distances up to 800 m will be ventilated usingauxiliary systems. The peak auxiliary airflow for development activity will be required todilute the emissions of one 40 t truck and one 14 t loader, amounting to 38 m³/s ofauxiliary airflow.Modelling indicates that two ducts will be required. Each duct will have two 55 kW fansbolted together in series. The duct size is 1,200 mm in diameter. This will supply38 m 3 /s up to a distance of 850 m. This arrangement will allow for adequate overheadclearance for a fully-loaded 40 t truck.DRAWPOINT VENTILATIONAn allowance of 12.5 m 3 /s was made for each active drawpoint, for dust, blast fume, anddiesel exhaust clearance. Modelling indicates that a single-stage 55 kW fan, with900 mm diameter low-resistance, low-leakage ducting will supply the required airflow to adistance of at least 250 m. An increase of ducting size to 1,100 mm can be employedfor stopes that require a longer forcing distance−up to 750 m.Pretium Resources Inc. 16-46 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC