Feasibility Study and Technical Report - Pretivm

The dilution factors were calculated from standard overbreak assumptions that arebased on AMC’s experience and benchmarking of similar long-hole open stopeoperations.• All stopes (primary and secondary) carry 0.8 m of dilution from rock overbreakinto the design hanging wall and design footwall, and 0.3 m of backfill dilutionfrom the floor.• Secondary stopes carry an additional 1.0 m of backfill dilution on each wall thatexposes a primary stope.• Sill pillar stopes are treated as secondary stopes, given the additional backfilldilution that can be expected from the roof.• Ore cross-cuts carry 0.5 m of dilution from rock overbreak into the designhanging wall and design footwall.• Production slashing of secondary stopes carries 0.5 m of backfill dilution oneach wall that exposes a primary stope.Further to the recovery factors applied to the various types of excavations in Table 15.2,the anticipated recovery of ore in proximity to the Brucejack Fault zone has been cappedat 75%. This percentage was applied to all excavations within the fault zone, which iscurrently estimated to host approximately 1.35 Mt (7%) of in situ mineral reserves.The application of the above parameters yields an overall LOM ore recovery of 93% andan overall ore dilution of 10%. The employment of parallel production drillholes instoping operations at Brucejack will provide improved dilution control in comparison tofan drilling; this is discussed further in Section 16.0.15.6 OREBODY DESCRIPTIONMineral reserves delineated at the $180/t NSR cut-off define an orebody consisting ofnumerous independent lenses in the VOK Zone and two distinct lenses in the West Zone,extending over a 550 m vertical distance, from the 1,000 m elevation to surface(approximately 1,550 m elevation).15.6.1 VOK ZONEThe VOK Zone hosts 21 lenses that each contain 60,000 t or more of mineral reserves.The mineral reserves are distributed between these lenses as follows:• 40% are within the Main Lens (M Lens)• 30% are within the next three largest lenses• The remaining 30% are distributed across 18 smaller lenses.Mineral reserves in the Galena Hill area are proximal to the VOK Zone and have beenconsidered as part of the VOK mineral reserves.Pretium Resources Inc. 15-6 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC