Feasibility Study and Technical Report - Pretivm

17.0 RECOVERY METHODS17.1 MINERAL PROCESSING17.1.1 INTRODUCTIONThe Brucejack deposit mineralization typically consists of quartz-carbonate-adularia, goldsilverbearing veins, stockwork and breccia zones, along with broad zones ofdisseminated mineralization. Gold and silver are the major economical metals containedin the mineralization. There is a significant portion of gold and silver present in the formof nugget or metallic gold and silver.The proposed concentrator will be conventional and will process gold and silver ore at anominal rate of 2,700 t/d with an equipment availability of 92% (365 d/a). Theconcentrator will produce gold-silver doré from the gold and silver recovered by gravityconcentration and smelting at the mine site. A gold-silver bearing flotation concentratewill also be produced, which will be sold and shipped off site. The mill feed will besupplied from the underground mine using conventional mining methods.17.1.2 SUMMARYThe process flowsheet developed for the Brucejack mineralization is a combination ofconventional bulk sulphide flotation and gravity concentration to recover gold and silver.The process plant will produce a gold-silver bearing flotation concentrate and gold-silverdoré from melting the gravity concentrate produced from the gravity concentrationcircuits. Based on the LOM annual average, the process plant is estimated to produceapproximately 4,300 kg of gold and 1,500 kg of silver as doré and 42,000 t of gold-silverbearing flotation concentrate from the mill feed, grading 12.0 g/t gold and 57.9 g/tsilver. The estimated gold recoveries to the doré and flotation concentrate are 41.6%and 54.9%, respectively, totalling 96.5%. The estimated silver recoveries reporting to thedoré and flotation concentrate are 3.0% and 86.6%, respectively, totalling 89.6%. TheLOM average gold and silver contents of the flotation concentrate are anticipated to beapproximately 130 g/t gold and 1,000 g/t silver. The flotation concentrate will beshipped off site to a smelter for further treatment to recover the gold and silver.The process plant will consist of one stage of:• crushing located underground• a surge bin with a live capacity of 2,500 t on surface• a primary grinding circuit integrated with a gravity concentration• rougher flotation followed by rougher flotation concentrate regrindingPretium Resources Inc. 17-1 1291990200-REP-R0012-02.1Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC