Feasibility Study and Technical Report - Pretivm

Figure 13.28 Variability Test Results – Silver Metallurgical Performance (2010-2011)13.3.9 LOCKED CYCLE TEST (2012 AND 2013)In order to better examine recovery and concentrate grade, four locked cycle tests werecompleted in 2012 on two master composites, which consisted of one blend from theVOK Zone (VOK-1, - 2, -3, -4) and one from the West Zone (WZ-1, -2). The procedureincluded:• primary grinding targeting a moderate size of 80% passing 80 to 85 µm• gravity concentration• rougher and scavenger flotation with the scavenger concentrate recycled• rougher concentrate cleaner flotation.For tests FLC1 and FLC3, the rougher concentrates were reground prior to cleanerflotation. In an effort to activate gold- and silver-bearing minerals, copper sulphate wasadded during the rougher and cleaner flotation stages.In 2013, two separate locked cycle tests were conducted on two composites generatedfrom the upper and lower zones of the VOK deposit. The test procedure used was similarto that used for the locked cycle tests in 2012.Pretium Resources Inc. 13-47 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC