Feasibility Study and Technical Report - Pretivm

• At 6% and 10% addition, consistently using MC binder (slag content 55%)produced a paste fill strength of more than double that of the GP mix.• At 6% and 10% addition, the SS binder (slag content 35%) consistentlyincreased paste fill strengths by over 50% compared to the GP mix.• Using FA in the paste fill mixes reflects the expected lower strength gain in theearly curing time (14 days) typical of FA mixes. However, the 28-day and final56-day strengths steadily gained higher strength levels, showing the benefit ofthe FA in partly replacing the GP cement.Table 16.4Summary of UC ResultsBatchTailings(%) Cement/Binder 14 days 28 days 56 days1 94 6% GP 405 448 5652 90 10% GP 875 1,038 1,2043 94 6% MC 909 1,145 1,4284 90 10% MC 2,008 2,507 2,7835 94 6% SS 577 738 9036 96 10% SS 1,525 1,831 1,9207 94 3% GP + 3% FA 340 537 6818 90 5% GP + 5% FA 1,050 1,824 2,415An outcome of the Stage 2 test work is the recommendation for further test work todetermine appropriate binder dosages. For this study, AMC adopted industry standarddosages to achieve the required 28-day strengths, as outlined in Table 16.3.16.3.6 WASTE MANAGEMENT AND STOPE FILLINGConsiderable waste rock will need to be disposed of on an ongoing basis throughout themine life.Stopes will be filled with development waste wherever possible, but some waste willinevitably be hauled to surface for disposal in Brucejack Lake. All waste generatedbefore the start of secondary mining must be hauled to surface given that it is unsuitablefor backfilling primary voids without a cementitious binder.It is normal that disused headings in mined-out areas are used for development wastedisposal, and an allowance has been made in the waste disposal profile in this respect.The disposal of waste rock in underground stopes has the effect of reducing the totalvoid volume requiring paste backfill, and hence reduces the percentage of mill tailingsthat can be returned to underground. Table 16.5 tabulates the volumes of waste to begenerated from milled ore and development headings, and the destination of thesevolumes over time. Over the LOM, 54% of development waste and 46% of tailingsgenerated from milled ore will be placed back underground. The balance will bedisposed of in Brucejack Lake.Pretium Resources Inc. 16-17 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC