Feasibility Study and Technical Report - Pretivm

The reground rougher concentrate will be initially upgraded in the first cleaner tank cells.The resulting concentrate will be pumped to the second cleaner circuit, while the tailingswill report to the cleaner scavenger flotation cells for further flotation. The cleanerscavenger flotation concentrate will be recycled to the head of the first cleaner flotationcell bank, together with the tailings from the second cleaner flotation. The first cleanerscavenger flotation tailings will be pumped to the rougher scavenger flotation feed box.The concentrate from the second cleaner flotation stage will be further upgraded by thethird cleaner flotation, and the second cleaner tailings will be pumped to the first cleanerflotation. The concentrate from the third cleaner flotation cells, which will be the finalconcentrate, will be pumped to the concentrate thickener. The third cleaner tailings willbe recycled back to the head of the second cleaner flotation circuit.The reagents used in the primary bulk flotation circuits will also be added to the threestages of cleaner flotation to float the target minerals. The cleaner flotation processeswill be carried out at the natural slurry pH level as well.GRAVITY CONCENTRATE UPGRADINGThe gravity concentrates produced from the primary grinding circuit and the regrindingcircuit will be upgraded by conventional tabling followed by smelting to produce goldsilverdoré. Upgrading will be conducted in a secure facility with security entrances and24-hour CCTV surveillance. Operations in the secured gold room will be conducted duringday-shift only, and access to the gold room will be restricted to authorized personnel only.Key equipment that will be installed in the gold room includes:• two gravity concentration tables – one for the coarse centrifugal gravityconcentrate, and the other for the fine centrifugal gravity concentrate• one table concentrate dryer• one flux mixer• one 175 kW induction melting furnace• one vault for storing doré and table concentrate• one off-gas and dust scrubbing system• ancillary equipment, including slag treatment devices.The coarse and fine centrifugal gravity concentrates from the primary grinding circuit andthe regrinding circuit will be pumped to separate table feed stock bins located in the goldroom. The two concentrates will be then upgraded by two different tables on a batchbasis. The concentrates from the tables will be dewatered, dried in a dryer, then weighedand stored in the vault prior to smelting. The tabling middling products will be recycledback to their respective table feed stock bins. The table tailings will be pumped to thefeed well of the centrifugal gravity concentrator in the primary grinding circuit forscavenging any potentially recoverable free gold and silver grains.Pretium Resources Inc. 17-10 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC