Pre-Concentration

A pre-concentration or “sorting" plant is planned to for the Hammerdown site.  Test work at multiple vendors throughout 2019 showed the mineralization containing pyrite and other sulphides is well suited to sorting methods, particularly utilizing laser and x-ray transmission (XRT) sensors to separate sulphide bearing particles from non-sulphide particles and dilution.  The sorting plant is designed to receive a feed from the on-site crushing and screening facility.  The sorting plant feed particles will be sized between 1/2” to 2 1/2” (+12.7-63.5mm) at a nominal rate of 1,400 tpd.  Fines measuring 1/2” minus (-12.7mm) are directed to the load out storage building.  Rejection rates and gold recovery through the sorting plant are expected to average 50% and 93% respectively over the life of the mine.  These factors vary depending on the feed grade and can range from 30-60% rejection and 92-95% gold recovery.  Rejects from the sorting plant will be stored adjacent to the plant and be used for back fill material for the underground mines.  At the end of the mine life, it is currently planned to place this waste material back into the Hammerdown open pit for closure.  A summary of the pre-concentration parameters is highlighted in Table 9.