Figure 8 – Simulations Results Summary Subsequently, both the Phase II grinding line and flotation circuits were also investigated and the assessment integrated with the previous findings for the Phase I grinding line. Opportunities to increase throughput for the Phase II grinding line included increasing SAG mill speed and power, but this would likely coarsen product size. This coarsening could be mitigated by increasing the ball charge and reducing water addition to the ball mill. Further increases in throughput may be achieved by sending crushed pebbles to the ball mill, shifting load from the SAG to ball mill, but this would also coarsen product size. Thus, opportunities were identified to increase throughput for Phase II grinding line, but product size would coarsen. The combined increase in throughput and coarsening of product size from implementation of recommendations for both grinding lines (i.e. including the previous recommendations for the Phase I grinding line) could have a significant impact on flotation circuit performance. Integrated simulations of the grinding and flotation circuits were conducted to evaluate the overall impact, and these included the following: • Sim 0 – Baseline throughput, ball charge and SAG mill speed for Phase I and II. • Sim 1 – Phase II: Increase SAG mill speed and power. • Sim 2 – Phase II: Sim 1 + Increase in ball mill ball charge. • Sim 3 – Phase II: Sim 2 + Reduce ball mill water addition (increase ball mill slurry density). • Sim 4 – Phase II: Sim 3 + Sending crushed pebbles to ball mill (i.e., “pebble crush forward”). • Sim 5 – Phase I & II: Sim 4 + Phase I opportunities (i.e., optimized SAG mill ball charge + reduce pebble crusher CSS + increased ball mill power). The simulation results are summarized in Figure 9. Combining all opportunities for both grinding lines (Sim 5) could increase throughput by 14% but would coarsen the grinding product size. The combined effect of higher throughput and coarser size could reduce copper flotation recovery by ~1% for the same concentrate copper grade.
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