815 SAG mill when treating the two extremes of ore competency independently. Figure 58 – SAG Mill Filling and Performance Processing the Two Extremes in Hardness Separately Error! Reference source not found. presents the frequency distribution of power draw m easurements for a 40-foot SAG mill over a six-month period. The mill has an installed power of 28 MW. As discussed previously, the most competent ores—typically hard and coarse materials—tend to exhibit longer residence times in the mill, resulting in higher mill fillings and elevated power draw. Under these conditions, the SAG mill has the potential to become the bottleneck of the mine value chain. Figure 59 – Frequency Distribution of SAG Mill Power Draw Readings over a 6-month Period In contrast, the least competent ores—generally softer and finer materials—exhibit shorter residence times, leading to lower mill fillings and reduced power draw. In such cases, the throughput constraint is more likely to lie outside the SAG milling stage. Blast designs therefore need to be tailored to ore competency, with the objective of maximizing SAG mill power utilization. This involves debottlenecking the SAG mill when processing the most competent ores, while promoting higher mill fillings and increased
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