Figure 9 – Drone-based inspections, indicating drone location while performing UT thickness measurement 4. GRINDING EFFICIENCY Clarabelle’s SAG mill is fed by at least 5 underground mines (with more mines coming online), with the ore consisting of 3 major sulfides: pentlandite, primary nickel mineral, chalcopyrite, primary copper mineral, and pyrrhotite, sulfide gangue mineral, with the balance being silicate gangue. The feed variability is significant; SAG specific energy ranging from 5 to 20 kWh/t. The feed size is also highly variable, typically F80 of 6” and product size of 2” (P80), though oversize material commonly enters the mill (sizes reaching up to 30”x6”) as well as variations in fines and coarse content are commonly observed, which further contribute to the challenges of maintaining a stable SAG mill operation. Pebble generation is typically between 10 and 30% (function of feed type/grade and state of liners), where it increases steadily over a given liner campaign. Under these conditions, the SAG mill operates at an average rate of 18,000 t/d. Figure 10 shows the SAG mill performance after the new Hi-Hi liner reline, demonstrating SAG mill tons/hour increased by 9% (+66 tons/hour) compared to the original Hi-Hi liner design, and specific energy consumption decreased by 7% (-0.4 kWh/t). It signifies improved charge lift, optimized ore/media trajectory, and more energy conversion towards ore breakage. The SAG used more available power to generate more throughput, essentially what the new liner design was expected to achieve.
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