836 Figure 3 –Hi-Lo shell liner profile, harmful charge trajectory simulation above charge toe at 10.8 rpm @ 30% mill charge, DE shell liners breakage Figure 4 illustrates severe peening, characterized by dimpled impact marks on the liner surface, which was prevalent on the Hi-Lo shell liner design (also present to a lesser extent on the original Hi-Hi design, though the impact was minor). Significant pegging was also observed on both the shell and feed-end liners (where grinding balls became trapped between ribs or lifting hooks and lifters). Peening failure mode from repeated high-energy media impacts induced cracks and accelerated wear onto the intermediate discharge-end liners. Pegging primarily impacts worker safety as trapped balls pose an overhead hazard and must be manually scaled out before personnel can enter the SAG mill. These routine scaling requirements activities not only increase exposure to safety hazards but also extend the scheduled maintenance downtime. Figure 4 – Severe peening on shell liner lifter, pegging on FE liners and cracks on DE intermediate liners 2.2. Historical Liner Failure Modes Historically, Clarabelle SAG mill has been experiencing several failure modes including intermediate discharge-end liner cracking, frequent failure of the discharge deflector cone bolts and undesirable shell liner packing—cemented rock-charge adhered within the space between the shell lifters (Royston, 2012). As well, severe peening—an impact induced deformation and work-hardening—on liners caused by frequent hammering from grinding media and ore are conditions that increase liner wear and may lead to breakage (Powel, 2006). Lastly, chronic presence of pegging—oversized particles and balls getting stuck between lifter bars, posed a safety risk for SAG entry during maintenance. Original Hi-Hi Shell Liner Failure Modes Figure 5 shows the original 60-3 row Hi-Hi liner with 7° face angle design and trajectory simulation at 10.8 max rpm (with no packing) with harmful media to liner impacts above charge toe. Also, this liner was designed to start-up and operate at max speed (10.8 rpm). This liner set was prone to significant packing which also depends on several factors such as ore types, slurry characteristics, liner design and wear profiles
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