reinstated. Thus, a root cause analysis was initiated. Figure 1 – Hi-Lo discharge-end shell liner plate cracked, installed in March 2021 and failed in March 2022. Fault Tree Analysis, a reliability engineering method for failure investigations, identified the excessive wide space with inadequate profile between lifters in the shell liner design was the primary cause of the failure. The combination of insufficient lifter face angle (27°) and uncontrolled charge trajectories at the operating SAG speed of 10.8 rpm resulted in frequent high-energy liner impacts and exacerbated abrasive wear, leading to the liners operating beyond their design capacity and ultimately resulted in fatigue fractures on the shell liner plate. Several contributing factors prevented early detection and mitigation of the failure mechanism. These included inadequate liner wear monitoring, the absence of a systematic liner integrity inspection program and insufficient operational control of SAG speed and charge levels in relation to the liner design requirements. Collectively, these factors created failure modes that exceeded the liner mechanical strength leading to fatigue fractures. The macro-fractography examination of the liner plate crack confirmed the failure mechanism. The affected liner plate exhibited significant wear with remaining thickness of 35 mm, below the manufacturer’s 40 mm minimum replacement threshold. Uneven liner plate wear profile contributed to localized stress concentration that promoted crack initiation. Additionally, fatigue cracking was also identified on a 50 mm thick liner plate (Figure 2), indicating that cycling impact can induce fatigue fractures even when thickness remained well above the recommended minimum. The liner thickness control was inadequate. The frequency of 3D laser scans performed prior to the failure contained too few sampling points, and lacked consistent cross-sectional coverage, leaving the critical wear condition undetected. Additionally, the absence of a systematic liner inspection program contributed to the lack of wear profile control.
RkJQdWJsaXNoZXIy MTM0Mzk2