Typical Reason to Replace a Ball Mill Trunnion ‘unexpectedly’

Typical Reason to Replace a Ball Mill Trunnion ‘unexpectedly’

What is the typical reason a ball mill trunnion needs to be replaced unexpectedly?

typical reason a ball mill trunnion needs to be replaced

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It is unclear if the trunnion damage was known ahead of time and planned for a change-out during the shell reline or if it was discovered during the reline work.

While, not knowing if this is the feed or discharge end trunnion, there could be a number of things causing this emergency repair job and plant downtime:

  • Dropped charge can cause stress fractures and/or deformation
  • Metallurgical quality issues from foundry (e.g. slag inclusion stress riser can initiate fatigue cracking)
  • Slurry racing behind trunnion liner or center discharge cones due to leak – erosion thins the metal and causes weakness.
  • Dirt/grit contaminates bearing – causes deep scoring of journal surface and poor lube pressure retention (lift)
  • Wearing through trunnion liner can cause localized erosion/weakness
  • Lube or operational failure may have caused overheating and/or galling damage of journal surface.

Other Typical, and maybe similar, reason is:

  • Poor maintenance or operation! Contamination of lube.
  • Washing/hosing dirt into trunnion when the feed chute leaks is another big one.
  • The cyclone underflow tube somehow sanded and plugged to the point of overflowing and spilled over the trunnion, causing slurry to enter.

 

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Typical ‘Approximate’ Grinding Mill Anatomy
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