Grinding & Classification Circuits

Grinding & Classification Circuits

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Ball Mill Discharge Trunnion with excessive wear (2 replies and 2 comments)

Eder Figueiredo
2 years ago
Eder Figueiredo 2 years ago

Hi everybody,

During performing some Ultrasonic Testing (UT) to measure the thickness of the mill discharge trunnion I found excessive wear. I can say it is in a critical state.

Everything indicates that slurry seeped underneath trunnion or shell liners and start washing the internal part of the trunnion. Probably the mill has operated for long periods of time causing excessive wear to the trunnion with the problem undetected.

Wondering if somebody could help me and give some orientations.

  • Is it possible to make some repairing on the trunnion?
  • How can I guarantee the safety operation of the mil without any risk of structural collapse?

Please have a look at the attached document.


2 years ago
David 2 years ago

Hi Eder,

Temporary fix is use Devcon or other reinforced urethane filler.
Second seek professional help from mill manufacturer or other specialists like Hoffmans engineering.

Eder Figueiredo
2 years ago

Thanks, David.
I will look for a Devcon representative in Brazil and also consider Hoffman engineering as a second option.
For temporary repair with reinforced urethane filler. Does the structural strength of the trunnion is kept?


Todd H
2 years ago
Todd H 2 years ago
1 like by David


I have used a company called Welding Service Inc in Georgia for on-site repairs of autoclave shells and they have the equipment to do this.  It was a long time ago so they may not be around anymore.  There is also this company

They are in Salt Lake and have done work for Newmont.  Not sure of your location but any competent welding service can do this job - I would look for someone with pressure vessel experience since they can check all the weld quality and ensure a quality seamless finish without risk of creating a weld failure.


Todd Harvey - Global Resource Engineering

Eder Figueiredo
2 years ago

Thanks Todd.
I have contacted some competent welding companies in Brazil do this job. However, they are concerned about the huge amount of material to be deposited during welding that can cause some deformation on the trunnion and the difficulties of performing stress-relieving after welding on-site.
In addition, we discussed the possibility of machining the internal part of the trunnion to get it flat and install a splited bushing and weld it.
What is your opinion?


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