Grinding & Classification Circuits

Grinding & Classification Circuits

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Balls Cracking After SAG Reline (3 replies)

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polyroly
7 years ago
polyroly 7 years ago

Good Evening Everyone. First time posting in the forum here!

We just recently relined our SAG mill and we have had some operational issues since starting back up. We have had a massive amount of filings ending up in the discharge magnet and I examined ball fragments from the magnet and it is not typical small round pieces of scat. It is though the balls are cleaving and breaking apart.

I believe the excessive amount of filings are due to operator error in underloading the mill but I am still uncertain about the ball fragments? A product of getting dropped out of the mill and readded?

I did the % volume calculations and It looks like only about a 1% difference so I don't think it's a matter of the mill being overcharged.

Any help or comments would be appreciated!

thanks,

polyroly

Alex Doll
7 years ago
Alex Doll 7 years ago
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1 like by David

My first guess is that the new liner has a face angle that is tossing the balls against the far wall of the SAG mill causing them to break on impact with the liner.  In the sort term you can drive up the load in the mill so that the balls are impacting the rock charge instead of the opposite liner, or slow the mill down if you have a variable speed drive.

Longer term solution is to fix the face angle on the lifters so that they don't destroy your balls this way.  Talk to the DEM software consultants to have your lifter design checked.

https://www.sagmilling.com/

David
7 years ago
David 7 years ago
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Welcome the 911Mets forum.

"I did the % volume calculations and It looks like only about a 1% difference" = What is the %# you came up with?

Increase your SAG's operating density. I don't when your %solids are at now, but you can go to %80+ 

Do as Alex suggested and if you can, load that mill up. If your ore is too soft/fine to hold a load in the mill, could you change the feeder draw speed to bring coarser material from your ore stockpile?

-Do slow the RPM if you have that option.

Other side parameters for the discussion:

What size mill is this?

How long did you run that other set of liner for?

What is you plate thickener, net lifter height, liner centre to centre spacing?

What size ball?  Who makes the ball? Who made your liners?

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D
dassahd
7 years ago
dassahd 7 years ago
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Sorry I am late in joining, does it happen during every startup? If yes then I recommend you do as Alex suggested. You may need to test the balls as well. Probably adding a new batch to the mill.

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