Grinding & Classification Circuits

Grinding & Classification Circuits2018-06-17T09:51:34-04:00
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Dear all, What can be the causes of coarse balls ejection from a ball mill? (4 replies)

Ilkaar
2 months ago
Ilkaar 2 months ago

Dear all, 

What can be the causes of coarse balls ejection from a ball mill? this happened after liners replacement.

 

Todd H
2 months ago
Todd H 2 months ago

The main reason why coarse balls are ejected from the mill is that the ball volume is too high.  Ball volumes in mills range but typical levels are 30-40% of full.  Too much mill feed can also push balls out but not likely.

https://www.911metallurgist.com/blog/ball-mill-charge-volume-calculation

Regards

 

Todd Harvey - Global Resource Engineering http://www.global-resource-eng.com

David
2 months ago
David 2 months ago

when you reline your mill, you reduce your mill radius by up to 15 cm, and therefore the mill volume.

i don't know what size ball mill you have but, if you take the time to do the simple math of approximate mill volume before VS after new liners are installed, you will see what Todd is referring to.

typically, you stop loading balls in your mill about 1 week before the reline job. it helps avoid/reduce full ball rejection on restart.

 

Ilkaar
2 months ago
Ilkaar 2 months ago

thanks David,

We are using more balls, than usual , in order to control Mill power which is dropping down with the same ore throughput and work index. Unfortunately balls are ejected.

Let me check the ball load as per Todd reply, and come to you later.

Many thanks !

htnenado
2 months ago
htnenado 2 months ago
1 like by David

Any increases to density within the mill when the ball loading is high can cause the balls to discharge. Keeping the BM % solids low will allow you to operate with higher loading but the mill becomes very sensitive to any water addition changes. The balls will 'float' out of the mill when the density gets too high.

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