Grinding & Classification Circuits

Grinding & Classification Circuits 2017-04-04T06:57:16+00:00
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SAG-MILL Ball charge (1 reply and 2 comments)

12 months ago
Gh99 12 months ago

I am a new in an iron ore plant were we are with magnetite ore using two Aerofall Mills but it's very hard for us to control the the mill feed rate, and we also have a problem with the Ball charge; we've tried different charges but it's still a problem; I would like to know if there's is any way to determine the optimal ball charge

Thanks in advance 



Alex Doll
11 months ago
Alex Doll 11 months ago
2 likes by mlticzon and Gh99

That is a very broad question.  Probably the best answer is you need to experiment and learn how your mills respond to your ore and adjust accordingly.  Some rules-of-thumb that can help direct things:

  • maximum ball size should be checked against existing formulae, such as Bond's ball size recommendation.
  • Hard ores are best ground with high ball charge levels and high mill speeds.
  • Soft ores are best ground with lower ball charge levels and lower mill speeds.
  • Media quality is rarely a problem if you are buying from a reputable ball vendor.

Look around on and you'll see hundreds of papers that describe how people have optimized mills and ball charges.  It is free to use as long as you are a member of one of the participating institutions, such as the AusIMM, CIM, IMM, SAIMM or IMM.

11 months ago

Thanks a lot, I really appreciate your help.
Now I understand, I just have one more thing, it's about when using different ball sizes. Can you explain a little bit why and when should we do so?
Thank you again

Alex Doll
11 months ago

Big rocks need big balls to grind effectively. Small rocks need small balls to grind effectively.

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