Grinding & Classification Circuits

Grinding & Classification Circuits 2017-03-23T09:46:37+00:00
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How to improve Grind size (4 replies)

5 months ago
maino.kaupa 5 months ago

What can i do to get best grind sizing in the mill:

  • add water?
  • decrease water?
  • add more balls?
  • Speed up mill?
  • or what more to do?
Bob Mathias
5 months ago
Bob Mathias 5 months ago

It depends on what your current have. Can you describe, in details, your current situation.

5 months ago
ThabisoKwenane 5 months ago

What is your target grind and the type of ore that you want to treat?

Greg Henderson
5 months ago
Greg Henderson 5 months ago
1 like by David

While we wait for your specific mill details, here's some general tips:

Adding water = reduced ore:ball contact and a coarser grind.  Unless the ore slurry is viscous, aim for a milling density in the vicinity of 42% solids v/v (not w/w).

Adding balls = more mill power and a finer grind generally (in a ball mill anyway).  In an open circuit SAG mill, more balls can actually destroy the intermediate pebbles that do the low energy abrasion grinding, producing a coarser grind.

Speeding up mill = more mill power, finer grind in a ball mill but potentially a coarser grind in an open circuit SAG mill due to higher rock breakage rates

Ball size = smaller balls produce a finer grind but don't handle coarse particles so you will produce more scats.  In a SAG mill, a makeup size of 100 to 125 mm dia is typically fine but in a secondary ball mill you need 50 to 65 mm top size.  In a primary closed circuit ball mill the top size can be anywhere from 50 to 90 mm, depending on ore hardness and feed F80 (Bond has a special equation to calculate the optimum ball size).

We can give you more specific advice when you send through info on your milling circuit, ore hardness, ore type and target grind size.

5 months ago
David 5 months ago

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