Grinding & Classification Circuits

Grinding & Classification Circuits

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How to get finer P80 grind (9 replies and 4 comments)

a
alaz
7 years ago
alaz 7 years ago

hello everyone 

my problem is we hardly get 80% smaller than 75µm 

we have a SAG mill and ball mill and we are running 300 TPH

  • on the sag mill the pulp S.G is 1.8 
  • the sag mill KW around  4500 and we are using 125 mm steel ball 
  • the ball mill 4900 KW and we are using 60 mm steel ball 
  • on the mills discharge sump the pulp S.G is 1.6 
  • the cyclone pressure is 1.1 bar 

my question why we are not getting 80% smaller then  75µm ? 

 thank you.

(unknown)
7 years ago
(unknown) 7 years ago
1 like by alaz

What are your SAG & ball mill dimensions?

What are your SAG & ball mill motor installed kW?

Do you have a BWi #?

What dimensions are your SAG grates & trommel?

R
Richard S
7 years ago
Richard S 7 years ago
1 like by David

You might consider adding a graded charge of balls into your ball mill to reduce the average size of the balls for better fine grinding.  You could substitute up to 30% of your charge with smaller balls.  I would try say 10% of your charge weight with 30mm or 40mm forged balls (high chrome for endurance) and see if it helps.  If it improves your grind, gradually increase the weight of the smaller balls.  I am assuming that you are getting good reduction in your SAG mill.  If you are feeding the ball mill too large of particles, you will not get the expected grind out of your ball mill.  If your SAG is not performing and leaving a large circulating load, you might need to consider a scalping screen and add a pebble crusher to the circuit. More information is needed to analyze your milling circuit, such as suggested by Bill Fraser.

G
Greg Henderson
7 years ago
Greg Henderson 7 years ago

If you can provide some fundamental information I can give you an idea of what capacity each milling stage can handle and if there is scope to reduce the P80 from the cyclones:

 

  • Mill inside shell dia x effective grinding length for both mills and motor sizes
  • Bond ball mill work index
  • Drop weight index or Axb product
  • Unconfined compressive strength
  • SPI
  • Bond crushing work index
H
banyechan
7 years ago
banyechan 7 years ago

It is necessary for have more data for working conditions.Hope you can provide more details

m
Mostafa
7 years ago
Mostafa 7 years ago

what is your cyclone's spigot diameter ?

J
Jim
7 years ago
Jim 7 years ago

Hi Alaz,

Your issue is definitely something we can assist with by running simulations in our software.  Generally however more information will be required.

If it is not against the groups policy I would like to put one of our team in touch with you and most likely arrange a site visit/audit to discuss in person.

Please let me know which country you are in and how we can get in touch with you.

G
Greg Henderson
7 years ago

Free advice only, no paid business development!!

J
Jim
7 years ago

Hi Greg. We actually visit customer sites and offer advice at no cost. If they end up buying products we manufacture as part of that process then we get a result.
If not, they still have their "free advice"

David
7 years ago
David 7 years ago

Guys, biz-dev is OK if accompanied with useful help. Thank you all for your help.

Watch https://www.youtube.com/watch?v=4nGVS4Xtk0M

Use the Social Share Bar on the Left. Tell everyone you can about https://www.911metallurgist.com/metallurgy/ It's FREE & GOOD.

a
alaz
7 years ago

thanks that was helpful i will try to adjust my profile

a
alaz
7 years ago
alaz 7 years ago

thank you for helping me i will try to answer all your questions  

What are your SAG & ball mill dimensions?

  • ball mill 9.3*6.2 
  • and sag mill 7.9 *5.2 

What are your SAG & ball mill motor installed kW?

  • our motors are 5500 kw 

Do you have a BWi #?

i'm not sure what are talking about 

What dimensions are your SAG grates & trommel?

  • trommel cut point is 16mm 
David
7 years ago

BWi=Bond Work Index

K
KRISHNADAS
7 years ago
KRISHNADAS 7 years ago

The suggestion given by Richard is practical & I would also like to add thta- Please check your gratings in the SAG mill , maybe it is worn out and needs repair.

Krishna

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