## mono-chamber ball mill - page 1 of 2

Hey, Can anyone tell me what are the requirements for ball charge design of a mono-chamber raw mill? How can you calculate the max ball size? And a typical ball charge for a mono-chamber mill? Thx

Raw mill with classifyingll lining -one compartment mill conventional close circuit mill:90mm=14%,80mm=19%,70mm=13%,60mm=14%,30mm=14%,25mm=16% & 20mm=10%Compensation--90mm : 60% & 30mm:40%Initial piece weight=139gm & Equilibirium piece weight=122gm

Hi Raj, Thanks for your reply. There is a hammer crusher before the raw mill so mill feed is very fine with d80 (80% passing size) of 4000 micron and 1% passing 3/8 mesh (9.5 mm sieve). Based on Bonds formula I calculated the max ball size to be 50 mm. Also, I forget to mention that the mill liner is lifting not classifying to we should limit the number of different balls to a minimum. Based on these facts can you revise your ball charge design. Thanks again.

There is a hammer crusher before the raw mill so mill feed is very fine with d80 (80% passing size) of 4000 micron and 1% passing 3/8 mesh (9.5 mm sieve). Based on Bonds formula I calculated the max ball size to be 50 mm. Also, I forget to mention that the mill liner is lifting not classifying to we should limit the number of different balls to a minimum.

Hi Fjalali,Thanks for sharing the more information.If feed is d80 (80% passing size) of 4000 micron than calculatedmaximum ball size of 50 mm seems o.k.Technically for such fine feed mono chamber mill a combination of lifting and classifying liner will be a good option.However, there is no standard grinding media size distribution is available in literature.For non classifying linining grinding media size distribution should be narrow.You may try the following equilibirium charges initially and fine tune the size distribution to achieve the desiredtarget fineness by practical experience.50mm =21%, 40mm=47%, 30mm =24% & 25mm=8%Piece weight initil=178 gm,Piece weight equilibirium =162 gmYou should also take-up the matter with original mill manufacturer regarding classifying lining issue.

Thanks for sharing the more information.If feed is d80 (80% passing size) of 4000 micron than calculatedmaximum ball size of 50 mm seems o.k.Technically for such fine feed mono chamber mill a combination of lifting and classifying liner will be a good option.However, there is no standard grinding media size distribution is available in literature.For non classifying linining grinding media size distribution should be narrow.You may try the following equilibirium charges initially and fine tune the size distribution to achieve the desiredtarget fineness by practical experience.

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