target particle fineness leaving raw mill

Hello,

Our cement plant is currently producing raw meal with 85% passing #170 sieve and averaging 26 microns. Is this too fine? What is the standard particle size entering preheater? Thank you.

 Branco

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Re: target particle fineness leaving raw mill

Branco,

85% passing a 170 mesh sieve is the typical fineness for raw meal.

Thanks

Dr Michael Clark

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Re: target particle fineness leaving raw mill

Thanks Dr. Clark,

Thank you for your quick reply. Just a follow-up question. A sample with 85% passing #170 sieve can be 26 microns in average or 46 microns in average or any other microns depending on the size distribution. What is the typical particle size (in microns) of raw meal leaving raw mill?

Branco

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Re: target particle fineness leaving raw mill

Hi Branco,

The way to characterise the fineness of any powder is to determine the sieve residue at 2 different particle sizes and use that to determine the Rosin Rammler distribution. Kiln feed with a 15% residue on a 90 micron sieve would typically have a Rosin Rammler position or characteristic grain size of around 50 microns. The material leaving the outlet of a ball mill for raw grinding would typically be coarser as it would then pass to the classifier and coarse particles be rejected for regrinding.

Dr Michael Clark

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