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Technical Cement Forum / Low temperature cement grinding

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Giovanni 18/07/2009 05:55:12

Low temperature cement grinding

Hello everybody!

Does anybody has experienced difficulties on mortar strength development and/or longer setting time when grinding on vertical mills at temperatures lower than 80°C ?

We are facing some difficulties to reach the same early strength (compressive resistance @ 1, 2, 3 days) on cement produced on vertical mills compared with the ones coming from ball mills.

We understand that the Particle size distribution is quite different due to the differences in grinding technology but we are also suspecting of poor gypsum dehydration...

Any comments or experiences are very welcome!

Thanks in advanced.

Basavaraj 19/07/2009 07:12:22

Hi Gio, Hope this is same Gio I met Natal SA.

Normally when clinker grinding in verucal mills, the mill outlet temperature is around 80-85 deg C only.

What I feel is try to optimise the dam ring height of the mill to have proper partical size distribution. This will help to increase the strength.

Raj

Michael Clark 21/07/2009 09:38:52

With the low residence time and low temperatures in vertical mills for cement grinding gypsum dehydration will not be completed. That might well affect the setting time, workability and compressive strength development of the cement. This is a well known phenomena.

Giovanni 24/07/2009 21:32:02

Thanks for your reply Dr. Clark!

Do you have any experience on how to deal with this situation?

Presently we have a gypsum with 19% of chemical water, the content of anhydrite is very low I guess.

What do you think of adding anhydrite to the mix?

Increasing the grinding temperature?

Modifying the particle size distribution?

Thanks in advanced!

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