Raju Verma
77 posts
TimePosted 05/05/2013 08:01:37

Role of SR and AR

Dear all

Really impressed by the postings and clarification by Ted.

On the above subject SR of raw mix determines the liquid
quantity in burning zone which helps effecting intermixing and C2S to combine
with abundant free lime and form C3S.

AR determines the quality of the liquid in terms of viscosity.
If AR is low then liquid will be more viscous and vice- versa.

Can anybody please clarify the physical significance of AR fluctuation
and impact in clinker quality as well as kiln operation?

I gone through the earlier blogs regarding the matter but requesting more clarification.









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Ted Krapkat
537 posts
TimePosted 06/05/2013 06:30:18

re Role of SR and AR

Hello COE,

I think you mean;- when the AR is low the liquid phase will be less viscous, not more viscous.

To answer your question, there are two factors which affect liquid phase quantity at any point in the kiln;- clinker chemistry and temperature. In the case of the AR, these two factors have a special relationship at what is called a eutectic point for the C-S-A-F system. This occurs at 1338 degC  and at this point, the quantity of liquid phase passes through a maximum when the AR = 1.38.  ie all of the potential aluminate and ferrite phases melt completely.

This means that if the raw mix AR fluctuates significantly above and below 1.38, the quantity of liquid phase, at the point in the kiln where the temperature just reaches 1338 DegC, will also fluctuate significantly.

If the AR fluctuations are large enough and frequent enough, the changing quantity of liquid phase at the eutectic point may be enough to cause significant nodulisation earlier than expected in the kiln, increasing the potential for clinker balling and/or kiln rings etc.

I hope this helps clarify the subject for you. If you have any further questions, please let me know.





Raju Verma
77 posts
TimePosted 07/05/2013 07:49:57

re Role of SR and AR

Dear Ted

Thanks for your clarification.

Can you please give any link of literature where AR role is explained in details which will help me to understand syncronizing SR, liquid content, AR and temperature profile, eutectice diagram of A-F at 1338 dec C.

If AR is high than the required level say 1.5 for a particular raw mix,  the liquid will be more viscous and surface tension of the liquid will be more. As explained by you liquid formation will start earlier region of the kiln. This phenomena will lead high coating as well as balling also.

Alternatively if AR is low say 1.3 to 1.4 , the liquid will be less viscous and mateial will flow easily because of low surface tension. As the total liquid content will be reduced drastically and kiln will be more dusty and less amount of C2S will get chance to combine with free available lime and form C3S.

Please clarify the above. 




11 posts
TimePosted 08/05/2013 15:58:44
Archi says

re Role of SR and AR

Dear Mr Ted and Experts!

To continue this subject, I want to ask operating with lowlow ar.

With some special reasons, we have kilnfeed chemical factor: lsf 106, sr 2.50, ar 1.00 – 1.05, and cannot change it now.

Sirs, what happen if we operate kiln with lowlow AR-kilnfeed on long time?

We make yellow hard core clinker very easy. And I think a relation between low ar and build-up piece at kilninlet and riser duct without lack of oxygen, because sometime we have yellow-soft core clinker with redundant oxygen at kilninlet, right?

Thanks Mr Ted and Experts!