re Role of SR and AR

Hello Archi,

I calculate your liquid phase quantities at 1338 and 1450oC to be;-   Liq.Ph 1338oC = 23.2   and Liq.Ph 1450oC = 27.6,  which are not too problematic.

I think the main issue with being forced to operate with an AR of 1.22, could be problems with attack on the bricks due to the lower viscosity of the liquid phase. You would need to keep a close eye on kiln shell temperature.

However, kilns which manufacture sulphate resisting cements (C3A <5%) operate with clinker chemistry similar to this all the time.

Regards,

Ted.

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re Role of SR and AR

Hello Tushar,

These two equations are necessary because, in theory, the only time all of the C3A and C4AF both completely melt at the eutectic point (1338oC) is when the AR = 1.38.

When AR>1.38, the excess of Al2O3 means that more C3A is formed, and the amount of C4AF is limited. This results in the complete melting of the ferrite phase, but  the C3A does not melt. Therefore there is no Al2O3 component in the equation.

When AR<1.38, Fe2O3 exists in higher concentrations and so more crystalline C4AF is formed. When melting commences at 1338oC, C3A melts completely, while only some of the C4AF melts and much the C4AF remains crystalline. The negative coefficient 5.22 * Fe2O3 represents the equivalent C4AF that does not melt. The coefficient 8.2 * Al2O3 represents the total C3A and C4AF calculated by Al2O3 content.

The coefficients in these equations have been derived from both theoretical and empirical study of the C-S-A-F quaternary phase system.

For more detailed information;-

http://orbit.dtu.dk/fedora/objects/orbit:117069/datastreams/file_90eb7b6b-a896-4e5d-b9ba-d3dc43205c60/content
(See Section 2.4.2 Clinker Phase Formation between 1250 and 1450oC)

To answer your second question, liquid phase is calculated at both 1338 and 1450oC to understand the distribution of liquid phase in the burning zone better and to predict where in the kiln  stable coating will form. The equations for liquid phase at 1338oC, give the amount of liquid phase first formed at the start of the burning zone, while the the equation for 1450oC gives the final (maximum) quantity of liquid phase in the burning zone.

The closer the two values are to each other the longer will be the stable coating zone. See;-

http://cementengineer.com/attachments/article/148/Cement%20Kiln%20Liquid%20Phase.pdf

 Regards,

Ted.

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re Role of SR and AR

I don't think Hal Taylor's comment is necessarily in conflict with the text from Lee. One appears to be talking about nodule formation from caclined raw meal uphill of the burning zone and the other about the abrasion of clinker nodules in or after the burning zone.

Also, in looking at a specific problem, it's worth remembering that some impurities (such as Manganese) are also said to affect the viscosity and surface tension of the liquid phase.

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re Role of SR and AR

Dear Ted

Thanks a lot for your further clarification and providing link.

Regards

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