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Technical Cement Forum / Effect of reducing raw meal SO3 in clinker alkali

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Erj 04/01/2012 14:32:29

Effect of reducing raw meal SO3 in clinker alkali

Gents:

Normally we produced clinker with average of 0.90% total alkali (potasium equivalent) using raw meal with an average total alkali of 0.64%. The SO3 in raw meal is 0.37%.

When we reduced the SO3 in raw meal from 0.37% to 0.16%, keeping the same level of total alkali in raw meal and the same fuel used, we experienced reduction in clinker total alkali from 0.90% to 0.67%.

I posted this experienced for me to understand clearly about the alkali reactions. And also we are on the process of producing low alkali clinker.

Need your comments. . .

Regards,

Erj

Ted Krapkat 05/01/2012 05:06:52

Hello Erj,

There is no chemical reaction that can reduce alkalis in the kiln system. Chemical inputs must balance outputs. However, in the short term (2 or 3 days) the effect of lowering raw meal SO3 content would be to increase alkali volatility, meaning less alkalis would escape the kiln in the clinker. But this effect would only be temporary and once the alkali/sulphur cycle returned to an equilibrium the alkali level in the clinker would return to normal.

So, in the long term, there are only three explanations for what you described above;-

1. Removal of alkalis via a bypass system, dust venting occurrences or regular removal of high alkali buildups etc.

2. A reduction in the alkali levels in your raw materials, fuels or AFRs.

3. An error in one or more of the alkali analyses.

Regards,

Ted.

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