Sulphates of alkali

Dear Sir,

It is claimed that sulphates of alkali came out from the kiln embedded in clinker.

But sod. sulphate is not stable at high temperature. Pl. tell wether it will be found

as Na2SO4 or Na2O in clinker.

 Regards,

Gulam Dastgir

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Re: Sulphates of alkali

The observed volatility depends of course on the (equilibrium) thermodynamic properties. I a compound is stable, it will go to clinker.

However, the kinetics has to be considered also, specially when solids are involved.
The decomposition can be slowed down or stopped for various reasons like a diffusion barrier in a solid. All the material or only a part of it can be subject to such barriers.

Therefore, the thermodynamic instability does not allow us to predict the volatility coefficient. A kinetic model is necessary for that. In practice it is very empirical.

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Re: Sulphates of alkali

Dear Mr.Gulam Dastgir,

A part of alkalis in excess of chloride combined with sulphur to form Na2SO4,K2SO4 and double salts such as Ca2K2(SO4)2.Alkalis not combined with chloride or sulphur will be present as Na2O and K2O embeded in the clinker minerals.

With regards,

R.M.Sahu,

India

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Re: Sulphates of alkali

Dear Mr. Raju,

This is what the exact case. But i overhear that Na2SO4

is not stable at high temp. and in burning zone it get decomposed in Na2O and SO3.

So the sulphate in the kiln is largely in form of K2SO4.

This is what i want to get confirmed.

Sincerely Yours,

Gulam Dastgir

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