Conversion C2S to C3S
Dear expert, goodmorning Iwant know that what are factor effecting the rate of reaction for conversion C2S to C3S in the kiln. with best regard gks
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Re: Conversion C2S to C3S
Without the presence of liquid, the conversion of C2S and free lime to C3S at normal clinkering temperatures would be almost impossible.
The most important clinker mineral, C3S (alite), requires the presence of liquid for its formation. In the absence of liquid, alite formation is extremely slow and would render commercial clinkering impossible. This explains why alite is formed essentially in the burning zone, where the amount of liquid is at a maximum.
To understand why alite formation requires liquid phase, one must first understand the alite formation sequence. First, C2S and free CaO dissolve in clinker melt. Then, calcium ions migrate toward the C2S through chemical diffusion. Finally, the C3S is formed and crystallized out of the liquid.
Without a liquid phase, the diffusion of Ca ions towards C2S would be extremely slow, and that of C2S almost impossible at commercial clinkering temperatures. It is important to mention that Na2O and K2O decrease the mobility of Ca ions, whereas MgO and sulphates increase it considerably. This is why the addition of gypsum to the raw mix promotes alite formation. Similarly, the addition of metallurgical slags to the raw mix promotes clinker formation.