- the liquid phase quantity
- the liquid phase quality
- the granulometry
- the reaction time
- the temperature

Dear Gks 

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.

Best regards

ILA

Hello Every one

Mr ILA you mentioned that gypsum promotes the formation of C3S , but i also listen that gypsum used to remove the exes   coating in the kiln.

Dear Mr Azher

The tendency toward coating formation or the coatability of the clinker increases with the amount of liquid. However, more coating does not necessarily mean better coating. Coating refractoriness, texture, and stability are far more important than the amount of coating deposited on the lining. A good example is the thin but stable coating in a white cement kiln, where the silica ratio of the raw mix is more than five and the C4AF is zero.

clinkers with sulphate-alkali ratio lower than 0.83 and low MgO would experience the negative effects of high liquid viscosty.

Best regards

ILA