41 posts
TimePosted 28/01/2013 11:51:59
Stephenb says

form of silica for alite and belite formation

Good day all.

Can someoen tell me what is the form of silica required in the kiln for alite and belite cyrstal formation? Is it 100% quartz required or can it be amorphous silica?



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Raj Sahu
198 posts
TimePosted 29/01/2013 06:35:51
Raj Sahu says

re form of silica for alite and belite formation

Free Silica (SiO2 in different form).Limiting range of free Silica in limestone is 0-3% and preferrable range is as low as possible.

A higher Free Silica:

1.Increase power and fuel consumption in pyro-processing

2.Causes difficulty in coating formation

3.Deteriorates refractory lining

4.Increase kiln exit gas temperature


Ted Krapkat
537 posts
TimePosted 31/01/2013 05:57:36

re form of silica for alite and belite formation

Hello Stephen,

Amorphous silica is far more reactive than quartz and is the preferred type of silica for good kiln feed burnability. Quartz must be ground extremely fine to achieve the same burnability since quartz particles above 30-40um will not fully react to form C3S in the time available in the kiln.

Not only are amorphous forms of silica more reactive, they are also easier to grind and some (such as diatomite) naturally have a large surface area due to the complex shapes of the particles.

Unfortunately amorphous silica is also much rarer than quartz, so unless you have access to an abundant supply close to the plant it is normally an expensive exercise to obtain this type of material.