Unit Operation
|
Temperature
range (ºC)
|
Description of reaction
|
Raw Grinding
|
20  100 |
- Raw materials are dosed to a predefined chemical
composition
- Evaporation of free H2O
- Fine grinding to form a intermediate product - raw meal
|
Homogenizing
|
|
- Storing and blending of raw meal to reduce
the chemistry variation.
|
| Preheating & Precalcinating |
100 300
|
- Loss of physically absorbed water
|
> 400
|
- Removal of structural H2O ( H2O and OH groups)
from clay minerals
|
> 500
|
- Structural changes in silicate minerals
|
600 900
|
- Dissociation of carbonates (CO2 being driven
out)
|
Kiln sintering
|
> 1000
|
- Formation of Belite, intermediate products, aluminates
and ferrite
|
> 1250
|
- Formation of liquid phase (aluminates and ferrite
melt)
|
~ 1450
|
- Formation of clinker melt
- Completion of reaction and
crystallization of Alite and Belite
|
Clinker cooling
|
1300 1240
|
- Crystallization of liquid phase into mainly aluminates
and ferrite
|
1240 140
|
- Recuperate sensible heat from clinker melt
|
| Finish grinding |
100-120 |
- Fine grinding to produce surface area for hydration
reaction
- Partial dehydration of gypsum
- Dosing of additive to regulate cement performance
|
 60 |
- Cement is cooled to a temperature suitable for
storage to prevent extended
dehydration of gypsum
|
