The dry process is preferred in places where hard and crystalline raw materials are available. This process has the advantage over the wet process, the fuel consumption is low. The raw material is first crushed in the dry state in multi chamber tube mill. This crushed raw material is then ground in the grin& mill. The dry powdered mixture is finely homogenized by means of compress air. This finely homogenized powdered material is then passed on to the rota kiln.
SETTING OF CEMENT
When cement is mixed with water, the resulting mass becomes hard and resistant to pressure with the passage of time. This process is called “setting cement”. The setting of cement is mainly due to hydration followed by hydrolysis and formation of new compounds. Setting of cement can be explained by mea of the following theories:
1. According to first theory, hydrolysis of tricalcium silicate and dicalcium aluminate causes the formation of a “gel” consisting of calcium hydroxi and aluminium hydroxide.
This ‘`gel” on drying causes the setting of cement. .
These colloidal gels separate in the form of very small crystals, which • interlock with one another and form a hard mass.