Cement can be manufactured either by dry process or wet process. Here are steps to manufacture cement by dry process.

Step ( i ):

The material is gathered from quarry with the help of dumper to manufacturing plant. The material gathered is having content of limestone and clay which is calcareous component and argillaceous component respectively. The material gathered is about more than 80 mm size.

Step ( ii ):

The collected material is fed into heavy crusher where the size of the material get reduced to 60 mm from 80 mm and later this size material is fed into light crusher (Tubemill/Ballmill) where the size reduced to 40-60 mm finally it is stored in the tank.

Step ( iii ):

Now, the grinding material called raw mix is fed into preheater (heater before rotary kiln ), the temperature is gradually increased up to 500°C due to this increase in temperature the raw mix get fraction into smaller size nearly (25 mm).

Benefits of Preheaters:

(a) It makes the process fast.

(b) Fuel consumption is reduced because the burning time of rotary kiln is get reduced.

Now, this raw mix is fed into rotary kiln where the temperature is 800-1000°C, 1000-1200°C, 1200°-1500°C.

In three separate zones respectively. The product obtained is of size 8 to 1 0 mm from rotary kiln is called clinker.

Rotary Kiln

Dimensions:

Diameter = 3 m

Length = 100 m

Revolutions = 3 rounds in 1 minute

Gradient 1 i n 25 to 1 i n 30.

 

 

Zone-1

(Drying zone): In this zone the raw mix, is fractioned into more smaller size. In this zone if there is some water or moisture exist in raw mix then it is also evaporated.

 

Zone-2

(Nodule zone): In this zone, the major breakdown of raw mix occurs. In this zone the calcination of limestone takes place:

Zone-3

(Burning zone): Now, the raw mix which is also called nodules, is sloped down and the major chemical reaction between ingredient of clinker occurs i.e. lime, silica, alumina, iron oxides.

Now, from this rotary kiln the product obtained is called clinker which is composed of major and minor compounds.

NOTE: The clinker obtained has high efficiency to react with water and set immediately (flash set) to prevent this immediately setting of clinker in presence of water is done by adding gypsum in a tubemill.

(v) Now, the clinker is cooled up to temperature of 100°C, after colling it is fed into tubemill where the gypsum is also added to it, the fine grinded powder having gray color is obtained which is called cement.

(vi) It is packed in 50 kg bag having ±5% volume capacity of 0.035 m3.

(vii) Now, after packing it is transported to dealers.