Discuss The Manufacture of Cement | How is Cement Made
In this article, we learn about how is cement made step by step so read the whole article and also others for more details because we try to answer in short in this post
Manufacture of Cement
The following stages are involved in the manufacture of the cement process
In the dry process of mixing (which is mostly adopted nowadays), the calcareous materials (like limestone) and argillaceous materials such as clay are crushed and fine grinded separately and then mixed in definite proportion.
This mixed material is then preheated and the temperature of the material is increased in stages from 65°C to 850°C
This preheated material is then fed to the rotary kiln for further burning.
The burning is carried out in an inclined rotary kiln of tubular shape with diameter varies from 2.5 meters to 3 meters and length varying from 90 meters to 120 meters.
The mixed material is fed to the kiln from the top. The hot gases are forced to eject out from the lower end of the kiln.
At the upper end of the kiln, water gets evaporated (if any) and nodules get formed. These nodules reach the lower end of the kiln where the temperature is about 1400 to 1500°C.
In the burning zone of the kiln (at the lower end), a calcined product of hard dark greenish blue colour gets formed. This is called clinker.
The size of the clinkers varies from 3 mm to 20 meters and they are very hot as they come out of the burning zone of the kiln.
These clinkers are then allowed to cool down to a temperature of about 90 to 95°C.
The clinkers obtained from the rotary kiln are ground very fine in ball and tube mills.
In the process of grinding, a small amount of gypsum is also added which acts as a retarder and controls the initial setting time of cement.
Without gypsum, the cement will set as soon as the water is added.
The finely grounded resulting cement is then stored in silos for packaging.
Cement is packed in bags of 50kg of the volume of about 35 litres.