Explain Manufacturing Process of Ordinary Portland Cement.

Cement is defined as a pulverized binding material possessing both adhesive and cohesive properties which sets, hardens and adheres to the other materials to bind them together. The raw materials required for manufacture of Portland cement are calcareous materials,
such as limestone or chalk, and argillaceous material such as shale or clay. The process of manufacture of cement consists of grinding the raw materials, mixing them intimately in certain proportions depending upon their purity and composition and burning them in a kiln at a temperature of about 1300 to 1500°C, at which temperature, the material sinters and partially fuses to form nodular shaped clinker. The clinker is cooled and ground to fine powder with addition of about 3 to 5% of gypsum. The product formed by using this procedure is Portland cement. Manufacture of cement can be carried out with two method (depending upon mixing & grinding of raw material) :

Wet process:

In wet process, limes....

Cement is defined as a pulverized binding material possessing both adhesive and cohesive properties which sets, hardens and adheres to the other materials to bind them together. The raw materials required for manufacture of Portland cement are calcareous materials,
such as limestone or chalk, and argillaceous material such as shale or clay. The process of manufacture of cement consists of grinding the raw materials, mixing them intimately in certain proportions depending upon their purity and composition and burning them in a kiln at a temperature of about 1300 to 1500°C, at which temperature, the material sinters and partially fuses to form nodular shaped clinker. The clinker is cooled and ground to fine powder with addition of about 3 to 5% of gypsum. The product formed by using this procedure is Portland cement. Manufacture of cement can be carried out with two method (depending upon mixing & grinding of raw material) :

Wet process:

In wet process, limestone from quarries crushed to smaller fragments & is then taken into ball mill where it is mixed with clay or shale & converted to slurry
(creamy liquid) with addition of 35-50% water. Chemical composition of slurry is then checked & corrected. The slurry is sprayed to rotary kiln against hot surface of hanging chain. The slurry gets dry & undergoes series of chemical change. The material gets fused at high temperature & converted into 3-20mm nodular form called clinker. The clinker so formed is dropped in to cooler & stored in silo/bins. The clinker is then ground to required fineness in ball-mill in addition of 3-5% gypsum.

• Energy consumption is high in this process.
• Produces good quality products.
• Dust emission is low.
  

Dry Process:

In dry process, raw materials are proportioned & mixing/grinding is carried out in dry condition. Then is blended/corrected for its composition. By addition of about 12% of water blended mass is converted in to pellets which permit air flow & exchange of heat in rotary kiln. The mass is then charged into kiln (1300-
1500 deg C) to form clinker. The clinker so formed is dropped in to cooler & stored in silo/bins. The clinker is then ground to required fineness in ball-mill in addition of 3- 5% gypsum.

• Energy consumption is less.
• Comparatively low quality product is obtained.
• Economical