Question
Download Solution PDFThe processes used for the manufacture of cement can be classified into ________ types.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFThe process of manufacturing cement involves mixing the calcareous and argillaceous components in a 3:1 ratio. Following by mixing of the materials, two processes can be followed to arrive at the final product of ordinary portland cement. The two processes include
- Wet Process
- Dry Process
Wet process:
- In this process, the crushed raw materials are fed to the ball mill, and a small quantity of water is added.
- The steel balls in the ball mill pulverize the raw materials to form a slurry.
- The slurry is passed in silos where proper proportioning of the constituents takes place. The slurry thus formed has a moisture content of around 40%.
- This slurry is passed through the rotary kiln, wherein the nodules are formed. The temperature maintained in the kiln is around 1600 °C. This temperature leads to the conversion of the nodules to clickers.
- The clinker is then cooled, and a small quantity of gypsum (about 3%) is added. The addition of gypsum is important as it avoids the flash setting of cement.
- Finally, cement is fed to silos from where it is supplied to the packing plant.
DRY PROCESS
- It is a newly evolved process that is mostly adopted in modern days. Precedence to this method is given owing to the excessive power and fuel utilization in the conventional wet process.
- In the dry process, the calcareous and the argillaceous materials are reduced to 25mm size with the help of mechanical crushers in the ball mill.
- After proper grinding, both materials are mixed to proper proportions before being fed to the rotary kiln.
- Before feeding the mixture to the rotary kiln, it is preheated to 850°C for 2 hours.
- Subsequently, the mixture is then fed to the rotary kiln.
- The product obtained from the rotary kiln is called Clinker, which is of the size between 3mm to 20mm.
- Addition of 2 - 3% of gypsum to the clinker is deemed necessary as it decreases the flash set property and setting time of the clinker.
- The final product obtained is the Calcium Silicate hydrate (C-S-H) gel, with calcium hydroxide being the byproduct.
Last updated on May 28, 2025
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