Manufacturing of portland cement
- 2. CEMENT:- • A powdery substance made by calcining lime and clay, mixed with water to form mortar or mixed with sand, gravel, and water to make concrete. • The raw materials required for manufacture of portland cement are calcareous materials ,such as lime stone and chalk and argillaceous material ,such as shale or clay
- 3. PROCESS OF MANUFACTURING OF CEMENT • The process of manufacturing of cement consists of grinding the raw materials , mixing them intimately in certain propor- tions depending upon their purity and composition and burning them in a kiln at a temperature of about 1300 to 1500 C , at which temperature clinkers are formed and they are made into fine powder in addition with 3 to 5% of gypsum to form port lad cement.
- 4. Types of processes Flow chart • There are two process known as “wet” and “dry” processes depending upon whether the mixing and grinding of raw materials is done in wet or dry conditions .For many years wet process remained popular because of the possibility of more accurate in the mixing of raw materials. Later, the dry process gained momentum with modern development of technique’s
- 5. Wet process • Wet process : In this process, the raw materials are changed to powdered form in the presence of water . In this process, raw materials are pulverized by using a Ball mill, which is a rotary steel cylinder with hardened steel balls. When the mill rotates, steel balls pulverize the raw materials which form slurry(liquid mixture). The slurry is then passed into storage tanks, where correct proportioning is done . Proper composition of raw materials can be ensured by using wet process than dry process. Corrected slurry is then fed into rotary kiln for burning.
- 6. Wet Process: Continued------ • This process is generally used when raw materials are soft because complete mixing is not possible unless water is added . Actually the purpose of both processes is to change the raw materials to fine powder.
- 7. Dry process • Dry process : In this process calcareous material such as limestone (calcium carbonate) and argillaceous material such as clay are ground separately to fine powder in the absence of water and then are mixed together in the desired proportions.
- 8. Dry process continued _ _ _ • Water is then added to it for getting thick paste and then its cakes are formed, dried and burnt in kilns. This process is usually used when raw materials are very strong and hard . In this process, the raw materials are changed to powdered form in the absence of water.
- 9. THE END PPT BY YERUVA NARENDRA BABU