12 Questions
What are the two types of materials required for the manufacture of Portland cement?
Calcareous materials and Argillaceous materials
At what temperature is the raw material mixture burned in a kiln during the manufacture of Portland cement?
About 1300 to 1500°C
What is the purpose of adding gypsum to the cement during its manufacture?
To control the time of set of the cement
What is the final product formed after grinding the clinker with gypsum?
Portland cement
What are the four stages involved in the manufacture of Portland cement?
Crushing and grinding the raw materials, Blending the materials, Burning the prepared mix, Grinding the burned product
What is the shape of the clinker formed during the manufacture of Portland cement?
Nodular shaped
What is the primary difference between the wet, dry, and semidry processes of cement manufacture?
The primary difference lies in how the raw materials are ground and fed to the kiln: wet (as a slurry), dry (as a powder), or semidry (as nodules).
What is the purpose of screens in the processing of soft materials?
The purpose of screens is to remove oversize particles from the fine slurry produced by vigorous stirring with water in wash mills.
How is thorough mixing of dry materials in silos ensured in the dry process?
Thorough mixing is ensured by agitation and vigorous circulation induced by compressed air.
What is the typical water content of the slurry in the wet process before filtering?
The slurry typically contains 35 to 45 percent water.
What is the purpose of filtering the slurry in the wet process?
The purpose of filtering is to reduce the water content of the slurry from 35 to 45 percent to 20 to 30 percent.
What is the purpose of blending in the cement manufacturing process?
The purpose of blending is to obtain a first approximation of the chemical composition required for a particular cement.
Study Notes
Manufacture of Portland Cement
- Raw materials required: calcareous (containing calcium carbonate) materials like limestone or chalk, and argillaceous materials like shale or clay
- Process consists of: grinding raw materials, mixing them in certain proportions, burning them in a kiln, and grinding the resulting clinker with gypsum to form Portland cement
Four Stages of Manufacture
- Crushing and grinding the raw materials
- Blending the materials in the correct proportions
- Burning the prepared mix in a kiln
- Grinding the burned product (clinker) with gypsum
Grinding and Crushing
- Soft materials are broken down by vigorous stirring with water in wash mills, producing a fine slurry
- Hard materials are crushed in two stages and then ground in rotating cylindrical ball or tube mills containing steel grinding balls
- Grinding can be done wet or dry, depending on the process
Blending
- Chemical composition of cement is controlled by selective quarrying and processing of raw materials
- Finer control is achieved by blending materials from two or more batches with slightly different compositions
- Dry process: materials are stored in silos and mixed by agitation and compressed air
- Wet process: slurry tanks are stirred by mechanical means or compressed air or both
Explore the process of manufacturing Portland cement, which involves grinding raw materials, mixing them in specific proportions, and burning them in a kiln at high temperatures. Learn about the raw materials required and the key steps involved.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
