Cement manufacturing:
components of a cement plant

This page and the linked pages below summarize the cement manufacturing process from the perspective of the individual components of a cement plant - the kiln, the cement mill etc..

For information on materials, including reactions in the kiln, see the ' Clinker ' pages. For a more detailed account of the cement production process, see the Understanding Cement book.

view of cement kiln showing kiln and preheater towerView of a cement kiln (the long nearly-horizontal cylinder) and preheater tower. (Picture courtesy Castle Cement.)

Summary of production process

Cement is typically made from limestone and clay or shale. These raw materials are extracted from the quarry crushed to a very fine powder and then blended in the correct proportions.

This blended raw material is called the 'raw feed' or 'kiln feed' and is heated in a rotary kiln where it reaches a temperature of about 1400 C to 1500 C. In its simplest form, the rotary kiln is a tube up to 200 metres long and perhaps 6 metres in diameter, with a long flame at one end. The raw feed enters the kiln at the cool end and gradually passes down to the hot end, then falls out of the kiln and cools down.

The material formed in the kiln is described as 'clinker' and is typically composed of rounded nodules between 1mm and 25mm across.

After cooling, the clinker may be stored temporarily in a clinker store, or it may pass directly to the cement mill.

The cement mill grinds the clinker to a fine powder. A small amount of gypsum - a form of calcium sulfate - is normally ground up with the clinker. The gypsum controls the setting properties of the cement when water is added.

Block diagram showing the basic components of the cement production processThe basic components of the cement production process.

The "Understanding Cement" book contains even more information!
Compared with this web site, the book has, for example, about two-and-a-half times as much on ASR, one-and-a-half times as much on sulfate attack and nearly three times as much on carbonation. It has sections on alkali-carbonate reaction, frost (freeze-thaw) damage, steel corrosion, leaching and efflorescence on masonry. It also has about four-and-a-half times as much on cement hydration (comparisons based on word count)

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