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Cement Manufacturing Overview
Four Steps to Produce Cement | Voluntary Code of Conduct
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Four Steps to Produce Cement

Portland cement manufacturing is a four-step process:

1. Virgin raw materials, including limestone and small amounts of sand and clay, come from quarries usually located near the cement manufacturing plant.
2. The materials are carefully analyzed, combined and blended, and then ground for further processing.
3. The materials are heated in a very large kiln which is a rotating vessel 60 to over 200 meters (200 to >650 feet) long with a diameter of 3 to 7.5 meters (10 to 25 feet). The kiln reaches temperatures of 1,450 degrees Centigrade (2,650 degrees Fahrenheit). The heat causes the materials to turn into a new marble-sized substance called clinker.
4. Red-hot clinker is cooled and ground with a small amount of gypsum. The end-result is a fine powder called portland cement. This cement is so fine that one pound of cement powder contains 150 billion grains.

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