To produce the most common type of cement
1. Limestone, shale, silica, and iron oxides are quarried from the ground.(Some limestones already contain enough silica).
2. Rock materials are run through a crusher that turns rock into smaller pieces.
3. Crushed limestone + silica + shale + iron oxides are mixed together and run through a rotary kiln.
4. Rotary kiln continously mixes ingredients and "calcines" limestone so that CO2 is driven off, forming clinker.
5. Clinker is ground to fine powder and mixed with gypsum (helps moderate how fast the cement sets), then bagged for sale.