Cement kiln Wikipedia
dolomite (CaMg(CO 3) 2) decomposes to calcium carbonate (CaCO 3), MgO and CO 2. 650 to 900 °C calcium carbonate reacts with SiO 2 to form belite (Ca 2 SiO 4) (also known as C2S in the Cement Industry). 900 to 1050 °C the remaining calcium carbonate decomposes to calcium oxide (CaO) and .