In short, limestone and other materials containing calcium, silicon, aluminum and iron oxides are crushed and milled into a raw meal. This raw meal is blended and then heated in the pre-heating system to start the dissociation of calcium carbonate to oxide. The meal goes further into the kiln for heating and reaction between calcium oxide and other elements to form calcium silicates and aluminates at t a temperature up to 1450 centidegree: so called clinker burning. The cyclone system is attached to the rotary kiln by a riser duct. Secondary fuel is fed to the riser duct, the main fuel mixture, coal/petcock, fires the kiln. Reaction products leave the kiln as a nodular material called clinker. The clinker will be interground with gypsum and other materials to cement.