The dry crude materials enter the kiln outlet, i.e. the high end of the cylinder through the preheater, and then are fed into the kiln by the tremie pipe. Due to the inclination of the cylinder and slow rotation of the material, the materials roll in hoop direction. On the other hand, the materials move from the high end to the low end, where they are decomposed, burnt, cooled in succession. Thus they become cement clinker, and are discharged from the low end of the cylinder. Finally, they enter the cooling device.