reacted and post mortem refractory bricks were also analyzed to verify microstructural changes. Polished surfaces of the unreacted and corroded samples have been characterized by scanning electron microscopy NOVA NANO SEM 200 from FEI equipped with a EDS system from EDAX. Additionally,the chemical and phase composition of solid particles of cement raw meal, i.e. the partly decarbonized material sampled from the 4-stage of cement kiln preheater was determined by wet chemical analysis and X-ray diffraction, respectively