Qualitative and quantitative investigation of post-mortem cement refractory: The case of magnesia spinel bricks

Post-mortem investigation of damaged refractory bricks remains an essential source of information to predict the reactions responsible for corrosion phenomena. In this context, the corrosion of two post-mortem magnesia spinel bricks, taking from the sintering zone of a rotary cement kiln, was investigated qualitatively and quantitatively. The results of the X-rays diffraction, combined with the Rietveld method supported by heating microscope and elemental analysis, revealed that the sulphur and the high temperature (> 1600 degrees C) were the main factors which caused the degradation of the refractory matrix of magnesia spinel bricks by the infiltrated mineralogical phases of the clinker melt. In fact, the appearance of the merwinite C3MS2, the akremanite Ca2Mg (SiO7), mayenite C(12)A(7) and Yeelimite CAS was the warning of the refractory matrix corrosion. Also, the deterioration rate of MgAl2O4 was more important in the hottest zone and it was deeper in brick 2 than in brick 1. As a result, the elasticity loss in brick 2 was more severe than in brick 1, which explains the length difference after a short duration of service (40 days).