Detailed studies on microstructural evolution during the high temperature corrosion of SiC-containing andalusite refractories in the cement kiln preheater

摘要

The corrosion chemistry of SiC-modified andalusite refractories has been studied using a post-mortem approach that considers both K+ and Ca2+ ions as the main corrosive agents existing in the cyclone preheater applied in the cement production line; The transient progress of corrosion reactions was investigated as the function of distance from the face exposed to the corrosive media (hot face) to the relatively little altered middle zone of Al2SiO5-SiC brick. Chemical alteration of the Al2SiO5 and SiC grains was examined and discussed on the basis of phase equilibria in binary (CaO-SiO2, K2O-SiO2) and ternary (K2O-Al2O3-SiO2, CaO-Al2O3-SiO2) systems. Ca and K-Si-oxide phases along with Ca-aluminosilicate - gehlenite Ca2Al2SiO7 and K-aluminosilicates - kalsilite KAlSiO4 and leucite KAlSi2O6 were formed as a consequence of the reactions between both SiO2 and Al2SiO5 with CaO and K2O. The heating microscopy thermal analysis was used to evaluate the behavior of SiC-/ZrSiO4-andalusite refractory bricks in contact with a partly decarbonized material.