The authors evaluated the influence of SiO_2 content increase caused by SiC oxidation on corrosion resistance of blast furnace ML castable, which has not been quantitatively studied. From a series of laboratory and commercial basis experiments, the following conclusion were obtained; 1. Despite the same level of SiO_2 content is analyzed, the corrosion resistance of castable refractory was differentiated by their SiO_2 increasing methods; increasing by silica fume addition and raising SiO_2 content by promoting SiC oxidation. That is, the former exhibited more deteriorated resistance than the latter in which SiO_2 was observed as the precipitated spherical body in micro pores. The reason for the harmlessness of precipitated SiO_2 rich phase formed by SiC oxidation is thought to be its conformation, too localized to give an apparent negative influence on corrosion resistance. 2. The castable with increased spinel content presented better corrosion resistance or smaller wear rate. This can be explained of better durability of spinel grain against the slag penetration than alumina as well as a change to well densified structure. 3. In the commercial operation, the improved ML castable whose spinel content and its grain size distribution were optimized presented remarkably smaller wear rate. This suggests of the effectiveness of spinel addition to blast furnace trough ML castable.
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