Alumina（Al2O3）－spinel（MgAl2O4）－silicon carbide（SiC）－carbon（C）system has been adopted for the metal line castable refractory in blast furnace main trough. Effect of NiO powder addition to blast furnace trough castable is described, focusing on oxidization behaviors of SiC under high temperature, 1400℃ in a series of the experiments in this report. In general, SiC in the castable tends to react with CO（g）forming SiO（g）which escapes out of the system. With NiO powder addition, this reaction is promoted due to higher equilibrium vapor pressure of Ni. Instead of escaping out, SiO（g）reacts with Ni（g）forming NiO－SiO2 glassy phase in the castable, causing densification of castable microstructure. The effect indicates a possibility in improving the castable physical properties, particularly in physical rigidity reliability of the relined castable.

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