It is very important to clarify the deterioration mechanism of coke at the lower part of blast furnace. In this study, the deterioration of coke, which was caused by the interaction of carbon and ash during heat treatment to 2000°C in a nitrogen atmosphere, was investigated.
The following findings were obtained.
(1) After the coke heated up to 2000°C, the weight of coke decreased by approximately 12%. The coke strength decreased with decreasing the weight of coke, and it decreased by 0.5% per 1% of the weight loss of coke.
(2) The vaporization of the ash and the volatile matter of coke and the interaction of carbon and ash caused the weight loss of coke, and the 70% of the weight loss was caused by the interaction of carbon and ash.
(3)The interaction of coke and ash mainly consisted of the reaction where SiC was formed by the interaction of SiO2 and 3Al2O3·2SiO2 included in ash and C in the coke, but at temperature above 1750°C, N2 in the atmosphere, SiO2 and 3Al2O3·2SiO2 interacted. At temperature between 1750°C and 2000°C, SiC and AlN were formed, and the amount of these compounds in the coke reached about 3% and 2% respectively.
