Evaluation of Characteristics of Coke Degradation after Reaction in Different Conditions

摘要

In this study, post reaction strength under various conditions was measured to investigate effects of gasification with CO_2 on coke degradation in the lower shaft of blast furnace. Post reaction strength of coke samples taken at the shaft of actual blast furnace was much higher than that in NSC tests, leading to slight change in mean size. The test for coke strength after reaction with the constant weight loss of 20% was not an effective way to evaluate commecial coke with high CSR and low CRI. When coke samples were gasified at a different temperature of 1 100-1 300℃, topochemical reacton was observed at over 1 200℃ by image analysis. Post reaction strength (CSRsbf) in the simulated blast furnace conditions was 14.9%P higher than conventional CSRs, which is attributed to different correlationship between reactivity and post reaction strength in two methods. This phenomenon seems to be caused by topochemical reaction on coke surface in blast furnaces which results into suppressing coke degradation. The post reaction strength test should be modified in accordance with the individual blast furnace operation, to simulate coke degradation due to solution loss in the shaft because solution loss in NSC tests is overestimated.