Reappraisal of the reactivity of blast furnace coke with CO_2

This paper briefly introduced the current coke reactivity test method used in China, which is a standardized method mainly measuring the anti-CO 2 gasification property of coke before it enters the raceway of a blast furnace as well as the anti-pulverization property of coke after it reacts with CO 2. Knowledge development about coke reactivity in China and foreign countries was reviewed. In the last century,coke reactivity was regarded as an index expressing the anti-CO 2 gasification property of coke in a blast furnace. It was considered then that a higher coke reactivity meant a lower coke strength after reaction and was thus unfavorable for blast furnace production. However,in the 21stcentury,Nippon Steel put forward that coke reactivity only reflected the activity of coke. The company held the view that the increase in coke reactivity would improve the reaction efficiency in a blast furnace and was thus favorable for blast furnace production. The above two conclusions contradict with each other as the understanding of blast furnace production has progressed with time. This paper also described the calculation of blast furnace carbon balance and the experiments for investigating the effects of CO 2 concentration and reaction temperature on coke reactivity. On the basis of the calculation and experiments,the behavior of coke in a blast furnace with coal injection has been analyzed and the reaction weight loss rate of coke before it enters the raceway has been determined. It has been pointed out that in the current national standard,Method of determining coke reactivity and coke strength after reaction,coke reactivity refers to the activity of coke in the reaction with CO 2. The reaction weight loss rate of coke in a blast furnace is mainly affected by the reduction performance of iron ore and the unburned pulverized coal( UPC) rate,and is irrelevant to the coke reactivity measured in labs.