Variability in Metallurgical Coke Reactivity Index (CRI) and Coke Strength after Reaction (CSR): An Experimental Study

The coke reactivity index and coke strength after reaction are critical parameters for the efficient operation of a blast furnace. Therefore, maintaining desired qualities of the produced coke as per coal blend chemistry and coke oven battery parameters is essential. However, the coke reactivity index (CRI) and coke strength after reaction (CSR) vary from laboratory to laboratory even though they have the same determination methodology. In the present investigation, a unique laboratory sample holder for reactivity test has been developed. The test method by Nippon Steel Corporation (NSC) has been compared with the newly developed sample holder method. The correlation between coke CRI and CSR has been studied with samples with a wide range of reactivity in the repeatability test. Results confirmed that the reactivity of coke highly depends on the reaction of individual coke pieces participating in the test. Despite undergoing strict process monitoring of the testing procedure of hot strength of coke, the present study confirmed that a variation of ±2 points in coke CSR and CRI does not affect coke quality in a single reading. The study also includes the influence of the number of coke pieces in the test sample to optimize the coke bed height. This paper described in detail the methodologies adopted, addressing the factors resulting in differences in CRI/CSR values within the same coke.