Effect of pore structure and matrix reactivity on coke reactivity and post-reaction strength

Metallurgical coke accounts for a significant portion of the costs associated with blast furnace operations. The coke reactivity index (CRI) and coke strength after reaction (CSR), determined via the Nippon Steel Corporation test, are the most popular indexes for estimating the high-temperature properties of coke. Multiple factors affect the coke solution-loss reaction, and the CRI and CSR depend on the composition and structure of the coke. The pore structure is one of the most important factors affecting this reaction. The effect of the pore structure on the coke reactivity was determined by quantitatively evaluating the CRI and CSR of 10 types of coke. In each case, the corresponding structure was determined via image analysis. Furthermore, the initial reaction rate of the coke matrix was determined via thermogravimetric analysis of the fine grains. Mathematical models, quantitatively describing the CRI and CSR, were formulated via multiple linear regression, and the fit of the results to the experimental data was verified via the regression coefficient and a significance test. The models indicated that pores with sizes of 60–120 µm have a strong positive impact on CRI. In the case of invariant CRI, the high reactivity of the matrix has a positive impact on the post-reaction strength of the coke.