Coke Reactivity in Simulated Blast Furnace Shaft Conditions

Despite the fact that H₂ and H₂O are always present in the gas atmosphere of a blast furnace shaft, their role in the solution-loss reactions of coke has not been thoroughly examined. This study focuses on how H₂ and H₂O affect the reaction behavior and whether a strong correlation can be found between reactivity in the conditions of the CRI test (Coke Reactivity Index) and various simulated blast furnace shaft gas atmospheres. Partial replacement of CO/CO₂ with H₂/H₂O was found to significantly increase the reactivity of all seven coke grades at 1373 K (1100 °C). H₂ and H₂O, however, did not have a significant effect on the threshold temperature of gasification. The reactivity increasing effect was found to be temperature dependent and clearly at its highest at 1373 K (1100 °C). Mathematical models were used to calculate activation energies for the gasification, which were notably lower for H₂O gasification compared to CO₂ indicating the higher reactivity of H₂O. The reactivity results in gas atmospheres with CO₂ as the sole gasifying component did not directly correlate with reactivity results in gases also including H₂O, which suggests that the widely used CRI test is not entirely accurate for estimating coke reactivity in the blast furnace.