Effects and mechanism of using ferro-coke in an ironmaking blast furnace – A virtual experiment

Abstract

• Feasibility of mixing ferro-coke in ore layers in an industrial blast furnace. • Proposed method to calculate thermal reserve zone temperature and proposed performance chart for evaluating industrial blast furnace. • Proposed mechanism for ferro-coke application in industrial blast furnace. Ferro-coke is a promising high-reactivity carbonaceous material for ironmaking blast furnaces (BFs) decarbonization. However, the effects of using ferro-coke on in-furnace phenomena and performance are not well understood. In this study, a multi-fluid industrial-scale BF model is further developed to investigate the feasibility of using ferro-coke in a BF in terms of temperature field, CO utilization efficiency, and reduction degree. A proposed calculation approach for the temperature of the thermal reserve zone and a chart for overall performance are used to analyze the possible mechanism of using ferro-coke in BFs. The results show that the ferro-coke mixed in the ore layer reacts preferentially with CO 2 than the metallurgy coke at high temperatures, and thus the coke can be protected. As the mixing ratio of ferro-coke increases, the BF temperature field decreases. By analyzing the updated RIST diagram, the decreased temperature of the thermal reserve zone can shift the equilibrium of wustite-iron reduction to high CO 2 /(CO 2 + CO) state, and the increased CO concentration improves the driving force for CO reduction. Besides, the metal iron brought by ferro-coke can improve the productivity of hot metal (HM). The maximum carbon saving is achieved when the ferro-coke ratio is 15 %, and 36.6 kg/tHM of carbon can be saved, leading to approximately 7.5 % carbon saving. On the other hand, it is worth noting that using ferro-coke could decrease the utilization efficiency of H 2 in iron oxides reduction. This study provides a cost-effective tool to understand and optimise ferro-coke use in BFs.

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