Investigation on Carbon-Deposition Behavior from Heating Cycle Gas in Oxygen Blast Furnace Process

Among the different ways to study carbon deposition in the ironmaking process, not much attention was paid to that of heating the gas mixture, especially cycle gas in an oxygen blast furnace. In this work, the carbon-deposition characteristics of heating 100 pct CO, CO-H₂ gas mixture, and cycle gas in the oxygen blast furnace process were, respectively, experimentally and theoretically investigated. First, the thermodynamics on carbon-deposition reactions were calculated. Then, the impacts of discharging operation temperature, the proportion of CO/H₂ in heating the CO-H₂ gas mixture, and the CO₂ concentration in heating the cycle gas of an oxygen blast furnace on the carbon deposition were tested and investigated. Furthermore, the carbon-deposition behaviors in heating the CO-H₂ gas mixture were compared with the thermodynamic calculation results for discussing the role of H₂. In addition, carbon deposition in heating cycle gas includes CO decomposition and a carbon-deposition reaction by hybrid of CO and H₂; the possible roles of each were analyzed by comparing thermodynamic calculation and experimental results. The deposited carbon was characterized by scanning electron microscope (SEM) to analyze the deposited carbon microstructure.