Measurement of the Reduction Rate of Molten FeO-CaO Oxide by CO Gas Injection Through an Immersed Nozzle

The reduction rate of molten iron oxides containing CaO was measured at 1723 K by injecting pure CO gas through an iron nozzle immersed in the molten oxide. Using the pressure pulse method, the size and generation cycle time of CO bubbles were identified during the reduction experiment. After the reduction experiment was held for 3600 s, dense iron particles were observed beneath the iron nozzle, and oxide containing metallic iron was deposited on the inner surface of the nozzle. The reduction degree and the reduction rate decreased linearly with an increase in CaO content. Although the reduction rate at 100% FeO was not directly measured in this experiment, the value extrapolated from the current results was found to be lower than those reported in previous literature. The effect of CaO on the reduction rate was opposite to that investigated in previous studies using the top-blow CO gas method. While the top-blow method is the most likely to involve CO₂ adsorption that controls the reduction rate, the CO gas injection method may be controlled by other factors, such as the activity of FeO.