Kinetics of Reduction of Fe_2O_3 Particles with H_2-CO Mixtures at Low Temperatures

摘要

The reduction rate of particulate hematite with H_2-CO gas mixtures in the temperature range of 550 to 650 deg C decreases as the concentration of carbon monoxide in the gas mixture increases. For example, at 600 deg C, the reduction rate with pure CO represents 51 percent with respect to that obtained using pure hydrogen. From a practical viewpoint, this conclusion indicates the use of pure hydrogen during reduction of iron ores in a fluidized bed configuration at low temperatures. In the low temperature range investigated, only hydrogen can yield complete conversion of iron oxides into metallic iron. Addition of carbon monoxide to the gas mixture contributes to a decrease in the maximum extent of conversion. The decrease in conversion is not linear with respect to CO. The lowest rate of conversion was found for the gas mixture containing 75 percent CO. The cause of this behavior is due to a higher rate of carbon deposition. A mixed control mechanism controls and reaction rate for conversions up to 50 percent.