Kinetic Analysis of Molten Oxide Reduction Using Bottom-Blown Hydrogen Injection

Hydrogen-based smelting reduction has received widespread attention as an important technology for realizing low-carbon development in hydrogen metallurgy. In this study, the thermodynamics of smelting reduction was firstly analyzed by using FactSage 8.1 thermodynamic software, on the basis of which smelting reduction experiments of iron oxides by using bottom-blown hydrogen were carried out. The experiments used oxidized pellets as experimental materials, and the effects of the reduction process were analyzed in terms of the reduction temperature, the reduction time, and the hydrogen flow rate. The experimental results show that under the experimental conditions of a temperature of 1550 °C and a hydrogen flow rate of 0.2 Nm3/h, the reduction rate of iron oxides in the process of reducing iron oxides by hydrogen is significantly faster in the first 10 min than after 10 min. The hydrogen utilization rate reached a maximum of 41.87%, then decreased continuously and finally maintained at about 20%. Using the method of model fitting, it was found that the hydrogen-based molten reduction conformed to the phase boundary reaction model (Gα=1−(1−α)1/2), the corresponding mechanism function is fα=2(1−α)1/2, where α stands for the reduction conversion, and the reaction rate constant k(T) is 2.37 × 10−4 s−1 under the experimental conditions.