| Microwave heating has many advantages over conventional heating. In recent years, people have been attempting to apply microwave technology in extractive metallurgy, but the research in this field is only at an early stage.; Although some researches have been done in the laboratory, so far the mechanism about the interaction between microwave and direct reduction of iron ore is still unclear.; In this project, a microwave heating system is set up and a series of experiments have been done. The results show that iron oxide is a good microwave receptor, and the feasibility of microwave application in the steelmaking is confirmed. In this project, hydrogen and carbon monoxide are used as reducing gas; nitrogen and argon are used as inert gas. Iron oxide reduction experiments are conducted via a combination of conventional and microwave enhanced heating.; Microwave enhanced heating has the potential for energy savings compared to conventional heating for the same reduction degree of iron oxide. In this reaction system, 500°C is the optimum temperature at which microwave energy should be applied after conventional heating. Mixed reducing gas can have a significant effect on the reduction rate of iron oxide than a single reducing gas. Experimental results obtained from this project can be very beneficial for future practical application of microwave in direct reduction of iron oxide.; Non-isothermal mathematical models are developed for the kinetic study of direct reduction of iron oxide by hydrogen and carbon monoxide. The grain model and multi-layer un-reacted core model are modified and integrated into a more reasonable discrete phase model.; Comparison of the reduction kinetics where heat is supplied by microwaves and conventional heat, results indicate that microwave can expedite the reduction rate. Model parameters are obtained from experimental data fitting. The new model may guide the practical application of microwave heating in the steelmaking industry in the near future. |
