Study on intrinsic reaction behavior and kinetics during reduction of iron ore pellets by utilization of biochar

Biochar, as an important renewable and carbon-natural energy, shows plentiful prospects to be used in the ironmaking industry. In this study, the effect of iron ore content and temperature on the reduction of iron ore-biochar pellets in nitrogen atmosphere were investigated. Results indicated that with the decrease of carbon to iron ratio, the iron ore indirect reduction was promoted more than char conversion which resulted in an decrease value of CO:CO2. Pellets reduction at 900 degrees C found that 60% iron ore in pellet exhibited considerable carbon conversion and the highest iron ore reduction amount. With the increase of reaction temperature, the char gasification reaction was promoted prior to the iron ore reduction, resulting in an increase of CO:CO2 ratio. The wustite and metallic Fe gradually increased, while hematite and magnetite gradually decreased, with the increase of temperature. Kinetics study found that carbon conversion was controlled by one-dimensional diffusion, while the iron phase reduction reaction was controlled by three-dimensional diffusion, and the increasing activation energy as the reaction proceeded restricted the iron reduction process. The intrinsic reaction behavior, thermal kinetics, and technical analysis may guide the application of bioenergy in the ironmaking industry.