关键词: 硼铁精矿, 含碳球团, 直接还原, 活化能, 数学模型

Abstract: The kinetic characteristics of reduction of boron-bearing iron concentrate and Boudouard reaction are studied by isothermal thermogravimetric analysis in CO/CO2/N2 atmosphere. The activation energy is assessed as 194.72, 74.72 and 65.74 kJ/mol for Boudouard reaction and the reduction reaction stages of Fe3O4→FeO and FeO→Fe, respectively. On the basis of these kinetic parameters, a mathematical model of carbothermic reduction of boron-bearing iron concentrate is built up, which is validated by comparison of the computed results with the experimental data. The effects of pellet size, porosity and activation energy are discussed based on the calculated results. The increase of pellet size from f16 mm×8 mm to f32 mm×16 mm slows down the initial reduction rate, but elevates the ultimate metallization rate from 85% to 99.4%. The effect of porosity on the reduction process is relatively slight. The rise in activation energy of Boudouard reaction suppresses the proceeding of reduction, but has little impact on the ultimate metallization rate; When the activation energy of the interface reduction increases from 95% to 105% of the original value, not only the reduction rate decreases, but also the ultimate metallization rate declines from 99.59% to 94.81%. It can be deduced from the effect of activation energy that the reduction process is initially under the mixed control of interfacial reduction and Boudouard reaction, but under control of interfacial reduction in the later stage.

Key words: boron-bearing iron concentrate, carbon iron ore pellet, direct reduction, activation energy, mathematical model