Abstract: Utilization of low-grade iron ore in the production of pellets is of great significance for reducing the production cost of blast furnaces with high-proportion pellets. By appropriate beneficiation, the iron grade of boron-bearing ore can exceed 50%, which is suitable for the production of pellets. In this study, the boron-bearing iron ore pellets were selected as the research object, and the reduction behavior as well as the kinetics of pellets under CO atmosphere were experimentally investigated. Simultaneously, the mechanism for the reduction process was elucidated. Meanwhile, the difference of pellets reduction behavior between the CO atmosphere and the H2 atmosphere was revealed. The results demonstrated that as the reduction temperature rose from 700℃ to 950℃, the final reduction degree of pellets under CO atmosphere was enhanced from 26.85% to 53.56%. Simultaneously, the variation in the reduction rate of pellets depended on the temperature. At low temperature (700~800℃), the reduction rate of pellets was firstly increased and then decreased, and the maximum value was reached at (60~80) min. Furthermore, at high temperature (850~950℃), the reduction rate was rapidly boosted to the maximum value at the initial reaction stage (within 10 min), and followed by a decreasing trend. Meanwhile, under the same reduction conditions, the reduction degree of pellets under H2 atmosphere was significantly greater than that under CO atmosphere. In addition, the reduction process of boron-bearing iron ore pellets under CO can be well described by f(x)=3(1-x)2/3. Based on this model, the apparent activation energy and pre-exponential factor were calculated, which were 29.2953 kJ/mol and 0.028629 ?min-1, respectively. This work could provide theoretical foundation and data support for the application of boron-bearing iron ore in the production of pellets.

Key words: boron-bearing iron ore, pellet, reduction behavior, kinetics, low-carbon ironmaking

摘要： 使用低品质铁矿生产球团对于降低高比例球团高炉冶炼生产成本具有重要意义。硼铁矿经选矿后铁品位超过50%，可用于球团矿生产。本研究以硼铁矿球团为研究对象，研究了CO气氛下硼铁矿球团的还原行为与动力学，阐明了还原反应机理，并对比分析了其与H2气氛下硼铁矿球团还原行为的差异。结果表明，当还原温度从700℃升高到950℃时，CO气氛下球团的最终还原率由26.85%增加到53.56%。同时，不同还原温度条件下，球团矿的还原速率呈现不同的演变规律，在低温阶段(700~800℃)，球团还原速率先增大后减小，在(60~80 min)之间达到最大；在高温阶段(850~950℃)，球团还原速率在反应初期(10 min内)达到最大值，随后逐渐下降并趋于稳定。另外，与CO气氛相比，H2气氛下硼铁矿球团的还原率明显更高。此外，硼铁矿球团在CO气氛下的还原过程可以用f(x)=3(1-x)2/3进行描述，其还原反应活化能和指前因子分别为29.2953 kJ/mol和0.028 629 min-1。本研究可为硼铁矿在球团生产中的应用提供理论基础和数据支持。

关键词: 硼铁矿, 球团矿, 还原行为, 动力学, 低碳炼铁