分段尝试法研究碱金属对铁氧化物还原的影响

Effect of alkali metal on reduction of iron oxide by sectioning method

为了研究碱金属在高炉内对Fe2O3还原的影响,采用热重分析方法研究含有不同碱金属含量的Fe2O3在不同温度下的还原特性。通过分析试样的还原度曲线,讨论温度和碱金属含量对还原过程的影响,发现随着温度的升高,反应速率增加,试样的还原度增加,接近完全还原的反应时间缩短;Na2O对Fe2O3的还原有抑制作用,抑制作用随着Na2O含量增加而加强,但这种抑制作用随着Na2O含量增加不是均匀增长的,会存在饱和点。针对还原过程的特点,采用分段尝试法建立了前期化学反应控速的未反应核模型和后期收缩核内扩散模型,并对实验数据进行分段拟合,求得相关动力学参数,同时定量地给出了不同的温度条件下2种控制转换的时间点。从拟合结果看,实验数据和模型取得了很好的吻合,说明所建模型与实际情况相符。

In order to study the effect of alkali metal on the reduction of Fe2O3 in the blast furnace,thermogravimetric analysis was used to study the reduction characteristics of Fe2O3 containing different alkali metal contents at different temperatures.By analyzing reduction curves of the sample,the effects of temperature and alkali metal content on the reduction process were discussed.The results show thatwith the increase of temperature,the reaction rate and degree of reduction of the sample increase with the reaction time near to complete reduction shortens Na2O has an inhibitory effect on the reduction of Fe2O3,and the effect increases with Na2O content increasing. However,this inhibition does not increase linearly and there is a saturation point.At the same time,according to the characteristics of the reduction process,the unreacted nuclear model and the shrinking intranuclear diffusion model were established by the sectioning method.The experimental data were fitted and the relevant kinetic pa- rameters were calculated.The time points of the two control transitions under different temperature conditions were quantitatively given.From the fitting results,the experimental data and the model are in good agreement,indicating that the model is consistent with the actual situation.The sectioning method,as a new method for studying kinetics,is suitable for studying the reduction process of iron oxides and other reaction process kinetics.