含碳高硅矿球团在H_(2)-H_(2)O-N_(2)和CO-CO_(2)-N_(2)气氛下还原过程研究

Reduction process of carbon-containing high-silicon ore pellets in H_(2)-H_(2)O-N_(2) and CO-CO_(2)-N_(2) atmospheres

针对高炉炼铁节能减排的新要求,在H_(2)-H_(2)O-N_(2)和CO-CO_(2)-N_(2)气氛下研究碳复合团块的反应行为。通过化学分析法、X射线衍射(XRD)和扫描电子显微镜-能谱(SEM-EDS)分析了复合团块的成分、矿相及微观形貌,对CO-CO_(2)-N_(2)和H_(2)-H_(2)O-N_(2)气氛下碳复合团块的还原行为进行了分析,并建立了复合团块反应动力学模型。结果表明,在1 073、1 173、1 273、1 373 K温度下,复合团块在H_(2)-H_(2)O-N_(2)气氛下的还原度和碳气化率均高于CO-CO_(2)-N_(2)气氛。对2种气氛下含碳团块在1 273 K时的反应过程进行分析,XRD图谱表明,在H_(2)-H_(2)O-N_(2)气氛下反应20 min后,团块中FeO相消失;在CO-CO_(2)-N_(2)气氛下,一直存在团块中FeO相,说明复合团块在H_(2)-H_(2)O-N_(2)气氛下还原性更好。对比2种气氛下的扫描电子显微镜(SEM)照片,当反应进行到25 min时,金属铁在复合团块边缘大量聚集。综合考虑气固相之间化学反应的质量守恒和传质行为,建立复合团块反应动力学模型。结合实验结果进行分析,模型拟合结果较好。

The study investigated the reaction behavior of carbon composite agglomerates in H_(2)-H_(2)O-N_(2) and CO-CO_(2)-N_(2) atmospheres to meet the new requirements for energy conservation and emission reduction in blast furnace ironmaking.The composition,mineral phases,and microstructure of the composite agglomerates were analyzed using chemical analysis,X-ray diffraction(XRD),and scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS).The reaction kinetics model for carbon composite agglomerates was established by analyzing their reduction behavior in CO-CO_(2)-N_(2) and H_(2)-H_(2)O-N_(2) atmospheres.The reduction degree and carbon gasification rate of the composite agglomerates were higher in the H_(2)-H_(2)O-N_(2) atmosphere than in the CO-CO_(2)-N_(2) atmosphere at temperatures of 1073,1173,1273 and 1373 K.A comparative analysis of the reaction process of carbon-containing agglomerates was conducted at 1273 K in both atmospheres.After 20 min of reaction in the H_(2)-H_(2)O-N_(2) atmosphere,the FeO phase disappeared from the agglomerates based on the XRD spectra.In contrast,in the CO-CO_(2)-N_(2) atmosphere,the FeO phase remained in the agglomerates,indicating better reducibility of the composite agglomerates in the H_(2)-H_(2)O-N_(2) atmosphere.Electron microscopy images were also compared for both atmospheres,and it was observed that a significant aggregation of metallic iron occurred at the edges after 25 min of reaction.A reaction kinetics model was developed for the composite agglomerates,considering the conservation of mass for both gas and solid components,as well as the mass transfer between the agglomerates and the gas phase.The model was found to fit well with the experimental results,demonstrating its reliability.