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转底炉用典型冶金尘泥特性分析及其微波还原焙烧机制

Characterization and analysis of typical metallurgical dust for rotary hearth furnace and its mechanism for microwave reduction roasting

  • 摘要: 转底炉是当前处理钢铁冶金尘泥的主流技术,但其生产实践仍面临球团还原均匀性差、深度脱锌困难、关键指标协同优化不足等挑战。本研究首先对转底炉用典型冶金尘泥的原料特性进行系统解析,并探究其微波还原焙烧效果;其次,运用Maps统计分析法对球团还原均匀性及孔隙结构特性进行可视化、数据化分析;最后,采用递进式能谱(energy dispersive spectroscopy,EDS)分析法对锌物相演变及脱锌机制进行从宏观到微观的系统研究。结果表明,冶金尘泥中铁物相主要包括FexO、Fe、Fe2O3和Fe3O4,而锌物相包括ZnS、ZnFe2O4和ZnO,且各原料在微波场中均具有优异的升温特性;相较于常规焙烧,微波焙烧可将金属化球团的金属化率提高约15个百分点、脱锌率增加约20个百分点、抗压强度提高约1 kN;同时,微波焙烧可同步提升金属化球团内部各区域的还原程度、结构致密性及脱锌效果,并改善球团径向还原及纵向脱锌的均匀性,具有低碳高效的优势。此外,金属化球团内部金属化率与残余锌质量分数的分布特性呈典型负相关关系,可为间接推断残余锌的分布特征提供有效依据,方便简单直观分析其分布规律;同时,冶金尘泥中的硫难以在还原焙烧过程中有效脱除,且易将锌捕集为ZnS或(Zn,Fe)S固溶体,导致脱锌效果不理想,而微波焙烧可减少锌被捕集固定。通过对转底炉用典型冶金尘泥的特性分析,结合Maps统计分析和递进式能谱分析,系统剖析了微波焙烧机制,揭示了其显著效果与作用机制,为冶金尘泥的低碳高效资源化利用提供了理论依据与技术指导。

     

    Abstract: The rotary hearth furnace is currently the mainstream technology for treating iron and steel metallurgical dust, yet its practical operation still faces challenges such as poor reduction homogeneity of pellets, difficulty in deep dezincification, and challenges in the synergistic optimization of key performance indicators. This study first systematically analyzed the raw material properties of typical metallurgical dust for rotary hearth furnace processing and investigates its effectiveness during microwave reduction roasting. Subsequently, Maps statistical analysis was employed to visualize and quantify the reduction homogeneity and pore structure characteristics of the pellets. Finally, a stepwise EDS(energy dispersive spectroscopy) analysis method was adopted to conduct a systematic investigation into the zinc phase evolution and dezincification mechanism, from the macroscopic to the microscopic scale. The results indicate that the iron phases in the metallurgical dust primarily include FexO, Fe, Fe2O3, and Fe3O4, while the zinc phases consist of ZnS, ZnFe2O4, and ZnO. All raw materials exhibit excellent heating characteristics within the microwave field. Compared to conventional roasting, microwave roasting can increase the metallization rate of metallized pellets by approximately 15 percentage points, raise the dezincification rate by about 20 percentage points, and enhance the compressive strength by roughly 1 kN. Microwave roasting synchronously improves the reduction degree, structural compactness, and dezincification effectiveness across different internal zones of the metallized pellets, while also enhancing the uniformity of radial reduction and longitudinal dezincification, demonstrating advantages in low carbon emissions and high efficiency. Furthermore, a typical negative correlation exists between the distribution characteristics of the metallization rate and the residual Zn content within the pellets, providing an effective basis for indirectly inferring the distribution features of residual zinc and facilitating simple, intuitive analysis of its distribution patterns. Concurrently, sulfur present in the metallurgical dust is difficult to remove effectively during the reduction roasting process and tends to capture zinc as ZnS or (Zn,Fe)S solid solutions, leading to suboptimal dezincification. Microwave roasting can mitigate this capture and fixation of zinc. Through the characterization of typical metallurgical dust for rotary hearth furnaces, combined with Maps statistical analysis and stepwise EDS analysis, this study systematically elucidates the mechanism of microwave roasting, reveals its significant effects and operative mechanisms, and provides theoretical foundation and technical guidance for the low-carbon and high-efficiency resource utilization of metallurgical dust.

     

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