烧结矿碱度对综合炉料交互反应的影响

Effect of sinter basicity on the interactive reaction of composite burdens

  • 摘要: 以不同碱度的烧结矿及烧结矿与块矿的混合矿为研究对象,利用荷重软化熔滴装置,考察了烧结矿碱度对综合炉料软熔性能及不同炉料间交互作用的影响。研究发现:随着烧结矿碱度增加,炉料结构中块矿的质量配加比例提高,炉料间的交互作用增强,主要表现为综合炉料软化开始温度及熔融开始温度降低,混合炉料的透气性得到改善。炉料结构的变化使矿物间的交互反应随着烧结矿碱度的提高而增强,进而导致液相成分发生改变,降低了初渣物相熔点,而烧结矿碱度过高时会恶化料柱的透气性。同时通过扫描电子显微镜−能量色散谱仪(SEM−EDS)及X射线衍射(XRD)精修表征整个还原过程烧结矿物相变化,渣相中主要物相为浮氏体和硅酸钙,随着烧结矿碱度增加,在不同断点2CaO·SiO2的含量呈现降低趋势,表明烧结矿还原过程生成的高熔点物相随之降低,综合炉料的液相生成温度随之降低,炉料间交互作用增强。因此,适当提高烧结矿碱度,提高块矿入炉的质量配比,利于高炉的强化冶炼。

     

    Abstract: With the deepening of the concept of interactive reaction and the development of several studies, metallurgists are no longer simply concerned with the metallurgical properties of a single charge. Instead, they comprehensively consider the interactive reaction of composite burdens. The interactive reaction is mainly affected by the chemical composition, microstructure, reduction temperature, and other factors of the ferrous burdens. In this study, taking a sinter with different basicities and a mixed ore of sinter and lump as the research object, the effect of sinter basicity on the smelting and dripping paraments of a composite burden and the interactive reaction between different burdens was investigated using melting–dripping equipment. The results show that the dripping temperature of a single sinter increases with sinter basicity. In the integrated burdens protocol, the proportion of lump ore increased, and the interaction between the burdens was enhanced, which is mainly manifested as a reduced softening start temperature and melting start temperature of the composite burden. The air permeability of the mixed charge was improved. A change of burden structure enhances the interaction between minerals with increasing sinter basicity, resulting in a change in the liquid phase composition, which reduces the melting point of the primary slag phase, and when the basicity of the sintered is too high, it will deteriorate the gas permeability of the material column. This result is not conducive to the intensive smelting of blast furnaces. At the same time, the sintered mineral phase changes throughout the reduction process were characterized using SEM-EDS and XRD, and the main phases in the slag phase are wustite and calcium silicate. The interactive reaction between the sinter and lump produces low melting point materials, which is verified by calculating the phase diagram of CaO–SiO2–FeO. With increasing sinter basicity, the content of 2CaO·SiO2 at different breakpoints decreased. This result shows that the high melting point phase formed during the reduction process of the sinter decreases, the liquid phase formation temperature of the composite burden decreases, and the interaction between the burdens increases. Therefore, appropriately increasing the sinter basicity and increasing the lump ore proportion benefits the enhanced smelting of a blast furnace. The theoretical and experimental results obtained in this research are of great importance for improving the production application of the proportion of lump in the furnace and developing efficient and low-carbon ironmaking.

     

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