含锌尘泥球团直接还原过程中渣相行为与固结强度关系研究

Relationship between slag behavior and consolidation strength of zinc-bearing dust pellets during direct reduction process

通过表征不同直接还原温度下碱性含锌尘泥球团外观形貌、物相组成、微观结构及抗压强度变化,并结合FactSage热力学计算,分析了碱性尘泥球团直接还原过程中渣相行为及其对球团固结强度的影响。结果表明,随着还原温度升高,碱性尘泥球团体积先膨胀后收缩,对应抗压强度也先减小后增加,碱性氧化物一直参与球团渣相的形成过程并最终形成复杂的含钙化合物渣相。固相反应是渣相形成的基础,其中间产物Ca 2SiO 4良好的固溶性促进了钙铁和钙镁低熔点物相的固相生成,铁氧化物的初步还原产物FeO有利于液相生成,促进球团中物相的迁移和重新排列,球团体积收缩,强度明显提高。

By characterizing the morphology,phase composition,microstructure,and compressive strength changes of basic Zn-bearing dust pellets at different direct reduction temperatures,and with the help of FactSage thermodynamic calculations,the slag behavior during the direct reduction process of basic dust pellets and its impact on the consolidation strength of the pellets were analyzed.The results show that with the increase of reduction temperature,the volume of basic dust pellets first expands and then contracts,while the corresponding compressive strength first decreases and then increases.Basic oxides are continuously involved in the formation of slag phase in the pellets,eventually forming complex calcium-containing compound slags.Solid-phase reaction is the basis for the formation of slag phase.The good solubility of the intermediate product Ca 2 SiO 4 promotes the solid-phase generation of low-melting-point calcium-iron and calcium-magnesium phases.The preliminary reduction product of iron oxide,FeO,promotes the generation of liquid phase,which enhances the migration and rearrangement of phases within the pellets,leading to pellet volume contraction and significant strength enhancement.