Reducing process of sinter in COREX shaft furnace and influence of sinter proportion on reduction properties of composite burden

COREX竖炉中烧结矿的还原过程及其对综合炉料还原性能的影响

In order to reduce the materials cost of COREX ironmaking process,sinter has been introduced into the composite burden in China.This work explored the reducing process of sinter in COREX shaft furnace to clarify its reduction properties change and then the effect of sinter proportion on metallurgical performance of composite burden was investigated.The results show that the reducing process of sinter in COREX shaft furnace was basically same with that in blast furnace but sinter seems like breaking faster.Under reducing condition simulated COREX shaft furnace,sinter possessed the worst reduction degradation index(RDI)and undifferentiated reduction index(RI)compared with pellet and iron ore lumps.Macroscopic and microscopic mineralogy changes indicated that sinter presents integral cracking while pellet and lump ore present surface cracking,and no simple congruent relationship exists between cracks of the burden and its ultimate reduction degradation performance.The existence of partial metallurgical performance superposition between composite and single ferrous burden was confirmed.RDI_(+6.3)≥70%and RDI_(+3.15)≥80%were speculated as essential requirements for the composite burden containing sinter in COREX shaft furnace.

为了降低COREX炼铁工艺的成本,中国在综合炉料中加入了烧结矿。本文研究了烧结矿在COREX竖炉中的还原过程,阐明了其还原性质的变化,并研究了烧结矿配比对综合炉料冶金性能的影响。结果表明,在COREX竖炉中烧结矿的还原过程与其在高炉中类似,但还原粉化发生得更快;在模拟COREX竖炉还原条件下,与球团矿和块矿相比,烧结矿的还原粉化性能(RDI)最差而还原性能(RI)差别不大。宏观和微观矿相分析表明,还原时烧结矿呈现整体开裂而球团矿和块矿均呈现表面开裂,炉料自身产生的裂纹与其最终还原粉化性能之间不存在简单的对应关系。COREX竖炉综合炉料与单一种类炉料之间存在部分冶金性能叠加性,配入烧结矿时综合炉料的低温还原粉化性能RDI_(+6.3)和RDI_(+3.15)应分别不低于70%和80%。