Evaluation of MgO on hematite swelling dynamics during CO-driven stepwise reduction  

作　　者：Fang Zhang Jun Peng Shuang Liu Yong-bin Wang Fan Yang 

机构地区：[1]School of Rare Earth Industry,Inner Mongolia University of Science and Technology,Baotou,014010,Inner Mongolia,China [2]Key Laboratory of Green Extraction&Efficient Utilization of Light Rare-Earth Resources,Inner Mongolia University of Science and Technology,Baotou,014010,Inner Mongolia,China

出　　处：《Journal of Iron and Steel Research International》2025年第3期564-577,共14页钢铁研究学报(英文版)

基　　金：support from the 2023 Basic Research Foundation Project for Universities in the Inner Mongolia Autonomous Region(Grant No.2023RCTD006);the National Natural Science Foundation of China(Grant No.51864041,51664044).

摘　　要：The significant effect of MgO in inhibiting the reduction swelling of iron ore pellets has been widely recognized.The swelling behaviors of pellets during the stepwise reduction by CO were assessed.The linear expansion of strip samples was measured using a linear dilatometer during the staged reduction process at a temperature of 900℃.The existence states of MgO in hematite,magnetite,and wüstite were investigated through thermodynamic calculations.The magnetite strip samples were subjected to oxidizing roasting at 1250℃ for 30 min to produce hematite strip samples.The strip samples with 0.49,1.49,2.49,and 3.49 wt.%MgO were analyzed for length change.It was observed that the sample with 2.49 wt.%MgO exhibited the least significant length change.The lengths of the samples with the initial length being 20 mm before reduction changed during the reduction stages of Fe_(2)O_(3)→Fe_(3)O_(4),Fe_(3)O_(4)→FeO,and FeO→Fe were 615,−25,and−378μm,respectively.The volume expansion of hematite to magnetite was primarily attributed to the crystal transformation.During the reduction stage from wüstite to metallic iron,a substantial contraction occurred,while the slag phase was able to retain its original basic shape.The enclosed areas,as indicated by the expansion change curves of the samples with 0.49,1.49,2.49,and 3.49 wt.%MgO,were measured at 3.76×10^(6),3.23×10^(6),3.05×10^(6),and 3.17×10^(6)μm s,respectively.

关 键 词：MGO HEMATITE Reduction swelling Step-by-step reduction 

分 类 号：TF046.6[冶金工程—冶金物理化学]