钒钛烧结矿还原粉化过程的矿相分析

Study of V-Ti Sinter Reduction Degradation by Mineralogical Analysis

低温还原粉化率RDI-3.15是评价烧结矿质量的一项重要指标,它会影响高炉焦比和产量。钒钛烧结矿的RDI-3.15高达60%以上,研究认为钙钛矿是造成RDI-3.15高的主要原因,但是随着钒钛烧结矿中钙钛矿含量的大幅降低,其低温还原粉化性能并未得到有效改善。本研究应用矿相分析法对比分析了普通烧结矿和钒钛烧结矿的微观结构差别,并观察了两种烧结矿在低温还原粉化前后的结构变化;发现骸晶状赤铁矿和气孔结构是发生粉化的主要区域,而钒钛烧结矿中存在大量的气孔结构,这是导致其还原后发生严重粉化的主要原因。调整成分以提高粘结相的流动性,有利于降低气孔率和骸晶状赤铁矿含量,并增加有效粘结相,从而可减少配碳量并降低烧结温度,限制铁酸钙的分解和钙钛矿等高熔点矿物的生成,增加强度较好的交织结构的数量。

Low temperature reduction degradation index RDI-3.15 is an important index for evaluating sinter quality,which influences the coke rate and productivity of blast furnace operation.The RDI-3.15 of V-Ti sinter is generally higher than 60%,some researches believe that perovskite is the main reason for this phenomenon,but RDI property doesn＇t improve much when the amount of perovskite in V-Ti Sinter is sharply reduced.Mineralogical analysis is used for comparing microstructure differences between common sinter and V-Ti sinter,structure variation of both kinds of sinters before and after low temperature reduction degradation is also observed;it is found that skeleton hematite and pore structure are the main regions where degradation happens,while this structure occupies much volume in V-Ti sinter,which is considered to be the main reason for its high RDI-3.15.It is proposed to improve the fluidity of sintering bonding phase by modifying chemical composition,which is beneficial for reducing porosity and the amount of skeleton hematite,meanwhile the amount of effective bonding phase is also increased,so coke rate can be reduced and sintering temperature can be lowered,then decomposition of calcium ferrite and formation of perovskite are restricted,and the amount of high strength fabric structure also increases.