Study on properties of sinter mineral phases  

作　　者：QI Wei MAO Xiaoming SHEN Hongbiao 

机构地区：[1]Research Institute,Baoshan Iron & Steel Co.,Ltd.

出　　处：《Baosteel Technical Research》2018年第3期16-24,共9页宝钢技术研究（英文版）

基　　金：the support of the National Key R& D Program of China ( No. 2017YFB0304300 & 2017YFB0304301)

摘　　要：In this study,the properties of sinter mineral phases were investigated by X-ray diffraction,optical microscopy quantitative observation,electron probe microanalysis,and the nanoindentation technique. The mechanisms that form return fines are discussed with respect to the factors of microregion composition,sintering temperature,and the reactive behavior of pisolite. The study results indicate the following：（ 1） Sinter mineral assemblage mainly comprises hematite,magnetite,calcium ferrite,and glass. In addition,the mineral assemblage of sinter products includes a great deal of calcium ferrite and melt-erosive magnetite,an abundance of secondary hematite,and a small amount of primary iron ore; whereas the mineral assemblage of return fines contains plentiful amounts of euhedral magnetite and secondary hematite,a large amount of relic pisolite with particle sizes less than1 mm,and relatively less calcium ferrite. In particular,some calcium ferrite was found to coexist with relic iron ore in a fiber-like microstructure.（ 2） Dentritic calcium ferrite has less SiO_2 and Al_2O_3,higher basicity（ w_（CaO）/w_（SiO_2））and a mole ratio of Fe_2O_3/CaO,whereas platy and blocky calcium ferrites have more SiO_2 and Al_2O_3,lower basicity and a mole ratio of Fe_2O_3/CaO.（ 3） The hardness of hematite is the highest（ around 18-22 GPa）,those of calcium ferrite and magnetite are relatively lower,and that of glass is the lowest. In terms of the formation mechanism of return fines,because of their weak ability to resist external shocks,these sorts of mineral phases and microstructures-（1） euhedral magnetite and glass formed in microregions with low basicity;（2） SFCA-Ⅰand relic iron ore formed in regions with a relatively low sintering temperature; and（3） relic pisolite and its nearby reaction regions-are inclined to form return fines.In this study,the properties of sinter mineral phases were investigated by X-ray diffraction,optical microscopy quantitative observation,electron probe microanalysis,and the nanoindentation technique. The mechanisms that form return fines are discussed with respect to the factors of microregion composition,sintering temperature,and the reactive behavior of pisolite. The study results indicate the following：（ 1） Sinter mineral assemblage mainly comprises hematite,magnetite,calcium ferrite,and glass. In addition,the mineral assemblage of sinter products includes a great deal of calcium ferrite and melt-erosive magnetite,an abundance of secondary hematite,and a small amount of primary iron ore; whereas the mineral assemblage of return fines contains plentiful amounts of euhedral magnetite and secondary hematite,a large amount of relic pisolite with particle sizes less than1 mm,and relatively less calcium ferrite. In particular,some calcium ferrite was found to coexist with relic iron ore in a fiber-like microstructure.（ 2） Dentritic calcium ferrite has less SiO_2 and Al_2O_3,higher basicity（ w_（CaO）/w_（SiO_2））and a mole ratio of Fe_2O_3/CaO,whereas platy and blocky calcium ferrites have more SiO_2 and Al_2O_3,lower basicity and a mole ratio of Fe_2O_3/CaO.（ 3） The hardness of hematite is the highest（ around 18-22 GPa）,those of calcium ferrite and magnetite are relatively lower,and that of glass is the lowest. In terms of the formation mechanism of return fines,because of their weak ability to resist external shocks,these sorts of mineral phases and microstructures-（1） euhedral magnetite and glass formed in microregions with low basicity;（2） SFCA-Ⅰand relic iron ore formed in regions with a relatively low sintering temperature; and（3） relic pisolite and its nearby reaction regions-are inclined to form return fines.

关 键 词：SINTER mineral assemblage composition of mineral phase hardness of mineral phase mechanismforming return fines 

分 类 号：TF046.4[冶金工程—冶金物理化学]