Gaseous reduction model for sinter in consideration of calcium ferrite reaction process (unreacted-core shrinking model for six interfaces).
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Data
2014
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Resumo
Reducible oxides containing iron in iron ore sinter are hematite, magnetite and quaternary calcium ferrite
(abbreviated by CF), which is the complex crystalline mineral produced from Fe2O3, CaO, SiO2 and Al2O3.
Equilibrium diagram for CF reduction with CO–CO2 gas mixture is a little but significantly different from
the one for pure iron oxides. In previous analyses for reduction reaction of iron oxides in a blast furnace,
however, sinter has been treated as pure iron oxides; existence of CF has been ignored. Reduction steps
for CF can be written as
CF(= ‘Fe2O3’) ‘Fe3O4’ ‘FeO’ ‘Fe’,
which are much the same as pure iron oxides, where ‘Fe2O3’, ‘Fe3O4’, ‘FeO’ and ‘Fe’ designate hematite,
magnetite, wustite and iron stages of CF, respectively. However, a reported variation of gas composition
with temperature measured in a blast furnace shows that the gas composition in the thermal reserve zone
is a little higher than the wustite/iron equilibrium, the reduction potential of which is less than that of
‘FeO’/‘Fe’ equilibrium and hence ‘FeO’ cannot be reduced to ‘Fe’. In the present work, therefore, gaseous
reduction model for sinter is developed in consideration of CF reaction process; unreacted-core shrinking
model for six interfaces is proposed to take into account reaction processes of CF as well as pure iron
oxides. Trial comparison of the calculated reduction curve with our previously reported experimental data
under simulated blast furnace conditions shows rather good agreement.
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Ironmaking, Blast furnace, Calcium ferrite, Sinter
Citação
USUI, T. et al. Gaseous reduction model for sinter in consideration of calcium ferrite reaction process (unreacted-core shrinking model for six interfaces). ISIJ Internacional, v. 55, n. 8, p. 1617-1624, 2015. Disponível em: <https://www.jstage.jst.go.jp/article/isijinternational/55/8/55_ISIJINT-2015-060/_html/-char/en>. Acesso em: 20 jul. 2017.