Oxidation and Sintering Characteristics of Magnetite Iron Ore Pellets Balled with a Novel Complex Binder

Abstract

Additives can give rise to obvious, step-wise changes both in the oxidation process and in the sintering process. Therefore, the oxidation and sintering characteristics measured in dried pellets prepared from pure magnetite concentrates can not be representative for those characteristics in dried pellets containing additives. The oxidation and sintering characteristics of magnetite iron ore pellets balled with a novel complex binder (namely MHA) were mainly investigated by batch isothermal oxidation measurements in this research. Combined results reveal that the thermal decomposition of MHA binder influences the oxidation and sintering processes of dried pellets. Oxidation rate of pellets increases obviously with increasing the oxidation temperature in the range from 800°C to 1000°C. And the remaining FeO content declines gradually when separately heated for 10 min at low temperature (<1000°C). However, the oxidation rate of pellets decreases distinctly when oxidation temperature is higher than 1000°C. In addition, when oxidation temperature increases from 1000°C to 1250°C, the FeO content of pellets goes up obviously, particularly at 1250°C. The FeO content in the core of sintered pellets heated at 1250°C can even reach 29.68%. SEM spectrum analysis demonstrate that some iron appears in forms of wustite in sintered pellets, which indicates that the reduction reaction of iron oxide occurs during the high temperature sintering process. This is explained by the occurrence of reducing atmospheres because of the pyrogenic decomposition of MHA binder.

Keywords:

• complex binder
• oxidation characteristics
• pellet
• reduction reaction
• sintering

ACKNOWLEDGMENTS

The authors want to express their thanks to National Science Fund for Distinguished Young Scholars (No.50725416), National Key Program of Science and Technology (No.2008BAB32B06), and the Graduate Degree Thesis Innovation Foundation of Hunan Province (No.CX2009B035 and No.CX2010B063) for financial supporting of this investigation.

Notes

Yan-fang Huang and Gui-hong Han contributed equally to this article.