Reduction kinetics of hematite powder mechanically milled with graphite

Ichiro Seki, Kazuhiro Nagata

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Reduction behavior of iron oxides mixed with graphite has been quantitatively investigated using a high temperature X-ray diffractometer. The mixture was mechanically milled using a vibration mill and heated under He gas flow from room temperature to 1 550 K with the heating rate of 10 to 40 K/min. The diffraction pattern showed the sequential change of products by reduction from hematite to iron through magnetite and wustite. The temperature at which each reduced product sequentially appeared was decreased by several ten degrees with increasing mechanical milling time up to 160 min. The intensity change of diffraction profiles of constituents with temperature was in accordance with the chemical stoichiometry of reduction reactions. The reduction reactions were first order of reaction. The activation energy of reaction decreased and the frequency factor of reaction increased with increasing mechanical milling time. On the other hand, the mixture of milled graphite powder and non-milled hematite powder gave less effect to the activation energy and frequency factor than the milled mixture.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalIsij International
Issue number1
Publication statusPublished - 2006
Externally publishedYes


  • Activation energy of reduction
  • Graphite
  • High temperature X-ray diffraction
  • Iron oxides
  • Milling

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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