Dehydration behavior of goethite blended with graphite by microwave heating

Youichi Saito, Keita Kawahira, Noboru Yoshikawa, Hidekazu Todoroki, Shoji Taniguchi

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

In ironmaking and steelmaking processes, dehydration of wet substances and minerals combined by H2O are often recognized to be a key to stable practices. This study aims at understanding dehydration behavior of goethite blended with graphite by microwave treatment simulating drying wet sludge and poor iron ore with combined water. Firstly blend specimens with various conditions, powdery or pelletized, were heated by microwave apparatus. Dehydration rate of goethite increased with increasing temperature. Denser specimen of palletized was confirmed to be less effective to heat up the whole part. It was found that surplus addition of graphite decreased efficiency in dehydration rate. Thus, it was estimated that a specimen with smaller amount of graphite, whose blend ratio of FeO(OH):C was 1:1, had sufficiently larger distance between graphite particles, through which microwaves could adequately penetrate into the core of the specimen. To prove this hypothesis, Network Analyzer helped evaluate penetration depth of microwave by the measurement of permittivity. The measured results showed that penetration depth decreased with increasing apparent density consistently with the heating behavior by microwave treatment. At the blend ratio of 1:2 of FeO(OH):C, however, the specimen was estimated to behave as if it was under percolation.

Original languageEnglish
Pages (from-to)878-883
Number of pages6
JournalIsij International
Volume51
Issue number6
DOIs
Publication statusPublished - 2011 Jun 15

Keywords

  • Decomposition
  • Dehydration
  • Goethite
  • Graphite
  • Microwave
  • Network analyzer
  • Permeability
  • Permittivity

ASJC Scopus subject areas

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

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