Title

MAGNESIUM DIFFUSION IN MAGNETITE-OLIVINE DIFFUSION COUPLE DURING OXIDATION AND REDUCTION Preliminary Laboratory Study

MAGNESIUM DIFFUSION IN MAGNETITE-OLIVINE DIFFUSION COUPLE DURING OXIDATION AND REDUCTION Preliminary Laboratory Study

Authorship

Semberg, Pär; Andersson, Charlotte; Björkman., Bo

Semberg, Pär

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Andersson, Charlotte

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Björkman., Bo

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DOI

10.5151/2594-357X-22220

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Abstract

The solid-state diffusion of magnesium through iron oxides is important in understanding the oxidation and reduction of iron ore pellets containing olivine. In this study, a diffusion couple was made of olivine (containing 50% MgO) and magnetite. Initially, experiments were conducted under oxidizing atmosphere at a temperature above 1,250ºC. A new 100-micron thick layer of magnesioferrite and 11% Mg now appeared at the interface of the couple. In the oxidized iron oxide layer there was no detectable presence of Mg. Subsequently, the oxidized samples were subject to reduction atmosphere sufficient for formation of wustite. The layers of oxidized magnetite (i.e. hematite) and the magnesioferrite reduced to wustite. In the reduced samples, the magnesium level in the wustite by the interface was found to be 1.5 wt%. At distance of 700-1,000 μm from the olivine boundary, the magnesium levels went below detection limit. A diffusion coefficient was estimated from the data. The implication of these observations in iron ore pellets will be discussed.

The solid-state diffusion of magnesium through iron oxides is important in understanding the oxidation and reduction of iron ore pellets containing olivine. In this study, a diffusion couple was made of olivine (containing 50% MgO) and magnetite. Initially, experiments were conducted under oxidizing atmosphere at a temperature above 1,250ºC. A new 100-micron thick layer of magnesioferrite and 11% Mg now appeared at the interface of the couple. In the oxidized iron oxide layer there was no detectable presence of Mg. Subsequently, the oxidized samples were subject to reduction atmosphere sufficient for formation of wustite. The layers of oxidized magnetite (i.e. hematite) and the magnesioferrite reduced to wustite. In the reduced samples, the magnesium level in the wustite by the interface was found to be 1.5 wt%. At distance of 700-1,000 μm from the olivine boundary, the magnesium levels went below detection limit. A diffusion coefficient was estimated from the data. The implication of these observations in iron ore pellets will be discussed.

Keywords

Reduction; Iron ore pellets; Olivine; Magnesium solid-state diffusion.

Reduction; Iron ore pellets; Olivine; Magnesium solid-state diffusion.