Oxidation and Sintering of Magnetite Ore under Oxidising Conditions

Abstract

The oxidation of magnetite mineral in a wide range of iron ore concentrates has been studied at sintering conditions. The degree of oxidation for a given ore closely depends on temperature, oxygen partial pressure of the atmosphere and reaction time. With increasing temperature the degree of oxidation increases and then declines because of particle coalescence and melt formation resulting in reduced porosity. For the same reasons, a lower oxidation degree is observed for more fusible ores at high temperatures. The oxygen partial pressure in atmosphere has been shown to strongly influence oxidation, particularly when p_O2 is below air. Measures to enhance magnetite oxidation during sintering are discussed based on current understanding of the fundamentals that control the sintering process.
The study has also shown that during sintering, the preferred bonding phase in sinter, i.e., SFCA, forms readily once magnetite is oxidised. The sintering behaviour of the oxidised magnetite is essentially similar to that of a natural hematite ore. However, silicates are still the dominant bonding phase for highly fusible magnetite ore sintered in an oxidising atmosphere.