Title

MINERALOGICAL AND STRUCTURAL EVOLUTION OF IRON ORE FINES REDUCED IN A LAB SCALE FLUIDIZED BED REACTOR

MINERALOGICAL AND STRUCTURAL EVOLUTION OF IRON ORE FINES REDUCED IN A LAB SCALE FLUIDIZED BED REACTOR

Authorship

Skorianz, Michael; Mali, Heinrich; Schenk, Johannes; Plaul, Friedemann; Pichler, Anton; Hanel, Martina

Skorianz, Michael

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Mali, Heinrich

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Schenk, Johannes

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Plaul, Friedemann

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Pichler, Anton

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Hanel, Martina

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DOI

10.5151/2594-357X-22442

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Abstract

In recent years alternative ironmaking technologies have been developed. Some of these so called direct or smelting reduction processes can use iron ore fines directly by means of the fluidized bed technique without prior agglomeration processes. Due to thermodynamic and morphologic constraints, fluidized bed reduction processes are limited regarding the reduction progress from iron ore to metallic iron. In order to investigate the reduction behavior and morphology, different iron ore fines were tested under fluidized bed conditions in a lab scale fluidized bed reactor. Six brands of fine ores with a grain size distribution between 63 μm and 4 mm were reduced by gas mixtures of CO, CO2, H2, H2O and N2 at temperatures between 450°C and 800°C. Based on these tests, the mineralogical and structural evolution during reduction in the magnetite, wuestite and iron stability field was investigated. Hematite and limonite ores were well reducible and had a similar behavior, whereas the limonite rich ores showed a slightly stronger inclination of the reduction degree gradients at the beginning of the reduction sequences. The reduction of magnetite showed an inhibited reduction behavior with a reduction degree far below hematite and limonite throughout the whole process.

In recent years alternative ironmaking technologies have been developed. Some of these so called direct or smelting reduction processes can use iron ore fines directly by means of the fluidized bed technique without prior agglomeration processes. Due to thermodynamic and morphologic constraints, fluidized bed reduction processes are limited regarding the reduction progress from iron ore to metallic iron. In order to investigate the reduction behavior and morphology, different iron ore fines were tested under fluidized bed conditions in a lab scale fluidized bed reactor. Six brands of fine ores with a grain size distribution between 63 μm and 4 mm were reduced by gas mixtures of CO, CO2, H2, H2O and N2 at temperatures between 450°C and 800°C. Based on these tests, the mineralogical and structural evolution during reduction in the magnetite, wuestite and iron stability field was investigated. Hematite and limonite ores were well reducible and had a similar behavior, whereas the limonite rich ores showed a slightly stronger inclination of the reduction degree gradients at the beginning of the reduction sequences. The reduction of magnetite showed an inhibited reduction behavior with a reduction degree far below hematite and limonite throughout the whole process.

Keywords

Fluidized bed; Fine iron ore; Morphology; Mineralogy.

Fluidized bed; Fine iron ore; Morphology; Mineralogy.