Influence of sintering conditions on the reduction behaviour of pure hematite compacts

Higuchi, Kenichi; Heerema, R. H.

doi:10.1016/s0892-6875(02)00180-2

Cited by 31 publications

(18 citation statements)

References 17 publications

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“…Figure 8 shows the influence of porosity on the reduction behavior of sintered hematite compacts whose pore size is Ϫ0.125 mm. Expansion of compacts during reduction was well corresponding to the strength after reduction, similarly as authors have pointed out, 1) therefore in the present paper, the strength after reduction in relation to reduction degree was showed. Low-temperature reduction at 550°C results in transformation of hematite to magnetite, and at relatively high-temperature reduction at 800°C, transformation to wustite takes place.…”

Section: Figsupporting

confidence: 88%

“…The results of preliminary tests showed that no formation of magnetite took place during sintering at this temperature. 1) After sintering, the mean gain diameter of hematite crystallites was 0.024 mm, which is comparable with the grain sizes observed in plant sinter.…”

Section: Preparation Of Hematite Compactssupporting

confidence: 76%

“…The strength of samples was defined as the percentage of particle size over 1 mm after the drops (W A ), against the total weight before the test (W B ) as shown in Eq. (1). A preliminary test showed that the mass fraction over 1 mm adequately reflected changes in the strength of samples as a large scale under these impact conditions.…”

Section: Figmentioning

confidence: 92%

“…3, in which the vertical expansion of a sample was measured during reduction. 1) In the present study, all tests were performed under a constant gas composition (COϭ22.5 %, CO 2 ϭ27.5 % and N 2 ϭ50 %) so that this would simulate the actual top gas composition prevailing in the blast furnace. As a result, Fe 3 O 4 is stable below 630°C and FeO is stable above this temperature.…”

Section: Reduction Testmentioning

confidence: 99%

“…In earlier work, the authors demonstrated that the microstructure, particularly the grain and pore structure formed during induration of pure hematite compacts, strongly affected the disintegration at low temperature reduction as a result of changes in internal stress development and expansion of the material. 1) There have been many studies on the influence of pores and porosity on reduction, however, detailed information on the influence of pore diameter is only limited and the findings are often in disagreement with each other. For example, some studies show that a small pore diameter is beneficial for the reduction of sinter and pellets, 2,3) whereas other studies claim that large pores are beneficial instead.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Artificially Induced Porosity on Strength and Reduction Behavior of Hematite Compacts

Higuchi

Heerema

2005

ISIJ Int.

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With the objective to gain more fundamental understanding of the influence of pore structure on the lowtemperature reduction behavior of iron ore agglomerates, laboratory-scale induration experiments were performed using pure hematite compacts doped with naphthalene as a porosity-generating agent. The pore structure was thus controlled up to 60 % porosity and 1.4 mm pore diameter, and no mineralogical changes were observed in these ranges after induration. The cold strength of indurated compacts was higher with pores smaller than 0.125 mm in diameter, as well as with pores larger than 1 mm. Changes in the cold crushing behavior of indurated compacts are discussed based on matrix length and distribution theory. Reduction tests in CO-CO 2 -N 2 gas at temperatures in the range of 350-800°C revealed high strength after reduction of compacts with fine pores less than 0.125 mm in diameter. Reasons for this high strength were the isotropic stress distribution within the compacts, as well as lower expansion due to development of a complex reduction front.

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Section: Figsupporting

confidence: 88%

Section: Preparation Of Hematite Compactssupporting

confidence: 76%

Section: Figmentioning

confidence: 92%

Section: Reduction Testmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Artificially Induced Porosity on Strength and Reduction Behavior of Hematite Compacts

Higuchi

Heerema

2005

ISIJ Int.

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Effect of Firing Temperature and Reducing Gas Composition during Low-Temperature Reduction of Nanocrystalline Fe2O3

Bahgat

Khedr

Nasr

et al. 2007

Metall Mater Trans B

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Pure nanocrystalline hematite (40 to 100 nm) compacts were prepared and sintered at various temperatures (300°C to 600°C) and then reduced with 100 pct H 2 at 500°C. On the other hand, fired compacts at 500°C were reduced with a H 2 -Ar gas mixture containing different concentration of hydrogen (100, 75, 50, and 25 pct) at 500°C using thermogravimetric techniques. Nanocrystalline Fe 2 O 3 compacts were characterized before and after reduction with X-ray diffraction, scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and reflected light microscope. It was found that the fired compacts at 400°C to 600°C have relatively faster reaction behaviors compared to that at lower firing temperature 300°C. By decreasing the firing temperature to 300°C, partial sintering with grain growth was observed clearly during reduction. Also, it was found that the reduction rate increased with increasing hydrogen content in the reducing gas. Comparatively, grain growth and partial coalescence took place during reduction with 25 pct H 2 due to long reaction time.

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Effect of Microwave Treatment Upon Processing Oolitic High Phosphorus Iron Ore for Phosphorus Removal

Tang

Liu

Zhang

et al. 2014

Metall Mater Trans B

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Influence of sintering conditions on the reduction behaviour of pure hematite compacts

Cited by 31 publications

References 17 publications

Influence of Artificially Induced Porosity on Strength and Reduction Behavior of Hematite Compacts

Influence of Artificially Induced Porosity on Strength and Reduction Behavior of Hematite Compacts

Effect of Firing Temperature and Reducing Gas Composition during Low-Temperature Reduction of Nanocrystalline Fe2O3

Effect of Microwave Treatment Upon Processing Oolitic High Phosphorus Iron Ore for Phosphorus Removal

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