Evaluation of Sinter Quality for Improvement in Gas Permeability of Blast Furnace

Takeuchi, Naoyuki; Iwami, Yuji; Higuchi, Takahide; Nushiro, Koichi; Oyama, Nobuyuki; Sato, Michitaka

doi:10.2355/tetsutohagane.99.448

Cited by 6 publications

(3 citation statements)

References 15 publications

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“…In the case of addition of small amount of H2, the RDI value increased, whereas more increase in the H 2 concentration to 12% led to a decrease of RDI values. In contrast, Takeuchi et al 12) pointed out that influence of H 2 gas on reduction disintegration behavior is slightly difference from Murakami's conclusion. According to his report, the RDI value increased due to the increase in the H 2 concentration, but the influence of the H 2 concentration on the RDI valuye decreases in the range of the H 2 concentration of 3.8 to 6.8 vol%.…”

Section: Introductionmentioning

confidence: 77%

“…[4][5][6][7][8][9][10][11][12][13] Although large numbers of studies of reduction disintegration of sinter with CO reduction were reported, [14][15][16][17] there is a few reports about reduction disintegration behavior associated with the H 2 reduction. 12,[18][19][20] The second problem is a decrease of Fe contents and an increase of SiO 2 contents of iron ore. [20][21][22] This causes increase of slag volume of sinter, resulting in increasing in the reducing agent ratio of the BF. 23) In contrast, Fe contents of pellet is higher as compared with the fine ore and stable, since their raw material is iron ore concentrates produced by a beneficiation process at the mining site.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Reducing Gas Composition on Disintegration Behavior of Iron Ore Agglomerates

et al. 2017

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H 2 injection through the shaft into blast furnace (BF) is a potential option for a further reduction of CO 2 emission from BF. H 2 promotes reduction reaction of burden materials, but its influence on their reduction disintegration behavior remains unknown in detail. This study has investigated the influence on the iron ore sinter, self-fluxed and acid pellets and specified essential factors governing the reduction disintegration behavior.Mass ratios of particles below 3 mm in size were measured as an index for reduction disintegration (RDI) after the reduction of burden samples applying the gas mixtures of CO-H 2 -CO 2 -N 2 at 823 K. The reduced samples were observed by an optical-microscope and an electron probe micro-analyzer for evaluation of reaction mode. Further, using the measurement results, stress, strain energy and crack area generated during reduction were calculated and formation mechanism of cracks was examined.RDI value of self-fluxed pellet increased under higher H 2 condition (40%N 2 -20%H 2 -10%CO-30%CO 2 ) and reached to 26 mass%. Such an increase was larger than expected from the standard RDI measure without H 2 . Sample observation revealed a fact that reaction mode governed RDI value, that is, disintegration worsened under the reduction with non-topochemical mode. The fact was explained by the calculation as an influence of crack formation and propagation. In a case of reduction with topochemical reaction, cracks generated in a concentric fashion. Meanwhile, reduction with non-topochemical reaction tended to generate cracks in radial direction, which causes pellet chipping and further degradation. Calculated crack areas showed good correlation with RDI values. The Crack area of non-toochemical reaction was more than double than that of topochemical reaction. This result indicates that disintegration does not much progress when crack area is less than the certain limit value, but it proceeds drastically when it exceeded the limit value.

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Section: Introductionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Influence of Reducing Gas Composition on Disintegration Behavior of Iron Ore Agglomerates

et al. 2017

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“…The permeability of the cohesive zone was reduced at low-cokerate operation of the traditional blast furnace, which resulted in the production efficiency of the blast furnace being reduced. Many research studies have proved that thinness and low location of the cohesive zone can improve permeability which promoted low-coke-rate operation of the blast furnace [1][2][3][4]. Therefore, low position and thin cohesive zone are desirable characteristics in a blast furnace.…”

Section: Introductionmentioning

confidence: 99%

Effect of reduction degree on cohesive zone and permeability of mixed burden

Pan

Zuo

Wang

et al. 2018

Ironmaking & Steelmaking

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Low-carbon operation, especially low-coke-rate operation, is very important for low CO 2 emission in blast furnace ironmaking. Maintaining the permeability of the cohesive zone is required under lowcoke operation of the blast furnace. The cohesive zone and permeability are determined by the softening and melting properties of the burden. In this study, the effect of reduction degree on the cohesive zone and permeability was investigated by using different reduction degree mixed burdens. The experimental results showed that as the reduction degree increased, the thickness of the cohesive zone decreased, the position of the cohesive zone moved downward, and the permeability of the mixed burden layer was significantly improved. The weight of the droplet and the carbon content of iron in the droplet decreased with the increase of reduction degree. The results of experiments provided an important guidance for improving the permeability of the mixed burden layer in low-coke operation of the blast furnace.

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Quantitative Evaluation of Reaction Mode and Reduction Disintegration Behavior of Iron Ore Agglomerates during Low Temperature Reduction

et al. 2018

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The utilization of H 2 in the ironmaking process is a potential option for a further reduction of CO 2 emission from the blast furnace (BF). H 2 promotes the reduction reaction of burden materials, but its influence on their reduction disintegration behavior remains unknown in detail. This study investigates its influence on the specified essential factors governing the reduction disintegration behavior of the iron ore agglomerates, i.e., iron ore sinters and pellets. Reduction disintegration index (RDI) values were measured after the reduction of the agglomerate samples using the gas mixtures of CO-H 2-CO 2-N 2. The mineral textures of reduced samples were observed using an optical-microscope and an electron probe micro-analyzer for the evaluation of reaction modes. Further, Thiele modulus (ϕ), which is considered as the index of reaction modes during reduction, was calculated using the measurement results. The calculated ϕ showed reasonable correlation with RMI values, which is one index of the reaction mode evaluated by an elemental analysis using EPMA. Disintegration does not make much progress when ϕ is larger than a certain limit value, whereas it proceeds significantly when ϕ is less than that value.

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Evaluation of Sinter Quality for Improvement in Gas Permeability of Blast Furnace

Cited by 6 publications

References 15 publications

Influence of Reducing Gas Composition on Disintegration Behavior of Iron Ore Agglomerates

Influence of Reducing Gas Composition on Disintegration Behavior of Iron Ore Agglomerates

Effect of reduction degree on cohesive zone and permeability of mixed burden

Quantitative Evaluation of Reaction Mode and Reduction Disintegration Behavior of Iron Ore Agglomerates during Low Temperature Reduction

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