Kinetic Analysis on the Rate of Stepwise Reduction of a Single Sinter with CO-CO&lt;SUB&gt;2&lt;/SUB&gt;-N&lt;SUB&gt;2&lt;/SUB&gt; Gas Mixture

Usui, Tateo; Ohmi, Munekazu; Hirashima, Shigeaki; Kitagawa, Nobukazu

doi:10.2355/tetsutohagane1955.73.15_1956

Cited by 13 publications

(13 citation statements)

References 9 publications

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“…It had been reported that there was no obvious difference in the chemical reaction rate of the reduction from hematite to magnetite in a single particle ore between CO/CO 2 and H 2 /H 2 O atmosphere, 19) but the interdiffusion coefficient De of H 2 /H 2 O gas was much higher than that of CO/CO 2 . 20) In addition, Murakami 8) indicated that the reduction of hematite by H 2 mainly proceeded along the cracks in the iron ore samples. Figure 9 shows the SEM photos of lump ore samples under different reduction temperatures.…”

Section: Comparison Of Co and H 2 Reduction Behaviorsmentioning

confidence: 99%

Reduction Disintegration Behavior of Lump Ore in COREX Shaft Furnace

Liu

2015

ISIJ International

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The heavy disintegration of lump ores would produce plenty of small particles in COREX shaft furnace, which would decrease the gas permeability and productivity of the shaft furnace, thus the proportion of lump ores in the burden of COREX shaft furnace is limited to a low level. In this work, the reduction disintegration behavior of lump ore samples was studied by simulating the reduction process of COREX shaft furnace. The influence of temperature, reduction time and gas composition on the reduction disintegration index (RDI -6.3 ) of lump ore samples were also evaluated. The results showed that the disintegration behavior of lump ores in COREX shaft furnace could be generally divided into three steps and the disintegration mainly occurred in the second step, which was in the temperature zone from 450°C to 650°C with low reduction degree. Meanwhile, the RDI -6.3 of lump ore samples all presented the tendency of "inverted V-shape" in the temperature range from 450°C to 650°C under different reduction time. However, the mutual promotion of reduction reaction and carbon deposition reaction (CDR) was attributed to the main reason for the heavy disintegration of lump ores in COREX shaft furnace. In addition, increasing H 2 concentration in reducing gas and rapid reducing at higher temperature would decrease the disintegration degree of lump ores in COREX shaft furnace.

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Section: Comparison Of Co and H 2 Reduction Behaviorsmentioning

confidence: 99%

Reduction Disintegration Behavior of Lump Ore in COREX Shaft Furnace

Liu

2015

ISIJ International

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“…9, when the gaseous reductions with H 2 or CO were conducted at 1 059 and 1 089 K. The dotted and dashed lines in Fig. 9 are described from each equilibrium data 14,15,18) on the basis of Rist model 10,11) under the assumption of the infinite reaction rate. In Fig.9, the initial outgoing gas compositions, which show the constant values, are considered to be the equilibrium values, and the equilibrium constants can be calculated from the following Table is uncertain, it seems that the temperature, at which both of H 2 and CO single reduction equilibria are equal, is calculated higher in the use of JANAF Table, because the value for the equilibrium constant of the H 2 reduction is lower, in particular.…”

Section: Reduction Equilibrium Of Feo 105 With H 2 or Comentioning

confidence: 99%

“…However, since the disagreement was found in the thermodynamic data on the reduction equilibrium, the examination was firstly carried out on the temperature, at which the reduction equilibrium with H 2 equals that with CO. The thermodynamic data on the gaseous reduction of FeO 1.05 with H 2 and CO are summarized by Ohmi and Usui, 14,15) and the following equations for the equilibrium constants are proposed on the basis of the data by Elliott et al 16) and Darken et al,17) Fig. 8.…”

Section: Reduction Equilibrium Of Feo 105 With H 2 or Comentioning

confidence: 99%

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Effect of Water-Gas Shift Reaction on Reduction of Iron Oxide Powder Packed Bed with H2-CO Mixtures

2003

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Although the hydrogen reduction is thermally more disadvantageous than the CO reduction, it is advantageous that the reduction rate with H 2 is much larger than that with CO. In order to examine the effective use of hydrogen, the reduction of FeO 1.05 powder packed bed with H 2 -CO mixture was conducted, and the results were analyzed by a proposed model. The temperature, at which the reduction equilibria of FeO 1.05 with H 2 and CO equal, is determined to be 1 093 K from the present results. The apparent rate constants are determined to be 33, 8.6 and 15 for the reduction of FeO 1.05 with H 2 , CO and H 2 -CO mixture (V -H 2 : V -CO ϭ1 : 1), respectively. In the proposed model, when the water-gas shift reaction is taken into account, the additivity is established on the dependence of the rate constant of the reaction on the gas composition. When the water-gas shift reaction is not taken into account, the rate constant deviates negatively from the additivity. The apparent rate constants of the reduction determined in the present study take the middle values, and the contribution of the water-gas shift reaction is estimated to be 3 % against its equilibrium. In reducing FeO 1.05 with CO, the time when the sample is perfectly reduced is shortened by adding a small amount of H 2 , and the rate enhancement effect of H 2 on the gaseous reduction remarkably appears at 1 093 K. The effect originates in the proceeding of the water-gas shift reaction.

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“…The equilibrium constant for the water-gas-shift reaction at each reduction stage is calculated by combining Eqs. (2) and (3) with the equilibrium constants for the reduction reactions of an iron oxide with CO, 17) respectively, and is represented as follows: The equilibrium constants for the reduction reactions of CF with H 2 can be derived by combining Eqs. (7) and (8) with Eqs.…”

Section: Application Of Rist Model For Fixed Bed To Powdered Iron Orementioning

confidence: 99%

Gaseous Reduction Behavior of Powdered Iron Ore Sinter and Analysis on the Basis of Rist Model for Fixed Bed.

2002

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Kinetic Analysis on the Rate of Stepwise Reduction of a Single Sinter with CO-CO<SUB>2</SUB>-N<SUB>2</SUB> Gas Mixture

Cited by 13 publications

References 9 publications

Reduction Disintegration Behavior of Lump Ore in COREX Shaft Furnace

Reduction Disintegration Behavior of Lump Ore in COREX Shaft Furnace

Effect of Water-Gas Shift Reaction on Reduction of Iron Oxide Powder Packed Bed with H2-CO Mixtures

Gaseous Reduction Behavior of Powdered Iron Ore Sinter and Analysis on the Basis of Rist Model for Fixed Bed.

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