Iron Carbide Formation with CO Gas and CO-H&lt;SUB&gt;2&lt;/SUB&gt; Gas Mixture under Low Sulfur Potential Using the Two-step Process of Metallization and Carbidization

Sawai, Satoshi; Iguchi, Yoshiaki; Hayashi, Shoji

doi:10.2355/tetsutohagane1955.84.12_844

Cited by 15 publications

(16 citation statements)

References 10 publications

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“…(5) In heating c-and q-iron carbides in air, they are not re-oxidized after being decomposed to metallic iron and free carbon, but they are directly re-oxidized to iron oxides plus carbon dioxide by the following direct reactions of the carbides with oxygen in the atmosphere; 3Fe 5 …”

Section: Discussionmentioning

confidence: 99%

“…According to the present authors, [2][3][4][5][6][7][8][9] sulfur adsorbed on the pore surface of reduced iron and iron carbides is capable to suppress decomposition of iron carbides and carbon deposition from the carburizing gas. The chemical compositions and the production conditions of the iron carbides used in this study are listed in Tables 2 and 3, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…on iron carbide production and its kinetics have been studied in several previous studies [1][2][3][4][5][6][7][8][9][10] involving the present authors' for the last decade. The iron carbides, q-iron carbide (cementite, Fe 3 C) and c-iron carbide (super iron carbide, Fe 5 C 2 ), are thermodynamically meta-stable.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of Decomposition and Re-oxidation Resistance of .THETA.- and .CHI.-Iron Carbides at Elevated Temperatures and Influence of Their Formation Conditions

2004

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The rate of decomposition of q-iron carbide (Fe 3 C) and c -iron carbide (Fe 5 C 2 ), which were produced by carburizing reduced iron from a hematite ore and a limonite ore with 80%CO-H 2 -H 2 S mixture of a S ϭ0.5, was determined from their compositional change. Their decomposition starts from about 873 K with Fe 5 C 2 and about 973 K with Fe 3 C. To mass fraction variation curves of q-and c -iron carbide, the integrated rate equation for the first order reaction was applied to obtain the rate constant, k. The value of k for Fe 5 C 2 is much greater than that for Fe 3 C. Fe 5 C 2 firstly decomposes to Fe 3 C plus carbon and secondly the formed Fe 3 C decomposes to metallic iron plus carbon. Microscopically, the metallic iron grows as if the flat interface between Fe 3 C and metallic iron propagates through the grain of Fe 3 C. And the iron carbide and formed metallic iron are always in front of pore. Therefore, the gas molecules in the atmosphere can react with the carbide, metallic iron and carbon throughout the reaction. The re-oxidation in dry air accelerated by the exothermic reaction for both iron carbides begins from about 623 K. The reason why the re-oxidation starts at the lower temperature than the decomposition does is direct oxidation of Fe 5 C 2 and Fe 3 C to iron oxides and CO 2 before their decomposition. The re-oxidation starting temperature is raised by the increase of the temperature of reduction and carburization, but the improvement is not very large.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Kinetics of Decomposition and Re-oxidation Resistance of .THETA.- and .CHI.-Iron Carbides at Elevated Temperatures and Influence of Their Formation Conditions

2004

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“…In our previous studies, [7][8][9]13) the rate of carbide formation from completely reduced iron ore in H 2 -H 2 S mixtures was accurately measured in CO-H 2 -H 2 S mixtures by gravimetric technique at 973 K. But, the measurements of the carbide formation rate were made only under total pressures 0.1013 MPa (1 atm) or less.…”

Section: Introductionmentioning

confidence: 99%

“…1) Since then, fundamental studies [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] concerning iron carbide production from iron ore have been actively performed. Since iron carbides are thermodynamically meta-stable, however, it is not formed until the carbon activity of the reaction gas is increased beyond unity.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of Cementite Formation from Reduced Iron in CO-H2-H2S Mixtures under Pressurized Conditions

2004

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Modelling the complex interactions between reformer and reduction furnace in a midrex‐based iron plant

2011

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This article studies the complex mass and energy interactions between the reformer and the reduction furnace in an iron plant based on Midrex technology. The methodology consists in the development of rigorous first principle models for the reformer and the reduction furnace, in addition to models for auxiliary units such as heat recuperator, scrubber and compressor. In this regard, a one-dimensional heterogeneous model for the catalyst tubes which takes into account the intraparticle mass transfer resistance was developed for the reformer unit, while the furnace was modelled with bottom-firing configuration. As for the reduction furnace, the mathematical model was based on the concept of shrinking core model. The furnace was modelled as a moving bed reactor taking into consideration the effects of water gas shift reaction, steam reforming of methane and carburisation reactions. The model was first validated using data from a local iron/steel plant and was then simulated to determine key output variables such as bustle gas temperature, degree of metalisation, carbon content, ratio of hydrogen to carbon monoxide, reductants to oxidants ratio and required compression energy. The effects of key input parameters on the performance of the plant were studied. These parameters included recycle ratio, scrubber exit temperature, injected oxygen flow rate, flow rate of natural gas after reformer, to transition zone, to reformer and to cooling zone. Useful profiles were compiled to illustrate the results of the sensitivity analysis. These results may serve as guidelines for a further optimisation of the plant.

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Iron Carbide Formation with CO Gas and CO-H<SUB>2</SUB> Gas Mixture under Low Sulfur Potential Using the Two-step Process of Metallization and Carbidization

Cited by 15 publications

References 10 publications

Kinetics of Decomposition and Re-oxidation Resistance of .THETA.- and .CHI.-Iron Carbides at Elevated Temperatures and Influence of Their Formation Conditions

Kinetics of Decomposition and Re-oxidation Resistance of .THETA.- and .CHI.-Iron Carbides at Elevated Temperatures and Influence of Their Formation Conditions

Kinetics of Cementite Formation from Reduced Iron in CO-H2-H2S Mixtures under Pressurized Conditions

Modelling the complex interactions between reformer and reduction furnace in a midrex‐based iron plant

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