Production of direct reduced iron by a sheet material inserting metallization method

Kamijo, Chikashi; Hoshi, Masahiko; Kawaguchi, Takazo; Yamaoka, Hideyuki; Kamei, Yasuo

doi:10.2355/isijinternational.41.suppl_s13

Cited by 13 publications

(9 citation statements)

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“…Midrex and HyL II processes. Recently, various types of the new processes [1][2][3][4][5] have been developed to produce reduced iron by heating mixtures of iron ore with carbonaceous materials such as coal, coke and coal char for a short time, e.g. about 10 min.…”

Section: Introductionmentioning

confidence: 99%

Carburized Carbon Content of Reduced Iron and Direct Carburization in Carbon Composite Iron Ore Pellets Heated at Elevated Temperature

Iguchi

Endo

2004

ISIJ International

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Section: Introductionmentioning

confidence: 99%

Carburized Carbon Content of Reduced Iron and Direct Carburization in Carbon Composite Iron Ore Pellets Heated at Elevated Temperature

Iguchi

Endo

2004

ISIJ International

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“…4) Reduction degree reached 95 % in about 10 min during the briquette descending to the bottom of heat reserve zone of 1 373 K. Therefore, Utilization of the carbon composite iron ore hot briquette was promising to decrease the fuel rate and the discharging amount of CO 2 , and elongate the furnace life. A Sheet Material Inserting Metallization Method (SMIMET), 5) in which a sheet of material consisting of the coal and iron ore mixture was inserted in a rotary hearth furnace, was developed for producing DRI. Over 90 % metallization was achieved with the coal ratio up to 20 %.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Carbothermic Reduction of Hematite in Hematite–Carbon Composite Pellets

2007

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Isothermal reduction experiments are carried out to study carbothermic reduction of hematite in hematite-graphite composite pellets. The carbothermic reduction is dominated by the direct reduction at the initial stage of reduction, and it is determined by the indirect reduction together with the carbon solution loss reaction when the CO partial pressure exceeds a certain value, which is dependent on the temperature. The reduction is greatly promoted due to the increment of the contact area between the hematite and graphite particles and enhancement of heat conduction in the hematite-graphite composite pellets.The indirect reduction together with the carbon solution loss reaction is markedly activated with increasing temperature. At a moderate carrier gas flow rate, the carbothermic reduction rate reaches the highest value. The reduction can also be effectively improved with decreasing the graphite particle size.The relationship of reduction products, heating temperature and holding time has been obtained from the XRD analysis results at the different stages for various temperatures under the present experimental conditions. The SEM observation indicates that the indirect reduction together with the carbon solution loss reaction should dominate the carbothermic reduction of hematite at the later stage of reduction.

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“…As described above, the only possibility remained would be the mixed control of the reduction of wustite with carburized carbon by the reaction (9) and the gaseous reduction of wustite with CO by the reaction (3), and/or the gasification reaction of carbon with CO 2 by the reaction (4 Fig. 10 might be considered as the rate constant of the mixed control of the carbon diffusion in the shell of metallic iron and the chemical reduction at the interface between the wustite core and the metallic iron shell.…”

Section: Discussion Of the Chemical Reaction Contributionmentioning

confidence: 99%

“…New ironmaking processes [1][2][3][4][5] by heating carbonaceous material composite iron ore pellet or dust pellet at elevated temperatures have been very actively developed for producing alternative iron source. And a few of them have been commercialized 1) for recycling dust from blast furnace and BOF.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of the Reactions in Carbon Composite Iron Ore Pellets under Various Pressures from Vacuum to 0.1 MPa

Iguchi

Yokomoto

2004

ISIJ International

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In order to clarify the mechanism of the complicated reactions in carbon composite iron ore pellets, carbon composite iron ore pellets of 3.5 mm in diameter were heated in the five conditions; (a) in vacuum, (b) the closed system after evacuation, (c)-(e) the closed system of initially 0.001, 0.01 and 0.1 MPa nitrogen after evacuation. The weight loss was measured in the five conditions (a)-(e) by gravimetric method. The individual curves were composed of the fast first step and the relatively slow second step. The first step was analyzed as zero order reaction and the rate constant, k s1 , was obtained. The second step was analyzed by applying the rate equations for the diffusion control in the product shell of the shrinking core model for spherical iron ore particles. The applicability of the equations was pretty good. The rate constant, k s2 , was a function of the total pressure p t and temperature T, which was expressed as k s2 ϭ A(p t )exp[ϪB(p t )/ T]. The apparent activation energy was ranged from 195 to 280 kJ/mol, which is near the activation energy for the diffusivity of carbon in g-iron. The rate of the fractional weight loss seems to be in a mixed control regime of the direct reduction, indirect reduction and indirect gasification. The transition fractional weight loss from the first step to the second step was evaluated in the conditions (a) and (b). It decreased with increasing the total pressure until it reached nearly zero in the conditions (c), (d) and (e), where Eq. (11) was applicable in the whole range of F t . KEY WORDS; iron ore; carbon; composite pellet; total pressure; carburization; direct reduction; indirect reduction: gasification; diffusion control; rate equation; transition.graphite are very poor, pretty good and excellent, respectively. Furthermore, as the carbon content of reduced iron approaches the solidus line of Fe-C binary phase diagram, the reduced iron particles are very easily coalesced and the particles of the coal char and coke are very easily liberated from the reduced iron particles. Thus, the coalescence of reduced iron particles seems to limit the carbon content up to the solidus line. They also have reported very important facts that the carbon content of reduced iron from composite pellets depends on the size range of carbonaceous materials.First objective of this study is to clarify the relationship between the rate of direct carburization reaction, Cϭ [C], and the rate of gasification reaction, CϩCO 2 ϭ2CO. For the purpose, the rate of reactions in the composite pellets was measured gravimetrically in a closed system of varied total pressures of an initially pure nitrogen atmosphere. The influence of the kind of carbonaceous materials on the rate in the composite pellets was also investigated.Second objective of this study is to quantitatively discuss the influence of the total pressure in the closed system on the overall rate of the reactions. For the purpose, the fractional weight loss curves were analyzed and the relationship between the overall rate and the t...

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Production of direct reduced iron by a sheet material inserting metallization method

Cited by 13 publications

References 0 publications

Carburized Carbon Content of Reduced Iron and Direct Carburization in Carbon Composite Iron Ore Pellets Heated at Elevated Temperature

Carburized Carbon Content of Reduced Iron and Direct Carburization in Carbon Composite Iron Ore Pellets Heated at Elevated Temperature

Mechanism of Carbothermic Reduction of Hematite in Hematite–Carbon Composite Pellets

Kinetics of the Reactions in Carbon Composite Iron Ore Pellets under Various Pressures from Vacuum to 0.1 MPa

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