Formation of Partially Reduced Iron by Heating Iron Ore-coal Char Composite Pellet in Oxygen Bearing Gas Flow: Reactions, Swelling Rate and Crushing Strength

Iguchi, Yoshiaki; Kamei, Ryo

doi:10.2355/tetsutohagane1955.85.6_439

Cited by 8 publications

(2 citation statements)

References 13 publications

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“…At longer heating times, a continuous metallic network becomes prominent and this may also impart strength to the cooled briquette. These results broadly agree with the work of Tsujihata [30], Gupta and Gautam [31], and Iguchi and Kamei [32]. Tsujihata attributed the mechanical strength of iron oxide agglomerates to the bonding between hematite crystals which are formed either by mutual diffusion or by slag generation.…”

Section: Effect Of Heating Timesupporting

confidence: 82%

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The Strength and Density of Green and Reduced Briquettes Made with Iron Ore and Charcoal

Somerville

2016

J. Sustain. Metall.

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Composite briquettes or pellets consisting of iron ore, carbon, and a binder are a source of direct reduced iron (DRI). In the handling of green and reduced briquettes, high strength is important to minimize briquette breakdown. The use of charcoal as a source of carbon, rather than coal provides a way of introducing renewable carbon into the ironmaking process. Composite briquettes were made with Australian hematite iron ore, low volatile charcoal and 2 % starch as a binder. The carbon-to-iron mass ratio was varied between 0.18 and 0.26. The green briquettes were heated to either 1300 or 1350°C for times varying from 3 to 15 min. After heating, the briquettes were tested for compressive strength, density, and the degree of iron metallization. The aim of the work was to determine the key strength forming features of the briquettes during heating and reduction. Dried green briquettes, made with a starch binder, were found to be very strong and required a force of at least 3800 N to yield under compression. After heating for 3 min, the briquettes lost strength rapidly before regaining strength at longer heating times of 10 and 15 min. Increasing the C/Fe ratio in the briquette mix decreased the strength and density, and increased the iron metallization of the heated briquettes. Briquette strength also increased with increasing time from 10 to 15 min and heating temperature from 1300 to 1350°C. These observations can be explained in terms of the distance between iron oxide particles in the briquette mix. At low C/Fe ratios, iron oxide particles will be relatively close together which facilitates the development of a connected slag network which acts as a binder and increases briquette strength.

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Section: Effect Of Heating Timesupporting

confidence: 82%

“…Iguchi and Kamei [32] investigated the swelling behavior and crushing strength of individual composite pellets during reduction in oxygen-containing nitrogen atmospheres. As reduction continued, pellet strength decreased to a minimum after about 2 min.…”

Section: Effect Of Heating Timementioning

confidence: 99%

The Strength and Density of Green and Reduced Briquettes Made with Iron Ore and Charcoal

Somerville

2016

J. Sustain. Metall.

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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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Reaction Model for the Formation of Partially Reduced Iron by Heating Iron Ore-coal Char Composite Pellet in Oxygen Bearing Gas Flow

Iguchi

1999

Tetsu-to-Hagane

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Formation of Partially Reduced Iron by Heating Iron Ore-coal Char Composite Pellet in Oxygen Bearing Gas Flow: Reactions, Swelling Rate and Crushing Strength

Cited by 8 publications

References 13 publications

The Strength and Density of Green and Reduced Briquettes Made with Iron Ore and Charcoal

The Strength and Density of Green and Reduced Briquettes Made with Iron Ore and Charcoal

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

Reaction Model for the Formation of Partially Reduced Iron by Heating Iron Ore-coal Char Composite Pellet in Oxygen Bearing Gas Flow

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