Rate of reduction of ore-carbon composites: Part I. Determination of intrinsic rate constants

Fortini, Otavio; Fruehan, R. J.

doi:10.1007/s11663-005-0088-y

Cited by 31 publications

(37 citation statements)

References 22 publications

(45 reference statements)

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“…It varies from 228 to 272 kJ/mol and is within the large range of values reported in literature 11,12,14,17,19,31,35,40) as characteristic for the Boudouard reaction.…”

Section: Gasification Rate Of Carbonaceous Reductantssupporting

confidence: 82%

“…It ranges from 370 to 280 kJ/mol and corresponds well to the values reported as characteristic for carbon gasification by CO2 under a purely chemical control. 14,17,31,35,40) These values are even slightly higher than those obtained from the gasification tests with pure carbon dioxide (Fig. 5).…”

Section: Limiting Reaction Stepmentioning

confidence: 58%

“…The activation energy of the fine iron oxide reduction by CO reported by Moon and Sahajwalla varie from 36 to 75 kJ/mol. 14) Fortini and Fruehan 17) estimate the activation energy of wustite reduction by CO as high as 168 kJ/mol which is a bit higher then upper limit of the 60-150 kJ/mol range given by Coetze et al 19) In our previous work 3) on the reduction of the scale by CO, the activation energy of reaction rate constant was found to be about 80 kJ/mol. It was also observed that the gaseous reduction of scale occurs according to the shrinking core model under chemical control, i.e.…”

Section: Limiting Reaction Stepmentioning

confidence: 72%

“…[11][12][13][14][15] Others propose a mixed control regime with the influence of both reactions (gasification and reduction)or a mixed gasification and heat transfer control regime. [16][17][18][19][20] Pure heat transfer control has also been postulated and modelled. 21) These findings are based on different experimental approaches such as the continuous weight loss of composite sample, the reactor output gas analysis and the temperature profiles inside the composite piece.…”

Section: Introductionmentioning

confidence: 99%

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Carbon Gasification in Self-reducing Mixtures

et al. 2014

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Self-reduction experiments of mill scale with four potential carbonaceous reductants (charcoal, coal char, blast furnace coke and petroleum coke) were carried out by thermogravimetry (TG) in order to choose one allowing the highest reduction rate and overall conversion. The fastest rate of self-reduction was measured for the charcoal and the slowest for the petroleum coke. The Friedman method of kinetics data analysis was used to calculate apparent activation energy at different conversion rates. Based on these values it can be concluded that the Boudouard reaction controls the rate of self-reduction with charcoal up to about 60% of conversion and even more for others reductants. It has also been demonstrated that the morphology of the iron produced strongly depends on reactivity of carbonaceous reductant.

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“…It varies from 228 to 272 kJ/mol and is within the large range of values reported in literature 11,12,14,17,19,31,35,40) as characteristic for the Boudouard reaction.…”

Section: Gasification Rate Of Carbonaceous Reductantssupporting

confidence: 82%

Section: Limiting Reaction Stepmentioning

confidence: 58%

Section: Limiting Reaction Stepmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

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Carbon Gasification in Self-reducing Mixtures

et al. 2014

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“…Fortini and Fruehan [16] and Halder and Fruehan [17] reported on the reduction of composite pellets made with charcoal. They showed that the reduction rate of composite pellets made with charcoal is higher than that of comparable pellets made using coal.…”

Section: Introductionmentioning

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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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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