Reduction of FeO in smelting slags by solid carbon: Re-examination of the influence of the gas-carbon reaction

Story, Scott R.; Sarma, Bidyut Bikash; Fruehan, R. J.; Cramb, A. W.; Belton, G. R.

doi:10.1007/s11663-998-0152-5

Cited by 41 publications

(37 citation statements)

References 6 publications

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“…Reaction rate constants for all carbonaceous materials are quite similar and comparable to the rates quoted in literature for smelting slags. 6,7) These results are in an excellent agreement with the results of Davies et al 18) and Sugata et al,19) that the reaction rate for iron oxide reduction to be generally independent of the type of carbonaceous material. They have concluded that mass transfer in the slag phase is the most likely predominant rate-controlling step.…”

Section: Reduction Kineticssupporting

confidence: 90%

“…These reactions involve diffusion of iron oxide from the bulk slag to the interface, chemical reactions at the slag/gas interface, diffusion of CO 2 to the interfacial region and participation in chemical reactions in the gas-carbon and liquid-carbon interfacial region. 6) In the temperature range 1 300-1 500°C, Sarma et al 7) have investigated the reduction of FeO in smelting slags, containing less than 10 % FeO with basicity of 1, by a range of carbonaceous materials. They have reported a small increase in reaction rates when coke was used as a reductant as compared to graphite and char and have proposed a mixed control model for overall reaction kinetics.…”

Section: Introductionmentioning

confidence: 99%

“…For coke however, the considerably lower reactivity of coke towards CO 2 at high temperatures appears to cause this reaction to have a significant influence. 6,10) Coal-chars however show a high reactivity towards gasification. There are two stable condensed phases coexisting in each reaction, i.e., SiO 2 and C or C and SiC.…”

Section: Introductionmentioning

confidence: 99%

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Coal-char/Slag Interactions during Pulverised Coal Injection in a Blast Furnace: Reaction Kinetics and Wetting Investigations

Mehta

Sahajwalla

2003

ISIJ International

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Section: Reduction Kineticssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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Coal-char/Slag Interactions during Pulverised Coal Injection in a Blast Furnace: Reaction Kinetics and Wetting Investigations

Mehta

Sahajwalla

2003

ISIJ International

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“…17) The impact of carbon selection is reported to be greater at higher FeO contents, where slag phase mass transfer is more rapid. 19) In the present study a rather different approach has been taken, with examination focused on the microstructural evidence obtained from partly reacted materials. By using a small sessile slag drop on a carbon substrate the materials can be rapidly cooled from the reaction temperature and the microstructure present at the reaction temperature is preserved unchanged; the samples then can be examined using optical and electron microscope techniques at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Observations of the Reduction of FeO from Slag by Graphite, Coke and Coal Char

Teasdale

Hayes

2005

ISIJ Int.

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The reduction of FeO from iron-saturated FeO-CaO-Al 2 O 3 -SiO 2 slags by graphite, coke and coal char at 1 673 K has been investigated using a sessile drop technique. Metallographic analysis of samples quenched from the reaction temperature, and "in situ" observations of the reaction interface, reveal significant differences in the slag/carbon contact, and in the morphologies of the product iron and its composition; these differences were found to depend on the carbon type used in the reduction. In particular it has been shown that, in the case of graphite and coke, liquid Fe-C droplets were rapidly formed at the slag/C interface. Reactions of the slag with coal chars, in contrast, result predominantly in the formation of solid iron. These observations indicate that the reaction pathways, and hence reaction kinetics, are dependent on carbon type.

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“…Previous studies 23,24) have shown that a gas ferrying mechanism describes the reaction between solid carbon and iron oxide due to the fact that the CO gas produced in the initial reaction between carbon and slag gets transported through the gas phase and reacts with FeO in slag to produce CO 2 and metallic iron. This CO 2 gets ferried back to carbon, where gasification of CO 2 to CO takes place via Boudouard reaction as follows:…”

Section: Discussionmentioning

confidence: 99%

Carbon/Slag Interactions between Coke/Rubber Blends and EAF Slag at 1 550°C

et al. 2009

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Using the sessile drop approach, interfacial reactions taking place in the slag/carbon region were investigated at 1 550°C in a horizontal tube furnace under inert atmosphere (1 L/min Ar). In this study, waste rubber tyres were blended with metallurgical coke, already used as injectant in electric arc furnace (EAF) steelmaking, in different proportions. Off gas analyses and physicochemical properties of the slag have been evaluated and correlated with the carbon/slag interactions. The gaseous emissions from metallurgical coke showed lower concentrations in comparison to the emissions from the coke-rubber blends. With an increase of rubber in the blend, gaseous emissions were enhanced. Significant carbon/slag interactions occurred when coke/rubber blends were used, with associated iron oxide reductions within the slag phase. Higher gas entrapment in the slag was also observed when the rubber partially replaced the coke.High levels of gas generation leads to increased likelihood of convective transport of reactants and products from the carbonaceous material surface due to evolution of gases as a result of slag/carbon interactions. The oxides present in the ash partially dissolve the molten slag, modifying the slag composition. The results have been discussed and correlated with the hydrogen, ash and sulphur contents of the carbonaceous residues as well as with the dynamic changes in slag composition.This study highlights significant differences in the carbon/slag interactions of coke/rubber blends with EAF slag, compared to interaction of coke with the same slag.KEY WORDS: rubber; EAF steelmaking; carbon/slag interactions; volume ratio; microscopic investigations. 1513© 2009 ISIJ factor is dependent on the bubble size and lamellae stability. 8) On the other hand, viscosity and surface tension influences the movement of the bubbles in the gas dispersed liquid. Foaming was described by Kozakevitch 9) and more recently by Hara et al. 8) in terms of surface chemistry. They measured the foam life and foam height for binary and ternary systems composed of CaO-SiO 2 -FeO and correlated the foam height with the physicochemical properties of metallurgical slags.Foaming is a dynamic phenomenon involving one dimensional two-phase flow.10) With time foaming shows fluctuating behavior due to the changes occurring in the slag composition.11) To account for these dynamic conditions Morales et al. 12) attempted to quantify the foaming behavior by introducing a foaming index which is correlated to the changes in the slag volume and the rate of generated gas. Bikerman et al.13) first described a foaming index which had been empirically related to physical properties of the slag such as the surface tension (s), viscosity (h), and density (r) of the liquid slag and the size of the bubbles (d b ). This index has a unit of time and can be considered as the residence time of the bubbles in the foam. Foaming has been shown to improve with decreasing surface tension and increasing viscosity of slag, 14) although the magnitude of the ...

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Reduction of FeO in smelting slags by solid carbon: Re-examination of the influence of the gas-carbon reaction

Cited by 41 publications

References 6 publications

Coal-char/Slag Interactions during Pulverised Coal Injection in a Blast Furnace: Reaction Kinetics and Wetting Investigations

Coal-char/Slag Interactions during Pulverised Coal Injection in a Blast Furnace: Reaction Kinetics and Wetting Investigations

Observations of the Reduction of FeO from Slag by Graphite, Coke and Coal Char

Carbon/Slag Interactions between Coke/Rubber Blends and EAF Slag at 1 550°C

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