Kinetics of Decaburization of Low Carbon Liquid Iron under Reduced Pressures

Harashima, Kazuumi; Mizoguchi, Shozo; Kajioka, Hiroyuki

doi:10.2355/tetsutohagane1955.74.3_449

Cited by 11 publications

(10 citation statements)

References 2 publications

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“…Harashimaet al 4,7) reported that the decarburization rate decreases with the increase of sulphur content in the carbon content range of 10 to 200 ppm. Figure (d=0,15m, T=1 873 K.…”

Section: Effect Of [S]mentioning

confidence: 99%

“…lOppm; closed triangular symbols represent experhnent with argon blown at a flow rate of 4.0 x 10~4 (Nm3/s)).…”

Section: Effect Of [S]mentioning

confidence: 99%

“…There are, however, very few studies of the decarburization kinetics of ultra-low carbon steel under reduced pressure. Harashimaet al 4) havestudied the decarburization reaction in the induction furnace of 12 kg iron melt under reduced pressure. The carbon concentration decreased from 600 ppm to less 391 than lOppm.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, it is concluded that the decarburization rate is controlled by the mass transfer of carbon in liquid iron. (4) The fact that the decarburization rate at a carbon content of more than 10ppm is affected by the total pressure of the chamberhas been explained by the change in interfacial area of the reaction between the gas and liquid phases resulting from CO boiling in the bulk melt. (5) The decrease in the decarburization rate in the ultra-low carbon concentfation range in RH is also caused by the decrease in interfacia[ area of the reaction between the gas and liquid phases.…”

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Decarburization Reaction in Ultra-low Carbon Iron Melt under Reduced Pressure.

et al. 1993

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The kinetics of the decarburization reaction with dissolved oxygen in a liquid iron in the ultra-low carbon concenttation range under reduced pressure have been studied, using an induction furnace with a 20kg melt, The results obtained are as follows:(1 ) The decarburization reaction proceeds to less than 5ppm of carbon, and the decarburization rate constant, K, decreases as the carbon content decreases. (2) As the pressure in the chamberdecreases, the decarburization rate increases with a carbon content of more than 10 ppm. On the other hand, the dependencyof decarburization rate on the pressure in the chamber is small, with less than 10ppm of carbon. The influence of the sulphur content on the decarburization rate is small with a carbon content of more than IOppm. The decarburization rates are not affected by the mass transfer of CO in the gas phase under experimental conditions. Thus, it is concluded that the decarburization rate is controlled by the mass transfer of carbon in liquid iron. (4) The fact that the decarburization rate at a carbon content of more than 10ppm is affected by the total pressure of the chamberhas been explained by the change in interfacial area of the reaction between the gas and liquid phases resulting from CO boiling in the bulk melt. (5) The decrease in the decarburization rate in the ultra-low carbon concentfation range in RH is also caused by the decrease in interfacia[ area of the reaction between the gas and liquid phases.KEY WORDS: kinetics; decarburization; molten iron; ultra-low carbon steel; RH degassing. Metal samples were taken by quartz tubes for analysis of [C] and [O]. Other compositions ([Si], [Mn], [P] and [S]) were analyzed and were found to be constant during experiments. The analytical method of carbon was combustion-infrared absorptiometry by electro resistance furnace. Type EMIA-U511 was used for this analysis. Samples were always cleaned by electropolishing before the analysis. Sucrose (C12H22011) was used as a standard reagent. In this paper, taking into account the accuracy of analysis of carbon, the decarburization reaction with a carbon content of more than 5 ppm will be discussed.Other experimental conditions are shown in Table 1. In some experiments, Ar gas was blown onto the melt surface. In other experiment. Ar gas bubbling i•nto the melt was performed. 1O ppm).of the melt was observed at all the surface of the melt, as shown in Fig. 2a). When carbon content decreased by 20~~O ppm, the evolution of CO bubbles was observed only at the interface between the crucible and the melt (Fig. 2b)). When carbon content decreased by less than lOppm (approximately lOmin after the start), the evolution of CO bubbles was not observed and hence, the surface of the melt became quiet (Fig. 2c)) . Figure 3 shows the typical changes in [C] and [O] (Fig. 2b)). At [C]

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“…Harashimaet al 4,7) reported that the decarburization rate decreases with the increase of sulphur content in the carbon content range of 10 to 200 ppm. Figure (d=0,15m, T=1 873 K.…”

Section: Effect Of [S]mentioning

confidence: 99%

“…lOppm; closed triangular symbols represent experhnent with argon blown at a flow rate of 4.0 x 10~4 (Nm3/s)).…”

Section: Effect Of [S]mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Decarburization Reaction in Ultra-low Carbon Iron Melt under Reduced Pressure.

et al. 1993

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“…16) In the Higbie's model, the mass transport coefficient for a rising bubble in a liquid can be expressed using the following equation. (15) where, D C is the diffusion coefficient of dissolved carbon in the melt (3.0ϫ10 Ϫ8 m 2 /s) 17) and t e is the contact time (s). In the case of a rising bubble in a liquid, the contact time between the bubble and a fluid, t e (s) is estimated using the following equation.…”

Section: )mentioning

confidence: 99%

A New Numerical Model for Predicting Carbon Concentration during RH Degassing Treatment

Park

2003

ISIJ International

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A new decarburization model for the RH system was constructed to calculate the decarburization reaction using a three-dimensional fluid dynamics program. The behavior of Ar gas and the entire fluid flow in the RH process were considered. On the basis of this fluid flow, the decarburization reaction could be calculated by establishing the decarburization reaction model, which considers thermodynamics, reaction kinetics, and the decarburization sites (Ar bubble surface, bath surface, and the CO bubble formation at inner sites). The model showed good agreement with two RH operation results. Using this numerical model, the contributions of each reaction were investigated.KEY WORDS: decarburization; reaction model; reaction site; reaction area; reaction rate.where g is the acceleration due to gravity (m/s 2 ), r l and r g are the densities of the Ar gas and the melt (kg/m 3 ), V p is the volume of the plume (m 3 ) and a is the average volume fraction of the gas. The plume volume was calculated from the plume shape, which is affected by the pressure of the vacuum vessel, nozzle number and position, gas flow rate etc.. The average volume fraction is the total volume ratio of gas in the plume realm. In addition, gas bubble expansion due to the pressure drop and heat transfer from melt during rising was calculated and this effect was considered when calculating the total buoyancy force. In the Ref. 9), the bubble expansion due to only pressure drop was considered. In this study, the numerical model was modified to consider both the thermal expansion and pressure drop, Szekely's model 11) is modified as In Eq. (2), r l is the density of the melt, R b is the radius of the bubble, T is temperature in the bubble, R b and T 0 are radius and temperature at the nozzle respectively, P V is the pressure of the vacuum vessel and H is the height of the melt. To solve Eq. (2), the temperature should be known. ) and C is the heat capacity (J/kg · K). h is the heat transfer coefficient (J/m 2 · s · K) and the value can be derived from the penetration theory with the assumption of gas phase control. Komarove et al. derived heat transfer coefficient from experiments.12) Because the analysis in the Ref. 12) was based on spherical and constant size bubble, there should be some difference in the value of h and further study should be necessary to derive more realistic h value.The buoyancy force calculated by Eq. (1) was inserted as the external force for the velocity components (u, v, w) in the three dimensional Navier-Stokes equation to calculate fluid flow. The numerical model can predict the effects of the operational conditions and shapes of the RH system on fluid flow. 13) Calculation of Decarburization ReactionIn this study, the decarburization reaction was simulated by calculating the dissolved carbon concentration during the RH process. The numerical model included mass transport of dissolved carbon and oxygen due to convection and diffusion and the reaction rate at the reaction sites. The reaction rate was calculated respectively...

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Kinetics for reaction of low-carbon steel melts with CO−CO2 gas mixtures using nonlinear rate equations

Susa

Nagata

1995

Metall Mater Trans B

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Kinetics of Decaburization of Low Carbon Liquid Iron under Reduced Pressures

Cited by 11 publications

References 2 publications

Decarburization Reaction in Ultra-low Carbon Iron Melt under Reduced Pressure.

Decarburization Reaction in Ultra-low Carbon Iron Melt under Reduced Pressure.

A New Numerical Model for Predicting Carbon Concentration during RH Degassing Treatment

Kinetics for reaction of low-carbon steel melts with CO−CO2 gas mixtures using nonlinear rate equations

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