Effects of Cu, Sn and W on the Rate of Nitrogen Dissociation on the Surface of Molten Iron

Ono-Nakazato, Hideki; Dohi, Yusuke; Yamada, Daisuke; Usui, Tateo

doi:10.2355/isijinternational.46.1306

Cited by 7 publications

(4 citation statements)

References 22 publications

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“…Figure 4), Ti, V, Nb, Cr, or Mn has similar effect on nitrogen activity coefficient and the coefficient rises with increasing the content of B, C, P, Si, S, Ni, or Cu. Those findings correspond well with previously reported ones [17][18][19][20] except for the effect of Al. It must be stressed that O and S are surface-active elements and even if S increases the activity coefficient of nitrogen and thus enhancing its removal rate, the total effect is negative.…”

Section: Boundary Treatmentsupporting

confidence: 94%

“…[14] Some related experiments on a laboratory scale have been conducted using a constant amount of surfaceactive elements and the results showed that the denitrogenation can be described as a second-order reaction. [8,15,16] The effect of some alloying elements on nitrogen removal behavior has also been examined [17][18][19][20][22][23][24] and the results revealed that the elements such as titanium (Ti), zirconium (Zr), vanadium (V), manganese (Mn), and chromium (Cr), which have stronger affinity with nitrogen than iron, would enhance the nitrogen dissociation rate (the reaction rate for the reverse reaction of nitrogen desorption), whereas the elements such as aluminum (Al), silicon (Si), boron (B), (copper) Cu, wolfram (W), and tin (Sn) having stronger repulsive force against nitrogen would retard the dissociation rate.…”

Section: Introductionmentioning

confidence: 99%

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Mathematical Modeling of Nitrogen Removal from the Vacuum Tank Degasser

Miettinen

Shao

et al. 2014

steel research int.

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The removal of nitrogen from an industrial vacuum tank degasser depends on a series of operational parameters, steel composition, and contents of surface-active elements in liquid steel, e.g., oxygen and sulfur. The effect of some specific elements on nitrogen removal in the vacuum degasser has been (well) examined. Still, it is quite challenging to assess the overall effect of the whole steel composition on the process. The focus of the present work was to predict nitrogen removal from the vacuum degasser specially taking into account the multi-component effect of steel composition. An integrated computational fluid dynamics (CFD) model for simulating nitrogen (and hydrogen) removal in industrial vacuum tank degassers was therefore developed based on theories and methods that are relatively separate in the literature. In order to include the multi-component effect, the model is coupled with an in-house thermodynamics code that can be used to determine the activity coefficient of nitrogen, oxygen, or sulfur as a function of steel composition and temperature. The code was verified by comparing the calculated activity coefficients against experimental measurements from various sources. Efforts were also put into developing an on-line use concept to control the nitrogen removal. The gas plume, flow field, and evolutions of nitrogen and hydrogen during vacuum treatment were predicted and the on-line concept was demonstrated by presenting two operating diagrams. The results showed that the final nitrogen content decreases with an increase in the chemical reaction rate constant and a decrease in the initial nitrogen content. By contrary, the final nitrogen content increases with a decrease in the chemical reaction rate constant and an increase in the initial nitrogen content. Finally, the operating diagrams were validated by industrial data and observations.

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Section: Boundary Treatmentsupporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Mathematical Modeling of Nitrogen Removal from the Vacuum Tank Degasser

Miettinen

Shao

et al. 2014

steel research int.

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“…The work by Choh et al revealed that manganese (Mn) and copper (Cu) in liquid steel may reduce the interfacial temperature because of the latent heat of vaporization, thus decreasing the nitrogen removal rate. Morita et al and Ono‐Nakazato et al argued that the elements (i.e. Ti, Zr, V, Mn, and Cr) that have stronger affinity with nitrogen than iron, would enhance the nitrogen dissociation rate (the reaction rate for the reverse reaction of nitrogen desorption), while those elements (i.e.…”

Section: Introductionmentioning

confidence: 99%

Modeling Study of Nitrogen Removal from the Vacuum Tank Degasser

Miettinen

Louhenkilpi

2014

steel research int.

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Low nitrogen content in liquid steel is required for most of the steelmaking companies, where vacuum degassing of liquid steel is usually carried out to remove nitrogen as well as other impurity elements during ladle treatment. This paper presents an integrated computational fluid dynamics (CFD) model for simulating the nitrogen removal in an industrial vacuum tank degasser (VTD). In the CFD model, oxygen and sulfur are considered as surface-active elements decreasing the denitrogenation rate at the gas-steel interface. An activity coefficient and a desulfurization sub-model are implemented to compute the effective activity coefficients of the related elements and the evolution of sulfur content in liquid steel during the process, respectively. The effect of various elements on denitrogenation rate in the VTD is studied with the developed model. For the used steel compositions the denitrogenation rate decreases with an increase in the content of [S] [Al]. The model is validated by comparing final nitrogen contents measured from the industrial plant with the ones predicted by the model and good agreements were found. The model has proven to be a useful and accurate tool for predicting final nitrogen content of liquid steel in the plant.

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“…For instance, mass transfer resistance in gas and liquid phases has been discussed in the light of rate-controlling step and chemical reaction rate constant is also being clarified. [1][2][3][4][5][6][7] Moreover, effects of surface active elements such as sulfur and oxygen on chemical reaction rate constant have been recently studied by many researchers. [8][9][10] Many studies have also been reported on measurement method of nitrogen removal.…”

Section: Introductionmentioning

confidence: 99%

Effect of Changes in Sulfur and Oxygen Concentration on Change in Nitrogen Concentration in Liquid Steel during CaO^|^ndash;CaSi Powder Blowing under Reduced Pressure

Numata¹,

Higuchi²

2012

ISIJ Int.

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In this paper, 1 500 kg scale experiments of CaSi mixed CaO powder top blowing onto the Al killed steel were carried out under reduced pressure. And the effects of CaSi alloy ratio in the mixture on reactions of desulfurization and nitrogen removal were examined. Aluminum decreasing rate decreased and rate constant of desulfurization and nitrogen removal increased with increasing CaSi mixing ratio to flux. It is supposed from the above that deoxidation and desulfurization reaction can simultaneously occur by blowing the mixture of CaSi and CaO powder and the effect of calcium mixing powder on desulfurization can be explained by promotion of CaO desulfurization and CaS formation. It is suggested that lower oxygen and sulfur activity due to reaction between molten steel and powder with CaSi increased rate constant of nitrogen removal.

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Effects of Cu, Sn and W on the Rate of Nitrogen Dissociation on the Surface of Molten Iron

Cited by 7 publications

References 22 publications

Mathematical Modeling of Nitrogen Removal from the Vacuum Tank Degasser

Mathematical Modeling of Nitrogen Removal from the Vacuum Tank Degasser

Modeling Study of Nitrogen Removal from the Vacuum Tank Degasser

Effect of Changes in Sulfur and Oxygen Concentration on Change in Nitrogen Concentration in Liquid Steel during CaO^|^ndash;CaSi Powder Blowing under Reduced Pressure

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