| 1. |
- Bjorkvall, J., et al.
(author)
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A model description of the thermochemical properties of multicomponent slags and its application to slag viscosities
- 2001
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In: Glass Physics and Chemistry. - 1087-6596 .- 1608-313X. ; 27:2, s. 132-147
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Journal article (peer-reviewed)abstract
- In view of the urgent need for an extrapolation of the thermochemical and thermophysical properties of multicomponent metallurgical slags, a semiempirical slag model has been developed at the Department of Metallurgy, Royal Institute of Technology, Stockholm. In this model, Temkin's description of ionic melts is coupled with Lumsden's total dissociation of polymerized silicate and aluminate species. The excess Gibbs energies are described by means of Redlich-Kister polynomials. The model parameters that correspond to binary silicate systems are generated from available experimental data and used consequently to describe systems of higher order. The model is successful in extrapolating the thermodynamic data for a number of ternary and higher-order silicate systems. in view of the uncertainties in the literature data in the case of the Al2O3-SiO2 system. Knudsen cell mass spectrometric measurements are conducted and the model parameters are assigned on the basis of these results. This enables reasonable predictions of the thermodynamic properties of multicomponent aluminosilicate slags. The model description is also used in linking thermodynamic data with slag Viscosities. The viscosities of ternary silicates could be predicted from the binary viscosities and the thermodynamic data.
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| 2. |
- Bjorkvall, J., et al.
(author)
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Thermodynamic description of Al2O3-CaO-MnO and Al2O3-FeO-MnO melts - a model approach
- 2000
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In: Calphad. - 0364-5916 .- 1873-2984. ; 24:3, s. 353-376
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Journal article (peer-reviewed)abstract
- Assessments for the binary systems. Al2O3-CaO, Al2O3-FeO and Al2O3-MnO were carried out using a slag model developed at the present department. Calculations of the oxide activities in the homogenous liquid phase have been performed for the Al2O3-CaO-MnO and Al2O3-FeO-MnO systems, The activities in the ternary systems were calculated using the parameters obtained from the binary subsystems. Comparison between experimental data and the model calculations demonstrates the ability of the model to describe the thermodynamics of ternary systems using only information ti-om the binary systems. In the case of the Al2O3-CaO-MnO system, the comparison between model calculations and the results of the only available experimental measurements is less satisfactory. This could partly be attributed to the non availability of experimental data for the subsystem CaO-MnO. Future experimentation in the Al2O3-CaO-MnO system is strongly recommended.
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| 3. |
- Bjorkvall, J., et al.
(author)
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Thermodynamic description of 'FeO'-MgO-SiO2 and 'FeO'-MnO-SiO2 melts - a model approach
- 2000
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In: High Temperature Materials and Processes. - 0334-6455 .- 2191-0324. ; 19:1, s. 49-59
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Journal article (peer-reviewed)abstract
- Activities of the oxide components in the 'FeO'-MgO-SiO2 and 'FeO'-MnO-SiO2 systems have been predicted based on the information of binary systems using a thermodynamic model. The model considers the ionic melt as an oxygen-ion matrix with the cations including Si4+ distributed in it. The interactions between different cations in the presence of O2- are considered as functions of both composition and temperature. The activities predicted by the model are in good agreement with the experimental data available in the literature.
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| 4. |
- Bjorkvall, J., et al.
(author)
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Thermodynamic model calculations in multicomponent liquid silicate systems
- 2001
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In: Ironmaking & steelmaking. - : Informa UK Limited. - 0301-9233 .- 1743-2812. ; 28:3, s. 250-257
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Journal article (peer-reviewed)abstract
- A thermodynamic model developed earlier in the present laboratory for oxidic melts was applied to some multicomponent systems, namely CaO-FeO-MgO-SiO2, Al2O3-CaO-MgO-SiO2, Al2O3-FeO-MnO-SiO2, and Al2O3-CaO-FeO-MgO-MnO-SiO2. Model calculations were carried out using only the parameters corresponding to the binary systems, which, in turn, were based on the available thermodynamic information for these systems. The predicted thermodynamic activities of the component oxides in higher order systems were compared with the experimental data published in the literature. In general, the agreement between the model predictions and the experimental values was found to be satisfactory within the limits of experimental uncertainties and limitations of the model calculations. Examples of model predictions for some typical slag compositions, relevant to the Swedish steel industry and used in the blast furnace, electric arc furnace, and ladle furnace are also presented.
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| 5. |
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| 6. |
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| 7. |
- Dayal, P., et al.
(author)
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Study of stag/metal interface in ladle treatment
- 2006
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In: Ironmaking & steelmaking. - : Informa UK Limited. - 0301-9233 .- 1743-2812. ; 33:6, s. 454-464
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Journal article (peer-reviewed)abstract
- In order to gain an insight into the mixing behaviour of slag and metal under different stirring conditions, samples of slag/metal interface were collected from an industrial 65 ton ladle furnace using a new sampling technique. Different stirring conditions and sampling positions in the ladle were chosen. Complementary cold model experiments were also performed. The experimental results strongly suggested that the shear force between the two liquids played an important role in slag-metal mixing. Evidence for the existence of slag droplets each surrounded by a very thin metal film was found in the samples taken under both gas stirred and induction stirred conditions. This observation strongly suggested that slag-metal system behaved similarly as oil-water system, wherein, the shear force owing to the bulk flow led to a packed 'sphere bed' of oil droplets each coated by a thin water film above the water bath. On the basis of the experimental results, preliminary mathematical models were developed to describe the rate of mass exchange at the slag/metal interface.
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| 8. |
- Thunman, Mikael, et al.
(author)
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Study on the formation of open-eye and slag entrainment in gas stirred ladle
- 2007
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In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 78:12, s. 849-856
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Journal article (peer-reviewed)abstract
- Laboratory experiments were carried out to study the phenomena related to open-eye formation in ladle treatment. Ga-In-Sn alloy with a melting temperature of 283 K was used to simulate the liquid steel, while MgCl2-Glycerol(87%) solution as well as HCl solution were used to simulate the ladle slag. No open-eye was formed at lower gas flow rates, but, occurred when gas flow reached a critical rate. This critical gas flow rate was found to depend significantly on the height of the top liquid. No noticeable amount of top liquid was observed in any of the samples taken from the metal bulk during gas stirring. To confirm this aspect, samples of slag-metal interface were taken around the open-eye in an industrial gas stirred steel ladle. No entrapped slag droplet was found in the solidified steel within the region between the interface and 2 cm from the interface. The accordance of the laboratory and industrial results suggests that the entrainment of slag into the steel bulk around the open-eye cannot be considered as the major contribution to inclusion formation.
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