| 1. |
- Condo, Adolfo Firmino Timoteo, 1976-, et al.
(författare)
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Sulfide Capacities in the Al2O3-CaO-MgO-SiO2 System
- 2018
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Ingår i: Steel Research International. - : John Wiley & Sons. - 1611-3683 .- 1869-344X. ; 89:8
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the sulfide capacities of the slags in the ternary Al2O3-CaO-SiO2 system at 1873K, and in the quaternary system Al2O3-CaO-MgO-SiO2 at 1823 and 1873K are experimentally measured using copper-slag equilibrium at controlled oxygen partial pressure. The experimental data, which has been unavailable, are needed for the improvement of a sulfide capacity model. An assessment of the available data for sulfide capacities in the Al2O3-CaO-MgO-SiO2 system and its sub lower-order systems are made. Based on this assessment and the present experimental results, the model parameters of the existing sulfide capacity model are re-optimized. The sulfide capacity model can be successfully used in the prediction of the sulfide capacities of multicomponent slags with satisfactory accuracy.
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| 2. |
- Lindvall, Mikael, 1981-, et al.
(författare)
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Determination of the vanadium solubility in the Al2O3-CaO(25mass%)-SiO2 system
- 2014
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Ingår i: Calphad. - : Elsevier. - 0364-5916 .- 1873-2984. ; 47, s. 50-55
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Tidskriftsartikel (refereegranskat)abstract
- Vanadium (V) solubility in the Al2O3-CaO(25mass%)-SiO2 system was determined experimentally at 1873K and at a fixed oxygen potential of 9.37•10-11 bar. EPMA microanalyses were employed to identify the phases and their compositions in the quenched samples. It showed that the solubility of V-oxide increased slightly with decreasing Al2O3-content in the interval from 3mass% to 53mass%. The maximum V-solubility was up to 7mass% (as V). A solid solution rich in V-oxide was detected. The Al2O3 solubility in this solid solution was found to increase with increasing Al2O3-content in the liquid.
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| 3. |
- Lindvall, Mikael, et al.
(författare)
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Determination of Vanadium Solubility in the Al2O3-CaO(30 Mass Pct)-SiO2 and Al2O3-CaO(35 Mass Pct)-SiO2 System
- 2015
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer Science and Business Media LLC. - 1073-5615 .- 1543-1916. ; 46:2, s. 733-740
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Tidskriftsartikel (refereegranskat)abstract
- The solubility of vanadium oxide in the Al2O3-CaO(30 mass pct)-SiO2 system and Al2O3-CaO(35 mass pct)-SiO2 system was determined experimentally at 1873 K (1600 °C) and at a fixed oxygen potential of 9.37 × 10−11 bar. EPMA microanalyses were employed to identify the phases and their compositions in the quenched samples. The solubility of vanadium oxide in the liquid phase was found to decrease with increasing CaO content in the liquid. The vanadium oxide solubility was especially low when both CaO and Al2O3 contents were high in the liquid phase. The maximum solubility of vanadium oxide was up to 7 mass pct (as V). Two solid phases were found, a solid solution of Al2O3 and vanadium oxide and an Al2O3-rich solid phase with 16.7 mass pct V2O3. The Al2O3 solubility in the solid solution was found to increase with increasing Al2O3 content in the liquid, the impact of the CaO content in the liquid on the solubility of Al2O3 in V2O3 was found to be small. The Al2O3-rich solid phase was identified as the mineral hibonite with fractionation of V into the crystal structure.
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| 4. |
- Lindvall, M., et al.
(författare)
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Possibility of Selective Oxidation of Vanadium from Iron and Phosphorus in Fe-V-P Melt
- 2010
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 81:2, s. 105-111
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Tidskriftsartikel (refereegranskat)abstract
- Experiments on a vanadium recovery method from vanadium containing BOF-slag using both a Tamman furnace (3 kg scale) and an induction furnace (150 kg scale) were conducted. The vanadium was extracted into the slag phase by bubbling oxidation gas into a metal bath consisting mainly of V (1-10 mass%), Si (less than 1 mass%) and P (about 1 mass%). The first experiments revealed that the slag formed during oxidation reaction had considerably high phosphate capacity High phosphorus content would rule out the possibility of using the slag as a raw material for the production of ferrovanadium of high quality In order to reduce the P-content in the slag, addition of slag former to reduce phosphate capacity was necessary. A suitable slag system (having the initial composition 40 mass% Al2O3 - 25 mass% CaO - 35 mass% SiO2) and a suitable atmosphere, by using CO2, that enhanced the oxidation of vanadium, but limit the oxidation of iron and phosphorus was found. However, more efforts should be put forward, e.g. study of the phase diagram, the viscosity of the slag and even oxide activities to gain more insight into the slag formed by selective oxidation.
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| 5. |
- Ragnarsson, Lars, et al.
(författare)
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Oxygen penetration in the protection shroud in steel casting
- 2010
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Ingår i: Steel Research International. - : Wiley-Blackwell. - 1611-3683 .- 1869-344X. ; 81:11, s. 965-973
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Tidskriftsartikel (refereegranskat)abstract
- Physical modelling of argon shroud used in ingot casting was carried out using a 2D 1:1 scaled model in order to determine the oxygen distribution around the steel stream. The oxygen concentrations were measured by an oxygen sensor. Complementary PIV measurements were also carried out for a gas inlet configuration using dual (horizontal and vertical) gas inlet. The main findings were: (1) The oxygen concentrations were considerably high in the ordinary operation conditions. The oxygen contents were the highest in the case of vertical gas injection (higher than 11% in all cases). (2) A minimized distance between the ladle and the collar on the top of the vertical runner would reduce the oxygen entrainment by convection and diffusion, in the case of horizontal gas injection and a dual gas inlet configuration. (3) A modest flow rate of argon gas should be used. Further increase of the gas flow would not improve the protection. (4) A dual gas inlet configuration would be more effective than a single inlet, especially in the case of larger distances between the ladle and the runner.
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| 6. |
- Thunman, Mikael, et al.
(författare)
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Study on the formation of open-eye and slag entrainment in gas stirred ladle
- 2007
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 78:12, s. 849-856
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Tidskriftsartikel (refereegranskat)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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| 7. |
- White, Jesse Franklin, 1971-, et al.
(författare)
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Mass Transfer in Slag Refining of Silicon with Mechanical Stirring : Transient Interfacial Phenomena
- 2014
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer Science and Business Media LLC. - 1073-5615 .- 1543-1916. ; 45:1, s. 96-105
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Tidskriftsartikel (refereegranskat)abstract
- Experiments have been carried out to study the rates of mass transfer between liquid silicon and CaO-SiO2 slag with impeller stirring at 1823 K (1550 A degrees C). The occurrence of transient interfacial phenomena related to the mass transfer of calcium has been observed; the evidence suggests that the reduction of calcium oxide at the interface leads to a rapid, temporary drop in the apparent interfacial tension. At low apparent interfacial tension, mechanical agitation facilitates the dispersion of metal into the slag phase, which dramatically increases the interfacial area; here, it has been estimated to increase by at least one order of magnitude. As the reaction rate slows down, the apparent interfacial tension increases and the metal recoalesces. The incidental transfer of calcium very likely promotes the transfer of boron by increasing the interfacial area. Mechanical mixing appears to be an extremely effective means to increase the reaction rate of boron extraction and could feasibly be implemented in the industrial slag refining of silicon to improve reaction rates.
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| 8. |
- Brandberg, Jenny, 1975-
(författare)
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Solubility of hydrogen in slags and its impact on ladle refining
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the present work was to clarify the mechanisms of hydrogen removal during vacuum degassing. The main reason for this was because the primary source of hydrogen pick-up in steel-making is the moisture in the furnace atmosphere and the raw material charged into the ladle furnace. Previous studies showed that the presence of hydroxyl ions in the ladle slag results in hydrogen transfer from the slag back into the steel bath. The main focus of this thesis was therefore to gain deeper knowledge of the ladle slag and its properties. For this purpose a number of slag compositions were examined in order to clarify whether these slags were single liquids at 1858 K. 14 out of 27 compositions in the Al2O3 CaO MgO SiO2 system was completely melted. These results were in disagreement with the existing phase diagrams.Water solubility measurements were carried out by employing a thermo gravimetric technique. The temperature was found to have negligible effect on the water solubilities. The experimental results showed that the water capacity values varied between 1x103 and 2x103 in the majority of the composition range. However, for compositions close to CaO saturation the water capacity value could reach higher than 3x103. The experimental determined water capacity was further used to develop a water capacity model for the quaternary slag system Al2O3 CaO MgO SiO2. The model was constructed by considering the affects of the binary interactions between the cations in the slag on the capacity of capturing hydroxyl ions. The model calculations agreed well with the experimental results as well as with the literature data.An attempt was made to develop a preliminary process model for dehydrogenation by using the results from CFD calculation. For this purpose industrial sampling was made during vacuum treatment. The hydrogen concentrations decreases fast in the initial stages of the degassing, but is slowed down in the final stage. The model calculations fit the initial stage of the dehydrogenation process well. In the final stage of the process the predicted values are somewhat lower than the plant data. The results from the model prediction showed that a dynamic process model could be satisfactorily constructed using the results from CFD calculation.The present work aimed at determining how big impact hydroxyl ions in the slag have on the final hydrogen concentration in the liquid steel. It was found that the effect is of less importance regarding the final concentration of the metal after the degassing treatment.
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| 9. |
- Brandberg, Jenny, et al.
(författare)
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Water capacity model of Al2O3-CaO-MgO-SiO2 quaternary slag system
- 2007
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Ingår i: Steel research. - : Wiley. - 0177-4832 .- 1611-3683. ; 78:6, s. 460-464
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Tidskriftsartikel (refereegranskat)abstract
- The focus of the present work was to develop a water capacity model for the quaternary slag system Al2O3-CaO-MgO-SiO2. In the model, a silicate melt was considered to consist of two ion groupings, viz. cation grouping and oxygen ion. The water capacity of a melt is supposed to depend on the interactions between the cations in the presence of oxygen ions. These interactions were determined on the basis of the experimentally measured water solubility data. Only binary interactions were employed in the model. For the system CaO-SiO2, disagreement in the literature data was found. Since the interaction between Ca2+ and Si4+ would play an important role, experiments were carried out to determine the water capacities of some CaO-SiO2 slags. For this purpose a thermogravimetric method was employed. Iso-lines of water capacities at constant MgO contents were predicted by the model and compared with the experimental data from literature. The model calculations agreed well with the experimental results.
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| 10. |
- Brandberg, Jenny, et al.
(författare)
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Water vapor solubility in ladle-refining slags
- 2006
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer Science and Business Media LLC. - 1073-5615 .- 1543-1916. ; 37:3, s. 389-393
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Tidskriftsartikel (refereegranskat)abstract
- A thermo-gravimetric technique was used to determine the hydrogen solubilities of some Al2O3-CaO-MgO-SiO2 quaternary slags. The focus of the work was to determine the water capacities in slags having lower SiO2 concentrations, which were relevant to industrial practices. The majority of the experiments were carried out in the temperature interval 1747 to 1827 K with water pressure of 157 mbar. The reliability of the experiments was confirmed using a quenching technique. The temperature was found to have a negligible effect on the water solubilities. The composition of the slag did not seem to significantly affect the water capacity. However, as the slag composition approached CaO saturation, a considerable increase of the solubility was noticed.
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