| 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. |
- Wang, Huijun, 1988-, et al.
(författare)
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Dissolution of MgO·Al2O3 spinel and MgO in CaO-Al2O3-MgO-SiO2 slag under forcedconvection
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this work, the dissolution mechanism of dense MgO·Al2O3 spinel and MgO rod into molten CaO-Al2O3-MgO-SiO2 slag was investigated at 1873 K with forced convection. The dissolutionexperiments were carried out by employing a newly developed rotating cylinder method. The effect of rotation speed and reaction time on the dissolution rate was studied. The measured dissolution rates of both spinel and MgO were dependent on the rotation speed, indicating that mass transfer in the slag phase to one of the rate-limiting steps. It was also found that the dissolution rate of spinel in slag was enhanced more rapidly than that of MgO with the increasing reaction time and rotation speed. It was also found that the composition of the slag at the interface was far from equilibrium value between the slag and solid. The results implied that the chemical reaction at the solid-slag interface should be the other important step that jointly controlling the dissolution process.
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| 9. |
- Wang, Huijun, 1988-, et al.
(författare)
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Dissolution of MgO Based Refractories in CaO-Al2O3-MgO-SiO2 Slag
- 2024
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Ingår i: Journal of the European Ceramic Society. - : Elsevier. - 0955-2219 .- 1873-619X.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Dissolution of different types of MgO based refractories into molten CaO-Al2O3-MgO-SiO2 slag was studied at 1873 K. The prepared refractory cubes were dissolved in both stagnant slagand slag stirred with different speeds. Even in a stagnant slag, the decarbonized commercial MgO-carbon refractory dissolved very fast. Formation of micro spinel particles by addition of either colloidal alumina or micro alumina powder in the MgO matrix efficiently reduced the dissolution. The dissolution of MgO refractories into slag was found to be controlled by the slag penetration into the MgO matrix. In the case of stagnant slag, the slag penetration would lead to the final dissociation of the decarbonized commercial MgO-carbon cube in less than 6 minutes. A slag penetrated layer was formed in the cubes with spinel particles formed in situ.The major dissolution took place between the MgO grains and the liquid in this penetrated layer. The increase of the thickness would slow down the dissolution process. In the case of forced convection, the slag penetrated layer was removed at high stirring speeds and partially removed at lower stirring speeds. The removal of the penetrated layer would enhance the dissolution process.
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| 10. |
- Allertz, Carl, et al.
(författare)
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A Study of Nitrogen Pickup from the Slag during Waiting Time of Ladle Treatment
- 2014
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:4, s. 689-696
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Tidskriftsartikel (refereegranskat)abstract
- An investigation of the nitrogen pickup of liquid steel from ladle slag after vacuum degassing was made. Nitride capacities, C-N, of a number of ladle slags were determined at controlled nitrogen and oxygen potentials at 1873K. The nitride capacities in the composition range studied were found to be very low. In accordance with the literature, the nitride capacity was found to increase with increasing SiO2 content. Industrial trials were performed. The nitrogen content of the steel was determined before and after vacuum degassing as well as after the waiting period. Three different trends of the variation of nitrogen content in the steel were observed. Both the laboratory study and the industrial trials revealed that the transfer of nitrogen from slag to steel was not the reason for nitrogen pickup in the steel subsequent to vacuum degassing.
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