| 1. |
- Fecht, H. -J, et al.
(författare)
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Thermophysical properties of liquids : Modelling and non-metallic materials
- 2005
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Ingår i: ESA SP. - 0379-6566 .- 1609-0438. ; :1281, s. 24-35
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Tidskriftsartikel (refereegranskat)abstract
- The accurate knowledge and high-precision measurements of the thermophysical properties of liquids is necessary for the numerical modeling of industrial processes where the solid-liquid phase transformation plays a crucial role. The reduction of magnetic levitation forces in microgravity leads either to a significant improvement in accuracy or makes the measurement possible in the first place. High-precision measurements on chemically highly reactive melts require containerless processing using non-contact diagnostic tools. Scientific precursor experiments were conducted in the TEMPUS containerless processing facility during the Spacelab IML-2 and MSL-1 missions, also.
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| 2. |
- Seetharaman, Seshadri, et al.
(författare)
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Estimation of liquidus temperatures for multicomponent silicates from activation energies for viscous flow
- 2000
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Ingår i: Metallurgical and Materials Transactions. A. - 1073-5623 .- 1543-1940. ; 31:1, s. 111-119
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Tidskriftsartikel (refereegranskat)abstract
- This article considers the viscous-flow phenomenon in molten silicate melts in the vicinity of their liquidus temperatures. An agglomeration of ionic species occurs in the liquid slag with decreasing temperatures and results in an increase in the viscosity and the activation energy for viscous flow. The latter was found to be nonlinear, increasing rapidly as the temperature is approached wherein a solid phase is likely to separate from the liquid. The second derivative of the activation energy for viscous flow with respect to temperature was found to show a discontinuity in the vicinity of the liquidus temperature. This has been verified in the case of viscous flow for both pure water and CaO-SiO2 melts. Experimental data for the viscosities, of complex silicate melts and mold fluxes have also demonstrated the occurrence of a discontinuity in the second-derivative function, which is in accordance with the liquidus temperature as determined by differential thermal analysis (DTA). Thus, the second derivative offers a useful way of estimating the liquidus temperatures of multicomponent silicates, which are often difficult to determine due to supercooling effects.
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| 3. |
- Sridhar, S., et al.
(författare)
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Abating environmentally harmful waste gases
- 2002
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Ingår i: JOM. - 1047-4838 .- 1543-1851. ; 54:5, s. 30-33
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Tidskriftsartikel (refereegranskat)abstract
- A gas-purification method, based on the condensation of nitrogen, sulfur, and carbon-containing environmentally hazardous gases produced from industrial processes, is proposed in this article. The method, which utilizes the cooling capacity of waste nitrogen in the oxygen plant to condense the hazardous gases, is capable of removing hazardous impurities up to 99.98%. Theoretical calculations underlying the condensation process are presented employing gases produced in a blast furnace and coke oven in an integrated steel plant. The cooling power required for, the condensation process is calculated using the waste nitrogen generated from an oxygen plant that generates captive oxygen for the steel plant. Design modifications that need to be made to the oxygen plant in order to utilize the cooling power of the waste nitrogen gas are also presented. As a case study, the advantages of the method are illustrated with purification of coke-oven gas. The economic impact and the investment aspects are also discussed.
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| 4. |
- Sridhar, S., et al.
(författare)
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Viscosity estimation models for ternary slags
- 2001
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Ingår i: Steel research. - : Wiley. - 0177-4832. ; 72:1, s. 3-10
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Tidskriftsartikel (refereegranskat)abstract
- Five models to estimate slag viscosity have been compared with the experimental data obtained using the rotating cylinder method. The comparison was made for four ternary silicate systems, viz. FeO-MgO-SiO2, CaO-MnO-SiO2, FeO-MnO-SiO2 and CaO-Feo-SiO2. The KTH model and the model using the Gibbs energy of mixing have been found successful in estimating the slag viscosity. On the other hand, the comparisons of the experimental results with the calculated viscosity using the Riboud, Urbain and NPL models have shown poor agreement. While the limited number of the data points used for parameter optimisation would be one of the reasons for the failure of the Riboud and NPL models when applied for these ternary systems, the description of the slag composition in Urbain's approach could probably explain the disagreement between the estimated and experimental viscosity. Further studies are needed for the KTH model to accommodate fluorides in the model structure.
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| 5. |
- Abbasalizadeh, A., et al.
(författare)
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Experimental investigation and thermodynamic modelling of LiF-NdF3-DyF3 system
- 2018
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Ingår i: Journal of Alloys and Compounds. - : Elsevier. - 0925-8388 .- 1873-4669. ; 753, s. 388-394
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Tidskriftsartikel (refereegranskat)abstract
- Electrolysis of molten fluorides is one of the promising methods for the recovery and recycling of rare earth metals from used magnets. Due to the dearth of phase equilibria data for molten fluoride systems, thermodynamic modelling of LiF-DyF3-NdF3 system using the CALPHAD approach was carried out. Gibbs energy modelling for LiF-NdF3 and LiF-DyF3 systems was performed using the constitutional data from literature. Ab initio calculations were used to obtain enthalpy of reaction of LiDyF4, an intermediate phase that is found to exist in the LiF-DyF3 system. Differential thermal analysis was carried out for selected compositions in the NdF3-DyF3 system, in order to determine liquidus and solidus temperatures. The Gibbs energy parameters for the limiting binaries determined in this work is used for modelling the Gibbs energy functions of equilibrium phases in the ternary system. Selected compositions of LiF-NdF3-DyF3 were subjected to DTA in order to validate the calculated phase temperatures involving melt.
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| 6. |
- Abbasalizadeh, Aida, et al.
(författare)
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Neodymium extraction using salt extraction process
- 2015
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Ingår i: Mineral Processing and Extractive Metallurgy. - : Maney Publishing. - 0371-9553 .- 1743-2855. ; 124:4, s. 191-198
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Tidskriftsartikel (refereegranskat)abstract
- The present paper deals with the feasibility of the neodymium recovery from spent Nd-Fe-B magnets using molten salt electrodeposition method. The salt bath consisted of a mixture of LiCl- KCl-NaCl corresponding to the eutectic composition. The experimental set-up with its salient features is presented. AlCl3 was used as flux and graphite rods dipped in the salt bath served as electrodes. The voltage for the electrolysis was chosen on the basis of the decomposition potential of NdCl3. The reaction sequence can be described as Iron-free neodymium deposition could be carried out successfully. In view of the proximity of the electrode potentials, the co-deposition of the aluminium and neodymium was observed to occur at the cathode, as revealed by SEM/EDS and XRD analyses of the electrodeposit.
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| 7. |
- Arvanitidis, I., et al.
(författare)
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Intrinsic reduction kinetics of cobalt- and nickel-titanates by hydrogen
- 2000
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Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 15:2, s. 338-346
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Tidskriftsartikel (refereegranskat)abstract
- The isothermal reduction of synthetic CoTiO3 and NiTiO3 in hydrogen (1 atm) was investigated using thermogravimetric analysis technique in the temperature range, 928-1287 K (CoTiO3) and 884-1387 K (NiTiO3). Shallow beds of fine titanate powders were reduced by hydrogen at a high flow rate. Quenched samples were analyzed by scanning electron microscopy. The rates of the reaction of the titanates with H-2 were very fast during the reduction of Co2+, Ni2+, or Fe2+ ions into metals. The reduction of the remaining titanium oxide was very slow. The activation energy for the reduction of CoTiO3 by hydrogen to Co and TiO2 was evaluated to be 151 +/- 1 kJ/mol, and the activation energy for the reduction of NiTiO3 by hydrogen to Ni and TiO2 was evaluated to be 153 +/- 1 kJ/mol. The study was complemented by hydrogen reduction of synthetic TiO2 (rutile). The results were also compared with the hydrogen reduction of FeTiO3.
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| 8. |
- Basu, S., et al.
(författare)
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Activity of Ferric Oxide in Steelmaking Slag
- 2010
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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. ; 41:2, s. 414-419
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Tidskriftsartikel (refereegranskat)abstract
- Refining reactions in steelmaking primarily involve oxidation of impurity element(s). The oxidation potential of the slag and the activity of oxygen in the metal (h(O)) are the major factors controlling these chemical reactions. In turn, the oxidation potential of the slag is influenced strongly by the equilibrium distribution of oxygen between ferrous and ferric oxides. We recently investigated the activity coefficient of FeO in steelmaking slag and the effect of chemical composition thereon. This work is focused on estimation of the activity coefficient of Fe2O3.
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| 9. |
- Basu, S., et al.
(författare)
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Activity of iron oxide in steelmaking slag
- 2008
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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. ; 39:3, s. 447-456
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Tidskriftsartikel (refereegranskat)abstract
- Most refining reactions in steelmaking involve oxidation of impurity element(s). The product(s) of oxidation either dissolve in the slag or escape as gaseous phase. The activities of oxygen in the metal (h (O)), and that of "FeO" in slag (a (FeO)), are major factors controlling these chemical reactions. The activities of oxygen and "FeO" are thermodynamically related, provided equilibrium distribution of oxygen between the slag and the metal is attained. This enables direct estimation of one parameter from the other. A thorough knowledge of the variation in activity of FeO, and factors affecting the same, is therefore of great importance in the process metallurgy of steelmaking. The present work experimentally measures the activity of FeO in steelmaking slags and attempts to develop a correlation for estimation of gamma(FeO) as a function of temperature and chemical composition of the slag.
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| 10. |
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