| 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. |
- 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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| 3. |
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| 4. |
- Basu, S., et al.
(författare)
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Thermodynamics of Phosphorus and Sulphur Removal during Basic Oxygen Steelmaking
- 2010
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Ingår i: STEEL RESEARCH INTERNATIONAL. - : Wiley. ; , s. 932-939
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Konferensbidrag (refereegranskat)abstract
- Removal of impurity elements from hot metal is essential in basic oxygen steelmaking. Oxidation of phosphorus from hot metal has been studied by several authors since the early days of steelmaking. Influence of different parameters on the distribution of phosphorus, seen during the recent work of the authors, differs somewhat from that reported earlier. On the other hand, removal of sulphur during steelmaking has drawn much less attention. This may be due to the magnitude of desulphurisation in oxygen steelmaking being relatively low and desulphurisation during hot metal pre-treatment or in the ladle furnace offering better commercial viability Further, it is normally accepted that sulphur is removed to steelmaking slag in the form of sulphide only However, recent investigations have indicated that a significant amount of sulphur removed during basic oxygen steelmaking can exist in the form of sulphate in the slag under oxidising conditions. The distribution of sulphur during steelmaking becomes more important in the event of carry-over of sulphur-rich blast-furnace slag, which increases sulphur load in the BOF. The chemical nature of sulphur in this slag undergoes a gradual transition from sulphide to sulphate as the oxidative refining progresses.
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| 5. |
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| 6. |
- Orrling, Diana, 1978-
(författare)
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Towards Abatement of Selected Emissions from Metals Manufacturing
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Although the metallurgical industry has made great strides in the reduction of unwanted emissions to the atmosphere as a result of production processes, significant challenges still exist. From a global perspective, even large reductions in emissions per produced ton become immaterial when considering that the total world production of metals continues to increase. Two such particularly hazardous emissions are sulfur dioxide, primarily from copper ore roasting, and mercury, which has had increasing emissions from the steel industry in recent years. Both pollutants have severe consequences for the environment and also for human health. The primary motivations of this work have hence been: (1). to study sulfate formation on soot from sulfur dioxide emissions reacting with ozone and H2O in the vapor phase and (2). to study factors involving the behavior of mercury adsorption on metal surfaces involved in steelmaking, in order to further the understanding of select emissions from scrap-based steelmaking. Gas phase experiments were conducted to examine the heterogeneous oxidation of sulfur dioxide on soot in the presence of ozone and water vapor. The sulfur dioxide oxidation into sulfate was quantified using a particle-into-liquid sampler coupled with ion chromatography to measure the sulfate formation at atmospheric pressure. Water vapor, ozone and sulfur dioxide concentrations were controlled. Due to the ozone oxidation, multilayer adsorption of sulfur dioxide on soot, as well as sulfate formation and physisorption on secondary surface layer sites were observed. The exposure also caused the soot to become hydrophilic, due to the sulfur dioxide adsorption and also likely the formation of carboxyl groups on the surface. No significant increase in sulfate formation was observed at ozone concentrations above 1000 ppm. The effects of common surface contaminants such as oxygen and chlorine were examined on the metal surfaces, as well as the impact of changes in temperature, with controlled conditions using thermal desorption auger electron spectroscopy. It was established that low temperatures (82 K through 111 K) were conducive to mercury adsorption, wherein physisorption and subsequent lateral mercury interactions in mercury adlayers occurred. Chlorine appeared to favor mercury uptake, as determined by the increased mercury coverage at low temperatures on polycrystalline iron, copper and zinc. Oxygen, however, was found to be an inhibitor of mercury, most notably at room temperature. It was surprising to establish that no mercury adsorbed on zinc surfaces at room temperature and only on polycrystalline samples at low temperature. The mercury signal intensity increased up to the limit of the melting temperature for iron systems, on the oxidized copper surface and the polycrystalline zinc surfaces, prior to desorption from the surfaces. It is suggested that this is due to a rearrangement of mercury atoms on the surface at increasing temperatures, whereas at 85 K, mercury adhered to its initial adsorption position. In other words, mercury wet these surfaces on annealing, transitioning from an islanded surface at low temperature to a smooth layer before desorption. Based on these results, it was concluded that the mercury bond to the oxidized surface was weakened compared to clean copper. Furthermore, it is proposed that a surface phase transition occurred on polycrystalline zinc prior to desorption. No such transition was observed on iron. Activation energies of desorption were calculated for the relevant metal surfaces. It was established that clean iron had the highest activation energy of desorption. The large bond strength between mercury and iron may account for the highest desorption temperature of the iron systems. Zinc and copper had similar activation energies and desorption temperatures, which were respectively lower than that of iron. X-Ray Photoelectron and Auger Electron Spectroscopy were used to ascertain common surface contamination, i.e. chlorine, oxygen and sulfur, which affected mercury adsorption. Laser Ablation Inductively Coupled Plasma Time of Flight Mass Spectrometry was used to determine the depth of mercury adsorption on the samples. The technique also showed that the samples contained mercury in the surface layers. Accompanied by the rising demand for metals is the increase in emissions from metals manufacturing. Moreover, it is critical to minimize sulfur dioxide emissions as particulates from soot continue to be released in the atmosphere. For scrap-based steelmaking, monolayer mercury adsorption on clean iron and copper at room temperature are significant results. With the rising use of electronic devices in vehicles, the sorting of scrap becomes increasingly important. Mercury not adsorbing on zinc at room temperature is also of relevance as it disproves the theory of increased mercury adsorption with the increased use of galvanized scrap in summer conditions. However, the low temperature studies showed multilayer adsorption of mercury on iron, zinc and copper, which has relevance for the reported temporal variations of mercury deposition in arctic regions. Keywords: mercury, iron, zinc, sulfur dioxide, adsorption, pollution, thermal desorption, polycrystalline, surfaces, spectroscopy
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| 7. |
- 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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| 8. |
- 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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| 9. |
- Ge, Xinlei, et al.
(författare)
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Salt extraction process-novel route for metal extraction Part 3-electrochemical behaviours of metal ions(Cr, Cu, Fe, Mg, Mn) in molten (CaCl2-)NaCl-KCl salt system
- 2010
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Ingår i: Mineral Processing and Extractive Metallurgy. - 0371-9553 .- 1743-2855. ; 119:3, s. 163-170
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Tidskriftsartikel (refereegranskat)abstract
- The present work is Part 3 of a novel salt extraction process towards the extraction of metal values from slag, low-grade ores, etc. The electrochemical behaviour of different metal ions, Cr(III), Cr(II), Cu(II), Fe(III), Mg(II) and Mn(II) was studied using cyclic voltammetry (CV) at 827°C in (CaCl 2-)NaCl-KCl system with a tungsten or glassy carbon electrode. The deposition process of Cr(III) species was found to be consisted of two electrochemical steps, while, in the case of other species, the deposition only involves one step. The deposition potentials and diffusion coefficients were determined from the cyclic voltammetrys. Electrodeposition of chromium was performed using a two-electrode cell under constant voltage, and pure dendrite and nodular-like crystals of chromium were obtained. The present study provides a good understanding of the electrochemical behaviour of these metal ions in molten salts, and thus is helpful to this novel salt process for the recovery of metal values from slag or other materials.
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| 10. |
- Sahajwalla, V., et al.
(författare)
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Structure and alkali content of coke in an experimental blast furnace and their gasification reaction
- 2004
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Ingår i: Iron & Steel Technology Conference proceedings. - Warrendale, Pa : Iron and Steel Society. - 1886362750 ; , s. 491-500
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Konferensbidrag (refereegranskat)abstract
- Coke samples excavated from LKAB's Experimental Blast Furnace (EBF) at MEFOS in Luleå, Sweden were used to observe the influence of in-furnace reactions on the changes in chemical stracture of cokes and their influence on kinetics of CO 2 reactivity. In addition to growth of carbon crystallite of coke, alkali concentration particularly potassium and sodium were found to increase as coke descended towards lower part of the EBF. The increase in carbon structure could be linearly related to measured temperature profiles of EBF. Isothermal and non-isothermal TGA measurements are shown to indicate that CO 2 reactivity of coke becomes progressively faster as it moves towards lower part of blast furnace. The study suggests that alkali enrichment of cokes in an operating blast furnace could have a strong catalytic effect on the CO 2 reactivity. Further research is expected to clarify the mechanisms of influence of coke minerals on reactivity and their implications in a blast furnace.
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