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  • 151. Mostaghel, S.
    et al.
    Matsushita, T.
    Samuelsson, C.
    Björkman, B.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Influence of alumina on physical properties of an industrial zinc-copper smelting slag Part 3 - Melting behaviour2013In: Transactions of the Institution of Mining and Metallurgy Section C - Mineral Processing and Extractive Metallurgy, ISSN 0371-9553, E-ISSN 1743-2855, Vol. 122, no 1, p. 56-62Article in journal (Refereed)
    Abstract [en]

    A combination of different experimental techniques and thermodynamic calculations has been used to investigate the melting behaviour of an industrial iron silicate slag and mixtures of this slag with 5, 10 and 15 wt-% alumina addition. Differential scanning calorimetry (DSC) and thermo-optical observation were applied to monitor the solidus temperature and softening behaviour of the samples respectively. Estimation of the liquidus temperature was made using the second derivative of activation energies for viscous flow, with respect to temperature. All experimentally detected values were compared to predictions made using the FactSageTM6·2 thermodynamic package. Results show that as the slag lies in the fayalite primary phase field, the liquidus temperature decreases due to the increased alumina concentration. In the hercynite primary crystallisation phase field, however, alumina addition to the system increases the liquidus temperature. The solidus temperature does not vary significantly due to the current changes in the total alumina content of the slag.

  • 152. Mostaghel, S.
    et al.
    Matsushita, Taishi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Samuelsson, C.
    Björkman, B.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Influence of alumina on physical properties of an industrial zinc-copper smelting slag: Part 1 - Viscosity2013In: Transactions of the Institution of Mining and Metallurgy Section C - Mineral Processing and Extractive Metallurgy, ISSN 0371-9553, E-ISSN 1743-2855, Vol. 122, no 1, p. 42-48Article in journal (Refereed)
    Abstract [en]

    The rotating cylinder method was applied to measure the viscosities of an industrial iron silicate slag and mixtures of this slag with 5, 10 and 15 wt-% alumina addition, in temperature range 1100-1300 C. The measured viscosities were compared with the predicted values using two of the commercially available software products for viscosity calculations, namely Thermoslag®1·5 and FactSageTM6·2. As the models can only predict viscosities for a solid free melt, obtained values by FactSageTM6·2 were modified using the Einstein-Roscoe equation. Results show that aluminium behaves as a network former cation in this type of slag, and by increasing the alumina concentration, the melt becomes progressively polymerised. Consequently, the viscosity of the slag increases at a given temperature, which is supported by thermodynamic predictions. According to the modified FactSage TM6·2 calculations, the viscosity of the solid containing slag increases from 2·1 to 5·5 poise at the industrial operating temperature (∼1250 C).

  • 153. Muhmood, L.
    et al.
    Viswanathan, N. N.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    A new approach for the diffusion coefficient evaluation of sulfur in CaO-SiO2-Al2O3 slag2011In: 6th International Conference on Diffusion in Solids and Liquids, DSL-2010, 2011, p. 626-634Conference paper (Refereed)
    Abstract [en]

    The Diffusion coefficient of sulfur in a ternary slag with composition of 51.5% CaO- 9.6% SiO2- 38.9% Al2O3 was measured at 1723 K by chemical diffusion from the variation of concentration of sulfur in silver metal. A MATLAB program was developed to find the concentration variation of sulfur in silver metal using various critical parameters like the diffusion coefficient of sulfur in slag available in literature, sulfur partition ratio, sulfide capacity of the slag and the its density. The P S2 and PO2 pressures were calculated from the Gibbs energy of the equilibrium reaction between CaO in the slag and solid CaS and confirming the same by using ThermoCalc. The density of the slag at 1723 K was obtained from earlier experiments. Initially the order of magnitude for the diffusion coefficient was taken from the works of Saito and Kawai but later was modified so that the concentration changes of Sulfur obtained from the program agreed with the experimental results. The diffusion coefficient of sulfur in 51.5% CaO- 9.6% SiO2- 38.9% Al2O3 slag at 1723 K was estimated as 4.14×10-6 cm2/sec.

  • 154.
    Muhmood, Luckman
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    A New Insight to Interfacial Phenomena Occurring at Slag-Metal Interfaces2011In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 82, no 12, p. 1375-1384Article in journal (Refereed)
    Abstract [en]

    Interfacial dilatational modulus was evaluated for slag-metal systems using oxygen and sulfur as tracers at 1823?K. The high values of the dilatational modulus (510 times that obtained for surfactant adsorption) was directly related to the higher change in apparent interfacial tension prevailing at the slag-metal interface. The variation in the dilatational modulus was attributed to the non-uniform distribution of surface active elements at the interface and also due to the varying surface pressure. Further, experiments were designed to estimate the surface shear viscosity. A relationship was established to find the surface/interfacial shear viscosity from the Newton's law of viscosity. The order of magnitude of the interfacial shear viscosity at the slag-metal interface was estimated from the values obtained earlier for the interfacial velocity. The order of magnitude obtained for slag-metal systems was roughly 10100 times that usually occurring in colloidal systems. The same could be attributed to the high bulk viscosities of the individual phases in slag-metal systems. The order of magnitude of the interfacial velocity was verified from the equation generated earlier by dimension analysis to be similar to those obtained from experiments.

  • 155.
    Muhmood, Luckman
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Investigations of thermophysical properties of slags with focus on slag-metal interface2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objective of this research work was to develop a methodology for experimentally estimating the interfacial properties at slag-metal interfaces. From previous experiments carried out in the division, it was decided to use surface active elements like sulfur or oxygen to trace any motion at the interface. For this purpose the following experimental investigations were carried out.

    Firstly the density of slag was estimated using the Archimedes Principle and the Sessile Drop technique. The density of the slag would give the molten slag height required for the surface active element to travel before reaching the slag-metal interface.

    Diffusivity measurements were uniquely designed in order to estimate the sulfur diffusion through slag media. It was for the first time that the chemical diffusivity was estimated from the concentration in the metal phase. Experiments carried out validated the models developed earlier.

    The density and diffusivity value of sulfur in the slag was used to accurately capture the time for sulfur to reach the slag-metal interface. The oscillations were identified by calculating the contact angle variations and the interfacial velocity was estimated from the change in the surface area of the liquid iron drop. The interfacial tension was estimated from the contact angles and the interfacial dilatational modulus was calculated.

    Based on cold model experiments using water as well as mercury, an equation of the dependence of the interfacial shear viscosity on the interfacial velocity and interfacial tension was established. This paved way for the estimation of the interfacial shear viscosity at the slag-metal interface.

    The present study is expected to have a strong impact on refining reactions in pyometallurgical industries where slag/metal interfaces play an important role. From a fundamental view point, this provides a deeper insight into interfacial phenomena and presents an experimental technique to quantify the same.

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  • 156.
    Muhmood, Luckman
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Density Measurements of Low Silica CaO-SiO2-Al2O3 Slags2010In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 41, no 4, p. 833-840Article in journal (Refereed)
    Abstract [en]

    Density measurements of a low-silica CaO-SiO2-Al2O3 system were carried out using the Archimedes principle. A Pt 30 pct Rh bob and wire arrangement was used for this purpose. The results obtained were in good agreement with those obtained from the model developed in the current group as well as with other results reported earlier. The density for the CaO-SiO2 and the CaO-Al2O3 binary slag systems also was estimated from the ternary values. The extrapolation of density values for high-silica systems also showed good agreement with previous works. An estimation for the density value of CaO was made from the current experimental data. The density decrease at high temperatures was interpreted based on the silicate structure. As the mole percent of SiO2 was below the 33 pct required for the orthosilicate composition, discrete SiO44- 4 tetrahedral units in the silicate melt would exist along with O-2 ions. The change in melt expansivity may be attributed to the ionic expansions in the order of Al3+ - O2- < Ca2+ - O2- < Ca2+ - O- Structural changes in the ternary slag also could be correlated to a drastic change in the value of enthalpy of mixing.

  • 157.
    Muhmood, Luckman
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Semykina, Anna
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Iwase, Masanori
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Some Novel Studies of Thermodynamics, Kinetics and Transport Phenomena in Slags2012In: High Temperature Materials and Processes, ISSN 0334-6455, E-ISSN 2191-0324, Vol. 31, no 4-5, p. 351-358Article in journal (Refereed)
    Abstract [en]

    The following paper revolves around the research work conducted in collaboration during Professor Iwase's brief visits to the Materials Process Science Division at Royal Institute of Technology, Stockholm. The paper focuses on the thermodynamic aspects of CaOFeO-SiO2 and CaO-FeO-SiO2-MnO slag oxidation in air and sulfur transport through CaO-Al2O3-SiO2 slag. Thermodynamics of slag oxidation in air opens potential new areas in terms of focus on effective recovery of iron oxide from slag. The slag transport studies are of fundamental nature and focuses on a novel technique to calculate the diffusion of species through slag by analyzing its corresponding concentration in the metal phase.

  • 158.
    Muhmood, Luckman
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Viswanathan, Nurni Neelakandan
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Studies of dynamic mass transfer at the slag-metal interface - Interfacial velocity measurements2012In: International Journal of Materials Research - Zeitschrift für Metallkunde, ISSN 1862-5282, E-ISSN 2195-8556, Vol. 103, no 7, p. 875-883Article in journal (Refereed)
    Abstract [en]

    The dynamics of oxygen transport along the slag-metal interface of pure iron and alumina-saturated CaO-Al2O3-SiO2 slag was studied using high-temperature X-ray image analysis. The oscillations of the metal drop occurring due to the interfacial movement of oxygen atoms driven by Marangoni forces were studied in detail. The change in interfacial area during the oscillations was measured using a digitizing software and MATLAB. It was observed that the interfacial velocity as a function of oxygen exhibits insignificant variation with temperature. Further, the values obtained for the interfacial velocity using oxygen concentration difference at the interface were slightly lower in comparison to those using sulfur. The possible reason for this lower velocity could be that, although oxygen is a smaller atom compared to that of sulfur, the energy barrier at the free iron surface is higher for oxygen, thus hindering its motion along the interface.

  • 159. Mukai, K.
    et al.
    Matsushita, Taishi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Mills, K. C.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Furuzono, T.
    Surface tension of liquid alloys - A thermodynamic approach2008In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 39, no 4, p. 561-569Article in journal (Refereed)
    Abstract [en]

    A formula is derived to describe the surface tensions of binary and dilute multicomponent alloys such as iron alloys. It was thermodynamically proved that the surface tension can be described by a function of the concentrations of the alloy components in bulk phase through the use of thermodynamic parameters. The formula was applied to the binary alloys, Fe-O-N and Fe-O-S systems. The described surface tensions were found to be in good agreement with the measured values.

  • 160. Mukai, K.
    et al.
    Matsushita, Taishi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Motion of fine particles in liquid caused by interfacial tension gradient in relation to metals separation technologies2005In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 34, no 2, p. 137-142Article in journal (Refereed)
    Abstract [en]

    Some ideas for promoting the metal separation process are proposed based on the consideration of the force caused by interfacial tension gradient as a driving force. The force drives the particle toward the direction of the lower interfacial tension side, which has been confirmed by water model experiments. Therefore, it is possible to move fine metal particles by producing interfacial tension gradient between fine metal particles and molten slag. The force in molten slag-metal (iron) system was evaluated under some assumptions. The evaluation indicates that the force is enough large to engulf the fine metal particle by the interface between metal particle and slag for promoting metal separation process.

  • 161.
    Muwanguzi, Abraham Judah Bumalirivu
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Jonsson, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Byaruhanga, J.
    State of the Art on the Exploration of Ugandaá Iron Ore for the Manufacture of Iron and Steel in Uganda2009Report (Other academic)
  • 162.
    Nakano, Anna
    et al.
    KTH. US DOE, USA.
    Nakano, Jinichiro
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Synthesis of nano-manganese ferrite by an oxalate method and characterization of its magnetic properties2015In: International Journal of Materials Research - Zeitschrift für Metallkunde, ISSN 1862-5282, E-ISSN 2195-8556, Vol. 106, no 12, p. 1264-1268Article in journal (Refereed)
    Abstract [en]

    In this work, nano-sized manganese ferrite (MnFe2O4) was synthesized through the decomposition of the mixed oxalates. The formation of the spinel manganese ferrite was confirmed by X-ray diffraction analysis. The morphology of the ferrite products was studied by scanning electron microscopy. The particle size, which was determined using the Scherrer formula, ranged from 25 to 30 nm. Magnetic properties of the manganese ferrite were analyzed using a vibrating sample magnetometry technique; a narrow hysteresis loop indicated the MnFe2O4 obtained was a soft ferromagnet. Magnetic properties of the manganese ferrite produced were in agreement with those reported in literature for MnFe2O4 nanoparticles prepared by conventional methods, including co-precipitation and mechanochemical processes. By plotting a series of literature data determined by different authors and techniques, a correlation between saturation magnetisation and particle size has been noted regardless of the synthesis methods. In general, the oxalate method seems to be able to produce nano-manganese ferrite in a shorter time (2-3 h) as compared to other conventional techniques reported in literature (up to 54 h).

  • 163.
    Nassar, Hani
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Peritectic Reactions and Transformations in Low-Alloy Steels2010In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 41A, no 11, p. 2776-2783Article in journal (Refereed)
    Abstract [en]

    Differential thermal analysis (DTA) experiments on low-alloy steels with varying C, Si, Cr, and Mo contents indicated an increase in the difference between the liquidus and peritectic temperatures during solidification with the decrease in C and increase in Mo contents. In a number of the quenched samples, massive transformations of ferrite to austenite were observed. Electron microprobe analysis of the diffusion across a massive transformation front, along with the high growth rates estimated, gives strong reason to believe that these growths are uncontrolled by diffusion. As ferrite transforms to austenite during the peritectic reaction, shrinkage in volume occurs, causing elastic straining at the interface separating the two phases. It was shown through thermodynamic analysis of the equilibrium at the triple point that the increase in energy of the two phases due to this strain can result in undercooling below the equilibrium peritectic temperature and decreases in the equilibrium peritectic concentrations.

  • 164. Nezafati, Maysam
    et al.
    Persson, Dan
    Savage, Steven J.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Corrosion Properties of Zr55Cu30Ni5Al10 Bulk Metallic Glass and Conventional Metallic Alloys for Biomedical Implants2010Conference paper (Other academic)
  • 165.
    Orrling, Diana
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Towards Abatement of Selected Emissions from Metals Manufacturing2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    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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    FULLTEXT29
  • 166.
    Orrling, Diana
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Fitzgerald, E.
    Department of Chemistry and Biochemistry, University of California.
    Ivanov, A.
    Department of Chemistry and Biochemistry, University of California.
    Molina, M.
    Department of Chemistry and Biochemistry, University of California.
    Enhanced Sulfate Formation on Ozone-Exposed Soot2011In: Journal of Aerosol Science, ISSN 0021-8502, E-ISSN 1879-1964, Vol. 42, no 9, p. 615-620Article in journal (Refereed)
    Abstract [en]

    Gas phase experiments were conducted to examine the heterogeneous oxidation of sulfur dioxide on methane soot in the presence of ozone and water vapor. The enhanced formation of sulfate at atmospheric pressure was confirmed by the use of a particle-into-liquid sampler (PILS) coupled with ion chromatography (IC). 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 formation of sulfuric acid and also likely the formation of carboxyl groups on the surface. The sulfate yield increased with ozone levels, but no increase was observed at ozone concentrations above 1000 ppm.

  • 167. Persson, Dan
    et al.
    Nezafati, Maysam
    Martin, Camille
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Savage, Steven J.
    Corrosion Properties of Zr55Cu30Ni5Al10 Bulk Metallic Glass and Conventional Metallic Alloys with Respect to use as a Medical Implant Material2011Conference paper (Refereed)
  • 168. Persson, Mikael
    et al.
    Matsushita, Taishi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Zhang, Jiayun
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Estimation of molar volumes of some binary slags from enthalpies of mixing2007In: Steel Research International, ISSN 1611-3683, Vol. 78, no 2, p. 102-108Article in journal (Refereed)
    Abstract [en]

    In an effort to interlink the thermo chemical and thermo physical properties of slags, the present work was undertaken to derive the molar volumes of complex slags from the enthalpies of mixing of the corresponding slags. As a first step, binary systems of the following oxides were investigated; Al2O3, CaO, FeO, MgO, MnO, and SiO2. An empirical correlation was derived between the enthalpies of mixing and molar volumes. A comparison of the computed results on the basis of the above relationship with the experimental data on molar volumes available in literature shows that the agreement between the calculated results and measured densities is satisfactory in the case of most of the binary systems, within the limits of experimentally uncertainties. The advantage of the present approach is that it would enable prediction of molar volumes of slags that are compatible with the thermodynamic data available.

  • 169.
    Persson, Mikael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Seetharaman, Sridhar
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Kinetic studies of fluoride evaporation from slags2007In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 47, no 12, p. 1711-1717Article in journal (Refereed)
    Abstract [en]

    In view of the environmental problems associated with the evaporation of fluoride from slags and fluxes, a systematic study of the fluoride emission from slags at temperatures, relevant to steelmaking and casting, has been initiated in the present work. The loss of fluoride from slag melts was monitored by Thermogravimetric Analysis (TGA). The present paper reports the fluoride evaporation in the three binary systems Al2O3-SiO2, CaC-SiO2 and MgO-SiO2 with additions of CaF2 (ca. 3.5, 5 and 9 wt%). The thermogravimetric experiments were carried out in argon atmosphere in the isothermal mode in the temperature range 1673-1873 K. The gas flow was kept above the starvation rate in order to avoid the gas phase mass transfer step. From the results, the Arrhenius activation energies for the evaporation reaction were evaluated. The activation energies were found to be dependent on temperature and slag chemistry for the various slags studied. In binary systems, the activation energy for fluoride evaporation was found to depend on the square of the activity of SiO2 in the slag melt. This correlation obtained in the case of the binary systems could be validated in the case of the results obtained for the ternary system Al2O3-CaO-SiO2 with 5 and 10 wt% of CaF2, The present results are considered to be useful in estimating the fluoride emissions from industrial slags and mould fluxes.

  • 170. Ricci, E.
    et al.
    Giuranno, D.
    Novakovic, R.
    Matsushita, Taishi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Brooks, R.
    Chapman, L. A.
    Quested, P. N.
    Density, surface tension, and viscosity of CMSX-((R)) superalloy2007In: International journal of thermophysics, ISSN 0195-928X, E-ISSN 1572-9567, Vol. 28, no 4, p. 1304-1321Article in journal (Refereed)
    Abstract [en]

    The surface tension, density, and viscosity of the Ni-based superalloy CMSX-4((R)) have been determined in the temperature ranges of 1,650-1,850 K, 1,650-1,950 K, and 1,623-1,800 K, respectively. Each property has been measured in parallel by different techniques at different participating laboratories, and the results are compared with the aim to improve the reliability of data and to identify recommended values. The following relationships have been proposed: density-rho (T) [kg.m(-3)] = 7,876 - 1.23(T - 1,654 K); surface tension-gamma (T) [mN.m(-1)] = 1,773 - 0.56 (T - 1, 654 K); viscosity-eta (T) [mPa.s] = 8.36 - 1.82 x 10(-2)(T - 1,654 K). For a comparison, surface-tension measurements on the Al-88.6 at% Ni liquid alloy with the same Al-content as the CMSX-4((R)) alloy were also performed. In addition, the surface tension and density have been theoretically evaluated by different models, and subsequently compared with new experimental data as well as with those reported in the literature. The surface-tension experimental data for the liquid CMSX-4((R)) alloy were found to be close to that of the A1-88.6 at% Ni alloy which is consistent with results from the compound formation model (CFM).

  • 171.
    Roseborough, Diana
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Gustavsson, I.
    Kimab.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Surface composition of industrial metal samples with potential for atmospheric mercury deposition2010Report (Other academic)
    Abstract [en]

    Laser Ablation Inductively Coupled Plasma Time of Flight Mass Spectrometry, Auger electron spectroscopy and X-ray photoelectron spectroscopy were used to study atmospherically exposed metal samples for surface mercury concentration at room temperature. The metals were collected from industrial and pre-conditioned sources. In most cases, mercury detection was impossible because the samples were found to be highly contaminated from sources such as oxygen, carbon, chlorine and sulfur. However, the methods were effective at determining surface atoms and bulk substrate atoms that may be surface diffusive. Depth profiling was conducted on the samples that were found to contain mercury.

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  • 172.
    Roseborough, Diana
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    The surface behavior of mercury on iron systems2006In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 37, no 6, p. 1049-1056Article in journal (Refereed)
    Abstract [en]

    Thermal desorption Auger electron spectroscopy (TDAES) was used to investigate the circumstances under which mercury is adsorbed on the surface of iron in the temperature interval of 85 to 298 K. The effects of chlorine and oxygen modifications on the iron surface have also been investigated within the same temperature interval. It was seen that chlorine reduced the adsorption of mercury on polycrystalline iron at 85 K, as did oxygen. On the clean iron system at 298 K, only one monolayer (ML) of mercury adsorbed. The physisorption of mercury on chlorine and oxygen layers at low temperatures (LTs) is discussed in combination with the calculated activation energies of desorption, as well as the factors affecting the mechanism of adsorption at room temperature.

  • 173.
    Roseborough, Diana
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Palmgren, P.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Surface chemistry of mercury on zinc and copper2006In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 37, no 6, p. 1057-1066Article in journal (Refereed)
    Abstract [en]

    Thermal desorption Auger electron spectroscopy (TDAES) was used to investigate mercury adsorption on the surfaces of zinc (Zn) and copper (Cu) in the temperature interval of 85 to 298 K. The effects of chlorine and oxygen modifications on the surfaces have also been investigated within the same temperature interval. On single crystalline Zn(0001), no mercury was adsorbed under any temperature or deposition conditions. On polycrystalline Zn at 85 K, a monolayer (ML) of mercury adsorbed, whereas no measurable quantity was observed at room temperature (RT). Predeposited chlorine was removed by exposure to mercury, most probably through formation of volatile HgCl2. Chlorine enhanced the adsorption of mercury on polycrystalline Cu at 87 K, whereas preoxidation reduced the coverage. Low temperatures (LTs) were conducive to mercury adsorption as compared to 298 K for the Cu systems studied. The physisorption of mercury on chlorine and oxygen layers at LTs is discussed, as well as the factors affecting the mechanism of adsorption at RTs. The desorption energies and surface enthalpies have been calculated for each system with mercury adsorption.

  • 174. Sahajwalla, V.
    et al.
    Khanna, R.
    Kapilashrami, E.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Depletion of carbon from Al2O3-C mixtures into liquid iron: Rate controlling mechanisms2007In: Canadian metallurgical quarterly, ISSN 0008-4433, E-ISSN 1879-1395, Vol. 46, no 1, p. 25-32Article in journal (Refereed)
    Abstract [en]

    A sessile drop investigation on the kinetics of carbon dissolution from an alumina-carbon composite (75% C, 25% alumina) and a commercial refractory (28.3% C, 66.67% alumina, 5% binder) into liquid iron at 1600 degrees C is reported. Carbon dissolution from refractory substrates was very slow reaching 0.84% C and 0.1% C, respectively after 60 minutes. Both substrates also showed poor wettability. Experimental studies were supplemented with atomistic Monte Carlo simulations to investigate the influence of composition, temperature and melt turbulence. High carbon systems (100% C and 75% C, balance alumina) were affected by both temperature and melt turbulence to some extent; increased levels of melt turbulence/higher temperatures had no influence on low carbon (30% C) system. While mass transfer was the dominant rate controlling mechanism for high carbon systems, poor wettability of alumina with liquid iron and its significant influence on inhibiting the penetration of liquid iron in the refractory matrix was found to be the dominant rate controlling factor for low carbon refractories.

  • 175.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Fundamentals of metallurgy2005Book (Other academic)
    Abstract [en]

    As product specifications become more demanding, manufacturers require steel with ever more specific functional properties. As a result, there has been a wealth of research on how those properties emerge during steelmaking. Fundamentals of metallurgy summarises this research and its implications for manufacturers. The first part of the book reviews the effects of processing on the properties of metals with a range of chapters on such phenomena as phase transformations, types of kinetic reaction, transport and interfacial phenomena. Authors discuss how these processes and the resulting properties of metals can be modelled and predicted. Part two discusses the implications of this research for improving steelmaking and steel properties.

  • 176.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Process Metallurgy-An Argosy Through Time2013In: Treatise on Process Metallurgy, Elsevier, 2013, Vol. 1, p. 1-13Chapter in book (Refereed)
  • 177.
    Seetharaman, Seshadri
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Andersson, G.
    Teng, Lidong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Retainment, Recovery and Recycling: A Swedish Success Story of ECO-Steelmaking2013In: Transactions of the Indian Institute of Metals, ISSN 0972-2815, Vol. 66, no 5-6, p. 567-575Article in journal (Refereed)
    Abstract [en]

    With a view to optimize the environmental aspects of steelmaking, the Swedish Steel Producers Association took the initiative to start a national project on ECO-steelmaking with financial support from Swedish Foundation for Strategic Environmental Research. The Division of Materials Process Science at the Royal Institute of Technology has an important part of the project, viz. "Retention, Recovery and Recycling", with emphasis on the retention of metal values in the steel bath without loss to the slag or gas phases, to recover the metal values that are lost to the slag phase by the development of new or optimized process concepts and aim at a total recycling of the metal values as well as the slag components within or outside the steel sector. The present paper describes the optimization of existing process concepts as well as evolving newer concepts to meet the above project goals. The use of CO2-O-2-Ar gas mixtures for the decarburization of high-alloyed steels, development of a low cost precursor for the addition of molybdenum to steel in EAF, direct alloying in EAF are some of the concepts initiated in the present work. Successful recovery of iron and manganese values by oxidation of the slag and separation of the magnetite or manganese ferrate by electromagnetic separation formed part of the recovery part. As part of the project, a salt extraction process was developed by which the metal values in slags could be extracted into a chloride phase followed by electrolysis in fused chloride medium. This method was found to be successful in the recovery of metal values from slags. This process could be extended to the recovery of a variety of metal values from a variety of secondary sources. The salient features of the process designs and the results are presented in this paper.

  • 178.
    Seetharaman, Seshadri
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Jelkina Albertsson, Jelkina
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Scheller, Piotr
    TU Bergakademie Freiberg.
    Studies of Vaporization of Chromium from Thin Slag Films at Steelmaking Temperatures in Oxidizing Atmosphere2013In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 44, no 5, p. 1280-1286Article in journal (Refereed)
    Abstract [en]

    In the present work, the volatilization of chromium from thin chromium-containing slag film surfaces was studied in oxidizing atmosphere in the temperature range 1673 K to 1873 K (1400 A degrees C to 1600 A degrees C). The slag films on alumina rings were exposed to air or pure oxygen and the loss of Cr from the post-experiment sample films was examined by SEM/WDS analysis. The mass loss of the samples was also monitored during the heat-treatment. The results indicate that chromium loss increased with increase in temperature and oxygen partial pressure was found also to be relatively less as the sample thickness increased. The implications of chromium escape from slags during the tapping of stainless steel slags are discussed.

  • 179.
    Seetharaman, Seshadri
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    McLean, A.
    Guthrie, R.
    Sridhar, S.
    Preface2013In: Treatise on Process Metallurgy: Volume 1: Process Fundamentals, Elsevier, 2013, Vol. 1, p. xvii-xxChapter in book (Other academic)
  • 180.
    Seetharaman, Seshadri
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    McLean, A.Guthrie, R.Sridhar, S.
    Treatise on Process Metallurgy2013Collection (editor) (Refereed)
    Abstract [en]

    Process metallurgy provides academics with the fundamentals of the manufacturing of metallic materials, from raw materials into finished parts or products. Coverage is divided into three volumes, entitled Process Fundamentals, encompassing process fundamentals, extractive and refining processes, and metallurgical process phenomena; Processing Phenomena, encompassing ferrous processing; non-ferrous processing; and refractory, reactive and aqueous processing of metals; and Industrial Processes, encompassing process modeling and computational tools, energy optimization, environmental aspects and industrial design.

  • 181.
    Seetharaman, Seshadri
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Mukai, K.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Viscosities of slags - an overview2005In: Steel Research International, ISSN 1611-3683, Vol. 76, no 4, p. 267-278Article in journal (Refereed)
    Abstract [en]

    Viscosities of slags constitute an important physical property needed for an understanding of the mass transfer phenomena in metallurgical processes. Viscosity is also the key that leads to a better understanding of the structure of slags. It is well-known that the viscosities of silicate slags decrease with the addition of basic oxides due to the breaking of the silicate network. The measurements of slag viscosities often pose experimental challenges, especially with respect to the choice of materials. This paper takes up the experimental problems and the various techniques adopted. Dynamic viscosity measurement, as a powerful tool towards an understanding of the kinetics of some high temperature reactions is brought out. A number of semi-empirical models have been developed to estimate the slag viscosities in the case of multicomponent slags. A critical survey of these models is presented in this paper. Earlier models by Riboud et al., Urbain et al. and Mills et al. have been developed further into a new generation of models. Some of the current important models are, (1) Model by lida et al., ( 2) CSIRO model, (3) Pyroresearch Model, (4) Model by Tanaka et al., (5) Model approach by Reddy et al., and (6) KTH-model. The predictions and capabilities of the various models are compared. Estimations of viscosities from thermodynamic data and prediction of liquidus temperatures from viscosities are presented. The concept of surface viscosities with reference to slags and viscosities of two-phase mixtures are also taken up in the presentation.

  • 182.
    Seetharaman, Seshadri
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Teng, Lidong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Hayashi, Miyuki
    Wang, Lijun
    Understanding the Properties of Slags2013In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 53, no 1, p. 1-8Article, review/survey (Refereed)
    Abstract [en]

    Understanding of the properties of slags is a pre-requisite in optimizing their functions towards the making and refining of steel. Important contributions towards this objective have been made over the past half a century, in different parts of the world, especially in USA, UK, Germany and most of all in Japan. Knowledge of the slag properties enables in understanding the slag structure as well. The present review paper summarizes the contributions made in this field by the Division of Materials Process Science, Royal Institute of Technology, Stockholm, Sweden. The paper deals with the measurement and modeling of (a) thermochemical properties of slags, (b) thermophysical properties and (c) inter-property correlations. Some important contributions during recent years, such as the determination of the valence states of Cr and V in slags, wetting characteristics related to hot-metal desulphurization, diffusion of sulphide ions in slags, partition of phosphorus between slag and metal phases and studies on process phenomena such as foaming are highlighted. The research work has led to the evolution of a new basicity concept. Dynamic physical property measurements are pointed out to be an experimental tool towards understanding of reaction mechanisms. Developments with respect to slag/metal interfacial phenomena, viz, the concept of surface velocity and surface viscosity and quantification of these properties are presented.

  • 183.
    Seetharaman, Seshadri
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Wang, Lijun
    A glimpse into the mystery of slags - by physicochemical measurements2013In: High Temperatures-High Pressures, ISSN 0018-1544, E-ISSN 1472-3441, Vol. 42, no 2, p. 97-114Article in journal (Refereed)
    Abstract [en]

    Measurements of the physicochemical properties of slags such as thermodynamic activities and viscosities have been very useful, not only from a process metallurgical view point, but also towards understanding of slag structure, which still remains a mystery. This paper presents some measurements of the slag properties carried out at the Royal Institute of Technology, Stockholm as well as at TU-Bergakademie, Freiberg, Germany that provide a unique insight into the structure of slags. The measurements include sulphide capacities of slags in the region between ortho- and meta- silicate compositions, which could be explained on the basis of the polymerization of silicates. Density measurements of aluminosilicate slags provide an insight into the relative bond strengths. Measurements of the chemical diffusivities have been carried out. This enables an understanding of the affinity of sulphide ions in the molten silicate. The surface velocity and viscosity measurements provide an understanding of the surface bondings between sulphur/oxygen and Fe atoms. The latest experimental technique developed jointly in Germany and Sweden provides a glimpse into the evaporation phenomena on thin slag films. The need for the application of newer experimental methods in the study of slag properties is emphasized in the present paper.

  • 184.
    Semykina, Anna
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Recovery of iron and manganese values from metallurgical slags by the oxidation route2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the modern practice, a sustainable development strategy in a domain of wasteutilization is shifting its focus from a general completeness of recycling to a morespecific attention to efficiently utilize elements in the wastes. This is well-illustrated bythe steelmaking slag industries. The major waste product from the steelmaking practiceis slag and its main constituents are: CaO, SiO2, Al2O3, MnO, FeO and so on. The mainfield of application for the steelmaking slags is civil engineering, especially for road andwaterway construction. However, a significant amount of the slag remains in the dumps,damaging the environment as well as requiring a land for secure storage. Efficientrecycling of these materials is of increasing interest worldwide as a result of increasingsustainability in processes with respect to increasing raw material costs and wastereduction.In order to find a practical solution, joint efforts are currently made at the RoyalInstitute of Technology, Sweden and National Metallurgical Academy of Ukraine. Theconcept is based on transformation of non-magnetic wüstite (FeO) to magneticmagnetite (Fe3O4) using an oxidizing atmosphere was proposed.In order to verify the feasibility of the proposed way of slag utilization, experiments onthe ternary CaO-FeO-SiO2 and quaternary CaO-FeO-SiO2-MnO slags systems,accompanied by thermodynamic and kinetic modelling, were performed. The crystalprecipitation during synthetic slag oxidation was observed by Confocal Scanning LaserMicroscopy (CSLM). Precipitated phases were found to be magnetite and manganeseferrite in the spinel form.Obtained magnetite and manganese ferrite can be separated from the slag by magneticseparation.The formation of nanosize manganese ferrite from the CaO-FeO-SiO2-MnO slag systemduring oxidation was investigated. Experiments were conducted in a horizontalresistance furnace in an oxidizing atmosphere (air). The final product was analysed by Xraydiffraction (XRD). The particles size of the manganese ferrite was estimated by theScherrer formula and was found to be of the order of 23-25 nm. In order to get anunderstanding of the magnetic properties of the manganese ferrite recovered from slagtreatment, it was necessary to synthesize a reference compound from pure precursors.The MnFe2O4 nanopowder was synthesized by the oxalate route. The size effects on themagnetic properties of manganese ferrite particles were investigated.IIThe potential way of the magnetite particles separation from liquid slags was investigatedby cold model studies. The experimental technique of mobilising non-conducting,nonmagnetic particles in conducting liquid in crossed electric and magnetic fields wasinvestigated in order to find the way of the particle separation from the liquidsteelmaking slags. The effects of the current density, magnetic field, size and shape ofthe particle on the particle velocity under action of the electromagnetic buoyancy force(EBF) in the electrolyte were analyzed.

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  • 185.
    Semykina, Anna
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    The Kinetics of Oxidation of Liquid FeO-MnO-CaO-SiO2 Slags in Air2012In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 43, no 1, p. 56-63Article in journal (Refereed)
    Abstract [en]

    The oxidizing kinetics of the liquid FeO-MnO-CaO-SiO(2) slags in air has been studied in the temperature range of 1500 K to 1600 K (1227 A degrees C to 1327 A degrees C) by using a thermogravimetric analysis (TGA). The reaction products after oxidation were analyzed by X-ray diffraction analysis (XRD). The surface topography of the obtained samples was analyzed by scanning electron microscopy (SEM). The products after oxidation showed the presence of manganese ferrite/magnetite and calcium silicate for all the samples in the experimental temperatures range. The oxidation process was developed through the following three consequent steps: (1) incubation period followed by a chemical reaction controlled stage (2) and later (3) diffusion of oxygen through the product layer. Appropriate mathematical relationships were constructed for these steps. Combining equations corresponding to the mechanism of oxidation, the experimental results were consistently reproduced, validating thereby the theoretical analysis.

  • 186.
    Semykina, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Belova, Lyubov
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Synthesis of nano-manganese ferrite by an oxalate method and its magnetic properties characterization2010Report (Other academic)
  • 187.
    Semykina, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Dzhebian, Iryna
    Shatokha, Volodymyr
    On the Formation of Vanadium Ferrites in CaO-SiO2-FeO-V2O5 Slags2012In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 83, no 12, p. 1129-1134Article in journal (Refereed)
    Abstract [en]

    Selective extraction of valuable elements (such as V, Cr, Mn, etc.) and their compounds from metallurgical slag is in a focus of many researchers. Although vanadium may be present in slag as oxides and/or complex spinels with Fe, Mn, etc. during an alloyed steel production, the majority of vanadium in metallurgical slags typically exists as V2O5, which comprises up to 35wt% of the slag in some cases. Due to the vanadium toxicity, these slags are forbidden in many civil engineering applications. As a result, hundreds of thousand tonnes of V2O5-bearing slags are landfilled every year. In the present work, the formation of vanadium ferrites (FeV2O4 and Fe2VO4) in synthesized CaOSiO2FeOV2O5 slags containing 5 wt% V2O5 was examined under different partial pressures of oxygen. For the current slag chemistry range, an XRD analysis confirmed the presence of vanadium ferrite in slag samples treated at 1773 K in an argon atmosphere (PO2 = 10(-1)10(-2) Pa) while no solid was noted in samples treated in air. Results were discussed based on thermodynamic consistency.

  • 188.
    Semykina, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Gorobets, O.
    Shatokha, V.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Cold Simulation of Particle Movement in a Conducting Liquid under Crossed Electric and Magnetic Fields. Magnetite Particles Separation from Molten Slags2011In: STEEL RES INT, ISSN 1611-3683, Vol. 82, no 4, p. 362-368Article in journal (Refereed)
    Abstract [en]

    The experimental technique of mobilising non-conducting, nonmagnetic particles in conducting liquid in crossed electric and magnetic fields was investigated in order to find the way of the particle separation from the liquid steelmaking slags. The effect of the current density, magnetic field, size and shape of the particle on the particle velocity under action of the electromagnetic buoyancy force (EBF) in the electrolyte was analysed. Potential way of the application of obtained results to magnetite particle separation from liquid EAF slags are discussed.

  • 189.
    Semykina, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Gorobets, O.
    Shatokha, Volodymyr
    Seeetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Investigation of the potential way of the magnetite particles separation from liquid EAF slags2010In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArticle in journal (Other academic)
  • 190.
    Semykina, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Nakano, Jinichiro
    Seetharaman, Sridhar
    Shatokha, Volodymyr
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Confocal Microscopic Studies on Evolution of Crystals during oxidation of the FeO-CaO-SiO2-MnO Slags2010In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 41, no 5, p. 940-945Article in journal (Refereed)
    Abstract [en]

    The current work investigates dynamic phenomena at the microstructural level during iron and manganese recovery from the liquid FeO-CaO-SiO2-MnO slags using an oxidation method. A hot-stage-equipped confocal scanning laser microscope (CSLM) was used to analyze the kinetic behavior of crystallization in synthetic slags. Based on observed precipitations on cooling in the 1273 K (1000 °C) to 1873 K (1600 °C) temperature range, a time–temperature–transformation (TTT) diagram has been created. The crystallization studies were conducted in air.

  • 191.
    Semykina, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Nakano, Junichiro
    Sridhar, Seetharaman
    Shatokha, Volodymyr
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Confocal Scanning Laser Microscopy studies of crystal growth during oxidation of a liquid FeO-CaO-SiO2 slag2011In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 42, no 3, p. 471-476Article in journal (Refereed)
    Abstract [en]

    The oxidation of FeO in 30 wt pct FeO-35 wt pct CaO-35 wt pct SiO2 slag was investigated as part of a wider study on the recovery of Fe units through magnetic separation. A confocal scanning laser microscopy (CSLM) technique was used to visualize the oxidation of FeO in the liquid slag. The formation event was observed in situ under the CSLM and the onset of precipitation on a surface of the slag liquid was recorded at various temperatures in an oxidizing atmosphere. A Time-Temperature-Transformation (TTT) diagram was constructed based on the CSLM results. Samples obtained from the CSLM heating chamber were analyzed by a scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS).

  • 192.
    Semykina, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshaddri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Recovery of manganese ferrite in nanoform from the metallurgical slags2011In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 42, no 1, p. 2-4Article in journal (Refereed)
    Abstract [en]

    The present work investigates the formation of manganese ferrite of nanosize by oxidation of MnO- and FeO-containing slag. A horizontal resistance furnace was used as an experimental setup. The experiment was conducted in the temperature range of 1573 K to 1673 K (1300 A degrees C to 1400 A degrees C) in an oxidizing atmosphere. The samples were quenched to the cold end of the furnace and were analyzed by X-ray diffraction (XRD). The XRD patterns of the products showed the presence of two phases-manganese ferrite and calcium silicate. The particle size of the manganese ferrite was estimated by the Scherrer formula to be in the range of nanometers.

  • 193.
    Semykina, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Shatokha, V.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Innovative approach to recovery of iron from steelmaking slags2010In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 37, no 7, p. 536-540Article in journal (Refereed)
    Abstract [en]

    The present work is aimed at the development of a new sustainable method for the utilisation of valuable elements from the steelmaking slag. In the framework of the innovative concept earlier proposed by the authors for utilisation of steelmaking slags, oxidation of iron mono-oxide in the liquid slag was studied experimentally in different atmospheres and in the temperature range 1623-1823 K using thermogravimetry technique. Synthetic (binary and ternary slag system) as well as industrial steelmaking slags were used in the experiments. Analysis of the reaction products was carried out using X-ray diffraction method. A possibility to transform the nonmagnetic iron bearing compounds to magnetite in the steelmaking slag by oxidation has been confirmed.

  • 194.
    Semykina, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Shatokha, Volodymyr
    Iwase, Masanori
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Kinetics of oxidation of divalent iron to trivalent state in liquid FeO-CaO-SiO2 slags2010In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 41, no 6, p. 1230-1239Article in journal (Refereed)
    Abstract [en]

    This work was devoted to the kinetics studies of the oxidation of divalent iron in liquid FeO-CaO-SiO2 slags to the trivalent state. The experiments were carried out using a thermogravimetric technique (TGA) in the temperature range of 1623 K to 1773 K (1350 °C to 1500 °C) in an oxidizing atmosphere. The reaction products after oxidation were analyzed by X-ray diffraction and optical and scanning electron microscopy. The results obtained show that during the first 10 to 15 minutes of oxidation, 70 to 90 pct of the Fe2+ in the slag was oxidized. Kinetic analysis of the TGA results indicates that the oxidation process may consist of three distinct steps, viz an initial incubation period, followed by a chemical-reaction-controlled stage, and later, a diffusion-control stage. Appropriate mathematical relationships were set up for the first two consecutive steps. After combining these equations suitably as the mechanism of oxidation shifts from one form to another, the experimental results for the first two parts could be reproduced. A linear correlation was found between the thermodynamic activity of FeO in the slag and the degree of oxidation.

  • 195. Shankar, A.
    et al.
    Gornerup, M.
    Lahiri, A. K.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Estimation of viscosity for blast furnace type slags2007In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 34, no 6, p. 477-481Article in journal (Refereed)
    Abstract [en]

    A viscosity model based on a new definition of basicity has been proposed for blast furnace type slags. Conceptually, this definition of basicity is close to Bell's definition of basicity as used for modelling of sulphide capacity of blast furnace type slags. The model developed in the present work is applicable for wide range of alumina, magnesia and titania containing blast furnace slags, while most of the models available in the literature are mainly applicable for a limited range of slag composition. Viscosity estimation by this model is close to the experimental value for all types of blast furnace slags. This model is based on the chemical composition of slag and is applicable for slags above liquidus temperature.

  • 196. Shatokha, V.
    et al.
    Semykina, Anna
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Nakano, J.
    Sridhar, S.
    Seetharaman, Seetharaman
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    A study on transformation of some transition metal oxides in molten steelmaking slag to magnetically susceptible compounds2013In: Journal of Mining and Metallurgy, Section B: Metallurgy, ISSN 1450-5339, Vol. 49, no 2, p. 169-174Article in journal (Refereed)
    Abstract [en]

    Sustainable development of steelmaking requires solving a number of environmental problems. Economically feasible and environmentally friendly recycling of slag wastes is of special concern. Research of the team representing National Metallurgical Academy of Ukraine, Royal Institute of Technology, Carnegie Mellon University and URS Corp revealed a possibility of the controlled phase transformations in the liquid silicate melts followed by formation of the magnetically susceptible compounds. This approach enables selective recovery of metal values from slag. In this paper, the results obtained and further research directions are discussed. A possibility to exploit physical properties of the transition metals, typical for the metallurgical slags (such as Fe, Mn, V and others), and corresponding specific properties of their compounds, such as non-stoichiometry, mixed valency, pseudomorphosis, thermodynamic stability etc, in production of value-added materials from slag wastes is discussed. The results of the studies of thermodynamics and kinetics of oxidation in slags followed by phase transformation with binary, ternary and complex oxides under various physicochemical conditions are discussed in the view of their application for production of the materials with predefined physical properties. Peculiarities of precipitation in slags with various basicities are analysed and demonstrate capacity of the proposed approach in the production of the material with a given structure and size - for example, nano-sized crystals with structure of spinel. The approaches towards industrial realization of the developed method are also discussed.

  • 197. Sterneland, Therese
    et al.
    Markstrom, Andreas
    Norgren, Susanne
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Investigation of (Cr,Co)(7)C-3-fcc-graphite equilibrium in the temperature interval 1373 to 1473 K2006In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 37A, no 10, p. 3023-3028Article in journal (Refereed)
    Abstract [en]

    In the current study, the phase equilibria between fee, graphite and M7C3 (M = Cr,Co) have been studied at 1373 degrees K, 1423 degrees K, and 1473 degrees K. The solubility of Co in the M7C3 phase and the solubility of Cr and C in the fee phase have been determined by the high-temperature equilibration and quenching technique. Appropriate mixtures of Cr7C3 + Co or Cr7C3 + Co + C were equilibrated and subsequently quenched in liquid nitrogen. The quenched samples were characterized by X-ray diffraction and by metallographic examination. The studies were carried out on the samples to determine the homogeneity of the sample as well as the phases and their composition. From the results, the compositional regions of the three-phase triangle M7C3 + fee + graphite could be accurately determined. The results show that the Co solubility in the Cr7C3 in the experimental temperature interval is higher than previous investigations performed at higher temperatures.

  • 198.
    Tabeshian, Ali
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Production, Characterization and Electrochemical Properties of Advanced Bulk Metallic Glasses for Hip Implant Applications2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of the present project was to investigate the possibilities of using a Zr55Cu30Ni5Al10 Bulk Metallic Glass (BMG) alloy as articulating surface in an artificial hip joint.

    In order for a material to be used in human body as an implant, the foremost requirement is the acceptability by the human body. The implantations should not cause diseases or other complications for the patients. Moreover, the biomaterials should possess sufficient mechanical strength, high corrosion and wear resistance in harsh body environment with varying loading conditions.

    There have been extensive research on the properties of stainless steel, Co-Cr-Mo alloys and Ti alloys regarding their bio-compatibility and they are currently being used as orthopedic implants, however less information is available for bulk metallic glasses. So, understanding the corrosion properties of BMGs is one of the key issues to evaluate their potential as biomaterials.

    In the first phase of the project there was an attempt to develop a Zr-based BMG from pure elements in a vertical resistance furnace and quenching in liquid nitrogen. Afterwards, samples were examined by X-Ray diffraction and microscopically to investigate the presence of crystalline phases.

     The second phase was electrochemical measurements to study the passivation behavior and the susceptibility to pitting corrosion for the crystalline Zr55Cu30Ni5Al10, amorphous Zr55Cu30Ni5Al10 BMG (received from Japan) and comparing the result with stainless steel and Co-Cr-Mo (F75). Investigations on corrosion properties were made in phosphate-buffered saline (PBS) with and without the addition of albumin fraction V, at a room temperature of 20 °C and body temperature (37°C) and in different pH values of 7.4 and 5.2. Running the experiment in lower pH shows the behavior of the implant against any probable inflation in the patient body.

    The last phase was to investigate the interaction between the protein and surface of materials. For this purpose, FTIR spectroscopy and Electrochemical Impedance Spectroscopy (EIS) were carried out.

    Download full text (pdf)
    MSc. tehsis- Ali Tabeshian
  • 199.
    Tabeshian, Ali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Persson, Dan
    Savage, Steven J.
    Yokoyama, Yoshihiko
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Electrochemical Properties of Advanced Bulk Metallic Glasses for Hip Implant Applications2011Conference paper (Refereed)
  • 200. Taniguchi, Y.
    et al.
    Sano, N.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Sulphide Capacities of CaO-Al2O3-SiO2-MgO-MnO Slags in the Temperature Range 1673-1773 K2009In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 49, no 2, p. 156-163Article in journal (Refereed)
    Abstract [en]

    With a view to estimate the sulphide capacities of slags used in hot metal pretreatment processes, the sulphide capacities of CaO-Al2O3-SiO2-MgO, CaO-Al2O3-SiO2-MnO and CaO-Al2O3-SiO2-MgO-MnO slags in low SiO2 concentration region were measured in the temperature range 1 673-1 773 K. The gas-slag equilibrium technique has been used for these measurements. From the results obtained, it was found that the MgO and MnO increased the sulphide capacity values of slag. A new empirical model based on optical basicity for sulphide capacity prediction of these slags was developed using the measured values of the present work and literature.

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