| 101. |
- 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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| 102. |
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| 103. |
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| 104. |
- 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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| 105. |
- Seetharaman, Seshadri, et al.
(författare)
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Estimation of viscosities of ternary silicate melts using the excess Gibbs energy of mixing
- 2000
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Ingår i: Metallurgical and Materials Transactions. A. - : Springer Science and Business Media LLC. - 1073-5623 .- 1543-1940 .- 1073-5615 .- 1543-1916. ; 31:1, s. 105-109
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Tidskriftsartikel (refereegranskat)abstract
- A correlation to predict the viscosities of ternary Silicates using the Gibbs energies of mixing of the silicate melts has been developed. This correlation has been employed to predict the viscosities of liquid slags in the systems FeO-MnO-SiO2, FeO-MgO-SiO2, CaO-FeO-SiO2, CaO-MnO-SiO2, and CaO-MgO-SiO2. The good agreement between the calculated viscosities and the experimental data in the ternary silicate systems has indicated that this approach can be successfully employed to predict the viscosities of ternary silicate melts.
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| 106. |
- Seetharaman, Seshadri, et al.
(författare)
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Preface
- 2013
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Ingår i: Treatise on Process Metallurgy. - : Elsevier. - 9780080969862 ; , s. xvii-xx
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 107. |
- Seetharaman, Seshadri, et al.
(författare)
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Preface
- 2013. - 2
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Ingår i: Treatise on Process Metallurgy. - : Elsevier BV. ; , s. xvii-xx
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Bokkapitel (refereegranskat)
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| 108. |
- Seetharaman, Seshadri, et al.
(författare)
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Treatise on Process Metallurgy
- 2013
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- 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. The work distils 400+ years combined academic experience from the principal editor and multidisciplinary 14-member editorial advisory board, providing the 2,608-page work with a seal of quality. The volumes will function as the process counterpart to Robert Cahn and Peter Haasenâ??s famous reference family, Physical Metallurgy (1996)--which excluded process metallurgy from consideration and which is currently undergoing a major revision under the editorship of David Laughlin and Kazuhiro Hono (publishing 2014). Nevertheless, process and extractive metallurgy are fields within their own right, and this work will be of interest to libraries supporting courses in the process area.
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| 109. |
- Semykina, A. S., et al.
(författare)
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Physical simulation of magnetite particle motion in the molten steelmaking slag
- 2011
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Ingår i: Metallurgical and Mining Industry. - 2076-0507 .- 2078-8312. ; 3:3, s. 82-86
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Tidskriftsartikel (refereegranskat)abstract
- The experimental technique is developed to study the motion of nonconducting particles in the conducting liquid in crossed electrical and magnetic fields and applied to simulate a process of magnetite particle separation, formed during oxidizing of steelmaking slags. The calculated velocity of magnetite particles under action of the electromagnetic buoyancy force in molten steelmaking slags is 0.1-0.5 mm/min.
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| 110. |
- Shahbazian, F., et al.
(författare)
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The effect of addition of Al2O3 on the viscosity of CaO-FeO-SiO2-CaF2 slags
- 2002
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Ingår i: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 42:2, s. 155-162
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Tidskriftsartikel (refereegranskat)abstract
- The viscosities of CaO-FeO-SiO2-CaF2 slags with various amounts of alumina addition were measured using a rotating-cylinder method in the temperature range 1714-1757 K. The first part of the experiments was conducted by measuring the viscosities under equilibrium conditions after small additions of Al2O3. Similar experiments were also conducted with one commercial mould flux in order to compare the results. In both cases, the viscosities were found to increase with the addition of Al2O3 at all the experimental temperatures, the increase in viscosity being somewhat linear with Al2O3 addition. In the case of the commercial mould flux, even an addition of 2.6 mass% Al2O3 led to a significant increase in the viscosity. Some isothermal experiments were also conducted with the above set of slags in the dynamic mode, wherein, the changes in the slag viscosities were monitored as a function of time as an Al2O3 disc dissolved continuously into the slag. The experiments were so designed that the dissolution of alumina occurred mainly along the vertical direction. The rate of dissolution of alumina is discussed in the light of the rate of change of viscosity as well as the composition profile in the slag after the experiments. An examination of the Al2O3 disc revealed the counter diffusion of the slag components into the solid alumina and that the dissolution took place by the solid product dissolving in the melt.
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