Dissertations / Theses: 'Iron liquor'

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Jamieson, Evan J. "Precipitation and characteristics of iron (III) oxyhydroxides from acid liquors." Murdoch University, 1995. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060816.130615.

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An important problem in the mineral processing industry is the removal of iron (III) from process and waste streams by precipitation as the metal hydroxide by elevation of pH. Caustic (NaOH),lime(CaO) and slaked lime (Ca(OH)2,), are cheap and effective reagents for this purpose, however iron (III) oxyhydroxides often form polymeric chains when precipitated at ambient temperature. This gelatinous material is slow to settle and difficult to filter, unlike the crystalline solids obtained at higher temperature. A systematic hdamental study was undertaken to assess the suitability of various characterisation techniques to the iron oxide and oxyhydroxide group of minerals. Techniques such as chemical dissolution methods, surface area, TEM and thermal gravimetry were found to be very useful for comparative purposes, but were not recommended as primary characterisation techniques. Mossbauer spectroscopy proved to be the most reliable method for deteimination of phase composition especially when used in conjunction with XRD. However cost and time for analysis prevent this technique being used extensively. It was found that XRD, settling rate and settled sediment volume were broadly applicable and able to identify variation between samples cheaply and efficiently. This study also methodically compared the settling rates, sediment volumes and iron oxide phases associated with using caustic solution, dry & slaked lime and dry & slaked magnesia. Pure sodium hydroxide and iron (III) chloride solutions were used to represent the simplest system Factors such as temperature, mixing, neutralisation rate, heterogeneous precipitation sulphate addition, the presence of divalent cations (Mg2') and strong iron (III) ligands (eg citrate, oxalate) were investigated with this system Generally the predominant iron phase precipitated was the poor order 0 or 2 XRD .line ferrihydrite. The temperature during precipitation was found to be the only critical parameter in changing product crystallinity and morphology. However, some other factors were able to produce small changes in agglomeration and settling rates, suggesting processes such as pulp recycle may prove beneficial. The iron (III) sulphate system induced a change in precipitates producing microcrystalline goethite, although settling rates were not improved. The use of slowly dissolving lime in the iron (III chloride system was unable to improve precipitate crystallinity or settling rate, however results suggest that lime and caustic can be used interchangeably. The lime / iron (III) sulphate system produced a co precipitate of ferrihydrite and gypsum of enhanced settling ability relative to the caustic system. The use of sparingly soluble magnesia failed to improve the precipitate of the iron (m) chloride system, however substantial improvement was found in the crystallinity and settling rate when using the iron (III) sulphate and mixed chloride / sulphate system, provided a range of conditions were met. This product resembled "dense amorphous basic ferric sulphate" (DABFS) and was identified as a highly ordered form of ferrihydrite by Mossbauer studies. It is suggested that this precipitate may form the basis for a new low temperature industrial precipitation process. To further investigate the iron precipitation process, iron (II) and mixed iron (II)/(III) chloride solutions were hydrolysed with the addition of sodium hydroxide, calcium oxide and magnesium oxide under well aerated conditions. Dense maghemite was produced with the caustic system at ambient temperature which settled faster than magnetite precipitated at 70°C. The divalent cations Ca2+ and Mg2+ appear to hinder precipitation of crystalline maghemite at ambient temperature, forming the gelatinous poorly ordered ferrihydrite. This fundamental and systematic study of the precipitation process of iron oxides and oxyhydroxides has led to an improvement in the integral understanding of iron (III) hydrolysis. The investigation of characterisation techniques has also led to an enhanced knowledge of their interaction with these precipitates and hence their strengths and weaknesses.

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Jamieson, Evan John. "Precipitation and characteristics of iron (III) oxyhydroxides from acid liquors /." Access via Murdoch University Digital Theses Project, 1995. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060816.130615.

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3

Parvin, Nader. "Interaction of liquid copper with sintered iron compacts." Thesis, Aston University, 1989. http://publications.aston.ac.uk/11880/.

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Interaction of liquid copper with sintered iron is important in brazing, liquid phase sintering and infiltration. In brazing, the penetration of liquid copper into the pores is to be `avoided', whereas in infiltration processes it is `encouraged', and in liquid phase sintering it should be `controlled' so that optimum mechanical properties are achieved. The main objective of the research is to model the interaction by studying the effect of the process variables on the mechanisms of copper interaction in Fe-Cu and Fe-Cu-C systems. This involves both theoretical and experimental considerations. Dilatometric investigations at 950, 1125 and 1200oC, together with metallographic analyses were carried out to clarify the copper growth phenomenon. It is shown that penetration of liquid copper into the iron grain boundaries is the major cause of dimensional changes. Infiltration profiles revealed that copper penetration between the iron interparticle contact points and along iron grain boundaries is a rapid process. The extent of copper penetration depends on the dihedral angle. Large dihedral angles hinder, and small angles promote copper penetration into the grain boundaries. Dihedral angle analysis shows that the addition of 0.6wt.% graphite reduces the number of zero dihedral angle from 27 to 3o and increases the mean dihedral angle from 9.8 to 41.5o. The dihedral angle was lowest at 1125oC and then increased to higher values as the system approached its equilibrium condition. Elementally mixed (E.M.) Fe-Cu compacts showed a rapid expansion at the copper melting point. However, graphite additions reduced compact growth by increasing the mean dihedral angle. In order to reduce the copper growth phenomenon, iron powder was coated with a thin layer of copper by an immersion coating (I.C.) technique. The dilatometric curves revealed an overall shrinkage in the I.C. compacts compared to their corresponding E.M. compacts. Multiple regression models showed that temperature had the most effect on dimensional changes and density had the most contributing effect upon the copper penetration area in the infiltrated powder metallurgy compacts.

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Sidhu, Mandeep Singh. "Liquid Aluminium Corrosion Characteristics of Cast Iron and Steel." Thesis, University of Canterbury. Mechanical Engineering, 2012. http://hdl.handle.net/10092/7013.

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Cast iron and steel alloys are commonly used for tooling and structural components in Al production, Al die-casting and the aluminizing industry due to their favourable properties including high strength, good formability and low cost. However, the iquid Al corrosion of these materials is one of the crucial concerns in maintaining the efficient production. Al is produced by the electrolytic smelting of alumina. Cast iron and/or cast steel pipes - commonly known as „tapping pipes‟ - are used to extract the liquid Al produced by smelting. Tapping pipes mainly degrade by material loss because liquid Al reacts with nearly all metals. Failure of tapping pipes is a significant contributor to the maintenance expenses; therefore, the primary aim of this research is to develop a material to enhance the life time of tapping pipes. Various test methods were developed in order to examine the effect of molten Al environment on cast iron and steel alloys. The corrosion resistance of these alloys was determined under different conditions of Al flow and temperature. The intermetallic compounds formed by exposing the ferrous to liquid Al were characterized using the Energy Dispersive X-ray Spectroscopy (EDS) and Electron Back Scatter Diffraction (EBSD) techniques. The formation, growth and nature of reaction products were revealed to establish a link to the liquid Al corrosion resistance. A relationship between the chemical composition and liquid Al corrosion resistance of cast irons could not established in the past. In the present work, the corrosion rate was found to depend upon the graphite morphology and fraction of each Fe-C phase of cast iron matrix, which can be controlled by selecting the chemical composition. Moreover, present research suggested the guidelines for producing a cast iron with enhanced liquid Al corrosion resistance. The presence of C-rich phases, graphite flakes and cementite was found to be effective in enhancing the liquid Al corrosion resistance of gray cast irons. Conversely, a higher Si content was found to enhance the susceptibility of cast irons to liquid Al corrosion. The corrosion mechanisms for ferrous alloys in liquid Al are not fully understood. Thus the subsequent analysis of the dissolution data was supported by investigating the reaction products formed between Al and substrate materials. In addition to commonly existent ε-Fe2Al5 and ζ-FeAl3 phases, the formation of Al4C3 and κ-Fe3AlC compounds was confirmed for the first time in the intermetallic layers of ferrous alloys. The Fe3Si phase in the intermetallic layers of high Si cast irons was found, which was believed to facilitate the high corrosion rates of high Si cast irons. Moreover, the mechanism by which C in Fe-substrates affects the liquid Al corrosion resistance can be better understood given the present work. Furthermore, the analysis presented here gives an understanding of the nature, growth and dissolution of intermetallic compounds in several cast iron alloys. Higher Si additions to cast irons played an important role in molten metal corrosion by accelerating the material loss and changing the nature of intermetallic layers. The results of this study clearly indicated that the dissolution and the growth of intermetallic compounds are interrelated and the dissolution and/or spallation of the intermetallic layers may be the primary mode of liquid Al corrosion of ferrous alloys.

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Monaghan, Brian Joseph. "The kinetics of liquid iron dephosphorization using lime based slags." Thesis, University of Strathclyde, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.626859.

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Lu, Qing. "Corrosion behaviour and characterisation of iron and steels in hot flowing Bayer liquors." Thesis, University of Manchester, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.682781.

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The flow-induced corrosion of steels, in flowing caustic Bayer liquor solutions at high temperatures, has been experienced in Bayer alumina production plants. The use of a rotating cylinder electrode (RCE) in an autoclave facility has been identified by previous workers as a suitable method to simulate the plant conditions. The characterisation of the corrosion behaviour of iron, mild steel and duplex stainless steel was investigated by using a RCE, in the temperature range of 100 to 230C^ and equivalent pipe velocities between 0.84 to 3m/s. Techniques such as, weight loss, polarisation measurement, ac impedance and surface analysis, were used to characterise corrosion behaviour during the experiments and also the corrosion products formed. The corrosion rates measured by weight loss techniques were in agreement with those obtained by using ac impedance measurements. At ISOC^ , the corrosion rates and the surface film morphologies of iron and mild steel have been found to vary significantly with the liquor flow velocity. This is in agreement with the proposed model of the process based on the active dissolution of the metals. However, for duplex stainless steel, the behaviour was different with little change observed between corrosion rates under the conditions studied. Corrosion processes including dissolution accompanied by adsorption, active-passive transition and passivation, were interpreted through a series of equivalent circuits. The combined effect of temperature and velocity on corrosion rate was demonstrated by the construction of corrosion maps for the materials tested. This method may be a useful way of providing a guide to optimise the process conditions in high temperature flowing environments such as those found in Bayer plants.

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Kapilasharmi, Era. "Investigation of Interactions between Liquid Iron Containing Oxygen and Aluminosilicate Refractories." Doctoral thesis, KTH, Materials Science and Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3625.

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The present work was initiated to investigate runnerrefractory corrosion by molten steel. The aim was to understandthe mechanism of inclusion formation during ingot casting. Thework is also of interest to other unit processes in steelmaking, where refractory corrosion and erosion are seriousproblems. The oxides investigated in the present work werealumina, silica and mullite, which are the main components inrunner refractory. In addition, industrial refractory materialwas investigated.

Two types of experiments were conducted. The first, "rodexperiments", involved dipping a rod of the oxide into an ironbath containing varying amounts of oxygen. After quenching, therods were examined through SEM/EDS analysis. In the second setsof experiments, the wetting behaviour of molten iron onrefractory oxides was investigated by means of the sessile-dropmethod. The reactions were followed in static as well asdynamic modes through contact angle measurements. Temperatureand oxygen partial pressure were, besides time the parametersthat were investigated in the present study. Oxygen partialpressure was defined by introducing a gas mixture of CO-CO₂-Ar into the furnace.

The experimental studies were preceded by a thermodynamicinvestigation of the refractory systems, in order to get afundamental understanding of the reactions that occurred. Phasestability diagrams for the systems were constructed based onthe data available in literature. The diagrams showed that thereaction between alumina and oxygen containing iron would leadto the formation of hercynite at a critical oxygen level in themetal. With silica, the reaction would lead to the formation offayalite. In the mullite case, the reaction products would behercynite at moderate oxygen levels in the melt and hercynitetogether with fayalite at slightly higher oxygenpotentials.

For all substrates, the contact angles started decreasing asthe surface-active oxygen came into contact with the iron drop.At a critical level of oxygen in the metal, a reaction productstarted forming at the drop/substrate interface. The reactionproducts were identified through SEM/EDS analysis and werefound to be in agreement with thermodynamic predictions. In thecase of SiO₂substrate, there were also deep erosion tracksalong the periphery of the drops, probably due to Marangoniflow.

Alumina-graphite refractory reactions with molten iron werealso investigated through Monte Carlo simulations. The resultsshowed that, with increased alumina content in the refractory,the carbon dissolution into the melt decreased. Further, thewetting behaviour at the interface was found to be an importantfactor to considerably reduce the carbon dissolution fromalumina-graphite refractories.

The experimentation was extended to the commercialrefractories used in the ingot casting process at UddeholmTooling AB, Sweden. The analysis of the plant trial samplesindicates that there is less likelihood of a strong corrosionof the refractories that could lead to a significant populationof inclusions in the end product. The impact of the presentexperimental results on refractory erosion is discussed. Theimportance of the results to clean steel processing anddevelopment of new generation refractories are alsopresented.

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Jones, Karen Lorraine. "Analysis of ferredoxin and flavodoxin in Anabaena and Trichodesmium using fast protein liquid chromatography." PDXScholar, 1988. https://pdxscholar.library.pdx.edu/open_access_etds/3812.

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Iron is an essential nutrient for growth of photosynthetic microorganisms such as cyanobacteria and algae. Iron is required for proteins involved in the important processes of carbon and nitrogen assimilation. Low concentrations of iron in cultures or natural waters can lead to iron limitation which affects many aspects of algal metabolism. In natural waters, iron limitation can have effects on the patterns and rates of primary productivity. The cellular content of certain proteins can be affected by media iron concentrations. Methods have been used that assay components of the cell as an indirect measure of iron nutritional status. For example, spectroscopy can be performed to determine the cellular concentration of iron-containing proteins involved in photosynthesis. Organisms grown in media that imitate natural conditions, or organisms collected from their natural habitat are usually dilute. Methods that assay iron nutritional status such as spectroscopy and column chromatography require large sample sizes which are difficult to obtain from natural samples. In addition, methods that utilize techniques such as immunology or radioactive labelling are complex and time-consuming. These considerations led to the necessity of developing a technique that would be simple, rapid and effective on dilute samples. The method developed here utilized fast protein liquid chromatography (FPLC), which fulfilled these requirements. A complete analysis could be done within two to three hours with minimal sample treatment. The FPLC was simple to operate and was effective on a sample containing less than 100 μg of protein. Some photosynthetic organisms, when iron-depleted, can produce the flavin-containing protein flavodoxin (Flv). This protein substitutes for the iron-containing protein ferredoxin (Fd) in Fd-dependent reactions such as the light-induced reduction of NADP. The FPLC technique identified and quantified, in relative terms, Fd and Flv in the cell. Optical spectroscopy was used to verify FPLC retention time assignments. The results illustrated how the FPLC could be used to observe the changes in relative Fd and Flv content as a function of media iron concentration in cultures of the cyanobacterium Anabaena grown in the laboratory. It was found that Fd content decreased and Flv content increased with decreasing media iron concentration. In addition, samples of the cyanobacterium Trichodesmium collected from the ocean near Barbados were analyzed using FPLC to assay relative Fd and Flv content. By analogy with Anabaena, Fd and Flv retention times were identified. Using this technique conclusions could be drawn regarding the changing iron nutritional status of Trichodesmium in its natural habitat .

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9

Palumbo, Enzo A. "The study of a magnesium wire feeding technique for the desulphurization of molten iron and liquid steel /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65333.

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10

Chapman, Michael Wallace. "Insoluble oxide product formation and its effect on coke dissolution in liquid iron." School of Mechanical, Materials and Mechatronic Engineering - Faculty of Engineering, 2009. http://ro.uow.edu.au/theses/3039.

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A significant body of work exists around coke dissolution into liquid iron, however there are key aspects of this important reaction that are not well described. This study was focused on gaining the answers to the questions “How does the coke mineral matter behave during coke dissolution?” and “Can the effects of sulphur and oxide layer formation on the dissolution rate be separated and quantified?”. Issues that must be addressed if the understanding of the kinetics of this reaction is to be advanced and coke's use in the blast furnace further optimised.To this end, a detailed investigation was conducted examining the influence of coke mineral matter on coke (carbon) dissolution into liquid iron. This project was focused on the mineral matter layer that forms at the coke/iron interface and how the presence of this layer affects the kinetics of carbon dissolution from the coke into the liquid iron. A range of experimental techniques were used to identify and characterise the mineral layer as it formed at the coke/iron interface and to assess the layers influence on the carbon dissolution kinetics.Carbon dissolution experiments, utilising a carburiser cover technique, were carried out where carbon and sulphur transfer to an iron-carbon melt was measured over time at temperatures of 1450°C, 1500°C and 1550°C. This technique allowed fundamental data on the dissolution rate constant to be calculated, and the effects of temperature, melt sulphur and different carbonaceous materials to be explored.Development of the mineral layer at the coke/iron interface as a function of both time and temperature was studied utilising a quenched carbon dissolution technique that was developed during the project. This technique had the additional benefit of allowing the composition of the melt to be determined for a larger range of elements than the dissolution experiments. The quenched carbon dissolution experiments complemented the carbon dissolution experiments and allowed direct comparisons between the dissolution behaviour measured in the dissolution experiments and the composition and morphology of the mineral layer observed in the quenched samples.The dissolution studies were further complemented by sessile drop measurements of the wetting behaviour of iron on the mineral phases that were identified in the mineral layer present at the coke/iron interface, thermodynamic modelling utilising the MTDATA software package and a conceptual model of the interfacial mineral layer.A mineral layer was observed to have formed at the coke/iron interface during coke dissolution into liquid iron at experimental temperatures ranging from 1450°C to 1550°C. The mineral layer was solid at these temperatures and persistent at the interface. The amount of mineral matter present in the mineral layer was observed to be increasing with increased reaction time. The composition and structure of the mineral layer changed with both experimental time and temperature. The composition of the mineral layer was principally composed of oxides of aluminium and calcium, present as various calcium aluminates and calcium sulphides. Initially the mineral layer was a loose agglomeration of particles of which a majority were alumina particles. As the dissolution reaction proceeded, the loose agglomeration of particles was replaced by an open acicular layer that was predominantly the calcium aluminate CaO.6Al2O3 (CA6). As the dissolution reaction continued further, the calcium aluminates became increasingly richer in calcium oxide, with the predominate phase present in the mineral layer progressing through the calcium aluminates phases CA6 to CaO.2Al2O3 (CA2) and onto CaO.Al2O3 (CA). The apparent calcium enrichment of the mineral layer was observed to occur more rapidly as the experimental temperature increased. Accompanying the compositional changes in the mineral layer, the morphology of the mineral layer was also observed to change. The mineral layer was formed as an initial loose agglomeration of alumina particles, changing to an open acicular structure consisting of CA6/CA2 before being converted to a dense layer as the dissolution reaction proceeded and the composition of the mineral layer changed to CA and calcium sulphide (CaS) appeared at the interface.It was found that the formation of the calcium sulphide layer was preceded by the formation of the calcium aluminate layer. Only after the calcium aluminate layer had experienced progressive calcium enrichment and the CA and CA2 phases had formed did the CaS phase appear at the iron interface. Thermodynamic analysis of the experimental results confirmed that the formation of the calcium enriched calcium aluminates, CA2 and CA, were a necessary requirement to stabilise the calcium sulphide layer for the coke composition studied.The kinetics of carbon dissolution from the coke to the liquid iron were observed to be dependent on the structure of the interfacial mineral layer. This dependence was manifest as two stage behaviour in the first order mass transfer plots. The initial stage, characterised by rapid carbon dissolution, was observed while the mineral layer was developing or had the open acicular structure of the CA6/CA2 layer. The second stage was characterised by a significant reduction in the rate of carbon dissolution. The onset of the second stage was coincident with the change in the composition of the mineral layer from CA6/CA2 to CA2/CA and the associated densification of the mineral layer. In stating that the nature of the mineral layer affects the dissolution kinetics, a change in the reaction control mechanism is implied. This represents a change in the coke dissolution kinetics from simple mass transfer control to a mixed control regime where both mass transfer and the mineral (product) layer are active.In an attempt to overcome the problems associated with the heterogeneity of coke a coke analogue was developed. In the coke analogue the composition and dispersion of the carbonaceous and mineral matter (oxides) are controlled and the porosity is fixed. When single phase calcium aluminates were introduced into the coke analogues, calcium enrichment of the resulting calcium aluminate mineral layer was observed. The observed carbon dissolution kinetics were dependant on the structure of the interfacial calcium aluminate layer. Consistent with the coke dissolution studies, the calcium aluminate layer formed at the coke analogue iron interface during carbon dissolution was at least in part rate controlling the carbon dissolution reaction for the coke analogues studied.Utilising the sessile drop experimental technique the wettability with liquid ironcarbon-sulphur alloys of the predominate phases that were observed in the mineral layer were measured. It was observed that the contact angle decreased as the proportion of lime (CaO) in the calcium aluminate increased. Further it was observed that while the presence of sulphur in the melt increased the contact angle for the alumina and CA6 substrates, on the CA2 and CA substrates the contact angle was decreased. The improvement in the wetting of the CA2 and CA substrates with sulphur was attributed to the formation of CaS at the substrate/droplet interface.This study has produced new fundamental data on the growth and development of the mineral layer and the wettability of the predominate calcium aluminates observed in the mineral layer. These detailed studies have illuminated the changing nature of the layer in terms of both composition and morphology and found that the kinetics of carbon dissolution from the coke to the liquid iron were dependant on the structure of the interfacial mineral layer.

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11

Antonsson, Tomas. "On the interaction between liquid/ solid during sintering and solidification." Doctoral thesis, KTH, Casting of Metals, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3464.

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12

McCarthy, Fiona Materials Science &amp Engineering Faculty of Science UNSW. "Interfacial phenomena and dissolution of carbon from chars into liquid iron during pulverised coal injection in a blast furnace." Awarded by:University of New South Wales. School of Materials Science and Engineering, 2005. http://handle.unsw.edu.au/1959.4/20797.

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As carbon dissolution rates have been determined for a few chars only, a systematic and comprehensive study was undertaken in this project on the dissolution behaviour of carbon from non-graphitic materials into liquid iron. In addition to measuring the kinetics of carbon dissolution from a number of coal chars into liquid iron as a function of parent coal and coal ash composition, the influence of chemical reactions between solute/solid carbon and ash oxides was also investigated. These studies were supplemented with investigations on one metallurgical coke for the sake of comparison. The wettability of coal chars and coke with liquid iron at 1550 degrees C was measured as a function of time. Being essentially non-wetting, only a marginal improvement in contact angles was observed with time. The accumulation of alumina at the interface was detected for all materials and was seen to increase with time in all cases. Calcium and sulphur also appeared to preferentially accumulate at the interface, concentrating at levels in excess of those expected from the ash composition alone. Despite the high levels of silica in the ash initially, very little silica was detected in the interfacial region, implying ongoing silica reduction reactions. A small amount of silicon was however detected in the iron droplets, indicating silica reduction with solute carbon. It was identified that the reduction reactions can also consume solute carbon in the liquid iron. As this is occurring simultaneously with carbon dissolution into liquid iron, the interdependency of silica reduction and carbon dissolution could potentially limit the observed carbon dissolution rate. A theoretical model was developed for estimating the interfacial contact area between chars and liquid iron. Wettability was found to have a very significant effect on the area of contact. A two-step behaviour was observed in the carbon dissolution of two chars and coke. Slow rates of carbon dissolution in stage II were attributed to very high levels of interfacial blockage by reaction products leading to much reduced areas of contact between carbonaceous material and liquid iron. The first order dissolution rate constants for four chars/coke and the observed trend in first order dissolution rate constants were calculated. These dissolution results compare well with the previously measured dissolution rate constants. The trends in dissolution can be adequately explained on the basis of carbon structure, silica reduction, sulphur concentration in the metal and ash impurities.

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Lartigue, Lénaïc. "Synthesis, Characterization, and Theranostic Application of Iron Based Magnetic Nanoparticles." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20092/document.

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La synthèse de nano-object connait un essor grandissant depuis ces 20 dernières années. Les études fondamentales de système a permis (et permet encore) de trouver de nombreux domaines d'application aux nanotechnologies, que ces soit en catalyse, en électronique, dans le domaine biomédical...La thèse se déroule autour de deux axes de recherches: la synthèse et la description des propriétés magnétique de nanoparticules de fer stabilisé par des liquides ioniques, et la synthèse, l'étude magnétique, et leur évaluation en tant qu'agent de contraste et médiateur d'hyperthermie de nanoparticules de de ferrite fonctionnalisé par des dérivées carbohydrates
The synthesis of nano-object is growing in the last 20 years. Basic research system has (and still allows) to find many areas of application for nanotechnology that is in catalysis, electronics, biomedical ...The thesis proceeds along two lines of research: the synthesis and the description of magnetic properties of iron nanoparticles stabilized by ionic liquids, and the synthesis, magnetic study, and their evaluation as a contrast agent and hyperthermia mediator of functionalized carbohydrate derivatives ferrite nanoparticles

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Liang, Yu [Verfasser]. "Ultrafast Dynamics of Metalloporphyrins, DNA and Iron-Lanthanide Clusters in the Liquid Phase / Yu Liang." Karlsruhe : KIT Scientific Publishing, 2013. http://www.ksp.kit.edu.

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McPhee, William A. G. "Liquid pool formation and the influence of iron on the sintering of Al-cu alloys /." St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16473.pdf.

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Wiencke, Jan-Christian. "Analysis of the electrochemical processes during the production of liquid iron by Molten Oxide Electrolysis." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0329.

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L'électrolyse en milieu oxydes fondus (MOE) peut être envisagée comme une nouvelle technologie de l’industrie sidérurgique pour la production de fer liquide sans émission de CO2. Dans ce concept, l'électrolyse est utilisée pour produire de l’oxygène gazeux et du fer liquide à des températures supérieures à 1810 K. Dans cette étude sont présentées les principales réactions électrochimiques lors de l’électrolyse en milieu fondu (MgO-Al2O3-SiO2). Une quantité importante de fer liquide a été produite lors d'électrolyses conduites pendant plusieurs heures. L'analyse MEB-EDS du dépôt a révélé un alliage de fer métallique quasi pur, uniquement contaminé par le matériau cathodique. Ce résultat traduit une sélectivité élevée du procédé électrolytique. L'étude de la réponse de l'électrolyte en fonction de la tension électrique et de la concentration de fer a révélé une limitation par la diffusion lors de l’électrolyse de bains de faibles concentrations en oxyde de fer, et à des potentiels inférieurs à 1,5 V. La demi-réaction de la cathode a été identifiée comme la réduction du fer ferreux en fer métallique. L’extrapolation des droites de Tafel sur les courbes courant-tension corrigées de la chute ohmique a conduit à des coefficients de transfert (de la réaction cathodique) proches à 0,6. L’ordre de réaction de réduction de FeII en Fe0 a été évalué autour de 1. L'analyse de la demi-réaction anodique dans les oxydes fondus à faible teneur en fer a montré que les premières espèces éctroactives sont les anions oxydes libres. Pour des tensions électriques croissantes, le transport des anions O2- libres devient limité et le transfert de charge est partiellement attribué à l’oxydation du fer ferreux. Au contraire, dans des mélanges d’oxydes fondus à concentrations élevées en fer, le transfert de charge est réalisé dans toute la gamme de tension par l'oxydation du fer ferreux. C’est seulement à haute tension, que l’oxydation des anions oxyde contribue au transfert des charges. Dans l'ensemble des compositions testées, aucune limitation du courant n’a été observée sur la réaction anodique
Molten oxide electrolysis (MOE) is an ambitious technique for the production of liquid iron by the use of renewable energies and thus lower CO2 emissions in the steel industry. In this concept, electrolysis is used to produce gaseous O2 and liquid iron metal at temperatures above 1810 K. In the experimental study presented here the key-parameters of the electrochemical reactions in a magnesio-aluminosilicate electrolyte and at the electrodes during MOE are investigated. A significant amount of liquid iron metal was produced during experiments of several hours. SEM-EDS analysis of the deposit revealed an alloy of iron metal and of the cathode material, which thereby indicates high process selectivity. Investigation of the electrolyte’s response in dependence of cell voltage and iron concentration inferred a diffusional limitation at low iron oxide concentrations at potentials below 1.5 V. The cathode half-reaction was identified as the reduction of ferrous iron to liquid iron metal. Using Tafel interpretation reaction-transfer coefficients close to 0.6 and an order of reaction around 1 were determined. The analysis of the anode half-reaction showed that in low iron bearing molten oxides, oxide anions were firstly oxidized into O2 gas. At high iron concentrations the charge transfer is conducted in the entire cell voltage range by the oxidation of ferrous iron. The participation of oxide anions in the charge transfer was only witnessed at high cell voltages. In the entire compositional range a limitation of the measured current due to the anode half reaction was not observed

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Lebeau, Timothy Charles. "Brake drum production by centrifugal casting." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2009r/lebeau.pdf.

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Teer, Joseph Edward. "A study of the biodegradation of modelled iron oxalate leach liquors in an upflow anaerobic sludge blanket (UASB) reactor." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309306.

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Aluru, Sreenivasa Charan Rajeev Gale W. F. "Microstructure - mechanical property relationships in transient liquid phase bonded nickel-based superalloys and iron-based ODS alloys." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/doctoral/ALURU_SREENIVASA_32.pdf.

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20

Posner, Esther [Verfasser], and David [Akademischer Betreuer] Rubie. "Mass transport and structural properties of liquid iron alloys at high pressure / Esther Posner ; Betreuer: David Rubie." Bayreuth : Universität Bayreuth, 2017. http://d-nb.info/1135260621/34.

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21

Wang, Huifeng [Verfasser]. "Surface science approach to catalyst preparation : Palladium deposition onto iron oxide films from the liquid phase / Huifeng Wang." Berlin : Freie Universität Berlin, 2012. http://d-nb.info/1029955042/34.

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Wang, Hui-Feng [Verfasser]. "Surface science approach to catalyst preparation : Palladium deposition onto iron oxide films from the liquid phase / Huifeng Wang." Berlin : Freie Universität Berlin, 2012. http://nbn-resolving.de/urn:nbn:de:kobv:188-fudissthesis000000039466-3.

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23

Rhamdhani, Muhammad Akbar Brooks Geoffrey. "Reaction kinetics and dynamic interfacial phenomena in liquid metal-slag systems." *McMaster only, 2005.

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24

Wang, Yu. "Mechanical properties and microstructure of laser sintered and starch consolidated iron-based powders." Doctoral thesis, Karlstad : Faculty of Technology and Science, Materials Engineering, Karlstads universitet, 2008. http://www.diva-portal.org/kau/abstract.xsql?dbid=1593.

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25

Rubasinghege, Gayan Randika S. "Chemical and photochemical reactions on mineral oxide surfaces in gaseous and liquid phases: environmental implications of fate, transport and climatic impacts of mineral dust aerosol." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/1173.

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Mineral dust aerosols emitted from the Earth crust during various natural and anthropogenic processes continuously alter the chemical balance of the atmosphere via heterogeneous processes and thus, impact on the global climate. Understanding of heterogeneous chemistry and photochemistry on mineral dust has become vital to accurately predict the effect of mineral dust loading on the Earth's atmosphere. Here, laboratory measurements are coupled with model studies to understand heterogeneous chemistry and photochemistry in the atmosphere with the specific focus on reactions on mineral oxide surfaces. Heterogeneous uptake of gas phase HNO3 on well characterized metal oxides, oxyhydroxides and carbonates emphasized binding of nitric acid to these surfaces in different modes including monodentate, bidentate and bridging under dry conditions. It is becoming increasingly clear that the heterogeneous chemistry, including uptake of HNO3, is a function of relative humidity (RH) as water on the surface of these particles can enhance or inhibit its reactivity depending on the reaction. All the studied model systems showed a significant uptake of water with the highest uptake by CaCO3. Quantitative analysis of water uptake indicated formation of multilayers of water over these reactive surfaces. Under humid conditions, two water solvated nitrate coordination modes were observed that is inner-sphere and outer-sphere, which differ by nitrate proximity to the surface. Photochemical conversion of nitric acid to gas phase nitrous oxide, nitric oxide and nitrogen dioxide through an adsorbed nitrate intermediate under different atmospherically relevant conditions is shown using transmittance FTIR and XPS analysis. The relative ratio and product yields of these gas phase products change with relative humidity. Photochemistry of adsorbed nitrate on mineral aerosol dust may be influenced by the presence of other distinct gases in the atmosphere making it complicated to understand. This thesis converses formation of active nitrogen, NOx and N2O, and chlorine, ClOx, species in the presence of co-adsorbed trace gases, that could potentially regulate the peak concentration and geographical distribution of atmospheric ozone. Here we report formation of atmospheric N2O, from the photodecomposition of adsorbed nitrate in the presence of co-adsorbed NH3 via an abiotic mechanism that is favorable in the presence of light, relative humidity and a surface. Estimated annual production of N2O over the continental United States is 9.3+0.7/-5.3 Gg N2O, ~5% of total U.S. anthropogenic N2O emissions. Not only NH2 but also gaseous HCl react with adsorbed nitrate to activate "inert" N and Cl reservoir species, yielding NOCl, NOx, Cl and Cl2, through adsorbed nitrate under different atmospherically relevant conditions. Mineral dust aerosol is a major source of bioavailable iron to the ocean with an annual deposition of ~ 450 Tg of dust into the open ocean waters. In this study, we report enhanced Fe dissolution from nano scale Fe-containing minerals, i.e.alpha-FeOOH, beyond the surface area effects that can be attributed to the presence of more reactive sites on specific crystal planes exposed. We further report with clear evidence that aggregation impacts on dissolution. Proton-promoted dissolution of nanorods is nearly or completely quenched in the aggregated state. Acid type, presence of oxyanions and light are several other key factors responsible for regulating for iron dissolution. The work reported in this thesis provides insight into the heterogeneous chemistry and photochemistry of mineral dust aerosol under different atmospherically relevant conditions.

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Simelane, Lusanda Susan. "Effect of a multiple micronutrient enriched maize-based liquid meal supplement on iron status of grade 3 and 4 learners attending Sunnyside primary school, Pretoria." Diss., University of Pretoria, 2015. http://hdl.handle.net/2263/46108.

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Background: About one half of school-age children in developing countries are estimated to be affected by iron deficiency. Failure to treat micronutrient deficiencies can negatively affect health and economic development. Objective: To determine the effect of multiple micronutrient maize-based liquid meal supplement on the iron status and the nutritional status of primary school children. Design: A randomized double-blind placebo controlled trial was conducted. Setting and subjects: The study took place at Sunnyside Primary School in Sunnyside, Pretoria, in the urban area of Tshwane (Gauteng Province, South Africa). Grades 3 and 4 male and female learners aged 8-12 years, enrolled in the 2010 academic year were recruited for the study. Methods: Participants were dewormed, to eliminate parasitic infestaion at the beginning of the study. The experimental product was a maize-based liquid meal supplement enriched with macronutrients and micronutrients including chelated ferrous bisglycinate, while the control had the same macronutrient profile but no added micronutrients. The learners took the meal supplement every morning on school days for 14 weeks. Iron status was measured by Haemoglobin (Hb) levels and the nutritional status was measured by anthropometric measures at baseline and end. Groups were compared with respect to change in Hb and change in anthropometry using an analysis of covariance (ANCOVA) with baseline Hb values as covariate. Testing was done at the 0.05 level of significance. Results: There was no significant difference in the Hb levels at baseline (12.6 ± 1.1 g/dL and 12.8 ± 1.1 g/dL) (P = 0.250) between the experimental and control groups respectively. The prevalence of mild anemia (Hb< 11g/dL) was low in both the experimental and control groups. Over the 14 weeks study period, consumption of experimental products was similar and there was no significant effect on Hb levels of the participants observed (P = 0.806) in the experimental and control groups. There was also no significant change observed in the anthropometry of the participants. Conclusion: The maize-based liquid meal supplement enriched with multiple micronutrients did not have a significant effect on the iron status of the participants in this study, possibly owing to low prevalence of anemia, a low rate of consumption and therefore iron absorption.
Dissertation (MSc)--University of Pretoria, 2015.
tm2015
Animal and Wildlife Sciences
MSc
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Ward, Nicholas Rhys. "The rate-limiting mechanism for the heterogeneous burning of iron in normal gravity and reduced gravity." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16673/.

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This thesis presents a research project in the field of oxygen system fire safety relating to the heterogeneous burning of iron in normal gravity and reduced gravity. Fires involving metallic components in oxygen systems often occur, with devastating and costly results, motivating continued research to improve the safety of these devices through a better understanding of the burning phenomena. Metallic materials typically burn in the liquid phase, referred to as heterogeneous burning. A review of the literature indicates that there is a need to improve the overall understanding of heterogeneous burning and better understand the factors that influence metal flammability in normal gravity and reduced gravity. Melting rates for metals burning in reduced gravity have been shown to be higher than those observed under similar conditions in normal gravity, indicating that there is a need for further insight into heterogeneous burning, especially in regard to the rate-limiting mechanism. The objective of the current research is to determine the cause of the higher melting rates observed for metals burning in reduced gravity to (a) identify the rate-limiting mechanism during heterogeneous burning and thus contribute to an improved fundamental understanding of the system, and (b) contribute to improved oxygen system fire safety for both ground-based and space-based applications. In support of the work, a 2-s duration ground-based drop tower reduced-gravity facility was commissioned and a reduced-gravity metals combustion test system was designed, constructed, commissioned and utilised. These experimental systems were used to conduct tests involving burning 3.2-mm diameter cylindrical iron rods in high-pressure oxygen in normal gravity and reduced gravity. Experimental results demonstrate that at the onset of reduced gravity, the burning liquid droplet rapidly attains a spherical shape and engulfs the solid rod, and that this is associated with a rapid increase in the observed melting rate. This link between the geometry of the solid/liquid interface and melting rate during heterogeneous burning is of particular interest in the current research. Heat transfer analysis was performed and shows that a proportional relationship exists between the surface area of the solid/liquid interface and the observed melting rate. This is confirmed through detailed microanalysis of quenched samples that shows excellent agreement between the proportional change in interfacial surface area and the observed melting rate. Thus, it is concluded that the increased melting rates observed for metals burning in reduced gravity are due to altered interfacial geometry, which increases the contact area for heat transfer between the liquid and solid phases. This leads to the conclusion that heat transfer across the solid/liquid interface is the rate-limiting mechanism for melting and burning, limited by the interfacial surface area. This is a fundamental result that applies in normal gravity and reduced gravity and clarifies that oxygen availability, as postulated in the literature, is not rate limiting. It is also established that, except for geometric changes at the solid/liquid interface, the heterogeneous burning phenomenon is the same at each gravity level. A conceptual framework for understanding and discussing the many factors that influence heterogeneous burning is proposed, which is relevant to the study of burning metals and to oxygen system fire safety in both normal-gravity and reduced-gravity applications.

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Orsine, Noeber Maciel. "Definição de tecnologias para desaguamento de ultrafinos ricos de minério de ferro : uma aplicação na Vale Carajás - Pará - Brasil." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/140518.

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O minério de ferro produzido no complexo de Carajás traz consigo características mineralógicas que conferem um elevadíssimo teor de Fe em todas as suas frações granulométricas. Dessa forma, ao final da cadeia produtiva, tanto os produtos comerciais mais grosseiros quanto os finos contem cerca de 62% de Fe contido na sua composição. Importante destacar que em Carajás as fases no processamento desse minério são apenas para cominuição e classificação por tamanho. Não existem etapas de concentração e os produtos são diferenciados por suas respectivas curvas granulométricas: o “granulado” - mais grosseiro (> 13 mm), o “Sinter-Feed” (< 13 mm e > 0,5 mm) e o “pellet feed” (< 0,15 mm). Garantir a correta distribuição granulométrica da matéria prima é uma premissa de mercado. A ultima etapa da classificação é feita através de hidrociclones e gera um overflow ultrafino de altíssima superfície específica maior que 6.500 Blaine e com 45% até 95 % < 7 μm. E ainda possui um elevado teor de Fe - cerca de 62 %. Dessa forma os objetivos gerais dessa pesquisa buscaram a solução para essa oportunidade de recuperar e vender esses rejeitos. O estudo sugeriu através de ensaios com tecnologias capazes de desaguar os ultrafinos gerados para 9,00 % de umidade, que é o valor que permite a movimentação e o manuseio desses rejeitos, além de permitir sua incorporação na blendagem de produtos mais grossos. Desse modo, foram realizados experimentos em diversos laboratórios externos e em escala piloto na Usina de Carajás com amostras dos dois rejeitos ultrafinos das duas fases de hidrociclonagem: o natural e o moído. Ficou evidente que o equipamento tem de combinar necessariamente e de forma eficiente dois fatores essências ao desaguamento: elevadíssimas pressões e altas temperatura na operação desses ultrafinos. A produtividade atingida foi da ordem de 50 t/h x m² para o rejeito da hidrociclonagem do Sinter Feed e 40 t/h x m² para o rejeito dos hidrociclones da Moagem.
The Iron ore that is produced in Carajás mining complex brings mineralogical characteristics that give a very high Fe content in all its size fractions. Thus, at the end of the production chain both coarser and fine contains about 62% Fe contained in its composition. Importantly, in Carajás stages in the processing of this ore are for reduction and classification by size. There is thus no concentration steps and products are differentiated by their respective size distribution curves: the "grain" - coarser (> 13 mm), the "Sinter-Feed" (<13 mm and > 0.5 mm) and the "pellet feed" (<0.15 mm). Ensure proper particle size distribution of the raw material is a market premise. The last step of classification is made using hydrocyclones and generates an overflow ultrafine high specific surface area greater than 6.500 Blaine and with 45% to 95% <7 μm. And has a high Fe content - about 62%. The overall objectives of this research sought the solution to this opportunity to recover and sell these “tailings”. The study suggested by testing with technologies capable of flowing into the ultrathin generated to 9.00% of moisture, which is the value that allows movement and handling these wastes, and allows their incorporation into the blending of thicker products. Thus, experiments were carried out in several external laboratories and pilot-scale plant in the Carajás with samples of both ultrafine “tailings” of the two phases of hydrocycloning: the natural and the ground. It was evident that the equipment must necessarily match and two efficiently factors essences to dewatering: very high pressure and high temperature operation of these “tailings”. The productivity achieved was around 50 t/h x m² in reject of the Sinter Feed hydrocycloning and 40 t/h x m² to reject of the grinding hydrocyclones.

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Chen, Shu. "FePt magnetic nanoparticles : syntheses, functionalisation and characterisation for biomedical applications." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2151.

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Iron platinum (FePt) has attracted growing interest because of its high Curie temperature, magneto-crystalline anisotropy and chemical stability. Nanoparticles (NPs) made of this alloy are promising candidates for a wide range of biomedical applications including magnetic separation, magnetic targeted drug delivery, hyperthermia for cancer therapy and also as magnetic resonance imaging (MRI) contrast agents. This thesis presents the synthesis, functionalization and characterization of FePt NPs along with a toxicity study and an investigation into their application as MRI contrast agents. Regarding their synthesis, different approaches have been explored including the co-reduction of Fe and Pt precursors in an aqueous media, the thermal decomposition in a conventional high-boiling solvent such as benzyl ether, and in low-melting organic salts (ionic liquids). The data revealed an inhomogeneous composition distribution of Fe and Pt between particles obtained in aqueous media, due to the iron salts hydrolysis, and a mismatch in the co-reduction kinetic of the two metal precursors. While the iron content in the NPs could be increased by using more hydrolytically stable iron precursors or stronger reducing agents, there are remaining limiting parameters which prevent further Fe content increase in NPs. In contrast, by excluding the water from the reaction system and using a Fe²⁻ iron precursor, homogenous 1:1 Fe to Pt ratio NPs can be obtained through a modified thermal decomposition pathway in benzyl ether. Based on the study of synthesis in this conventional chemical, the potential of ionic liquids (ILs) to be used as novel solvents for FePt NPs synthesis was further explored. It was then demonstrated that ionic liquids (ILs) can not only be used as a solvent for synthesis of FePt NPs, but also can provide an exciting alternative pathway to direct synthesis fct-FePt NPs. In the context of the bioapplication of FePt NPs, a family of FePt NPs was specifically designed to enhance their MRI contrast agents properties. In contrast with previous reports, this thesis demonstrates that FePt NPs can be made non-toxic and provides the first data on their cellular uptake mechanisms. A six times increase in the FePt based T₂ contrast properties compared to clinical iron oxide NPs is reported. The relationship between the MRI contrast properties and the NPs architecture is explored and rationalised as the basis for the design of NPs as enhanced MRI contrast agents. Finally, the first observations of cellular and in vivo MR imaging with FePt NPs is also reported. This study opens the way for several applications of FePt NPs such as regenerative medicine and stem cell therapy, thus providing a bio-platform to develop novel diagnostic and therapeutic agents.

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Chen, Chih-Yao. "A study on positive electrode materials for sodium secondary batteries utilizing ionic liquids as electrolytes." Kyoto University, 2014. http://hdl.handle.net/2433/192207.

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31

Roberts, Melissa Delane. "Assessment of arsenate bioavailability in iron-rich environments: development of a high-pressure liquid chromatography method of quanitification for arsenate sorbed by Fe3+-substituted chelating resins in arsenic-bearing ferrihydrite suspensions." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2450.

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Given that the mobility, bioavailability, and toxicity of arsenate in natural systems is often controlled by the strong binding capacity of iron oxyhydroxides, the objective of this study was to document the interactions of Dowex M4195 Fe3+-substituted chelating resins (a potential fieldbased tool for the quantification of potential arsenate bioavailability) and arsenic-bearing ferrihydrite (AFH) as a function of suspension pH, suspension concentration, and background electrolyte concentration. In 0.5 g AFH/L (0.001 M NaNO3) suspensions, arsenate sorption to the resins was proportional to the degree of acidification of the AFH suspensions by the resins. H+-enhanced dissolution of ferrihydrite artificially increased the arsenate in solution, causing a consistent overestimation of potential arsenate bioavailability. Resin-induced acidification was decreased with increasing suspension concentration. Arsenate sorption to the resins in 0.5 g/L suspensions at pH 8 decreased with increasing NaNO3 concentrations, reflecting the decreasing activity of arsenate under these conditions. The results of this study indicate that the high buffer capacity of natural soils would prevent acidification as a result of resin introduction. Thus, Dowex M4195 Fe3+-substituted chelating resins should provide a reasonable assessment of potential arsenate bioavailability from poorly-crystalline iron oxide minerals. Possibly more importantly, Dowex M4195 Fe3+-substituted chelating resins appear to be a new choice of passive equilibrium sampling device that should work well for the determination of bioavailable arsenate concentrations in the field.

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Hrabovský, Jan. "Biodegradabilní kostní implantáty na bázi železa." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442443.

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This work deals with a current topic, which are biodegradable bone implants. These implants seem to be a suitable candidate for temporary fixations, with their gradual decomposition. An important parameter is not only the mechanical properties so that the material can withstand the load, but above all the corrosion properties and the degradation process. This work introduces the physiology of bone, trace elements and also describes current trends in the field of implants. The last part is a theoretical introduction to cross-stage processes. The practical part is focused on the preparation of iron-based samples with various dopants, subsequent annealing and analysis.

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Farias, Francisco Edson Mesquita. "ProduÃÃo de Hidrocarbonetos atravÃs da SÃntese de Fischer-Tropsch utilizando Catalisadores de Fe/K." Universidade Federal do CearÃ, 2007. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=1273.

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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
A reaÃÃo de sÃntese de Fischer-Tropsch tem merecido grande atenÃÃo pelo seu interesse tecnolÃgico e cientÃfico. Este interesse estÃ associado a conversÃo do gÃs natural em produtos lÃquidos de alta qualidade (gasolina e diesel) e elevado valor agregado. No presente trabalho Ã descrito a metodologia empregada na sÃntese e caracterizaÃÃo de catalisadores de ferro usados na sÃntese de Fischer-Tropsch, com Ãnfase nos catalisadores suportados em sÃlica e catalisadores industriais (utilizados na sÃntese de amÃnia) promovidos com potÃssio e cobre. Pretende-se com esta discussÃo, identificar possÃveis vias para o desenvolvimento de catalisadores mais ativos e seletivos, variando a composiÃÃo do promotor estrutural para fins de otimizar a distribuiÃÃo dos produtos em fraÃÃes de hidrocarbonetos especÃficos (gasolina, diesel e graxa). A reaÃÃo foi conduzida em um reator de leito de lama. O estudo seguiu um planejamento experimental do tipo fatorial quadrado com ponto central e os resultados foram analisados baseados na metodologia dos grÃficos de superfÃcie de respostas. Os efeitos das diferentes condiÃÃes operacionais (temperatura e pressÃo) e dos diferentes teores de potÃssio na distribuiÃÃo dos produtos lÃquidos foram comparados baseados nos cromatogramas, nÃmero mÃdio de carbono (Nn) e no grau de dispersÃo dos produtos. Para todos os catalisadores de ferro empregados neste trabalho, observou-se um aumento no Ãndice que representa o comprimento da cadeia de hidrocarboneto (Nn) com o aumento do teor de potÃssio. Indicando um maior grau de polimerizaÃÃo para os catalisadores de ferro suportados com 18K em ralaÃÃo aos outros (12K, 6K e industrial). Os resultados mostram que, para catalisadores suportados, em pressÃes elevadas (25 e 30atm) favorecem a produÃÃo de graxa, enquanto a seletividade para hidrocarbonetos lÃquidos Ã favorecida a baixa pressÃo (20atm) e baixa temperatura (240ÂC). Para os catalisadores industriais, observou-se um aumento na fraÃÃo graxa em baixas temperaturas (240-255ÂC) e elevadas pressÃes (30atm). Contudo, os resultados de todas as corridas para o catalisador suportado e o industrial promovido e nÃo-promovido apresentaram quantidades significativas de n-parafinas com no mÃximo 35 Ãtomos de carbono que pode ser causados atravÃs das limitaÃÃes geomÃtricas e espaciais dentro dos poros do catalisador que tambÃm podem explicar o motivo pelo qual o Ãndice de dispersÃo da distribuiÃÃo de hidrocarbonetos serem mais baixos para um maior nÃmero de carbonos mÃdio.
The Fischer-Tropsch synthesis has been focus of attention of the scientific and industrial community. This interest is related to the conversion of natural gas into high quality liquid products, such as gasoline and diesel, which have high commercial value. In this work the methodology applied to synthesize and characterize iron-based catalyst used in the Fischer-Tropsch synthesis was described. Emphasis was given to catalysts supported in silica and to industrial catalysts (used in the synthesis of ammonia) impregnated with potassium and copper. The catalysts were tested to identify more active and selective catalysts, changing the amount of structural promoter in order to optimize the product distribution of specific hydrocarbons (gasoline, diesel, wax). The reaction was carried out in a slurry phase reactor. The experiments followed a 22 factorial experimental planning with central point and the results were analyzed based on the surface response methodology. The effects of the operating conditions (temperature and pressure) and of the amount of potassium in the catalyst on the liquid product distribution were compared based on the chromatographs, number average number of carbons (Nn) and distribution dispersion. In all iron based catalyst used in the research, the number average number of carbons (Nn) increased with increasing amount of potassium in the catalyst formulation. This result indicates that the catalyst with 18 K supported in silica showed the highest degree of polymerization in comparison with all other catalysts produced in this research. The results showed that for the catalyst supported in silica high pressures (25 to 30 atm) favor the production of wax, while higher selectivity towards liquid fuels was favored by low pressure (20 atm) and low temperature (240ÂC). For the industrial catalyst, an increase in the wax cat was observed at low temperatures (240-255ÂC) and high pressures (30 atm). The experiments carried out with the both catalysts (silica-supported and alumina-supported) have presented significant amounts of n-paraffins with a maximum of 35 carbons and low dispersion of the product distribution which can be caused by space limitations within the catalyst pores.

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Buckley, Ragan. "The purine world: experimental investigations into the prebiotic synthesis of purine nucleobases and intercalation of homopurine DNA duplexes." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/48971.

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Formamide is a solvent of great interest to prebiotic chemists because it is liquid over a wide range, it is less volatile than either water or HCN, and it possesses a versatile reactivity. When formamide is heated in the presence of minerals or inorganic catalysts, a variety of products including purine nucleobases are generated. Irradiation of formamide reaction solutions with ultraviolet light increases the yield and diversity of products, and eliminates the need for a mineral catalyst. We have also performed formamide reactions in the presence of pyrite, a mineral which is likely to have been available on the primordial Earth, under a variety of atmospheric conditions. Our results indicate the greatest yield and diversity of products result from the combination of a pyrite mineral catalyst, heat, UV irradiation, and a carbon dioxide atmosphere. Purine nucleobases are simple to synthesize in model reactions and they stack well in aqueous solution; it has been hypothesized that the first nucleic acids were composed of only purine bases, and that water-soluble, cationic, aromatic molecules with large stacking surfaces (“”molecular midwives””) may have aided the assembly of the earliest nucleic acid analogs. We have characterized the interactions of various intercalators with a standard DNA duplex as well as with an antiparallel homopurine DNA duplex and have determined that molecules which possess four or more rings and a curved shape interact selectively with all-purine DNA; such molecules can serve as models for putative prebiotic midwives.

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35

Silva, Jorge Ayrton da. "Analise termica na solidificação de ferros fundidos cinzentos hipoeuteticos." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264734.

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Orientador: Amauri Garcia
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-08T17:48:12Z (GMT). No. of bitstreams: 1 Silva_JorgeAyrtonda_M.pdf: 5941604 bytes, checksum: 9ec8b76ce4cbb57c06994f1a8307f767 (MD5) Previous issue date: 2007
A análise térmica é amplamente utilizada como método de controle de processos metalúrgicos e na investigação da composição química de ferros fundidos na prática de fundição. Um meio confiável de avaliação da composição de ferros fundidos é disponibilizado pela técnica do Carbono Equivalente, que é baseada na mudança de inclinação da curva de resfriamento na temperatura liquidus durante o resfriamento de uma amostra de ferro fundido a partir do estado líquido. O presente trabalho é focado no desenvolvimento de um novo sensor para análise térmica, um sensor de imersão, que objetiva contribuir com determinações mais confiáveis de composição durante as operações de fundição. Foram desenvolvidos experimentos em diferentes empresas de fundição, utilizando-se tanto o sensor de imersão quanto o tradicional sensor tipo cápsula, normalmente utilizado na prática de fundição. As comparações de composições químicas, medidas por essas duas técnicas e medidas fornecidas por análise de espectrometria de emissão óptica, demonstram que geralmente o sensor de imersão fornece resultados mais confiáveis. Uma análise térmica realizada durante o resfriamento de ferro fundido em um dispositivo unidirecional com uma coquilha, e utilizando um conjunto de termopares, permitiu também a determinação quantitativa de variáveis térmicas de solidificação, tais como: coeficientes transitórios de transferência de calor metal/molde e molde/ambiente e taxa de resfriamento à frente da isoterma liquidus
Abstract: Thermal analysis is a widely used method for metallurgical process control and investigation of alloy composition of cast irons in foundry practice. A reliable means of rapidly evaluating the composition of cast irons is available by the Carbon-Equivalent technique, which is based on the change in thermal arrest temperature of the liquidus as the sample of molten cast iron freezes. The present work focuses on the development of a new sensor for thermal analysis, a dip-sensor, wich aims to contribute to more reliable determination of alloy composition during casting operation. Experiments were carried-out in different foundries by using both the dipsensor and the traditional capsule-sensor, which is normally used in foundry practice. The comparison of alloy compositions measured by these two techniques with analysis performed by Arc/Spark spectrometry has shown that generally the dip-sensor provides more reliable results. Thermal analysis conducted during cooling of molten cast iron in a unidirectional chill apparatus, by using a set of thermocouples, has also permitted the quantitative determination of solidification thermal variables, such as: transient metal/mold and mold/ambient heat transfer coefficients and tip cooling rates
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica

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36

Almeida, Sheila Kênia de. "Detecção de bactérias redutoras de sulfato em efluente e sedimento de mina de urânio." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2005. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=44.

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Um dos graves problemas ambientais oriundos da indústria de mineração é a drenagem ácida de mina que ocorre quando a pirita e outros minerais sulfetados são oxidados devido à presença de oxigênio e água, produzindo ácido sulfúrico que solubiliza metais presentes no solo/rocha. Em uma planta das Indústrias Nucleares do Brasil INB, na Unidade de Tratamento de Minérios (UTM) este problema tem se pronunciado de forma preocupante levando a dissolução de espécies radioativas e metálicas presentes. O tratamento da água ácida usando bactérias redutoras de sulfato, proporciona decréscimo da acidez que é decorrente da redução do sulfato a sulfito e precipitação dos metais como sulfetos. Nesse contexto, o presente estudo foi realizado visando a caracterizar sazonalmente e espacialmente populações de bactérias redutoras de sulfato (BRS) nos efluentes líquidos e amostras de sedimento da cava da mina (CM) e nos bota-foras 4 e 8 (BF4 e BF8) coletadas na UTM. Tais informações poderão permitir posteriormente, estudar mecanismos de biomanipulação a fim de remediar situações impactantes. Menores valores de pH , abaixo de 3,5, foram medidos no período de março a abril em amostras de água da cava da mina e a maior população de BRS (2,8 NMP. mL-1) foi observada em fevereiro em amostras do BF8. Os valores encontrados para matéria orgânica na água foram menores do que aqueles encontrados no sedimento. A concentração de oxigênio dissolvido na água variou de 0,65 g/L a 13,3 g/L. As amostras de sedimento apresentaram maiores valores de BRS (10,2 NMP/mL), quando comparadas com amostras de água (0,63 NMP/mL). Tais resultados eram esperados uma vez que, nas amostras de água coletadas próximas ao sedimento foram observadas menores concentrações de oxigênio dissolvido (7,10g/L) e maiores concentrações de matéria orgânica disponível (17,0 mg/L) quando os resultados foram comparados com aqueles obtidos para amostras de água coletadas na superfície (0,004mg/L). Os resultados mostram, portanto, que o efluente ácido gerado apresenta altos teores de metais estáveis e radioativos, sulfato, baixo pH e presença de bactérias redutoras de sulfato.
One of the most serious environmental problems created by the mining industry is acid mine drainage. In one plant of Nuclear Industries of Brazil - INB, this problem is a matter of concern. The presence of iron sulfites, such as pyrite, generates water with acidity above the levels allowed by the legislation and therefore, inappropriate for releasing straight into the environment. The industry maintain a high cost treatment in acid water from mines and waste disposal which consists in neutralizing and precipitating heavy metals. The treatment of acid water using SRB (sulfate-reducing bacteria) has been used in other countries with quite good technical results as well as economical advantages and thus, the object of this research. The use Sulfate Reducing Bacteria takes to a decreasing of the acidity by reducing sulfate to sulfite and precipitating the stable metals as sulfides. A seasonal study was carried out on the sulfate-reducing bacteria present in the liquid effluent discharged from two wastes disposal of the uranium mine, in phase of decommission, in Caldas/MG. This study shows the presence of SRB in the analyzed environmental, as well as some factors that are related with the amount of SRB presents, such as: dissolved oxygen, pH and organic matter. SRB was presented in water samples with high concentrations of heavy metals and low pH values, as well as in samples with high oxygen levels. The sediment samples were the preferential place for SRB occurrence and site BF8 presented the highest values of SRB.

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37

Pinkert, Katja. "Mesoporöse Kohlenstoffmaterialien und Nanokomposite für die Anwendung in Superkondensatoren." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-154422.

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Die effiziente Speicherung von elektrischer Energie im elektrochemischen System des Superkondensators wird realisiert durch die Ausrichtung von Elektrolytionen im elektrischen Feld polarisierter, poröser Kohlenstoffelektroden. Der Energieinhalt und die Leistungscharakteristika der elektrostatischen Zwischenspeicherung von Energie bei Lade- und Entladezeiten von wenigen Sekunden bis zu einigen Minuten wird entscheidend durch die Eigenschaften der zur Ladungsspeicherung genutzten Grenzfläche zwischen dem Elektrodenmaterial und dem Elektrolyten bestimmt. Für die Optimierung des Energieinhaltes und der Leistungscharakteristika von Superkondensatoren durch die rationale Modifizierung dieser Grenzfläche konnten entscheidende Trends herausgearbeitet werden. Durch Einbindung eines pseudokapazitiven Eisenoxids in die spezifische Oberfläche des mesoporösen CMK-3 im Redoxverfahren ist die Darstellung einer neuartigen Nanokompositstruktur möglich. Diese weißt eine dreifach höhere spezifische Kapazität im Vergleich zur nicht-modifizierten Kohlenstoffoberfläche unter Beibehaltung der Strombelastbarkeit der Kohlenstoffmatrix auf. Entscheidend für die Weiterentwicklung von Synthesestrategien und die anwendungsorientierte Optimierung für Nanokompositstrukturen ist deren ausführliche Charakterisierung mittels angepasster Verfahren. Die in dieser Arbeit erstmals zur Analyse von porösen CMK-3 basierten Nanokompositstrukturen verwendeten Methoden der Aufnahme eines Tiefenprofils mittels Auger Elektronen Spektroskopie (DP-AES) und der energiegefilterten Transmissionselektronenmikroskopie (EF-TEM) lieferten die Grundlage zur Weiterentwicklung der rationalen, nanoskaligen Grenzflächenfunktionalisierung. In einem weiteren, stark vereinfachten und effektiveren Verfahren der Schmelzimprägnierung der porösen Matrix mit Nitrathydraten, sowie deren anschließendes Kalzinieren zum Übergangsmetall, respektive pseudokapazitiven Übergangsmetalloxid, konnte eine nochmals optimierte Nanokompositstruktur dargestellt werden. Das entwickelte Verfahren wurde für die Einbettung von Nickel/Nickeloxid und Eisen/Eisenoxid in die Oberfläche des mesoporösen CMK-3 eingesetzt. Ein gesteigerter Energieinhalt, wie auch eine deutlich gesteigerte Stabilität der Kapazität bei hohen Strombelastungen für die resultierenden Elektrodenmaterialien konnte eindeutig nachgewiesen werden. Die signifikante Erhöhung der Leistungscharakteristika ist dabei auf die optimale Kontaktierung des Übergangsmetalloxids durch das Übergangsmetall als Leitfähigkeitsadditiv im Sinne einer Kern-Schale Struktur realisiert. Der für das Nanokomposit C-FeO10 berechnete Kapazitätsverlust von < 11 % bei Erhöhung der spezifischen Stromstärke von 1 A/g auf 10 A/g verdeutlicht die beeindruckende Strombelastbarkeit des Materials. In einem weiteren in dieser Arbeit diskutierten Ansatz zur Steigerung des Energieinhaltes eines Superkondensators wurde auf die Verwendung von Ionischen Flüssigkeiten (IL) als Elektrolyt eingegangen. Die gezielte Darstellung eines oberflächenmodifizierten aus Cabiden gewonnen Kohlenstoffmaterials (CDC) unter Beibehaltung der Textur des porösen Systems ermöglichte die Untersuchung des Einflusses der Oberflächencharakteristika des Elektrodenmaterials auf die Strombelastbarkeit des Energiespeichers. Es konnte klar herausgestellt werden, dass für den vielversprechenden IL-Elektrolyten EMIBF4 eine verminderte Polarität, sowie die Abwesenheit azider Protonen an der Oberfläche des Kohlenstoffs deutlich zur Steigerung der Strombelastbarkeit des Speichers beiträgt. Realisiert wurde die Modifizierung der Oberfläche durch deren Chlorierung. Die Einordnung der vielversprechenden Kombinationen aus maßgeschneiderten Elektrodenmaterialien und Elektrolytsystemen wurde anhand der Kenngrößen im Ragone-Diagramm vorgenommen. Die Ergebnisse der Arbeit reihen sich in die derzeit schnell voranschreitende Technologieentwicklung bei Superkondensatoren ein.

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38

Nguyen, Nhung Phuong. "Axial Ligand Mutant: H229A." Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/honors_theses/1.

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Many pathogenic bacteria use their iron acquisition mechanisms to live inside hosts. Streptococcus pyogenes is a pathogenic bacterium that uses streptococcal iron acquisition ABC transporter to obtain heme. SiaA (HtsA, spy1795), a lipoprotein located on the cell surface, serves as a heme binding protein. To understand the iron-uptake mechanism, histidine 229, one of the two proposed axial ligands in SiaA, was mutated to alanine. SiaA H229A was expressed in E. coli, lysed by French Press, and purified by fast protein liquid chromatography (FPLC). SDS-PAGE indicated that pure protein was isolated. Nickel affinity FPLC gave purer H229A when 0.5 M imidazole was added to the binding buffer. Overall, histidine 229 is likely to be an axial ligand in wild type SiaA, as shown by the fact the mutant readily lost heme as evidenced by UV-vis spectra.

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39

Komora, Mojmír. "Závislost povrchové struktury Fe2O3(012) na prostředí." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-382255.

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Táto diplomová práca sa zaoberá štúdiom alfa-Fe2O3(012) vystaveného vodnému prostrediu. Súčasný stav poznania ohľadom oxidov železa s pozornosťou vkladanou do popisu alfa-Fe2O3 a jeho (012) povrchu je stručne zhrnutá. Experimentálná časť tejto práce začína s popisom unikátného zariadenia na depozíciu kvapalnej vody na povrchy monokryštalických vzoriek compatibilného s podmienkami ultra vysokého vákuua. Jednotlivé konštrukčné časti a detaily sú diskutované. Navrhnutý systém bol testovaný na vzorkách striebornej fólie a monokryštálu Fe3O4 s povrchovom v rovine [100]. Chemické zloženie a morfológia povrchu po experimente s kvapalnou vodou je diskutovaná. Navrhnuté zariadenie bolo použité na štúdium interakcie vody so známymi (1x1) a (2x1) povrchovými alfa-Fe2O3(012). Experimentálne dáta ukazujú, že voda sa viaže na obe reconštrukcie disociatívne s určitým množstvom molekulárnej vody naviazanej na adsorbované hydroxydi. (1x1) sa zdá javý stabilná po expozícii rôznym tlakom vodnej pary, zatial čo (2x1) vykazuje zmenu na (1x1) pri expozíciach vyšším tlakom vodnej pary alebo po niekolo minútovej expozíci electrónovému zväzku. Ďalej sú v tejto práci prezentované prvé výsledky z štúdie prechodu (1x1) rekonštrukcie na (2x1) pomocou mikroskpie nízkoenergiových elektrónov. Výsledky ukazujú, že táto premena na nižších teplotách je inciovaná na hranách atomárnych vrstiev a defektov na povrchu, ktorá potom postupuje smerom k stredu atomárnych terás. Meranie na vyšších teplotách vykazuje postupnú premenu povrchu naznačúju viaceru nukleačných centrech z ktorých sa (2x1) povrch širi ďalej.

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40

Semeniuk, Konstantin. "Correlated low temperature states of YFe2Ge2 and pressure metallised NiS2." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274346.

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While the free electron model can often be surprisingly successful in describing properties of solids, there are plenty of materials in which interactions between electrons are too significant to be neglected. These strongly correlated systems sometimes exhibit rather unexpected, unusual and useful phenomena, understanding of which is one of the aims of condensed matter physics. Heat capacity measurements of paramagnetic YFe$_{2}$Ge$_{2}$ give a Sommerfeld coefficient of about 100 mJ mol$^{−1}$ K$^{−2}$, which is about an order of magnitude higher than the value predicted by band structure calculations. This suggests the existence of strong electronic correlations in the compound, potentially due to proximity to an antiferromagnetic quantum critical point (QCP). Existence of the latter is also indicated by the non-Fermi liquid T$^{3/2}$ behaviour of the low temperature resistivity. Below 1.8 K a superconducting phase develops in the material, making it a rare case of a non-pnictide and non-chalcogenide iron based superconductor with the 1-2-2 structure. This thesis describes growth and study of a new generation of high quality YFe$_{2}$Ge$_{2}$ samples with residual resistance ratios reaching 200. Measurements of resistivity, heat capacity and magnetic susceptibility confirm the intrinsic and bulk character of the superconductivity, which is also argued to be of an unconventional nature. In order to test the hypothesis of the nearby QCP, resistance measurements under high pressure of up to 35 kbar have been conducted. Pressure dependence of the critical temperature of the superconductivity has been found to be rather weak. μSR measurements have been performed, but provided limited information due to sample inhomogeneity resulting in a broad distribution of the critical temperature. While the superconductivity is the result of an effective attraction between electrons, under different circumstances the electronic properties of a system can instead be dictated by the Coulomb repulsion. This is the case for another transition metal based compound NiS$_{2}$, which is a Mott insulator. Applying hydrostatic pressure of about 30 kbar brings the material across the Mott metal-insulator transition (MIT) into the metallic phase. We have used the tunnel diode oscillator (TDO) technique to measure quantum oscillations in the metallised state of NiS$_{2}$, making it possible to track the evolution of the principal Fermi surface and the associated effective mass as a function of pressure. New results are presented which access a wider pressure range than previous studies and provide strong evidence that the effective carrier mass diverges close to the Mott MIT, as expected within the Brinkman-Rice scenario and predicted in dynamical mean field theory calculations. Quantum oscillations have been measured at pressures as close to the insulating phase as 33 kbar and as high as 97 kbar. In addition to providing a valuable insight into the mechanism of the Mott MIT, this study has also demonstrated the potential of the TDO technique for studying materials at high pressures.

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41

Leclerc, Olivier. "Etude analytique de l'action des dithiocarbonates sur la pyrite : application a la flottation." Paris 6, 1987. http://www.theses.fr/1987PA066474.

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42

Grosselin, Nadège. "Mise au point d'une technique voltampérométrique pour la caractérisation de particules individuelles conductrices de quelques dizaines de microns : application à l'étude de l'adsorption des ions argent et mercure ainsi que du thymol sur la pyrite." Nancy 1, 1998. http://www.theses.fr/1998NAN10142.

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Au cours de ce travail, une nouvelle technique ultramicroélectrochimique pour la caractérisation des grains individuels conducteurs de quelques dizaines de microns à été mise au point. Elle permet, en particulier, la détection d'espèces solubles formées à l'électrode sans devoir imposer des vitesses de balayage extrémement élevées comme c'est le cas avec les ultramicroélectrodes conventionnelles (10 MV/S suffisent). Les études sans ajout d'électrolyte support sont aussi possibles. La comparaison des voltampérogrammes de AG#2SE avec ceux obtenus par les méthodes classiques a mis en évidence qu'il est possible de caractériser des grains du minéral sans interférence contrairement aux pates de carbone. La technique a ensuite été utilisée parallélement à des méthodes spectroscopiques pour l'étude de l'adsorption de AG#+ et de HG#2#+ sur la pyrite FES#2 (pulpes à 0,5% en poids). Il s'avère que les spéciations de l'argent et du mercure à la surface de FES#2 dépendent fortement de la concentration des ions métalliques en solution. Dans le cas où l'argent est à faible concentration, seul AG#2S se forme. Quand la concentration est plus forte, de l'argent métallique est aussi présent. De même, selon la concentration en mercure, une ou deux espèces de stabilité différente se fixent à la surface de la pyrite. La quantité maximale de mercure s'adsorbant sur le minéral (3,5 10#-#5 MOL/G) est vingt fois moins importante que celle d'argent (6,6 10#-#4 MOL/G). Quand de la pyrite est conditionnée simultanément avec les ions AG#+ et HG#2#+, seul le mercure est adsorbé à sa surface. Il libère en solution l'argent si ce dernier était préalablement fixe sur le minéral. La quantité de mercure alors adsorbée atteint 3,2 10#-#4 MOL/G. Enfin, l'action du thymol sur la pyrite a été envisagée dans le but d'inhiber l'oxydation chimique du minéral. Les mesures électrochimiques ont montré que c'est le produit d'oxydation du thymol, et non lui-même, qui s'adsorbe sur la pyrite et limite son oxydation

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43

Heyd, Marie. "Les représentations de la mort dans la création artistique actuelle : histoire, contextualisation, comparaisons." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAC002.

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Alors que les individus dans la société contemporaine sont unis non par une propriété mais par un devoir et par une dette, par un manque, par une limite prenant la forme d’une charge pour celui qui en est affecté, la postmodernité rend à la mort et à l’absence toute sa densité. À travers la répétition, entre jubilation et désespérance, les artistes figurent la temporalité de l’épreuve par une écriture qui travaille l’instant. Ils racontent ces évènements infimes qui sont les plus fragiles, les plus précaires, ayant pourtant une forte efficacité. Il s’agira ici d’étudier les nouvelles postures devant l’événement historique, quand l’artiste se tient au plus singulier
While individuals in contemporary society are united not by property but by a duty and a debt, a lack, by a limit taking the shape of a responsibility for the one who is affected, postmodernism returns to death and absence all its density. Through repetition, between jubilation and despair, the artist represents the temporality of the event. His writing works the moment. He tells these tiny events that are the most fragile, the most precarious, having nevertheless a strong efficiency. This thesis will try to study the new postures in front of the historic event, when the artist stands in the most singular

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44

Lin, Shu Hung, and 林書弘. "Preparation of Iron Oxide Powders for Waste Liquor Recovery from Steel Industry Pickling Wastewater." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/85351748863613743443.

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碩士
吳鳳科技大學
光機電暨材料研究所
102
Abstract This study used ferrous chloride (acid waste liquid) as the raw material to prepare Fe3O4 and Al2(SO4)3- Fe2O3 powder through neutralization recycling method. The results showed that as the sintering temperature is up to 600℃, and Fe3O4 powder turns into α-Fe2O3 based on thermal dissociation. As the sintering temperature rises, the average particle size increases from 30.87nm to 41.45nm, and powder color changes as well. The Fe2O3 powder containing different proportions of Al2(SO4)3 was examined in the XRD diagram. As seen, when the Al2(SO4)3 content is up to 7%, the unsintered Fe2O3 powder is CaSO4-2H2O. After high-temperature sintering, α-Fe2O3 appears and CaSO4-2H2O turns into CaSO4. According to the SEM diagram, as the temperature rises and Al2(SO4)3 content increases, clustering appears on the surface. The average particles size increases as the temperature rises. As shown in the chromaticity diagram, as the Al2(SO4)3 content increases, powder color changes. The optimal content of Al2(SO4)3 is 15% and optimal sintering temperatures are 750℃ and 800℃. Bright orange for the prepared powder is more acceptable pigment in the market. Light and dark colors of the powder can be controlled by adding different proportions of Al2(SO4)3. Fe2O3 powder prepared in this study can be applied in coating, plastic, rubber, ceramic, printing ink and art paint, thus achieve waste acid recycling.

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45

Lai, Ang-chih, and 賴昂志. "Numerical model of carbon dissolution in liquid iron." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/49450752146498428866.

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碩士
國立中山大學
機械與機電工程學系研究所
103
In this study, a numerical model is built to investigate the factors on carbon dissolution rate and develop a lump system for carbon particle dissolution in hot liquid metal. We assume the carbon particles dissolve in the molten iron is a quasi-steady process. Therefore, the steady state model has been developed. The simulation data shows the distribution of mass dissolution rate at the particle surface is significantly affected by the flow circulation behind a particle as a relative flow velocity is applied. The lump system has been developed by the correlation of Reynolds number and Schmidt number, which can predict the carbon particles dissolve at times of different state. The correlation of mass/heat transfer are as following: Sh=2.81+0.52 Re^0.52 Sc^0.38 Nu=0.53+0.27 〖Re〗^034 Pr^0.16 The study also established a transient model, and compare the time of dissolution between two models. Simulation results of transient model show that when the Reynolds number is smaller, the dissolution rate of carbon particles goes to be slightly longer.in addition this study also building a two dimension injection model through the simulation result of different model confirm the reliability of lump system

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46

Hu, Chen-Yu, and 胡鎮宇. "Production of Graphite from Catalytic Liquid Cast Iron Bath." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/f987bp.

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碩士
國立清華大學
材料科學工程學系
106
Via the use of iron-carbon phase diagram and the theory of graphitization of carbon in cast irons, this study investigates an innovative method for continuously, effectively and efficiently, as well as environment-friendly producing graphite in a catalytic cast iron bath. It is concluded that the transformation from amorphous carbon to graphite via the method is available, and the degree of graphitization (DOG) described in this study reaches a high value of more than 93% like that of Acheson’s. Furthermore, the DOG is process-controlled and is independent of carbon source in the hypereutectic catalytic cast iron melt. The observance of graphite flotation in liquid catalytic cast iron bath manifests the production of graphite is achievable by the fluidized bed method. The first part of this study describes the inductive melting (IM) of alloys of iron, carbon, and silicon at 1600oC for full melting; holding at temperatures higher than the eutectic temperature of 1500oC for 4 h for graphitization of carbon; and then lower the temperature to 25oC for test specimens. The IM specimens, being XRD and OM-checked firstly, are further pickled to obtain graphite that is also XRD-, OM- and ICP-analyzed to compare with graphite obtained from nodular cast iron and gray cast iron. The second part is about the vacuum arc re-melting (VAR) experiment of the specimens that are obtained in the first part. The effects of the number of VAR process and the addition of synthetic graphite on the DOG are checked with OM. The graphite samples of VAR specimens after pickled are checked with graphite production yield analysis, XRD for the comparison of the DOG, and ICP for the composition analysis.

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47

Curr, Thomas Robert. "The dissolution of a Transvaal chromite in liquid silicate slags under an inert atmosphere at 1550 celcius degrees and 1650 celsius degrees." Thesis, 1990. https://hdl.handle.net/10539/24333.

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A dissertation submitted to the faculty of Engineering, University of the Witwatersrand, in fulfillment of the requirements for the degree of Master of Science in Engineering.
The role of chromite dissolution in the smelting of ferrochromium was investigated with the object of improving the throughput and chromium recovery of the process. The solubility of a typical Transvaal chromite in silicate slags with cao/si02 ratios from 0,03 to 0,55 at 1550·C and 1650·C was determined. Synthetic slags were melted in porous chromite crucibles and the slag underwent repeated reactions with the chromite grains as it penetrated the crucible wall. Finally the slag came into equilibrium with -''the ,original chromite towards the outer part of the crucible wall. Microprobe analysis of this slag yielded the maximum or saturated solubilities of the chromite constituents in the slag. The solubility of cr203 was found to be low (-1 per cent) while the remaining components' solubilities (A1203 -16 per cent, FeO)T 12 per cent and MgO-8 per cent) were significantly higher. CaO/Sio2 ratios greater than 0,1 lowered the solubility of Mg0 significantly (e.g. from 14,1 per cent to 5,8 per cent at 1650·C). The complete dissolution of this chromite in these slags requires the slag to contain less than the solubility limits of each of these species simultaneously. It was recommended that the best way to achieve this in practice would be a well-stirred slag bath containing suspended carbon particles, in which a cao/Sio2 ratio of less -than 0,1 was maintained. Further work to investigate the effect of slag composition (including Na20 and CaF2) on the kinetics of chromite reduction in such a system was recommended.
AC 2018

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48

Cham, S. Tsuey Materials Science &amp Engineering Faculty of Science UNSW. "Investigating factors that influence carbon dissolution from Coke into Molten iron." 2007. http://handle.unsw.edu.au/1959.4/40685.

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The need for more efficient blast furnaces is even greater now that there are stricter environmental regulations on greenhouse gas (GHG) emissions. Coke within the blast furnace not only supports the furnace bed and allows gas flow, it also carburises liquid iron. The carburisation of iron is one of the most important reactions and must be better understood if the ironmaking process in the blast furnace is to be made more sustainable. By understanding what coke properties influence the rate at which coke dissolves in iron we can predict a coke?s performance and use it to determine its quality. As carbon dissolution rates have only been determined for a few cokes, a systematic and comprehensive study was conducted on the dissolution of carbon from nine Australian cokes into liquid iron. The kinetics of carbon dissolution from Cokes A to I was measured and a range of experimental techniques were used to elucidate the dominant rate influencing factors. The role of coke structure, coke inorganic matter composition and yield and temperature were investigated. Furthermore, the influence of interfacial products and dynamic wettability studies were also conducted. The carburiser cover method was used to measure carbon pick-up as a function of time over the temperature range of 1450-1550 ??C. Fundamental data on the apparent carbon dissolution rate constant (K) in molten iron at 1550 ??C for Cokes A to I were obtained and ranged from K (x 103 s-1) = 0.47 to K (x 103 s-1) = 14.7. The wide variation in K showed that not all cokes dissolve at similar rates. In fact one of the nine cokes in this investigation dissolved at a rate comparable to graphite dissolution rates. The apparent carbon dissolution activation energy, Ea, for two of the nine cokes plus synthetic graphite (SG) was also determined. The Ea obtained for SG (Ea = 54 kJ / mol) was in agreement with literature values and was consistent with a diffusion controlled mechanism. The observed Ea values for Cokes D and F (313 kJ / mol and 479 kJ / mol respectively) are an order of magnitude larger than the Ea obtained for SG. The difference in Ea between cokes and SG does not appear to be solely due to differences in the structure of the carbon source. The difference in Ea between the cokes was attributed to differences in their inorganic matter composition. The interfacial contact area is a function of inorganic matter yield and composition, which in turn is a function of temperature. Therefore, as temperature decreases the slag / ash layer produced at the carbon / iron interface can increase in area and viscosity and thus hinder carbon dissolution and transfer, and increasing the apparent activation energy for carbon dissolution. Thus, the differences in viscosity and melting temperature of the interfacial product play a key role. Wettability experiments were carried out using the sessile drop technique. The wettability of Cokes D, F and G with liquid iron at 1550 ??C was measured as a function of time. All three coke samples showed non-wetting behaviour with contact angles ranging between 123-129?? in the initial stages and between 109-114?? after two hours of contact. The differences in the wettability of the three coke samples could not explain the large differences in dissolution rates observed between these cokes. Thus, the wettability of these coke samples was not considered a dominant factor in influencing the rate of carbon dissolution. The sessile drop technique was also used to study the interfacial products formed at the coke / iron interface. The interfacial products formed on the underside of the iron droplet after contact with Cokes F and G were initially different in regards to the morphology and chemical composition. The interfacial product formed with Coke G had a network or mesh like structure that seemed to wet the iron droplet much better than the interfacial product formed with Coke F. In contrast, Fe globules and discrete interfacial products were observed in Coke F. It was suggested that this was due to differences in inorganic matter content, especially in calcium (Ca) and sulfur (S) content in the coke. Formation of interfacial products containing sulfides, such as calcium sulfide (CaS) and manganese sulfide (MnS), were observed on the iron side of the interface of both Cokes F and G. As a result, the interfacial products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution and decreasing the rate of carbon dissolution. The presence of MnS may act to lower the liquidus temperature of the interfacial product, which in turn can affect the overall viscosity of the interfacial layer. Thus, the deposition of reaction products at the interfacial region can have a significant effect on carbon dissolution rates. The mineral pyrrhotite was also identified as a significant factor in influencing the rate of carbon dissolution. Electron dispersive X-ray analyses of Coke F identified iron to be in close association with sulfur. These Fe / S species have atomic ratio similar to pyrrhotite (Fe1-xS) or troilite (FeS). Pyrrhotite in coke can decompose to release gaseous sulfur and metallic iron, which can be carburised by carbon in the surrounding area to form Fe-C particles. Thus, carburisation of liquid iron can occur via Fe-C particles. There was little difference in structure between the nine coke samples and therefore the high dissolution rates of Coke F, cannot be explained on the basis of crystallite size or anisotropic carbon content. Inorganic matter yield and composition were identified as the dominant rate influencing factors on carbon dissolution. More specifically: - High content of iron phases, such as iron oxides and pyrrhotite, can lead to an increase in carbon dissolution rates. This maybe due to increased amounts of Fe-C particles that are formed upon the reduction of magnetite and decomposition of pyrrhotite, and carried through the slag layer to carburise the bulk liquid iron. - High aluminium oxide content can lead to a decrease in carbon dissolution rates. This maybe due to higher ash fusion / melting temperature or decrease in wettability, both of which lead to a decrease in carbon / iron contact area. - Formation of interfacial products, such as CaS and MnS, can lead to a decrease in carbon dissolution rates. Such products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution. However, the presence of MnS may act to lower the liquidus temperature of the interfacial product. - An increase in temperature increases the rate of carbon dissolution. This dependence is predominantly due to the composition of the inorganic matter present in cokes, which influences the viscosity and melting point of the interfacial product formed and hence contact area between coke and iron.

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Ferreira, Marnus Gert. "Review of the liquid line of descent in iron rich basalts." Diss., 2015. http://hdl.handle.net/2263/50899.

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Abstract:

This research project aims to highlight and identify the main assumptions made, and the methods implemented during the construction of the liquid line of descent (LLD) for iron-rich basalts. The project investigates the potential influence of these assumptions on the resultant LLD. The most important factors involved in the construction of a LLD, namely oxygen fugacity (ƒO2) and H2O are examined and presented here in some detail. Alternative methods for analysing the evolution of these iron-rich rocks are discussed and critically assessed. In order to investigate the assumptions and methods for the construction of the LLD, two case studies were performed on iron-rich intrusions, namely: the Birds River Complex in the Eastern Cape, South Africa; and the Skaergaard layered intrusion, Greenland. For Skaergaard, four of the main LLDs proposed for its liquid evolution were chosen and critically assessed. The Birds River Complex is a small and relatively unknown intrusion, therefore it has received significantly less attention, but presents a good example of a local iron-rich intrusion. These two intrusions were used as testing grounds for the application of the thermodynamic modelling software AlphaMELTS to investigate the potential influence of ƒO2 and H2O on crystallising melts. It was found that H2O had the most significant influence on the maximum iron-enrichment possible for a melt, and that maximum iron-enrichment is attained under anhydrous conditions for all the starting compositions investigated. The effect of ƒO2 was significant, however, its influence varied between starting compositions.
Dissertation (MSc)--University of Pretoria, 2015.
tm2015
Geology
MSc
Unrestricted

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50

LI, SHI-JIAN, and 李世堅. "A study of iron powder method for treating laboratory's heavy metal waste liquid." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/65934670624376455141.

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Dissertations / Theses on the topic 'Iron liquor'

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