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Govan, Premesh. "Manipulating aqueous chemistry environments in extractive metallurgy." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/10529.
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The Anglo Research Nickel (ArNi) process is a novel extractive metallurgical process that arose out of the need to develop a processing route for the recovery of nickel from lateritic ore deposits that is both economical and environmentally acceptable.
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Gilligan, Rorie. "The extractive metallurgy of brannerite: Leaching kinetics, reaction mechanisms and mineralogical transformations." Thesis, Gilligan, Rorie (2017) The extractive metallurgy of brannerite: Leaching kinetics, reaction mechanisms and mineralogical transformations. PhD thesis, Murdoch University, 2017. https://researchrepository.murdoch.edu.au/id/eprint/36793/.
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Brannerite, ideally UTi2O6 is a refractory uranium mineral found in many uranium and rare earth element ore deposits around the world, including many in Australia. As brannerite is refractory, ores containing brannerite require more intense leaching conditions than typical uranium ores. Brannerite is the most common refractory uranium mineral, and the most important uranium ore mineral after uraninite (UO2) and coffinite (U(SiO4)1-x(OH)4x).
Several high-brannerite uranium deposits in Australia remain un-developed, despite being discovered as early as the 1950s. The aim of this study was to understand the leaching chemistry of brannerite in a variety of systems, starting with the conventional acidic ferric sulphate system and alternatives including the ferric chloride-hydrochloric acid system and the alkaline-carbonate system. The principal assumption is that an improved understanding of the leaching chemistry of brannerite will lead to more effective extraction processes, improving the extractions at existing mines, and enabling the development of new ones.
Brannerite was found to undergo congruent dissolution in acid, contrary to the often-reported mechanism in which a titanium oxide coating forms on the surface. Phosphate released by gangue minerals such as apatite can cause the formation of this layer however. When leaching with acidic ferric solutions, sulphate media is superior to chloride media. Alkaline carbonate leaching was also found to be effective for brannerite leaching, albeit much slower than acid leaching. These same alkaline leaching conditions were applied to a sample of refractory uranium ore from Queensland high in acid soluble gangue and shown to be effective. These findings are discussed in detail below.
A sample of brannerite from the Dieresis deposit in the Sierra Albarrana region of Spain was characterised in detail by XRD and SEM-EDX methods. The brannerite was found to be altered and metamict (rendered amorphous by self-irradiation), as is typical for brannerite. Many brannerite particles contained linear zones of titanium oxide surrounded by silicon enriched and uranium depleted brannerite, consistent with descriptions of naturally altered brannerite. These altered zones were more susceptible to leaching, regardless of the leaching conditions. All leached residues were analysed by the same methods to understand the changes taking place in the solid phase during leaching. This suggests that the extent of natural alteration influences the leachability of a particular brannerite.
The leaching of brannerite was studied in acidic ferric sulphate media (0.05 mol/L or 2.8 g/L Fe3+) over a range of temperatures (25-96°C) and acid concentrations (10-200 g/L H2SO4) for five hours. Leached brannerite was pitted and corroded. The rate of leaching was strongly dependent on temperature and weakly dependent on acid concentration. At lower temperatures, brannerite dissolved incongruently in the early stages of leaching. At higher temperatures brannerite dissolved congruently for the entirety of the leaching experiment. The transition between these two mechanisms happened at lower temperatures when the acid concentration was higher. In the incongruent dissolution reaction, the activation energies for uranium and titanium release were 36 and 48 kJ/mol respectively. In the congruent dissolution process, the activation energy was 23 kJ/mol for both uranium and titanium dissolution.
At high temperatures (>75°C) and low acid concentrations (<25 g/L H2SO4), the concentration of titanium dropped after the first hour of leaching and some secondary anatase (TiO2) formed. This anatase was distinct from the anatase in the original material in that it contained iron and did not contain uranium, confirming that it formed during leaching.
Ferric chloride and cupric sulphate lixiviants were studied over a similar range of temperatures and acid concentrations. As with the ferric sulphate leaching tests, the oxidising cation concentration was kept constant at 0.05 mol/L. The leaching behaviour of brannerite in cupric sulphate media was quite similar to what was observed in ferric sulphate media; the rate of leaching was slightly lower than what was observed in ferric sulphate media under comparable conditions. In chloride media, the rate of leaching was slow compared to sulphate media at the same temperature and acid concentration. This suggests that the formation of stable uranium complexes is an important part of the dissolution process. Uranyl sulphate complexes are much stronger than uranyl chloride complexes.
Certain leaching experiments were repeated with the addition of minerals commonly associated with brannerite to gain a clearer understanding of the effects of deleterious gangue. These experiments were run at the extremes and middle of the range of temperatures and acid concentrations studied. Ilmenite accelerated the precipitation of anatase while fluorite significantly increased the rate of uranium and titanium dissolution. Fluorapatite greatly reduced the rate of brannerite dissolution. These results showed a previously unknown interaction between phosphorus and titanium. Phosphate helped to initiate the formation of a titanium oxide coating on the leached brannerite, inhibiting the leaching reaction. Higher concentrations of sulphuric acid reduced these negative effects. Interestingly, phosphate improved the rate of leaching in chloride media, suggesting that chloride leaching may be a viable option when processing high-phosphate refractory uranium ores.
Alkaline leaching may be an effective alternative processing option. While it is often reported that brannerite and similar minerals will not readily dissolve in alkaline media, leaching experiments with sodium carbonate based lixiviants showed that alkaline leaching of brannerite is possible. Compared with acid leaching, it is slow however. Uranium extractions of 83% were achieved over 24 hours of leaching at 90°C in sodium carbonate media. These leaching experiments were repeated with a high-carbonate refractory uranium ore from Queensland and resulted in comparable extractions. Alkaline leaching is a viable alternative when dealing with high-acid consuming ores that contain brannerite.
This study has shed more light on the reaction mechanisms involved in brannerite leaching in typical industrial leaching systems, resulting in a much clearer understanding of brannerite leaching chemistry, potentially enabling the extraction of uranium from overlooked ore deposits. Mineral texture and alteration were also found to influence brannerite leaching. The negative and positive effects of certain gangue minerals have been understood in greater detail, and ways of mitigating or utilising these effects have been devised. Finally, alkaline leaching has been tested and shown to be effective for the leaching of brannerite and refractory uranium ores. Further work is needed to establish the most effective range of conditions and reagent dosages for the leaching of refractory uranium ores and develop economically viable processes based on this new information.
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Burns, Alexander D. "Uranous sulfate precipitation as a novel route to uranium purification in extractive metallurgy." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/54279.
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Uranous sulfate can be crystallized from uranium(IV)-containing solutions by raising the temperature and adding sulfuric acid. Several important aspects of the process have never been investigated, however, making its successful application as a real-world extractive metallurgy technology far from certain. This dissertation addresses several fundamental questions surrounding the crystallization of uranous sulfate from acidic process solutions. The effects of various parameters on the solubility of uranous sulfate and the kinetics of its precipitation are demonstrated, including temperature, acid concentration, and agitation, based on the results from a series of bench-scale experiments. The effects of various impurities on the selectivity and efficiency of the crystallization process are also determined. Two new uranous sulfate x-hydrate polymorphs, the hexahydrate and the octahydrate, are characterized using single-crystal x-ray diffraction, vibrational spectroscopy, and chemical assay data, and an understanding of the conditions under which they form is developed. The thermal stability and decomposition characteristics of uranous sulfate tetrahydrate, hexahydrate, and octahydrate are demonstrated through fundamental thermodynamic calculations and through the examination of thermal analysis data. The fundamental kinetics of uranium(IV) oxidation in acidic solutions are quantified through the interpretation of experimental data under various conditions of acidity, temperature, and oxygen partial pressure. Finally, a hydrometallurgy flow sheet incorporating uranous sulfate precipitation is presented, and the viability of the complete process is demonstrated experimentally, including electrolytic reduction, precipitation, filtration, drying, and calcining. This work demonstrates that uranous sulfate precipitation is viable as a hydrometallurgical process technology, and that further work is justified.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Photos, Euphemia. "Early extractive iron metallurgy in N Greece : a unified approach to regional archaeometallurgy." Thesis, University College London (University of London), 1987. http://discovery.ucl.ac.uk/1348990/.
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Aspects of early Greek extractive iron metallurgy are investigated here, for the first time, with particular emphasis on Macedonia, Greece's most metals-rich province. The subject is approached experimentally by considering equally the ores, slag and artefacts of iron in Macedonia, through the analytical examination of archaeological slag and artefacts, the experimental smelting of Macedonian ores and subsequent analytical investigation of the slag and blooms produced. The mineral resources geology of Macedonia is presented. The historical background to mining and metal working in Macedonia from the Early Iron Age (tenth century BC) to the turn of the present century is documented. The literature on the introduction of iron into Greece, and the East Mediterranean more generally, is critically reviewed, and in the light of results obtained, especially from Thasos, it is argued that the origins of iron making in Macedonia, if not elsewhere in Greece, should be sought locally during the Late Bronze Age. Despite the absence of excavated furnace remains, it has been possible, through analytical examination of metallurgical waste, to trace the operation of the bloomery in Macedonia continuously for nearly thirty centuries. That a considerable variety of iron ores were exploited was elucidated by the analysis of slag inclusions in a large number of iron artefacts from Vergina and from sites on Thasos and the East Macedonian Mainland, spanning chronologically the Early Iron Age to the Byzantine period. The titanium-rich magnetite sands on Thasos and at Vrontou on the Mainland were shown to have been worked from the Hellenistic/Roman to the turn of this century. A second century BC nickel-rich bloom found at the Hellenistic site at Petres in West Macedonia testified, for the first time, to the smelting of nickel-rich iron laterites in Greece, while the manganese-rich iron deposits in Palaia Kavala district were worked for their precious metals content, probably during Ottoman times and perhaps as early as the Classical period. It is suggested that the Skapte Hyle of the classical texts may be located in the Palaia Kavala district. A fresh appraisal of the depiction of furnaces on Black and Red Figure Attic vases of the sixth and fifth centuries BC suggests that the bloomery process may have developed at that time to a level not previously suspected. The classical texts, the function of the cauldron on the furnace top and experimental meltings carried out in the process of this work all point to the production of wrought iron/steel through the decarburisation of high carbon iron in a fining hearth. It is argued that the furnaces depicted on the vases are themselves fining hearths, the cauldron sealing the furnace top in order for the air blast to be directed over the molten mass.
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Mead, D. A. "Investigation of the supported liquid membrane process for metal extraction." Thesis, University of Hertfordshire, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376472.
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Parker, N. I. "Contacting schemes for copper extraction." Thesis, University of Bradford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380357.
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Adipuri, Andrew Materials Science & Engineering Faculty of Science UNSW. "Chlorination of Titanium Oxycarbide and Oxycarbonitride." Publisher:University of New South Wales. Materials Science & Engineering, 2009. http://handle.unsw.edu.au/1959.4/44405.
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The project undertook a systematic study of chlorination of titanium oxycarbide and oxycarbonitride with the aim to develop further understanding of kinetics and mechanisms of the chlorination reactions. The project studied titania, ilmenite ores, and synthetic rutile reduced by carbon in argon and nitrogen and chlorinated at different temperatures, gas flow rates and compositions. Chlorination of titanium suboxides, iron and impurities in ilmenite was also examined. Chlorination of titanium oxycarbide Ti(O,C) or oxycarbonitride Ti(O,C,N) can be implemented at 200 to 400 deg.C, while the commercial chlorination process in the production of titanium metal or titania pigment requires 800 to 1100 deg.C. This makes chlorination of Ti(O,C) or Ti(O,C,N) an attractive technology in processing of titanium minerals. Chlorination reaction is strongly exothermal, which increased the sample temperature up to 200 deg.C above the furnace temperature. The chlorination of Ti(O,C) or Ti(O,C,N) was ignited at 150 deg.C to 200 deg.C depending on the sample composition. Their chlorination at 235 deg.C to 400 deg.C was close to completion in less than 30 min. The chlorination rate of titanium oxycarbide or oxycarbonitride increased with increasing gas flow rate. Sample composition had a significant effect on the extent of chlorination. The optimum results were obtained for titanium oxycarbide or oxycarbonitride produced with carbon to titania molar ratio of 2.5; these samples contained no detectable excess of carbon or unreduced titanium suboxides. In chlorination of reduced ilmenite ores and synthetic rutile, Ti(O,C) or Ti(O,C,N), metallic iron and Ti2O3 were chlorinated. The rate and extent of chlorination of titanium increased with increasing carbon to TiO2 ratio. Chlorination of Ti2O3 was slow relative to Ti(O,C) or Ti(O,C,N) and iron; chlorination of impurity oxides such as MgO, SiO2 and Al2O3 was not observed. The project also examined chlorination of Ti(O,C) or Ti(O,C,N) in ilmenite ore and synthetic rutile after removal of iron, which was achieved by aerated leaching of reduced samples in heated flask containing 0.37 M of ammonium chloride solution. Iron removal from the ilmenite ore or synthetic rutile resulted in higher rate and extent of chlorination of titanium oxycarbide or oxycarbonitride.
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Jespersson, Niklas, and Torbjörn Sandberg. "Evaluation of different non-metallic inclusions in steel chips by using electrolytic extraction : Evaluation of a methodology for electrolytic extraction and scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS) analysis." Thesis, KTH, Materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298419.
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Analysing non-metallic inclusions (NMI) by conventional microscopy is prone to errors. Better imaging can be achieved by using electrolytic extraction (EE) to effectively dissolve the metal matrix, freeing the inclusions so that they can be collected on a filter. This method of studying NMI was tested on a 157C steel chip, with EE taking place three times on the same surface with increasing levels of charge applied. The relationship between charge and extracted layer depth was examined, so as to facilitate the targeting of NMI from specific depths. A selection of the extracted inclusions were micrographed with scanning electron microscopy (SEM) and had their compositions measured with energy dispersive spectroscopy (EDS). Based on this data, two methods of classifying NMI were briefly examined: manual classification, mostly based on images, and a semi-automated process based on a sorting algorithm applied to the compositions. The study implies that it is possible to dissolve a 157C steel to a desired depth by applying a charge proportional to it, but the current method introduces an error which might limit the resolution of depth by a significant amount. Also in the current method, there was no systematic way to select NMI for micrography, and no solution to this problem was found. The semi-automated classification algorithm was compromised by inaccurate readings of compositions from the EDS, and could not be thoroughly tested.Konventionell mikroskopi kan lätt ge felaktig information vid analys av icke- metalliska inneslutningar (NMI), men bättre resultat kan uppnås om metall- matrisen löses upp med elektrolytisk extraktion (EE), så att inneslutningarna frigörs och kan samlas upp på ett filter. Denna metod att studera NMI testades på ett spån av 157C-stål, med trefaldig EE på samma yta och successivt ökande maximal laddning. Sambandet mellan laddning och upplöst lagerdjup undersöktes för att möjliggöra extraktion av NMI från givna djup. Ett urval av de frigjorda inneslutningarna fotograferades i ett SEM och sammansättningarna fastslogs av EDS. Dessa data låg till grund för en undersökning av två klassifikationsmetoder för NMI: manuell klassificering, till största del bildbaserad, och en halvautomatisk klassificering där en algoritm sorterar efter sammansättningar. Denna studie antyder att ett 157C-stål kan lösas upp till önskat djup genom att åläggas en laddning proportionell mot djupet, men den nuvarande metoden introducerar ett fel som kan ha betydande påverkan på noggrannheten. Den aktuella metoden saknar ett systematiskt sätt att välja NMI för mikroskopfotografi, och ingen lösning har kunnat framföras på detta problem. Den halvautomatiska klassifikationsalgoritmen rubbades av störningar i EDS-resultaten och kunde inte undersökas till fullo.
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Danard, Yolaine. "Développement d'alliages de titane transformables par déformation : étude des relations microstructure/propriétés mécaniques." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEC035.
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Le travail concerne le développement de nouveaux alliages de titane possédant des propriétés uniques de déformation plastique (une ductilité près de 3 fois supérieure aux alliages classiques) et d’écrouissage. Un travail initial (Bourse CIFRE de Cédrik Brozek, 2013-2016) a permis de transposer des approches utilisés initialement sur des alliages modèles (Ti-Mo en particulier), à des matériaux potentiellement industrialisables en vue d’applications dans le domaine de l’aéronautique. C’est sur ces nouvelles nuances industrialisables, basées sur le système Ti-Cr-Sn que nous souhaitons aujourd’hui faire reposer la collaboration avec notre partenaire industriel. Ces alliages possèdent la capacité à se transformer sous contrainte, par maclage mécanique et transformation de phase induite, ils possèdent une combinaison de propriétés inédite (une ductilité très importante accompagnée d’un écrouissage non encore atteint dans les alliages de titane) mais ils se caractérisent aussi par une complexité microstructurale très élevée sur laquelle nous ne possédons que peu d’information pour le moment. L’objet de la présente demande porte donc sur l’étude des relations microstructures/propriétés mécaniques dans cette nouvelle famille d’alliages de titane (les alliages "TRIP/TWIP")The work concerns the development of new titanium alloys possessing unique properties of plastic deformation (distortion) (a ductility near 3 times superior to the classic alloys) and work hardening. An initial work (CIFRE PhD of Cédrik Brozek, 2013-2016) allowed to transpose approaches used initially on model alloys (Ti-Mo in particular), in materials potentially industrialisables with the aim of applications in the field of the aeronautics. It is on these new industrialisables nuances, based on the system Ti-Cr-Sn that we wish today to base the collaboration with our industrial partner. These alloys possess the capacity to be transformed under constraint, by maclage mechanics and transformation of induced phase, they possess a new combination of properties (a very important ductility accompanied with a work hardening not yet reached in the alloys of titanium) but they are also characterized by a very high microstructural complexity on which we don't possess that much informations for the moment. The project concerns the study of the relations microstructures / mechanical properties in this new family of titanium alloys (alloys "TRIP/TWIP")
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Tarkan, Haci Mustafa. "Air-assisted solvent extraction." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102735.
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Air-Assisted Solvent Extraction (AASX) is a novel concept that uses a solvent-coated bubble to contact the organic and aqueous phases. The advantages over conventional solvent extraction (SX) are high solvent to aqueous contact area with reduced solvent volume and ease of phase separation due to the buoyancy imparted by the air core. This opens the way to treat dilute solutions (<1 g/L), such as effluents.The novel contribution in this thesis is the production of solvent-coated bubbles by exploiting foaming properties of kerosene-based solvents.
The basic set-up is a chamber to generate foam which is injected through a capillary (orifice diameter 2.5 mm) to produce solvent-coated bubbles (ca. 4.4 mm) which release into the aqueous phase. This generates a solvent specific surface area of ca. 3000 cm-1, equivalent to solvent droplets of ca. 20 mum. Demonstrating the process on dilute Cu solutions (down to 25 mg/L), high aqueous/organic ratios (ca. 75:1) and extractions are achieved. The solvent readily disengages to accumulate at the surface of the aqueous solution.
The LIX family of extractants imparts some foaming to kerosene based solvents but D2EHPA does not. An extensive experimental program determined that 1.5 ppm silicone oil provided the necessary foaming action without affecting extraction or stripping efficiency, greatly expanding the range of solvents that can be used in AASX.
To complement the foam study, films on bubbles blown in solvent were examined by interferometry (film thickness) and infra-red spectroscopy (film composition). A "bound" solvent layer was identified with an initial thickness of ca. 2 - 4 mum, comparable to that determined indirectly (by counting bubbles in an AASX trial and measuring solvent consumption). The film composition appeared to be independent of film thickness as it decreased with time.
As a start to scaling up, the single bubble generation system was adapted by installing up to 8 horizontal capillaries. The bubbles generated were ca. 3.4 mm. Trials showed the multi-bubble set up was a simple replication of the individual bubble case. Preliminary analysis of kinetic data shows a fit to a first-order model.
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Langlais, Joseph. "Strontium extraction by aluminothermic reduction." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22447.
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The Melt-Leach-Evaporation (MLE) process is under development for the extraction of valuable Group IA or IIA metals of the Periodic Table, such as lithium, calcium, magnesium and strontium. The process consists of mixing and contacting the value metal source material, which might be an ore or concentrate, with an excess of molten metal which is acting as a reductant and lixiviant. In the process, the value metal extracted from the source material is dissolved in the excess molten metallic solvent and is subsequently extracted as a vapour by vacuum distillation. The vapour is condensed and recuperated in the metallic state.An experimental program involving eight experiments was carried out. The experimental procedure consisted in essence of melting the aluminum reductant in a crucible and adding the source material, SrCO$ sb3,$ and other reactant (Mg or Bi). (Abstract shortened by UMI.)
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Suriyachat, Duangkamol. "Zirconium solvent extraction using organophosphorus compounds." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60718.
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This study compares zirconium extraction from hydrochloric acid solutions using either Cyanex 923 or Cyanex 925 in kerosene. While both are mixtures of trialkyl phosphine oxides, the trialkyl groups in the former have straight chains, while those in the latter have branched chains.The major variables studied were hydrochloric acid, extractant and zirconium concentrations, and phase ratio. With both reagents, zirconium is extracted rapidly. Extraction increases with increasing hydrochloric acid concentration, and zirconium is loaded as its neutral tetrachloride complex by a solvation reaction. The loaded zirconium forms a di-solvate, except at high excess extractant concentrations, where solvation numbers greater than 2 are found. At a constant total chloride concentration, the zirconium extraction level is maintained if hydrochloric acid is partially replaced by lithium chloride, provided sufficient hydrochloric acid is retained to prevent zirconium hydrolysis. Distribution coefficients decease with increasing zirconium concentration, suggesting that polymerization occurs in the aqueous phase.
For given conditions, zirconium extraction into Cyanex 923 is higher than for Cyanex 925. However, loading selectivity for zirconium over other metals has not been studied. A few preliminary experiments have shown that aqueous solutions of ammonium carbonate are potential stripping agents.
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Bergfors, Simon, and Davida Flink. "Electrolytic Extraction of Aluminium Bifilms." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277872.
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Bifilms is the oxide layer created between two surfaces in the melt of light metals that form an oxide layer. These become planar inclusions in the final casting and are problematic for the mechanical properties such as cracks and crack initiations. Bifilms are too thin to be viewed properly in two dimension cross-section method as they will only appear as thin lines. Because of this, it is relevant to test if it is possible to use electrolytic extraction (EE) as a alternative method to investigate bifilms. Both the deeply etched surface and the inclusions on a filter from the extraction are looked at in the scanning electron microscope (SEM) to get an understanding of the size and shape of the inclusions. With this, a greater understanding of these types of defects can be achieved. After both the filtered inclusions and the surface are examined in SEM with images and Energy-dispersive X-ray spectroscopy (EDS), the images are measured in the software ImageJ. The measurements and analysis show that it is probably bifilms and that they can be relatively large, and not so circular. However, the measurements with the filter have shown high levels of oxygen and carbon. Some levels of chlorine, nitrogen and iron have also been found. But if the surface is compared to the metal surface, it can be concluded that it is likely that bifilms have been found. There are sufficient levels of aluminum and oxygen present. Images in SEM also show the appearance of film-like inclusions. If the method of electrolytic extraction is to be improved to investigate bifilms,optimizations such as filters of other compositions are recommended.Bifilms är det oxidskikt som skapas mellan två ytor i smältan hos lätta metaller som bildar ett oxidskikt. Dessa blir sedan plana inneslutningar i den slutliga gjutningen och är problematiskt för de mekaniska egenskaperna i form av sprickor och sprickinitieringar. Bifilms är för tunna för att de ska kunna ses korrekt i en tvärsnittsmetod, eftersom de bara kommer att visas som tunna linjer. På grund av detta är det relevant att testa om det är möjligt att använda elektrolytisk extraktion (EE) som en alternativ metod. Både den djupt etsade ytan och inneslutningarna på ett filter från extraktionen tittas på i svepelektronmikroskop för att få en förståelse för inneslutningarnas storlek och form. I och med det kan en högre förståelse uppnås för dessa typer av defekter. Efter att både de filtrerade inneslutningarna och ytan granskats i SEM med bilder och Energy-dispersive X-ray spectroscopy (EDS), mäts bilderna i en mjukvara, ImageJ. De mätningarna och analyserna visar att det antagligen hittats bifilms och att de kan vara förhållandevis stora, samt inte så cirkulära. Däremot har mätningarna med filtret visat höga halter av syre och kol. Även vissa halter av klor, kväve och järn har hittats. Men om ytan jämförs med metallytan så kan en slutsats dras om att det är troligt att bifilms har hittats. Där finns tillräckliga halter av aluminium och syre. Även bilder i SEM påvisar filmliknande inneslutningar till sitt utseende. Om metoden med elektrolytisk extraktion ska förbättras för att undersöka bifilms behövs optimeringar, som till exempel filterav en annan sammansättning.
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Ashrafizadeh, Seyed Nezameddin. "Solvent extraction and liquid membrane separation of rhodium." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37698.
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The aim of this work was to develop a viable solvent-extraction based system for the separation of rhodium (Rh) from aqueous chloride solutions. Ultimately, two different systems were developed. Kelex 100, a commercially available derivative of 8-hydroxyquinoline, was used as the extractant reagent in both of these systems. One of the systems involved the supported liquid membrane (SLM) extraction of Rh. In this system a very thin microporous "Gore-Tex" polymer sheet, impregnated with an organic solution of Kelex 100, served as the SLM. The other system involved the conversion of the chlorocomplexes of Rh to bromocomplexes prior to their solvent extraction with Kelex 100.The results of the lab-scale experiments using a SLM of Kelex 100 having a surface area of 44 cm2 are reported. The optimum conditions for Rh permeation were found as a feed solution of 2.5 M HCl and a strip solution of 0.1 M HCl. The SLM was quite stable at the optimum conditions with no sign of organic loss or membrane deterioration after 72 hours of operation. It was determined that the HCl activity gradient across the membrane acts as the driving force that "pumps" the non-aquated Rh chlorocomplexes against their concentration gradient. The mechanism of Rh permeation was the ion-pair formation between the protonated Kelex 100 and RhCl6 3- complexes. The rate of Rh permeation was in the order of 10-6 mol.m-2.s-1. The mechanism of HCl and H2O permeation, which were co-extracted along with Rh chlorocomplexes, were found to be the hydration of protons at the low feed acid region and the formation of microemulsions at the high feed acid region. The permeated acid and water were separated from the SLM receiving phase by contacting the latter phase with an organic solution of trioctylamine (TOA). The chlorocomplexes of Rh(III) and acid are readily extracted to the TOA organic phase and subsequently subjected to differential stripping with a concentrated solution of Cl- and a mild NaOH solution, respectively. By interfacing the TOA solvent extraction with the SLM of Kelex 100 highly concentrated solutions of Rh (at least 10 times the initial concentration) and raffinates essentially free of rhodium were produced.
The UV-Visible investigations revealed that the bromocomplexes of Rh undergo aquation to a much lesser extent than that of the chlorocomplexes. The chlorocomplexes of Rh were converted to bromocomplexes by precipitating first the Na(NH4)2Rh(NO2)6 salt and subsequently dissolving that in an HBr solution. The newly formed bromocomplexes of Rh(III) responded very favorably to extraction with Kelex 100. Relatively high distribution coefficients, about 20, and very steep extraction isotherms were generated. The freshly loaded Kelex 100 organic was efficiently stripped upon contact with a strip solution of 6--8 M HCl and a contact time of 10--12 hours. The developed system shows high promise from a practical implementation point of view.
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Smeets, Alexander Arnoldus Johannes. "Extraction of lithium by vacuum thermal reduction." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304440.
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Guo, Shuo. "Evaluation of deformed MnS in different industrial steels by using electrolytic extraction." Thesis, KTH, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217880.
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The inclusions have a different chemical composition and give the steel different mechanical properties. These inclusions affect several properties of steel. In order to understand how the inclusions will affect the steel properties, the electrolytic extraction of 3D investigate method is applied on the steel grade of 42CrMo4. Then follow with Scanning Electron Microscope (SEM) observation. Steel samples from both ingot and rolling with and without heat treatment are observed and compared with different ratios. The result shown that, heat treatment can be applied for removing carbides successfully. And most inclusions are belonging to Type RS which is rod like MnS. The percentage of broken particles can be up to 80%, which means that the reason for the inclusions broken should be find. And heat treatment can affect the characteristics of elongated MnS.
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Rolinska, Monika. "Extraction Replicas of Common Engineering Alloys for Analysis of Small Precipitates." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291204.
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Characterization of small precipitates is important for development of new alloys. One inherent difficulty in characterisation of small precipitates with electron microscopy techniques while the particles are embedded in the matrix, is that the surrounding bulk material will contribute to the analysed signal- limiting, for example, the quantification of the composition of particles. In order to avoid the matrix contribution, the extraction replica technique was developed in the 1950's. Extraction replicas are made by extracting only the particles from a material onto a thin film for further analysis by scanning or transmission electron microscopy. Different types of particles can be examined by this technique, including various carbides, nitrides, oxides and borides, as well as many intermetallic phases. In this work, direct replication techniques were compared to two-stage replication for low-alloyed steel, concluding that both are suitable for qualitative analysis, but direct replication is preferred for quantitative analysis. Successful replication of the zirconium-based Zirlo and the stainless steel 254 SMO was performed, where the precipitated phases were isolated and the composition quantified. Particle extraction was successful also for the zirconium-based Zircaloy-2 and two types of aluminium alloys, but no quantification of composition could be made due to different problems associated with etching of each alloy, showing that properchoice of etchant is crucial for the quality of the replicas.Karaktärisering av små utskiljningar är viktigt för utveckling av nya legeringar. En svårighet vid karaktärisering av små utskiljningar med elektronmikroskopi när partiklarna sitter kvar i matrisen är att matrisen kommer ge ett bidrag till den analyserade signalen, därför är t.ex. möjligheterna för kvantifiering av sammansättning begränsade. För att undvika bidraget från matrisen utvecklades extraktionsrepliker på 1950-talet. Extraktionsrepliker tillverkas genom att extrahera partiklar från ett material till en tunn film som sedan kan analyseras med hjälp av svep- eller transmissionselektronmikroskopi. Olika sorters partiklar kan undersökas med hjälp av denna metod. Dessa inkluderar olika typer av karbider, nitrider, borider, oxider och många olika sorters intermetalliska partiklar. I detta arbete jämfördes direkta metoder med tvåstegsrepliker på låglegerat stål. Slutsatsen blev att båda metoderna lämpar sig för kvalitativ analys av små partiklar, men direkta metoder är att föredra för kvantitativ analys. Lyckade repliker tillverkades även av zirkoniumlegeringen Zirlo och det rostfria stålet 254 SMO, där utskiljningarna kunde isoleras och sammansättningen kvantifieras. Extraktion av partiklar var lyckad även för zirkoniumlegeringen Zircaloy-2 samt två typer av aluminiumlegeringar, men ingen kvantifiering av sammansättningen kunde göras på grund av olika problem relaterade till den valda etsmetoden för varje legering, vilket visar att valet av etsmedel ar avgörande för kvaliteten av replikerna.
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El-Ammouri, Elias G. "Hafnium solvent extraction from chloride solutions using organophosphorus reagents (Cyanex 923, 925)." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69792.
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A comparison of hafnium solvent extraction from hydrochloric acid solutions using either Cyanex 923 or 925 (organic extractants) diluted in kerosene was established. Since understanding of the hafnium-hydrochloric acid solution is important, development of a speciation diagram for such a solution was carried out. While both Cyanex 923 and 925 are mixtures of trialkyl phosphine oxides, the trialkyl group in the former have straight chains, while those in the latter have branched chains.Experimentally, the major variables studied were hydrochloric acid, hafnium and Cyanex concentrations. Hafnium is rapidly loaded as the tetrachloride complex by a solvation reaction forming a disolvate with the extractant (923 or 925). While extraction increases with increasing acid concentration, it decreases with increasing hafnium concentration due to polymerization. Total chloride level is the controlling factor provided there is enough acid to prevent hafnium hydrolysis and polymerization. Cyanex 923 is a more powerful extractant than Cyanex 925 for given conditions. A few experiments have shown that a very dilute hydrochloric acid solution is suitable as a stripping agent.
The main objective is to evaluate the potential of Cyanex 923 (or 925) as an alternative to MIBK due to the problems associated with the latter. MIBK is the conventional extractant for hafnium and zirconium extraction and separation from hydrochloric acid/thiocyanate solutions. Thus, preliminary studies of hafnium and zirconium (existing separately or together) extraction from hydrochloric acid/thiocyanate solutions were also performed. When existing separately, hafnium and zirconium are similarly extracted into either Cyanex reagents, but when both metals coexist in the same solution, preferential separation of hafnium is observed.
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Mihaylov, Indje O. (Indje Ognianov). "Gallium solvent extraction from sulphate solutions using organophosphoric acid reagents (D2EHPA, OPAP)." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70338.
Full textAbstract:
The subject of this work is gallium extraction from sulphate solutions--an additional source of this metal from hydrometallurgical zinc production--with organophosphorus acid reagents: di-2-ethyl hexyl phosphoric acid (D2EHPA) and OPAP, a mixed extractant consisting of mono- and di-octyl phenyl phosphoric acids. Extraction proceeds via cation-exchange and Ga$ sp{3+}$ is the reacting species. Gallium is extracted with D2EHPA mostly as GaR$ sb3$ - HR. The results for OPAP suggest existence of four reactions, which form GaM$ sb3,$ GaM$ sb2$D, GaMD$ sb2,$ and GaD$ sb3;$ this explains and allows prediction of behaviour over a wide range of OPAP compositions. Sulphate complexation causes decrease in concentration of the reacting species, and thus lower $D sb{ rm Ga}$ values and extraction rates. Prior knowledge on gallium aqueous complexes is used, and an algorithm developed, to allow quantitative prediction of complexation effects on extraction. The model of mass-transfer with chemical reaction, verified with several known criteria for reaction site determination, describes well the kinetic data for the Ga-D2EHPA system. The model is further developed to account for the stronger acidity and the monomer/dimer equilibria typical for the kind of extractants used. A detailed reaction mechanism is proposed and the first organic ligand addition is found as rate-limiting. The model parameters, estimated from extraction kinetic data, are reasonable, when compared with those obtained for other metals elsewhere. The model's predictions agree with the results from stripping kinetics; the equilibrium conditions (zero rate) can also be satisfactorily predicted, as found by comparisons with the equilibrium data. Ga-D2EHPA and Ga-OPAP systems are compared with an emphasis given to the potential for metal separation; the importance of the ligand exchange rate constant is illustrated with the example of Ga and Al extraction/stripping and their separation based on different rates with
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Benguerel, Elyse. "An investigation on the solvent extraction of rhodium from aqueous chloride solutions /." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61340.
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The aqueous behaviour of rhodium (III) (Rh) in chloride solutions was investigated with the objective of evaluating its response to solvent extraction with 8-hydroxyquinoline derivatives. A theoretical analysis of the abundance of the various chloro-complexes in solution revealed that monoaquo-pentachlororhodate and hexachlororhodate are the most common forms of Rh(III) in chloride solutions ($>$0.5M Cl$ sp{-}$) and that the relative abundance of hexachlororhodate may be lower than was previously reported.The extraction degree of Rh(III) with 8-hydroxyquinoline derivatives from solutions ranging in acidity from 0.7 to 8.0M and in chloride concentration from 0.7 to 4M was found to follow the calculated abundance of hexachlororhodate (about 5 to 40% in the region investigated). Also, the extraction mechanism was deduced to be ion-pair formation.
The extraction degree of Rh(III) from similar solutions but previously treated with SnCl$ sb2$, was also investigated, and in this case the extraction was quantitative throughout the acidity and chloride concentration ranges tested. Virtual quantitative stripping can be achieved with four five-minute contacts with 1.7M H$ sb2$SO$ sb4$ + 1M Na$ sb2$SO$ sb4$. A preliminary flowsheet for the industrial application of this solvent extraction process for Rh is presented.
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Ciriello, Carmine. "Nickel solvent extraction from dilute acidic sulphate solutions using octyl phenyl acid phosphate (OPAP)." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69789.
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The subject of this work is nickel extraction from dilute, acidic sulphate solutions through the use of organophosphorous acid reagents. The focus is primarily on OPAP, a mixed extractant consisting of mono- and di-octyl phenyl phosphoric acids, as well as on di-(2-ethyl hexyl) phosphoric acid (D2EHPA). The effects of certain parameters on the extraction of nickel, both quantitative and qualitative, have been studied. The parameters include: modifier presence, concentration and type; OPAP concentration; phase ratio; aqueous environment; age of organic solution; and mono-/di-OPAP ratio. The ability to strip nickel from the organic solution as well as selectivity and kinetic tests were carried out.The use of 10% isodecanol as a modifier was found to be essential for the purpose of OPAP solubility in kerosene and phase separation. Furthermore, the cation exchange reaction proceeds very quickly, attaining equilibrium within 10 minutes. Unlike other phosphoric acid reagents, OPAP is able to extract significant amounts of nickel in the acidic pH range of 1 to 2. As well, nickel is easily stripped using a 1.0 M sulphuric acid solution.
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Davidson, Raymond John. "Innovations in gold extraction." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1004975.
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The thesis takes the form of a collection of publications and patents concerning gold extraction which were presented over a period of 18 years while employed at the Anglo American Research Laboratories.
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Aprahamian, Vicken Haroutiun. "The behaviour and control of impurities during the solvent extraction of platinum metals with an alkylated 8-hydroxyquinoline /." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61135.
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In order to understand and control the deportment of common impurity elements in the Pt(IV)-Pd(II)-HCl-8-hydroxyquinoline (TN 1911)$ sp{ rm a}$ system, their solvent extraction chemistry in chloride solution has been studied. The investigated elements were Fe(III), Cu(II), Ni(II), Zn(II), Pb(II), Sn(IV), Ag(I), As(V), Sb(V), Bi(III), Se(IV) and Te(IV). Extraction experiments carried out using multi-element and single element feed solutions helped to elucidate the extraction behaviour of the elements with the extractant TN 1911. From the collected data it was deduced that the majority formed anionic chlorocomplexes and extracted via the ion-pair mechanism involving the protonated extractant. Consequently, scrubbing procedures were developed to control the deportment of these elements. These scrubbing steps were then incorporated into a tentative flowsheet which was simulated in a batch-wise fashion in the laboratory. The most contaminating elements were found to be Zn(II), Pb(II), Ag(I), Te(IV), Se(IV) and Bi(III). The first five were effectively scrubbed with 2.0M HCl whereas Bi(III) could only be scrubbed with 2.0M H$ sb2$SO$ sb4$ at A/O ratios of $>$3:1. The element Sn(IV) which was found to build-up in the organic, could only be scrubbed with a 1.0M NaOH solution for long contract times (60 minutes). ftn$ sp{ rm a}$A proprietary alkylated derivative of 8-hydroxyquinoline (Schering Berlin AG).
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Sole, Kathryn Clare. "Solvent extraction of first-row transition metals by thiosubstituted organophosphinic acids." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186480.
Full textAbstract:
Organophosphorus compounds are well known as solvent-extraction reagents. Two new reagents in this class are Cyanex 302 and Cyanex 301, the respective mono- and dithio analogs of the commercial extractant, Cyanex 272 (bis(2,4,4-trimethylpentyl)-phosphinic acid). The replacement of oxygen by sulfur in these reagents decreases their pKₐ, and enables extraction to be carried out at much lower pH than previously attained. A comparative characterization of Cyanex 272, Cyanex 302, and Cyanex 301 is undertaken. The aggregation and partitioning behavior of these reagents is determined. A comparison of the solvent extraction behavior of first-row transition-metal ions from manganese to zinc in acidic sulfate solution by these reagents is reported. Distribution coefficients shift to lower pH with increasing sulfur substitution of the extractant, the greatest effect being observed for soft Lewis acids. These reagents are found to be strong extractants for the transition metals examined, but poor extractants for alkaline-earth ions and manganese(II). Certain metal ions, in particular copper(II) and silver(I), are, however, extremely difficult to strip, which may mitigate against potential applications. Stoichiometry of the extraction reactions and the nature of the metal complexes formed are postulated based on slope-analysis techniques and spectroscopic and molecular-mass measurements. Molecular modelling of the extractants and extracted species is presented. Some reasons for the enhanced stability of the complexes formed with certain metals are discussed in terms of d-electron effects, donor-/acceptor-atom interactions, ligand-field observations, and steric effects associated with the extractants.
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Bell, Katherine Jane. "Receptors for the extraction of the hexachloroplatinate anion." Thesis, University of Nottingham, 2008. http://eprints.nottingham.ac.uk/14404/.
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This thesis presents research into the binding, extraction and transport of the hexachloroplatinate anion, [PtCl6]2-, by organic receptors in a solvent extraction process. The target anion is produced during the processing of platinum-containing ores and the aim was to develop reagents that can selectively extract [PtCl6]2- to optimise the recovery of platinum. Chapter One outlines reasons for the interest in [PtCI6]2-and provides an overview of the processes and techniques used to refine precious metals. An introduction to anion coordination chemistry relevant to the research project is also presented. Chapter Two discusses the design features incorporated into organic receptors to enable strong and selective binding of [PtCl6]2-. These features include a tertiary amine protonation site, hydrogen-bond donor groups and organic solubilising moieties. The synthesis of a series of functionalised tripodal tris(2-aminoethyl)amine based receptors with sulfonamide, amide, urea, thiourea or pyrrole NH hydrogenbond donor groups are reported. Complexation reactions between the receptors and H2PtCl6 to form [(LH)2PtCl6] ion pairs are discussed. Crystallographic analysis of the [(LH)2PtCl6]complexes with TREN-based sulfonamide, urea and amide receptors confirms the presence of hydrogen-bonds between the NH donor groups and the outer-sphere of [PtCl6]2-. The low organic solubility of the complexes prevented the study of these systems in solvent extractions. Chapter Three describes the variation of terminal substituents of the tripodal receptors with the aim of improving the organic solubility of the extractants and their [PtCl6]2-complexes. In these "second generation" receptors the terminal substituents assessed include 3, 5-dimethylphenyl, 4-iso-propylphenyl, 4-tert-butylphenyl, 3, 5- dimethoxyphenyl, 3, 4 dimethoxypheynl and 3, 4, 5-trimethoxyphenyl. Through reaction of the receptors with H2PtCl6 the solubility of the resultant complexes are assessed. Chapter Four describes the development of an optimised solvent extraction method to study the extractive behaviour receptors. A pH swing mechanism is utilised to control the uptake and release of [PtCl6]2-. The extraction results for trioctylamine and the soluble tripodal urea and amide receptors are compared. Attempts are also made to confirm the stoichiometry of the complex in solution. Chapter Five describes the synthesis of tris(2-aminoethyl)amine based receptors with hydrogen- and halogen-bond donor groups with the aim of increasing the strength of the interaction between a receptor and [PtCI6]2-. Receptors with an extended tripodal scaffold based on a tris(3-aminopropyl)amine with urea and amide moieties are also presented. The results of the complexation reactions and solvent extraction studies with these modified extractants are presented. Chapter Six presents the design and synthesis of bipodal and monopodal receptors in order to assess the role of the number of hydrogen-bond donor functionalised arms. The results of the solvent extraction studies with these receptors are discussed and comparisons made between tripodal, bipodal and monopodal extractants. The crystallographic analysis of the [(LH)2PtCl6] complexes formed between the bipodal urea and amide receptors is described. Chapter Seven highlights the important findings from this work. Conclusions are drawn as to the optimum receptor system developed and this is compared to the extractant system thought to be in current use for the extraction and transport of [PtCl6]2-.
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Benguerel, Elyse. "Solvent extraction of rhodium from chloride solutions in the presence of SnCl2 with Kelex 100tm." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40321.
Full textAbstract:
The aim of this work was to devise and investigate a solvent extraction system for rhodium, from aqueous chloride solutions, having potential industrial applicability. The extractant investigated was Kelex 100, a commercially available derivative of 8-hydroxyquinoline. Ultimately, two different systems were developed. Both are based on an initial complexation reaction between the aqueous rhodium chloride complexes, (RhCl$ rm sb{6-n}(H sb2O) sb{n} rbrack sp{(3-n)-}$ and stannous chloride, referred to as the activation stage, but the two systems use a different Sn:Rh molar ratio. In both cases, the Rh-Sn complexes, either (Rh(SnCl$ sb3) sb5 rbrack sp{4-}$ or (RhCl$ rm sb3(SnCl sb3) sb3 rbrack sp{3-},$ respond well to extraction with Kelex 100. One of the main differences between the two systems is in the stripping medium which is used to transfer the rhodium from the loaded organic phase back into an aqueous phase. In the case of the high Sn:Rh ratio feeds, the stripping stage is based on sulfuric acid, whereas in the case of low Sn:Rh ratio feeds, the rhodium is stripped from the organic phase using a sulfite containing hydrochloric acid solution.The two systems were characterized in terms of their equilibrium and kinetic behaviour during all three stages; activation, extraction, and stripping. Activation was found to proceed either at room temperature or at elevated temperatures and the above-mentioned expected Rh-Sn complexes were identified through $ sp{119}$Sn NMR and Raman spectroscopy. The extraction stage was found to be quantitative for rhodium and it was also found to be very rapid, with contact times of less than five minutes sufficient for rhodium extraction. The extraction mechanism was determined to be ion-pair formation with the protonated Kelex 100 molecules at a stoichiometry such that the overall charge in the organic phase is neutral, i.e., three Kelex 100 molecules for (RhCl$ rm sb3(SnCl sb3) sb3 rbrack sp{3-}$ and four for (Rh(SnCl$ sb3) sb5 rbrack sp{4-}.$
The stripping stages were the most problematic for both systems. In one case, the system was eventually abandoned due to limitations in the amount of rhodium which could be transferred to the sulfuric acid strip solution. For the low Sn:Rh system, reasonable rhodium transfer and concentration level were obtained. The rhodium complex in the strip solution has been proposed to be (RhCl$ rm sb2(SO sb3) rbrack sp{3-}.$ Strip solutions up to $4 times10 sp{-2}$M in rhodium concentration have been produced, from initial feed solutions having a rhodium concentration of about $4 times10 sp{-3}$M. Preliminary flowsheets are proposed for further refinement for both systems, although only the second system, the low Sn:Rh ratio system which uses sulfite stripping, is advocated for further development.
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MacLean, Donald William John. "The kinetics of zinc extraction in the di(2-ethylhexyl) phosphoric acid, n-heptane-zinc perchlorate, perchloric acid, water system." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30023.
Full textAbstract:
The kinetics of zinc extraction from perchlorate solutions with di(2-ethylhexyl) phosphoric acid in n-heptane have been measured using the rotating diffusion cell technique.
The extraction of zinc is controlled by the mass transfer of reactants (Zn²⁺ and D2EHPA) to the interface. At low zinc concentrations, the system is controlled by the aqueous transport of Zn²⁺ to the interface; at higher zinc concentrations transport of D2EHPA becomes rate controlling. For the range of D2EHPA concentrations examined, the transport of D2EHPA is rate controlling. Bulk pH has a negligible effect, except perhaps at the lowest pH values examined, where there may be a slight decrease in extraction rate. This decrease was attributed to less favourable thermodynamics at low interfacial pH values. It appears that the chemical reaction rate is fast enough that it has a negligible effect on the overall extraction rate. A basic mathematical model was developed which is adequate for predicting the extraction rate under variable conditions of zinc concentration, D2EHPA concentration, and pH.
The effect of using a partially loaded organic extractant was also investigated, and the system was found to be mass transfer controlled. An extended mathematical model was developed which predicts that the speciation of organic complexed zinc changes with increasing preload, and at high loadings the direction of ZnL₂HL and ZnL₂(HL)₂ flux reverses, with these species providing extractant to the interface. At very high loadings, ZnL₂HL provides almost all the extractant to the interface.
Experimental studies of the effect of temperature on the rate of zinc extraction resulted in a calculation of the activation energy which was consistent with a diffusion controlled mechanism. Finally, the effect of different filter pore sizes on extraction was examined. The extraction rate decreases significantly with a very small filter pore size, while there appeared to be little or no effect for larger filter pore sizes. For the filter pore size used in this study, it was therefore concluded that the filter pores do not pose an additional resistance to mass transfer.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Buyukakinci, Ergin. "Extraction Of Nickel From Lateritic Ores." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609291/index.pdf.
Full textAbstract:
The aim of this study was to extract nickel and cobalt from the lateritic nickel ores of Gördes region by hydrometallurgical methods under the optimum conditions. Limonitic and nontronitic types of Gö
rdes lateritic nickel ores were used during experiments. Agitative and column leaching experiments at atmospheric pressure were conducted with various parameters
these were duration, temperature and initial sulfuric acid concentration of leach solution. It was shown that in agitative leaching, under the optimum conditions that were determined as 24 hours of leaching at 95°
C with initial sulfuric acid concentration of 192.1 g/L for nontronite and 240.1 g/L for limonite, nickel and cobalt extractions were 96.0% and 63.4% for nontronite
93.1% and 75.0% for limonite, respectively. Overall acid consumptions of ores were calculated as 669 kg H2SO4/ton dry ore for nontronitic type nickel ore and 714 kg H2SO4/ton dry ore for limonitic type nickel ore. Column leaching experiments also showed that nickel and cobalt could be extracted from both ore types by heap leaching. Nontronite type of laterite was found to be more suitable for column leaching by sulfuric acid. In column leaching, the calculated nickel and cobalt extractions were 83.9% and 55.2% for nontronite after 122 days of leaching with 100 g/L sulfuric acid concentration. Acid consumption of nontronite was found to be 462 kg H2SO4/ton dry ore.
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Du, Toit Zita. "Simulation of a palladium extraction circuit." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019/536.
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MacRuary, Kirstian Jennifer. "Investigation into the mode of action of chloride and chloridoplatinate extraction : a computational and experimental study." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/25794.
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This thesis investigates the mode of action of cationic reagents in the recovery of platinum group metals (PGMs) by anion exchange solvent extraction. Industry uses a range of extractants to achieve efficient concentration and separation of PGMs in hydrometallurgical processes, but an understanding of the processes at a molecular level is limited and restricts the options to improve efficiency. The research, sponsored in part by Johnson Matthey and Anglo American, explores two different aspects of the mode of action of reagents used to recover chloride and platinum. Chapter 1 reviews the extraction of chloridometalates in hydrometallurgy and other methods used to recover PGMs. The chapter also covers current ideas on whether formation of outer-sphere anion-cation molecular assemblies or whether larger supramolecular aggregates are responsible for the extraction of PGMs. These two separate routes of study can be investigated by various computational and experimental methods, which are discussed in Chapter 2. In Chapter 3, the model systems chosen to develop the methodologies utilised throughout the thesis are presented. The development involves the extraction of chloride ions by tributyl-phosphate (TBP) and then is extended to extraction of PGM chloridometalates in Chapter 4. Computational methods are used to probe the atomistic and supramolecular theories in predicting the most likely assemblies which will be formed in the transfer of anions between the aqueous and organic phase. Slope analysis and the determination of the contents of the organic phase is used to validate computational models, along with spectroscopic techniques to determine shape and size of assemblies formed during extraction. The application of these methodologies to an amide extractant is discussed in Chapter 5. Computational methods predict the probability of formation of specific complex assemblies during the extraction of PtCl62- by protonated forms of the amide. Determination of the stoichiometry involved in formation of the complex assemblies by slope analysis is reported along with analysis of water, metal and chloride content to confirm the computational model. Final conclusions on all systems explored within the thesis and suggestions for future work are presented in the final chapter. The combination of experimental and computational methods are shown to be very efficient in defining mechanisms of extraction, involving determination of structures formed during the process and how and why they form.
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Ozdemir, Veysel. "Hydrometallurgical Extraction Of Nickel And Cobalt From Caldag Lateritic Ore." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607777/index.pdf.
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In this study, an attempt has been made to hydrometallurgical extraction of cobalt and nickel by atmospheric pressure sulphuric acid leaching and a pug-roast-leach process using two stage roasting for lateritic ore. The ore used in the study was obtained from Çaldag Lateritic Ore, Manisa, Turkey. The metal contents of the ore are 2.1 % Ni, 0.12 % Co, 32.45 % Fe, 1.01 % Mn, 2.58 % Cr, 0.78 % Mg and 1.01 % Al. The reserve of lateritic ore deposit is approximately 40 million tonnes. In the study, first sulphuric acid leaching was applied at atmospheric pressure for leaching the Ç
aldag lateritic ore. The effect of various parameters, such as leaching time, leaching temperature, particle size, pulp density and acid strength on Ni and Co extractions were determined. By leaching at 80oC for 40 wt % H2SO4 addition of ore, 1/3 pulp density, Ni and Co extractions were found 44.49 % and 53.03 % respectively, yielded a pregnant solution containing 3.11 g/L Ni and 0.12 g/L Co. But the result of atmospheric pressure sulphuric acid leaching was considered insufficient from the recovery point of view. In the pug-roast-leach process, which is consisted of a two stage roasting followed by water leaching, decomposition temperature differences of sulphates of cobalt, nickel and iron are exploited. In this process, amount of acid, sulphatization and decomposition temperature, sulphatization and decomposition time, leaching temperature and time, solid/liquid ratio, and the effect of water addition during pugging were optimized. Under the optimized conditions (sulphuric acid: 25 wt % of ore
moisture: 20 wt % of ore
sulphatization temperature: 450oC
sulphatization time: 30 minutes
decomposition temperature: 700oC
decomposition time: 60 minutes
leaching temperature: 70oC
leaching time: 30 minutes and solid-liquid ratio: 1/4 by weight), Co and Ni extractions were found 91.4 and 84.4 percent, respectively. A pregnant solution containing 3.084 g/L Ni and 0.185 g/L Co was obtained. These results were considered sufficient for the leaching of lateritic nickel ores.
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O'Brien, Evan Daniel. "Welding with Low Alloy Steel Filler Metal of X65 Pipes Internally Clad with Alloy 625: Application in Pre-Salt Oil Extraction." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469018389.
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Mehta, Punita. "Evaluating the potential of alder-Frankia symbionts for the remediation and revegetation of oil sands tailings." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84099.
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Tailings are the waste produced as a result of the extraction of oil from the tar sands in northern Alberta. Many avenues for the reclamation of tailings are being researched, but one area that has received little attention is phytoremediation. The Alder-Frankia symbiotic relationship in the tailings was investigated for its potential in revegetation and remediation of the tailings. Two species of alders were examined Alnus glutinosa and A. rugosa. The impact of the alders was monitored through the investigation of the differences in the microbial community present in the oil sands tailings and composite tailings (CT) with and without alders. For our investigation we used culture dependent techniques (plate counts and mineralization assays) and culture independent techniques (16S rRNA gene PCR, catabolic PCR and DGGE). The alders lowered the pH of the tailings, increased rates of mineralization, increased the general microbial population in the tailings by one to two orders of magnitude and increased the microbial diversity.A. rugosa however, had a greater impact on the mineralization of poly aromatic hydrocarbons (PAHs) and, being native to Alberta, was chosen for further experimentation, using only composite tailings. The aim of the experiments was to determine the effect of a Frankia inoculum on the growth of A. rugosa in (CT) and the associated microbial community. The microflora in the bulk soil, rhizosphere and inside the root of inoculated and non-inoculated A. rugosa were compared through microbial enumerations of the community, with general and selective media and mineralization assays. A. rugosa inoculated with Frankia was taller and the roots were more developed and the endophytic community of inoculated A. rugosa had greater rates of naphthalene mineralization.
The results indicate that A. rugosa inoculated with Frankia could be used for the phytoremediation of tailings and for the re-establishment of a forest ecosystem.
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Pateyron, Bernard. "Contribution a la realisation et a la modelisation de reacteurs plasmas souffles ou transferes appliques a la metallurgie extractive et a la production de poudres ultrafines metalliques ou ceramiques." Limoges, 1987. http://www.theses.fr/1987LIMO0030.
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Lakay, Eugene Marlin. "Novel ion-exchange materials derived from poly(styrene-co-maleimide) and a study of the extraction and recovery of gold (III) chloride from acidic solutions." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80148.
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Thesis (PhD)--Stellenbosch University, 2013.ENGLISH ABSTRACT: In this study an economical, environmentally friendly, selective and efficient process for the extraction and recovery of [AuCl4]- from aqueous acidic chloride-rich solutions, particularly those aqueous solutions having low concentrations of the precious metal complexes has been investigated. Functionalized poly(styrene-co-maleimide) (PSMI) nanoparticles were synthesized by thermal imidization of the poly(styrene-co-maleic anhydride) (PSMA) copolymer with 3-N,N-dimethylaminopropylamine. Stable water-based dispersions were obtained containing spherical, monodisperse PSMI nanoparticles with a narrow size-distribution and average diameters of 50 ± 5 nm. The specific surface area of the bulk PSMI nanoparticles is 88.1 ± 2.2 m2/g with an average pore diameter of 82.3 Å. 13C NMR, FTIR and elemental analyses confirmed the successful and complete conversion of PSMA into the PSMI derivative. The functionalized PSMI nanoparticles synthesized were investigated as a novel anion-exchange material for the extraction of [AuCl4]- ions from aqueous acidic solutions. Batch sorption studies were carried out as a function of various parameters, such as initial gold concentration, PSMI mass, contact time and agitation rate. The [AuCl4]- extraction occurred with extremely fast sorption kinetics and is dependent on the rate of agitation during the batch sorption process. The functionalized PSMI nanoparticles show a maximum gold loading capacity of 1.76 mmol/g (347.7 mg/g). Langmuir and Freundlich isotherm models were applied to analyze the experimental sorption data. The best model describing the sorption process is given by the Langmuir model. Desorption efficiencies of about 80 % and 93 % were obtained using acidified thiourea (0.25 M thiourea/2 M HCl) and a mixture of 10 M HNO3/0.5 HCl as elutant solutions, respectively. X-ray photoelectron spectroscopy (XPS) analysis unambiguously confirms that the immobilized gold species exists in several oxidation states of 0, +I and +III on the PSMI nanoparticles. This proves that the [AuCl4]- ions initially present in the gold feed solutions unfortunately are subject to a reduction phenomenon on the surface of the functionalized PSMI nanoparticles. The existence of the various gold species contributed significantly to poor desorption efficiencies. In addition to PSMI nanoparticles, micro- to millimeter size PSMI resin beads was prepared by an electrospray methodology. This allows for a wide range of PSMI spherical and quasi-spherical bead diameters of shape to be prepared by manipulation of the experimental conditions employed during the electrospray process, such as the concentration of the PSMI in solution, the capillary tip-to-collector distance, flow rate and the applied voltage. 13C NMR and FTIR spectroscopy analyses show that the electrospray methodology allows PSMI resin beads preparation without any change in chemical composition of the PSMI material. Surface area and porosity analysis shows that 450 μm and 1620 μm PSMI beads selected for use in the gold extraction experiments are microporous and have BET specific surface areas of 2.8 ± 0.4 m2/g and 2.0 ± 0.1 m2/g, respectively. Micro- to millimeter size PSMI resin beads of 450 μm and 1620 μm diameter were tested as potential anion-exchange resins for the extraction of [AuCl4]- from aqueous acidic solutions. The time-dependent studies reveal that the extent of gold uptake increases with an increase in contact time and is dependent on the gold concentration in the [AuCl4]- feed solutions. A maximum loading capacity of 120.7 mg/g and 98.16 mg/g was attained for the 450 μm and 1620 μm resin beads, respectively. The experimental sorption data followed a linear trend consistent with a Freundlich sorption model. This sorption trend for [AuCl4]- suggests that a multi-layer sorption process predominates. Desorption of immobilized gold species from the loaded PSMI resin beads was investigated using various elutants such as HCl, HNO3, thiourea, NaCN and NaOH solutions. The best results were obtained using a mixture of 10 M HNO3/0.5 M HCl as elutant with a desorption efficiency of about 97%. Finally, superparamagnetic magnetite (Fe3O4) nanoparticles with a high degree of crystallinity and phase purity were synthesized by a chemical co-precipitation of Fe2+ and Fe3+ salts. The average diameters of the obtained Fe3O4 nanoparticles were about 7 – 8 nm. The Fe3O4 nanoparticles were coated with oleic acid surfactant molecules and used as seed particles for the preparation of 50 nm diameter magnetic PSMI nanoparticles via an in situ imidization reaction. TEM analysis confirmed that the magnetically responsive PSMI nanoparticles consist of magnetite core-polymer shell structure, although more work is required to perfect such materials.
AFRIKAANSE OPSOMMING: In hierdie studie is ‘n ekonomiese, omgewings vriendelike, seleketiewe en effektiewe proses vir die ekstraksie en herwinning van [AuCl4]- uit suur chloried-ryke oplossings, spesifiek oplossings van lae konsentrasies van edel metal komplekse was bestudeer. Gefunksionaliseerde poli(stireen-ko-maleïmied) (PSMI) nanopartikels was gesintetiseer deur middel van termiese imidisasie van die poli(stireen-ko-maleïk anhidried) kopolimeer met 3-N,N-dimetielaminopropielamien. Stabiele dispersies in water was gevind wat soos sweriese mono-disperse PSMI nanopartikels met ‘n noue partikel-grootte verspreiding met ‘n gemiddelde deursnee van 50 ± 5 nm. Die spesifieke oppervlak area van die massa PSMI nanopartikels is 88.1 ± 2.2 m2/g met ‘n gemiddelde porie-grootte van 82.3 Å. 13C NMR, FTIR en elementêre analiese bevestig die suksesvolle en volledige omskakeling van PSMA na PSMI. Die gefunksionaliseerde PSMI nanopartikels was bestudeer as ‘n nuwe anion-uitruil material vir die ekstraksie van [AuCl4]- ione uit suur oplossings. Stel sorpsie studies was uitgevoer as ‘n funksie van verskeie parameters soos onder andere die goud konentrasie in oplossing, PSMI massa, kontak tyd en ‘n mengings tempo. Die [AuCl4]- ekstraksie gebeur met ‘n geweldige sorpsie kinetika en is afhanklik van die mengings tempo gedurende die stel sorpsie proses. Die gefunksionaliseerde PSMI nanopartikels het ‘n maksimum goud sorpsie kapsiteit van 1.76 mmol/g (347.7 mg/g). Langmuir en Freundlich isoterm modelle was gepas en geanaliseer op die experimentele sorpsie data waarvan die Langmuir isoterm model die data die beste gepas het. De-sorpsie effektiwiteit van ongeveer 80 % en 93% was vekry vir die aangesuurde thiourea (0.25 M thiourea/2 M HCl) en ‘n mengsel van 10 M HNO3/0.5 M HCl as elueer oplossings, onderskeidelik. X-straal foto-elektron spektroskopie (XPS) analiese bevestig ongetwydeld die geimmobileerde goud spesies in oksidasietoestande van 0, +I, en +III op die PSMI nanopartikels. Hierdie is bewyse dat die [AuCl4]- oorspronklik teenwoordig in die goud oplossings is onderhewe auto-reduksie fenomeen op die oppervlak van die gefunksionalieerde PSMI nanopartikels. Die bestaan van verskeie goud spesies dra by tot die power de-sorpsie effektiwiteit van ge-immobiliseerde goud. Bykomend tot die nanopartikels is mikro- tot millimeter grootte PSMI partikels voorberei met ‘n elektro-sproei proses. Hierdie metode stel ons instaat om ‘n wye reeks sferiese en quasi-sferiese PSMI partikel se deersnee voorteberei. Deur die manupulasie van die eksperimentele kondisies gedurende die elektro-sproei proses, soos die konsentrasie van die PSMI in oplossing, die kapilêre punt-tot-ontvanger afstant, vloeispoed en die toegepasde potensiaal. 13C KMR en FTIR spectroskopiese analiese wys dat die elektro-sproei proses die PSMI partikel bereiding toelaat sonder enige veranderinge in die chemiese samestelling van die PSMI materiaal. Oppervlak area en porie-grootte analise wys dat 450lksdfhld en dskl jmm partikels gebruik in die goud ekstraksie eksperimente is mikro-porieës en het spesifieke oppervlak-areas van 2.8 ± 0.4 m2/g en 2.0 ± 0.1 m2/g onderskeidelik. Mikro- tot millimeter grootte poli(stireen-ko-maleimied) (PSMI) partikels van 450 μm en 1620 μm deursnee was getoets as potensieele anion-uitruilings-hars vir die ekstraksie van [AuCl4]- vanuit suur oplossings. Die tyd afhanklike studies gee aanduiding dat die mate van goud opname toeneem met ‘n toename in kontak-tyd en is afhanklik van die goud konsentrasie in die [AuCl4]- oplossings. ‘n Maksimum opname-kapasiteit van 120.7 mg/g en 98.2 mg/g was verkry vir die 450 μm en 1620 μm hars partikels onderskeidelik. Die eksperimentele sorpsie-data volg ‘n lineêre neiging in ooreenstemming met die Freundlich model. Die sorpsie neiging van [AuCl4]- dui aan dat ‘n meervuldige laag sorpsie proses domineer. De-sorpsie van die geimobiliseerde goud spesies vanaf die PSMI hars partikels was bestudeer deur gebruik te maak van verskeie elueermiddels soos HCl, HNO3, thiourea, NaCN en NaOH oplossings. Die beste resultate is verkry deur ‘n mengsel te gebruik van 10M HNO3/0.5M HCl as elueermiddel met n de-sorpsie effektiviteit van ongeveer 97%. Superparamagnetiese magnetiet (Fe3O4) nanopartikels met ‘n hoë graad van kristaliniteit en fase-reinheid was voorberei deur ‘n chemiese ko-neerslagvorming van Fe2+ en Fe3+ soute. Die gemiddelde deursnee van die Fe3O4 nanopartikels was ongeveer 7 – 8 nm. Die Fe3O4 nanopartikels was omhul met oleic suur benatter molekules wat gebruik word as saadjies vir voorbereiding van 50 nm deursnee-magnetiese PSMI nanopartikels deur middel van ‘n imidisasie reaksie. TEM analiese bevestig dat die magnetiese PSMI partikels nanopartikels bestaan uit ‘n magnetiet-kern polimeer-skil struktuur.
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Leroy, Marc. "La sidérurgie ancienne en Lorraine avant le Haut Fourneau : étude du développement historique et des conditions techniques de l'utilisation du minerai oolithique lorrain (La Minette) en metallurgie de réduction directe." Besançon, 1993. http://www.theses.fr/1993BESA1020.
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Cette étude aborde la question de l'utilisation de minerai calcaire et phosphoreux en sidérurgie ancienne, antérieurement à l'apparition des hauts fourneaux. La mise en œuvre d'une recherche pluridisciplinaire, à double approche archéologique et archéométrique, met en lumière l'utilisation du minerai sédimentaire oolithique de lorraine centrale (la minette), dès l'époque antique, préférentiellement à un minerai de surface en grains pourtant plus riche en fer. La genèse et les modalités du programme de recherche, les bases documentaires, sont replacées dans le cadre des recherches développées en pale métallurgie du fer au sein d'un vaste programme fédératif, France et l'est (chapitre 1). L'inventaire des vestiges miniers et métallurgiques répertoriés (221 sites) permet d'évaluer l'état et l'importance de la documentation archéologique. Les analyses chimiques de déchets de production (290 échantillons de minerais et scories) permettent de relier les ateliers de réduction au type de minerai utilisé (chapitre 2). Un long développement est consacré à l'étude des conditions techniques de la réduction du minerai oolithique, à travers l'apport de l'étude archéologique, chimique et métallographique des vestiges de trois ateliers de réduction fouilles. Des données sur la réductibilité du minerai, la fusibilité de sa gangue, la marche des bas fourneaux et le rendement en fer sont ainsi rassemblées (chapitre 3). Un ensemble de vestiges (structures de combustion et déchets de production) associés majoritairement à des contextes d'habitat permet d'introduire le débat sur l'identification des étapes de travail qui suivent la réduction du minerai et aboutissent à la fabrication des objets. Des éléments de réponses sont apportés (chapitre 4). L'étude se termine par un tableau synthétique et novateur de l'évolution historique de cette sidérurgie ancienne en lorraine, depuis l'époque gauloise jusqu'à la fin du moyen âge. La date d'apparition du procédé indirect est discuté en confrontant sources historiques et archéologiques (chapitre 5).
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Panda, Deepankar. "Development of Al-Fe3Al Composites by Powder Metallurgy Route." Thesis, 2016. http://ethesis.nitrkl.ac.in/8031/4/2016_613MM3015_DPanda_development.pdf.
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Aluminium based MMCs are one of the most prominent materials due to their low density, high specific strength and stiffness and increased fatigue resistance which make them suitable for various wear and structural applications in various aerospace and automotive industries. Aluminium (Al) is widely used due to its excellent properties such as low density high thermal and electrical conductivity. However, Al has poor wear resistance behaviour, low hardness and poor fatigue properties. This is why Al is very often reinforced with hard materials like carbides, borides, nitrides, oxides and intermetallics. Rising interests in intermetallic compounds is connected with their high strength, corrosion resistance and wear resistance. Among the several intermetallic compounds available iron aluminide (Fe3Al) has been frequently considered for high-temperature structural applications because of their unique physical and mechanical properties. Fe3Al intermetallic compound has a high melting point, high hardness, low density and good oxidation and corrosion resistance. In the present work, an attempt has been made to study the effect of addition of Fe3Al as reinforcement in Al metal matrix composites. Here, in the present research work Al-10, 20, 30 vol. % Fe3Al composites have been developed by powder metallurgy route and their microstructure, hardness and wear properties have been investigated. In the present research work both as-received Fe3Al and Fe3Al developed by 40 h of mechanical alloying (MA) of Fe75Al25 powder followed by heat treatment at 1100oC for a period of 2 h in Ar atmosphere has been used as reinforcement. Nanocrystalline Al developed by milling Al powder for a period of 20 h has been used as the matrix for all the Al-Fe3Al composites developed in this study. The milled powders were analyzed using x-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDX), high resolution transmission electron microscope (HRTEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The 20 h milled nanocrystalline Al was mixed with both the as-received Fe3Al powder and the Fe3Al powder synthesized by MA in different vol. % and compacted under a uniaxial load of 222 MPa and sintered at 500oC for a period of 2 h in Ar atmosphere. The microstructure of the various Al-Fe3Al sintered composites was analyzed using optical microscope, SEM and EDX. The relative density of the various sintered composites was determined by the Archimedes’ principle. Dry sliding wear test of the various sintered composites was done on a ball-on plate tribometer to determine the wear behaviour of the composites. The hardness of the composites was determined using a Vickers microhardness tester. It was found that both the hardness and the wear resisiatnce of the various Al-Fe3Al sintered composites increased with the increase in Fe3Al content.
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Agrawal, Saurabh. "Carbonization of eucalyptus wood and characterization of the properties of chars for application in metallurgy." Thesis, 2014. http://ethesis.nitrkl.ac.in/5689/1/7.pdf.
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In view of the prominent energy & environmental problems associated with the use of fossil fuels, an increasing attention is now being paid by the metallurgists for the alternate energy sources which are renewable and environment friendly in nature. Biomass (i.e. wood) obtained by fast growing trees appears to be highly beneficial and found suitable for plantations under Indian conditions. Charcoal obtained from these energy crops can be used as a reducing agent for iron-ore reduction. The aims of the present project work is i) Characterization of the properties of different components of eucalyptus tree, such as wood, bark, branch and leaves, and ii) Characterization of the physical and chemical properties of charcoals obtained at different carbonization conditions such as, temperature, heating rate and soaking time. It is found from the proximate analysis that the ash content of different components of eucalyptus wood is very low as compared to coal. It is also found that the calorific value of eucalyptus wood is higher than the other components of eucalyptus tree. The results shows that yield of char and their physical & chemical properties depends on the carbonization conditions, viz. temperature, heating rate and soaking time. The char yield decreases gradually with the increasing carbonization temperature and most of the volatilization occurs up to 800°C. The fixed carbon content increases while volatile matter decreases with increase in carbonization temperature. The calorific value of charcoals increases marginally with increase in carbonization temperature. Reactivity of Eucalyptus wood chars towards CO2 was measured and the effects of carbonization conditions were determined. It is found that the reactivity decreases with increasing carbonization temperature. Charcoals obtained under rapid carbonization were found to be more reactive than the chars obtained under slow carbonization.
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Patra, Dharanidhar. "Study of Reduction Behaviour Of Iron Ore Lumps." Thesis, 2009. http://ethesis.nitrkl.ac.in/191/1/dharani_1.pdf.
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Studies on chemical and physical properties, and reduction behaviour (in coal) of hematite iron ores, procured from ten different mines of Orissa, were undertaken to provide information to the iron and steel industries (sponge iron plants in particular). Majority of the iron ores were found to have high iron and low alumina and silica contents. All these iron ores were free from the deleterious elements (S, P, As, Pb, alkalies, etc.). The results indicated lower values of shatter and abrasion indices, and higher values of tumbler index in all the iron ore lumps except Serazuddin (previous) and Khanda Bandha OMC Ltd.. For all the fired iron ore pellets, the degree of reduction in coal was more intense in the first 30 minutes after which it became small. Slow heating led to higher degree of reduction in fired pellets than rapid heating. All the iron ores exhibited more than 90% reduction in their fired pellets in 2 hrs. time interval at a temperature of 9000C. Iron ore lumps showed lower degree of reduction than the corresponding fired pellets.
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Piprani, Vikas, Prachi Samal, and Vaneshwar Sahu. "Fatigue Life Estimation of Pre-corroded Aluminium Alloy." Thesis, 2009. http://ethesis.nitrkl.ac.in/214/1/final.report.for.upload.pdf.
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The effect of time and mode of corrosion in fatigue life of pre-corroded 7020-aluminum alloy has been determined and compared with that of uncorroded specimens. It is known that fatigue properties of any material depend on the homogeneity of the material mostly the surface uniformity .Any irregularity present may cause fatigue crack initiation at a stress comparably lower than that shown by the S-N curve and thus the pre-corroded specimens’ S-N curve shows some deviation from the actual curve due to the presence of corrosion pits.
As the fatigue failure process exploits the weakest links (discontinuities) within the test material, which act as nucleation sites for crack origins, the fatigue properties of uncorroded and pre-corroded 7020-aluminum alloy in aqueous solution of NaCl (3.5% NaCl , 8.2 pH) along with forced corrosion at different sweep rates have been studied and compared in this project. The properties being the S-N curve, fatigue life, endurance limit, fatigue crack growth mechanism, SEM fractograph and probable crack initiation cause and spot.
Round specimen generally used in classical fatigue tests for life estimation have been used in this experiment. S-N curve is plotted by using Moore’s rotating cantilever beam type fatigue testing machine. The tests are conducted in uncorroded specimen and in pre-corroded specimen and then results are compared. Also the mechanism and spot of crack initiation is predicted by using fractographs under SEM.
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Pati, Rashmi Ranjan, and Vinay M. "Reduction Behaviour of Iron Ore Pellets." Thesis, 2009. http://ethesis.nitrkl.ac.in/238/1/rashmi_report.pdf.
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Demand of sponge iron and pre-reduced pellets for the manufacture of different varieties of steel is increasing day by day and new solid reductants based sponge iron plans are being commissioned. In the existing blast furnace an increase in production by at least 25 to 35% can
be achieved by using pre reduced iron ore. Pre-reduced iron ore pellets have been established as a good substitute for steel scrap in an electric arc furnace which enhances the productivity of the arc furnace. A lot of investigations have been carried out on direct reduction process of iron oxides by carbonaceous materials, but little work has been done on the characterization of properties and reduction behavior of iron ore of. In the present project work, an attempt has been made to study the reduction behavior and kinetics of iron ore fired pellets. The effect of different reduction parameters such as temperature (850-1000ºC), time (15-120 minutes.), mixing of particles of different sizes at different ratios for pellet preparation etc. on the reduction behavior of iron ore pellets. These form the subject matter of the thesis. First chapter gives the
introduction about the subject. It speaks about the need of DRI industry, scope, present status and future planning of DRI industry in India, world wise DRI production, etc. It gives a general idea of raw materials quality required for producing DRI, especially in Rotary Kiln. The second
chapter deals with the literature survey. The third chapter deals with planning of experiments, selection of raw materials, preparation of samples, preparation of iron ore pellets, experimental procedure , evaluation of reduction and activation energies, etc. The results obtained and the discussions made from these observations have been outlined in chapter four. The result for fired
iron ore pellets indicated an increase in degree of reduction with increase in reduction temperature (850-1000ºC) and time. The reduction kinetics of Zenith iron ore pellets were studied in temperature range of 850-1000ºC. The data were fitted on a differential model and the activation energies of reduction of pellets were calculated. Analysis of swelling behavior was also done.
Results obtained from chapter four have been summarized in chapter five. Lastly, these conclusions have been followed by the list of references.
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Mohapatra, Binayak. "Study of Reduction Behaviour Of Iron Ore Lumps." Thesis, 2009. http://ethesis.nitrkl.ac.in/1150/1/dharani_1.pdf.
Full textAbstract:
Studies on chemical and physical properties, and reduction behaviour (in coal) of hematite iron ores, procured from ten different mines of Orissa, were undertaken to provide information to the iron and steel industries (sponge iron plants in particular). Majority of the iron ores were found to have high iron and low alumina and silica contents. All these iron ores were free from the deleterious elements (S, P, As, Pb, alkalies, etc.). The results indicated lower values of shatter and abrasion indices, and higher values of tumbler index in all the iron ore lumps except Serazuddin (previous) and Khanda Bandha OMC Ltd.. For all the fired iron ore pellets, the degree of reduction in coal was more intense in the first 30 minutes after which it became small. Slow heating led to higher degree of reduction in fired pellets than rapid heating. All the iron ores exhibited more than 90% reduction in their fired pellets in 2 hrs. time interval at a temperature of 9000C. Iron ore lumps showed lower degree of reduction than the corresponding fired pellets.
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Nath, Subhasisa. "Study of Reduction Kinetics of Iron Ore Pellets by Noncokingcoal." Thesis, 2009. http://ethesis.nitrkl.ac.in/1479/1/MY_FINAL_THESIS.pdf.
Full textAbstract:
Demand of sponge iron and pre-reduced pellets for the manufacture of different varieties of steel is increasing day by day and new solid reductant based sponge iron plants are being commissioned. In the existing blast furnace an increase in production by at least 25 to 35% can be achieved by using pre reduced iron ore. Pre-reduced iron ore pellets have been established as a good substitute for steel scrap in an electric arc furnace which enhances the productivity of the arc furnace. Also majority of fines which are generated during the course of handling, mining, transportation etc are exported at a through away price which need to be utilized by making iron ore pellets for sponge iron making.
A lot of investigations have been carried out on direct reduction process of iron oxides by carbonaceous materials, but little work has been done on the characterization of properties and reduction behavior of iron ore of some mines of Orissa. In the present project work, an attempt has been made to study the reduction behavior and kinetics of fired iron ore pellets. The effect of different reduction parameters such as temperature (850-10000C), time (15-120 min.), reductant quality, pellets Vs lump, mixing of particles of different sizes at different ratios for pellet preparation etc. on the reduction behavior of iron ore pellets. These form the subject matter of the thesis.
First chapter gives the introduction of the subject. It speaks about the need of DRI industry, scope, present status and future planning of DRI industry in India, world wise DRI production, etc. It also presents the mechanism of direct reduction process.
The second chapter shows the literature review.
The third chapter deals with planning of experiments, selection of raw materials, preparation of samples, preparation of iron ore pellets, experimental procedure for characterization of different chemical and strength properties of the selected iron ore lump, proximate analysis of selected noncoking coals, evaluation of reduction and activation energies, study of swelling behavior, evaluation of strength properties of pellets, etc.
The results obtained and the discussions made from these observations have been outlined in chapter four. The result for fired iron ore pellets indicated an increase in degree of reduction with increase in reduction temperature (850-10000C). Fired iron ore pellets showed higher degree of reduction of iron ore pellets than iron ore lump. The reduction behavior of iron ore was identical in all the selected coals.. Abnormal swelling was observed at temperature 8500C and 9000C; whereas shrinkage in the pellets was observed at 9500C and 10000C. The reduction kinetics of Zenith iron ore pellets were studied in the temperature range of 850-10000C. None of the data were found to fit to the kinetic models. So the activation energies of all the iron ore – coal combinations were calculated using Integration method. Pellets made from fines of (-100#) 100% + (-18+25#)10% + (-10+16#)% were showing reduction in activation energy as compared to the pellets made from fines of -100#. In all the studied coal size, least activation energy was observed with coal of -6+16# size.
Results obtained from chapter four have been summarized in chapter five. Lastly, these conclusions have been followed by the list of references.
a) The degree of reduction increased with increase in reduction temperature from 850-10000C
b) There was no effect of type of coal on the degree of reduction of iron ore pellets
c) Iron ore lumps were less reducible than their corresponding iron ore pellets.
d) The reduction behavior of iron ore pellets made from fines of different sizes were comparable with pellets made from fines of -100#.
e) At 8500C and 9000C, the iron ore pellets were showing abnormal swelling after reduction, whereas at 9500C and 10000C, shrinkage was observed in the reduced iron ore pellets
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Behera, J. K., and V. N. Waddar. "Study of Kinetics Involved in Oxidation of Nonferrous Metal Sulphides." Thesis, 2010. http://ethesis.nitrkl.ac.in/1625/1/Microsoft_Word_-_Complete..pdf.
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In the present investigation, an attempt has been done to study the simultaneous effects of the major processing variables on the extent of oxidation of commercially pure sphalerite ore pellets. These process variables taken into consideration were time and temperature. The oxidation was carried inside a muffle furnace where there was mild oxidation in the presence of atmospheric air. The pellets were charged for roasting inside the furnace in a graphite crucible. This process of roasting was carried out at four temperatures 7500 C, 8000 C , 8500 C and 9000 C .The project goal is to compare the oxidation or roasting at different temperature and time. At all instance of comparison one of the parameter was kept constant. The percentage (degree) of oxidation of sphalerite pellets was calculated at 15, 30, 45 and60 minutes, after the furnace reached the predetermined oxidation temperature. The experiments were statistically designed such that the effect of each variable can be quantitatively assessed and compared. The results showed that, temperatures above 8500C, time remaining constant, with the increase in temperature there is increase in the rate of oxidation (roasting) of sphalerite ore pellets. Further more for a constant temperature with the increase in time of exposure, rate of oxidation of Sphalerite (ZnS) pellets increases. This is valid for temperature range above 8500C. Another observation was made that temperature remaining constant, the rate of oxidation of Sphalerite (ZnS) ore pellets increases with time of exposure to attain a maximum limit than suddenly decreases followed by increment in the rate again. This observation was made in the temperature range of less than 8000C.
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Nayak, Deepak, Himansu Shekhar Mahapatra, and Navin Kumar. "An attempt at optimizing the flow characteristics of blast furnace slag by investigation with synthetic slag prepared in the laboratory using pure oxides." Thesis, 2010. http://ethesis.nitrkl.ac.in/1839/1/Deepak_Thesis.pdf.
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In the cohesive zone the ore layer becomes compacted due to softening-melting and the gas passes predominantly through the sandwiched coke layer (coke slits). Minimizing the size and lowering the position of the cohesive zone will improve productivity and decrease coke rate. This work is designed at arriving at a slag composition through actual experimentations which will ensure the lowering of the cohesive zone of the blast furnace with simultaneous decrease in the difference between the softening temperature (ST) and flow temperature (FT) of the slag. Slag samples from SAIL, Rourkela were brought and their flow characteristics were measured under the heating microscope. With the same composition as obtained from the plant, a synthetic slag was prepared in the laboratory. It was melted to 1600 °C and then water quenched to form the glassy state. Flow characteristics for the same were also determined. In addition, all slag samples were sent to DISIR, Rajgangpur for slag analysis as well as to determine the mineralogical phases present in them. For this, they heated the slag samples to 1500 °C followed by slow cooling to convert them to crystalline form. Then, XRD analysis was done to determine the mineralogical phases. Finally, with relevant phase diagram study, we arrived at a composition which will ensure the lowering of cohesive zone. Moreover, flow characteristics data of synthetic slag was compared with that obtained from Blast Furnace slag.
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Kumar, Avinash, and Satwinder singh Kalsi. ""Reduction kinetics of iron ore pellets made by addition of -100# size fines in conventional pellets"." Thesis, 2010. http://ethesis.nitrkl.ac.in/1778/1/project_report_2010.pdf.
Full textAbstract:
The increasing trend in the prices of steel scrap and its short supply led the steel technologists to find a suitable charge mix in the form of sponge iron or Direct Reduced Iron (DRI). Sponge Iron or DRI is obtained from the direct reduction of iron ore and has iron content between 84 to 95 percent. Technically and technologically, sponge iron has been found to be a suitable material for charging in blast furnaces. In the existing blast furnace an increase in production by at least 25 to 35% can be achieved by using pre reduced iron ore. Sponge iron is a better substitute for scrap for steelmaking through EAF / IF routes due to its homogenous nature, Improved productivity and lower coke consumption. Also majority of fines which are generated during the course of handling, mining, transportation etc are exported at a through away price which need to be utilized by making iron ore pellets for sponge iron making. According to industry experts, the preference for usage of DRI will lead to the use of 80 percent DRI in the charge mix in EAFs by 2009-10 which may even reach the 85 percent level by 2011-12 in the various regions of India. A lot of investigations have been carried out on direct reduction process of iron oxides by carbonaceous materials, but little work has been done on the characterization of properties and reduction behavior of iron ore of some mines of Orissa. In the present project work, an attempt has been made to study the reduction behavior and kinetics of fired iron ore pellets. The effect of different reduction parameters such as temperature (900-950°C), time (15-60 min.), reductant quality, mixing of particles of different sizes at different ratios for pellet preparation etc. on the reduction, swelling behavior of iron ore pellets. These form the subject matter of the thesis. First chapter gives the introduction about the subject. It speaks about the need of DRI industry, scope, present status and future planning of DRI industry in India, world wise DRI production, etc. It gives a general idea of raw materials quality required for producing DRI, especially in Rotary Kiln. The second chapter deals with the literature survey. The third chapter deals with planning of experiments ,selection of raw materials, preparation of samples, preparation of iron ore pellets, experimental procedure , evaluation of reduction.
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The results obtained and the discussions made from these observations have been outlined in chapter four. The result for fired iron ore pellets indicated an increase in degree of reduction with increase in reduction temperature (900-950ºC) and time. The reduction kinetics of Sakaruddin iron ore pellets were studied in temperature range of 900-950ºC. Analysis of swelling behavior was also done. Results obtained from chapter four have been summarized in chapter five. Lastly, these conclusions have been followed by the list of references.
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Patnaik, Pallabi, and Shivani Dumpawar. "An attempt at optimizing the flow characteristics of blast furnace slag by Investigation with slag obtained from blast furnace of Rourkela steel plant, SAIL." Thesis, 2010. http://ethesis.nitrkl.ac.in/1933/1/pallu_final_thesis.pdf.
Full textAbstract:
Due to the softening-melting of the burden in the cohesive zone of the blast furnace, the ore layer becomes compacted and the gas passes predominantly through the sandwiched coke layer known as coke slits. For improved productivity and reduced coke rate, it is required to minimize the size
and lower the position of the cohesive zone in the blast furnace. This work is designed by arriving at a slag composition through actual experimentations which will ensure the lowering of the cohesive zone of the blast furnace with simultaneous decrease in the difference between the softening temperature (ST) and flow temperature (FT) of the slag. Slag samples from SAIL, Rourkela were collected and their flow characteristics were measured using the heating microscope. With the same composition as obtained from the steel plant, a synthetic slag was
prepared in the laboratory using pure oxides, by another group. It was melted to 1600 °C and then water quenched to form the glassy state. Flow characteristics for the same were also determined. The flow characteristics data of Blast Furnace slag were compared with that obtained from synthetic slag. All the slag samples were sent to DISIR, Rajgangpur for slag analysis as well as to determine the mineralogical phases present in them, for which the slag
samples were heated to 1500 °C followed by slow cooling to convert them to crystalline form. Then, XRD analysis was done to determine the mineralogical phases. Finally, with relevant phase diagram study, we arrived at a composition which will ensure the lowering of cohesive zone.
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Patra, Deepak, and Sharath V. "Effect of Firing Temperature and time on swelling behavior of reduced iron ore pellets." Thesis, 2011. http://ethesis.nitrkl.ac.in/2132/1/final_year_project_2011_by_Deepak_patra_and_sharath_V.pdf.
Full textAbstract:
The increasing trend in the prices of steel scrap and its short supply led the steel technologists to find a suitable charge mix in the form of sponge iron or Direct Reduced Iron (DRI).
Sponge Iron or DRI is obtained from the direct reduction of iron ore and has iron content between 84 to 95 percent. Technically and technologically, sponge iron has been found to be a suitable material for charging in blast furnaces. In the existing blast furnace an increase in production by at least 25 to 35% can be achieved by using pre reduced iron ore. Sponge iron is a better substitute for scrap for steelmaking through EAF / IF routes due to its homogenous nature, Improved productivity and lower coke consumption. Also majority of fines which are generated during the course of handling, mining, transportation etc are exported at a through away price which need to be utilized by making iron ore pellets for sponge iron making. According to industry experts, the preference for usage of DRI will lead to the use of 80 percent DRI in the charge mix in EAFs by 2009-10 which may even reach the 85 percent level by 2011-12 in the various regions of India.
A lot of investigations have been carried out on direct reduction process of iron oxides by carbonaceous materials, but little work has been done on the characterization of properties and reduction behavior of iron ore of some mines of Orissa. In the present project work, an attempt has been made to study the reduction behavior and kinetics of fired iron ore pellets. The effect of firing temperarure (1000, 1100 and 1300oC), binder (concentrated sugar cane juice) on strength of pellets and the effect of different reduction parameters such as temperature (850-1000°C), time (0-90min.), reductant quality, mixing of particles of different sizes at different ratios for pellet preparation etc. on the reduction, swelling behavior of iron ore pellets. These form the subject matter of the thesis. First chapter gives the introduction about the subject. It speaks about the need of DRI industry, scope, present status and future planning of DRI industry in India, world wise DRI production, etc. The second chapter deals with the literature survey.
The third chapter deals with selection of raw materials, preparation of samples, preparation of iron ore pellets, experimental procedure. Results and discussions are out lined in fourth chapter. Lastly, these conclusions have been followed by the suggestion for future work and list of references.
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Dash, Supratik, and Nachiketa Mohanty. "Optimization of Flow Characteristics of Blast Furnace Slag." Thesis, 2012. http://ethesis.nitrkl.ac.in/3194/1/Full_Thesis.pdf.
Full textAbstract:
A study of the flow characteristics of blast furnace slag is important to record the softening and melting phenomena in blast furnace which greatly influence the extent and location of the cohesive zone having a direct say on the blast furnace operation, quality of hot metal and the coke consumption. In the present work, a noble technique (heating microscope) is adopted to determine the flow characteristics of blast furnace slags obtained from different blast furnaces. It is seen that the results so obtained agree very closely with the values obtained from adopting conventional methods of determining the same using the slag atlas. It is also seen that the characteristics temperature are altered with the alteration of C/S ratio and also the MgO content of the blast furnace slag.
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Agarwal, Anup, and Sudhir Saha. "Determining the flow characteristics of synthetic slag and optimizing the slag characteristics." Thesis, 2012. http://ethesis.nitrkl.ac.in/3224/1/Anup_Sudhir_Thesis.pdf.
Full textAbstract:
In the dynamics of blast furnace slag plays an important role in the quality of the hot metal produces and also the efficiency of the blast furnace. The quality of the hot metal depends on the formation and other mineralogical transformation that the slag undergoes during the passage of the burden. The minerals such as SiO2 and Al2O3 increases the viscosity of the slag whereas, CaO decreases the viscosity of the slag.The cohesive zone determines gas flow pattern. The cohesive zone's thickness is determined by the melting zone of the slag. The ore is compacted due to softening and melting in the cohesive zone. Minimizing the size, lowering the level of the cohesive zone, increases the efficiency of the blast furnace, improves productivity and decreases coke rate. The work is designed at arriving at a slag composition through actual experiments which will ensure the lowering of the cohesive zone of the blast furnace with simultaneous decrease in the difference between the softening temperature (ST) and flow temperature (FT) of the slag.Synthetic slags were formed by imitation of blast furnace slag using the major oxides (CaO, MgO, SiO2 and Al2O3) and disregarding the minor oxides. The mineralogical compositions of the slag can be varied to obtain different synthetic slag and thus the flow characteristics of the slag can be experimented for different synthetic Slags.