Relevant bibliographies by topics / Gibbsite

Academic literature on the topic 'Gibbsite'

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Published: 4 June 2021
Last updated: 12 February 2022

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Journal articles on the topic "Gibbsite"

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Gan, Bee K., Ian C. Madsen, and James G. Hockridge. "In situX-ray diffraction of the transformation of gibbsite to α-alumina through calcination: effect of particle size and heating rate." Journal of Applied Crystallography 42, no. 4 (June 30, 2009): 697–705. http://dx.doi.org/10.1107/s0021889809021232.

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A study was conducted on the gibbsite to α-alumina (α-Al2O3) transformation dynamics with particular reference to the influence of particle size and heating rate. Coarse- and fine-grained gibbsites were used to examine the transformation paths for the two materials, with particular reference to the upper and lower branch sequences described by Wefers & Misra [Oxides and Hydroxides of Aluminium, (1987), Alcoa Technical Paper No. 19 Revised, Aluminium Company of America]. The main techniques used to assess gibbsite calcination were thermogravimetric differential scanning calorimetry andin situX-ray diffraction, which provided complementary information on transformation behaviour. Whilst the quantitative phase analysis results indicated that the coarse- and fine-grained gibbsites followed both the upper and the lower branch sequences, detailed analysis of the results highlighted specific differences in the transformation behaviour for the two materials. With the loss of three molecules of water as gibbsite transformed to transition aluminas and finally α-Al2O3, there was a high degree of disorder in the crystal structure, resulting in broad and diffuse reflections in the diffraction patterns.
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Chandran, P., S. K. Ray, T. Bhattacharyya, P. Srivastava, P. Krishnan, and D. K. Pal. "Lateritic soils of Kerala, India: their mineralogy, genesis, and taxonomy." Soil Research 43, no. 7 (2005): 839. http://dx.doi.org/10.1071/sr04128.

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In this study, we report the chemical and mineralogical characteristics of 4 benchmark Ultisols of Kerala to elucidate their genesis and taxonomy. The taxonomic rationale of the mineralogy class of Ultisols and other highly weathered soils on the basis of the contemporary pedogenesis is also explained. The Ultisols of Kerala have low pH, low cation exchange capacity, low effective cation exchange capacity and base saturation, with dominant presence of 1 : 1 clays and gibbsite. Presence of gibbsite along with 2 : 1 minerals discounts the hypothesis of anti-gibbsite effect. Since the kaolins are interstratified with hydroxy-interlayered vermiculites (HIV), the formation of gibbsite from kaolinite is not tenable. Thus, gibbsite is formed from primary minerals in an earlier alkaline pedo-environment. Therefore, the presence of gibbsite does not necessarily indicate an advanced stage of weathering. On the basis of a dominant amount of gibbsite, a mineralogy class such as allitic or gibbsitic does not establish a legacy between the contemporary pedogenesis and the mineralogy. The dominance of kaolin–HIV in the fine clays of Ultisols and their persistence, possibly since early Tertiary, suggests that ‘steady state’ may exist in soils developed on long-term weathered saprolite. Since the present acid environment of Ultisols does not allow desilication, the chemical transformation of Ultisols to Oxisols with time is difficult to reconcile as envisaged in the traditional model of tropical soil genesis.
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Bhattacharyya, T., D. K. Pal, and P. Srivastava. "Formation of gibbsite in the presence of 2:1 minerals: an example from Ultisols of northeast India." Clay Minerals 35, no. 5 (December 2000): 827–40. http://dx.doi.org/10.1180/000985500547269.

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AbstractThere are two different views regarding the genesis of gibbsite in tropical acid soils: (1) direct weathering of primary Al-silicate minerals; and (2) transformation through clay mineral intermediates. We investigated the genesis of gibbsite in two representative Ultisols from northeastern India. Gibbsite in these Ultisols appears to be the remnant of earlier weathering products of aluminosilicate minerals formed in a neutral to alkaline pedochemical environment. The mere presence of gibbsite in these soils, therefore, does not indicate their advanced stage of weathering. The formation of typically rod-shaped and well-crystallized gibbsite in both the coarse and fine soil fractions in the presence of large amounts of 2:1 minerals indicates that the anti-gibbsite hypothesis may not be tenable in these tropical acid soils. A schematic model for the formation of gibbsite and kaolin in Ultisols is proposed.
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Vendrame, Pedro Rodolfo Siqueira, Robélio Leandro Marchão, Osmar Rodrigues Brito, Maria de Fátima Guimarães, and Thierry Becquer. "Relationship between macrofauna, mineralogy and exchangeable calcium and magnesium in Cerrado Oxisols under pasture." Pesquisa Agropecuária Brasileira 44, no. 8 (August 2009): 996–1001. http://dx.doi.org/10.1590/s0100-204x2009000800031.

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The objective of this work was to assess the relationship between macrofauna, mineralogy and exchangeable calcium and magnesium in Cerrado Oxisols under pasture. Twelve collection points were chosen in the Distrito Federal and in Formosa municipality, Goiás state, Brazil, representing four soil groups with varied levels of calcium + magnesium and kaolinite/(kaolinite + gibbsite) ratios. Soil macrofauna was collected in triplicate at each collection point, and identified at the level of taxonomic groups. Macrofauna density showed correlation with contents of kaolinite, gibbsite and exchangeable Ca + Mg in the soils. Mineralogy and exchangeable Ca + Mg had significant effects on taxonomic groups and relative density of soil macrofauna. The termites (Isoptera) were more abundant in soils with low exchangeable Ca + Mg; earthworms (Oligochaeta), in soils with high levels of kaolinite; and Hemiptera and Coleoptera larvae were more abundant in gibbsitic soils with higher contents of total carbon.
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Watling, Helen, Joanne Loh, and Helen Gatter. "Gibbsite crystallization inhibition." Hydrometallurgy 55, no. 3 (April 2000): 275–88. http://dx.doi.org/10.1016/s0304-386x(00)00061-x.

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Watling, Helen. "Gibbsite crystallization inhibition." Hydrometallurgy 55, no. 3 (April 2000): 289–309. http://dx.doi.org/10.1016/s0304-386x(00)00062-1.

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Frenzel, Johannes, Augusto F. Oliveira, Helio A. Duarte, Thomas Heine, and Gotthard Seifert. "Structural and Electronic Properties of Bulk Gibbsite and Gibbsite Surfaces." Zeitschrift f�r anorganische und allgemeine Chemie 631, no. 6-7 (May 2005): 1267–71. http://dx.doi.org/10.1002/zaac.200500051.

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Clemente, Celso Augusto, and Antonio Carlos de Azevedo. "Mineral weathering in acid saprolites from subtropical, southern Brazil." Scientia Agricola 64, no. 6 (December 2007): 601–7. http://dx.doi.org/10.1590/s0103-90162007000600007.

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Because weathering of minerals releases chemical elements into the biogeochemical cycle, characterization of their weathering products helps to better model groundwater quality, formation of secondary minerals and nutrient flux through the trophic chain. Based on microscopic and elemental analyses, weathering of riodacite from Serra Geral formation was characterized and weathering paths proposed. Three weathering paths of plagioclase phenocrystals were identified: plagioclase to gibbsite (Pg1); plagioclase to gels and gibbsite (Pg2); and plagioclase to gels, gibbsite and kaolinite (Pg3). Pyroxenes weathered to smectite and goethite (Py1), or to goethite and gibbsite (Py2), and magnetite weathered directly into iron oxides. Rock matrix comprises 90% of rock volume, and weathered to kaolinite and gibbsite, which explains why these minerals were the most abundant in the weathering products of these saprolites.
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Wu, Zheng Ping, Li Jiao Zhou, Qi Yuan Chen, and Zhou Lan Yin. "Reactive Ability and Bong Strength Analysis on Al(OH)3 Crystals with Three Different Crystalline." Advanced Materials Research 396-398 (November 2011): 614–19. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.614.

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The crystal structure models of three kinds of different Al(OH)3 crystals, which are gibbsite, bayerite and nordstradite, are built respectively according to the corresponding experimental crystal lattice. Geometry optimizations are implemented by CASTEP program module using general gradient approximation (GGA) and local density approximation (LDA) methods respectively based on density functional theory (DFT). Total energy, electronic structure, atomic and bond populations are also calculated. The calculation results of total energy indicate that gibbsite is steadier than the other two from the point of view of energy, and the effect of basis set of GGA-PW91 is highest. At the same time, energy bond structure and density of states calculated at GGA-PW91 and LDA-CA-PZ levels show that the different of energy gap ΔE (ELUMO-EHOMO) at the first group of BZ is not obvious, and that the highest value of ΔE of gibbsite is more lower than the other two Al(OH)3 crystals. It may be likely to say that gibbsite may be more active than the other two crystals. According to the analysis of populations, it can be found that bond populations value of H-O and Al-O bonds of gibbsite is smallest in three different Al(OH)3 crystals, it is to say that the combination force of H-O and Al-O bonds of gibbsite is smallest and gibbsite may be more easier to be calcined theoretically.
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Wang, Jing, Qi Na He, and Zhen Gao. "The Effect of Different Solvent on the Microstructure of Gibbsite during Hydrothermal Treatment." Advanced Materials Research 160-162 (November 2010): 76–80. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.76.

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Phase structure and micromorphology of gibbsite after hydrothermal treated in different solvents were studied. Results showed that there was a relationship between micromorphology and phase structure of as-synthesized product. The cubic slice-like boehmite microstructure can be obtained in water. The 3D flowerlike boehmite microstructure can be obtained in isopropanol or sodium carbonate solution. The global ammonium aluminum carbonate hydroxide (AACH) architectures assembled by the lathes can be obtained in urea solvent. Gibbsite can transform to boehmite after 12h hydrothermal treatment in water. In isopropanol or sodium carbonate solution, this time decreased to 6h. In urea solution, Aluminum hydroxide turned from gibbsite to the mixture of boehmite, gibbsite and AACH. Finally, AACH is synthesized. This procedure needs 24h.
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Dissertations / Theses on the topic "Gibbsite"

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Fleming, Sean D. "Computer modelling of gibbsite crystallization." Curtin University of Technology, School of Applied Chemistry, 1999. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=10273.

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This thesis documents the development and application of a computer model for gibbsite, an aluminium tri-hydroxide polymorph. In particular, the work has emphasized the idea of computer modelling techniques combining with ex- observations to provide greater insight than either could separately. Chapter One provides an overview and introduction to the fields of solid state chemistry, crystallization and computer modelling. These ideas are extended in Chapter Two to include a more detailed discussion of the theoretical principles behind the modelling in this project. The development of transferable oxalate and hydroxide potential models, intended primarily for sodium oxalate and gibbsite, is described in Chapter Three. Both ab initio hypersurface fitting and lattice fitting techniques were utilized, with an average structural fitting error of under two percent. In addition, the potentials were used to successfully reproduce several (related) crystal structures, thus establishing the quality of the model. In Chapter Four, the model for gibbsite was employed in generating equilibrium and growth morphologies. The equilibrium morphology was found to give excellent agreement with experiment, with all observed faces present. However, the importance of the prismatic planes is underestimated. Also discussed in the chapter is a method for predicting the phenomenon of crystalline twinning. This technique was successfully applied to a number of systems, including gibbsite and sodium oxalate. In Chapter Five, the equilibrium morphology calculations performed earlier were extended by probing the effects of cation incorporation on the habit of gibbsite. This study was conducted in order to provide a first step in estimating the role of the crystallizing solution. Calculations of the change in surface energy caused by the replacement of a surface proton with a cation from solution ++
were made. Different crystal habits were constructed by applying a range of defect surface coverage values to each of the faces appearing in the morphology. The resulting defect morphologies were in excellent agreement with crystal habits commonly observed by experimentalists. Also, the work provided an explanation for the earlier underestimation of the prismatic faces. Chapter Six documents molecular simulations of solutions containing the major species known to be present in industrial and experimental Bayer liquors. The structuring in two solutions, one containing sodium hydroxide and the other potassium hydroxide, was probed by constructing graphs of the radial distribution functions. These plots indicated that a significant degree of ion pairing was occurring between the alkali metal cations (Na+ and K+) and the aluminate monomer ([Al(OH)4(subscript)]-). Furthermore, these cations were found to be acting as 'bridges' which stabilize multiple aluminate monomers, allowing them to form clusters. This data was used to assist in explaining vibrational spectra, and to postulate that clustering may be the origin of the fine particle suspensions noted during the induction period.
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Gückel, Katharina. "Structural analysis of ternary actinyl(V/VI) sorption complexes on gibbsite." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-126300.

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For the safety assessment of high-level nuclear waste repositories, it is mandatory to know the transportation paths of contaminants, e.g. actinyl ions, in the geological barrier. The most attention needs to be focused on the transport in aquifers, because water contamination, depending on retention and migration processes of radionuclides in the geosphere, is of primary environmental concern. The migration behavior of actinides in ground water is mainly controlled by aquatic speciations and sorption processes at water-mineral interfaces. Hence, the investigation of complexspecies in aqueous solutions and at mineral surfaces becomes essential for the safety assessment in the near and far field of nuclear repositories. For deep ground repositories, clay and clay minerals are considered as possible host rocks, because they show a low permeability and are expected to have a high retention capacity towards actinyl ions. But the complexity of naturally occurring minerals in particular their surface often hampers the unequivocal interpretation of results obtained from sorption experiments. The use of model phases only showing one particular functional group at the surfaces with a well defined surface topology is an appropriate approach for the understanding of the basic sorption processes. Aluminum oxide and hydroxides are of special interest because they represent main components in clays and clay minerals. In particular, gibbsite is widely used as a model system because it represents not only the most common crystalline aluminum hydroxide but also a ubiquitous weathering product of alumosilicates. Furthermore, the elemental structural unit of gibbsite, that is the Al(OH)6 octahedron, occurs ubiquitously as part of the structure of common clay minerals like kaolinite. In the present study, the sorption processes of U(VI) and Np(V) on gibbsite were studied under consideration of the aqueous speciation.
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Mitchell, Scott Christian. "An Improved MUSIC Model for Gibbsite." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd831.pdf.

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Chiang, Yu-Lun. "Antisolvent gibbsite crystallisation from synthetic Bayer liquor." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/8927.

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Includes bibliographical references (leaves 45-49).
The current Bayer precipitation of gibbsite is notoriously slow and is considered to be the rate limiting step of the Bayer process. The present industrial reactor configuration involves precipitating gibbsite inside a series of large stainless steel agitated vessels due to the slow precipitation kinetics of gibbsite from pregnant Bayer liquor. The scope of this study is to investigate the effectiveness of using water as an antisolvent to increase the overall gibbsite yield and the associated particle behaviours under isothermal conditions. The experiments were performed in a series of batch experiments which were divided into two subsets. Firstly, the effect of different caustic concentrations present in the anti solvent on gibbsite yield was tested. Secondly, the effect of different seed loading (50 and 100 grams seeds per liter of synthetic liquor) on aggregation and fines formation were investigated. All batch experiments were conducted isothermally at 80°C under a closed system using a baffled stainless steel 316 agitated vessel. The experimental results indicated water to be a feasible medium for the isothermal antisolvent crystallisation of gibbsite from synthetic pregnant Bayer liquor. It was found that the extent of overall gibbsite yield exhibits a power law correlation to the change in the antisolvent caustic concentration with R2 ～1 (R2 = 0.99974). This finding is important as the regressed curve will be used to correlate gibbsite yield as a function of anti solvent purity. From the seed loading experiments, an Increase In seed loading under constant temperature and initial liquor supersaturation resulted in an overall decrease in product particle size due to a rise in inter-particulate attrition. However, crystal growth was not dominant during any period of the experiments with aggregation being more prominent for the system with the lower seed load. Gibbsite morphology determination from SEM revealed hexagonal solids which, in the presence of a higher seed loading indicated signs of fracture due to attrition. Quantitative evidence of this mechanism is shown USIng the discretised population balance method by Bramley et al. (1996) with the aid of the computational technique developed by Hounslow (2005) in Mathematica. Results generated using this method show decreasing aggregation with liquor de supersaturation and increased seed loading. The overall particle behaviours from the current investigation are validated by results obtained from previous gibbsite studies under very similar conditions. Although the gibbsite yield can be increased drastically in the presence of an anti solvent, the average particle size generated from this study is still too small to be commercially feasible due to the increase in initial supersaturation. Thus it is recommended that further particle size optimisation may be conducted inside a fluidised bed reactor where particles generally experience lower shear than inside a conventional agitated vessel.
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Siebentritt, Matthieu. "Étude de l'entartrage par la gibbsite influence d'un substituant halogéné sur l'adsorption de l'alcool benzylique sur l'acier et la gibbsite." Mémoire, Université de Sherbrooke, 2010. http://savoirs.usherbrooke.ca/handle/11143/4886.

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Le procédé Bayer est la première des deux étapes majeures dans la production de l'aluminium. Il permet la cristallisation sous forme de gibbsite ([alpha]-Al(OH)[indice inférieur 3]) des oxydes et hydroxydes d'aluminium contenus dans la bauxite. Ce procédé, mis au point en 1888, a lieu en milieu alcalin, puisque la bauxite est dissoute jusqu'à sursaturation dans une solution d'hydroxyde de sodium concentrée pour donner ce qui est communément appelé la"liqueur Bayer". Les travaux présentés dans ce mémoire font partie d'une étude importante menée par de nombreux membres de l'équipe de recherche du laboratoire. Lors de la phase de refroidissement de la liqueur Bayer, un phénomène d'entartrage apparaît dans les échangeurs de chaleur du fait de la sursaturation en gibbsite. Ce phénomène d'entartrage occasionne alors d'importantes pertes, tant énergétiques qu'économiques, de par la diminution d'efficacité des appareillages. II faut alors procéder à différents traitements, physiques ou chimiques, pour éliminer le dépôt de tartre de gibbsite, ce qui entraîne également des coûts du fait du temps d'immobilisation des conduites concernées et des méthodes utilisées. L'une des voies explorées pour remédier à ce problème est l'adsorption de molécules organiques ou inorganiques pour empêcher, ou tout du moins ralentir la formation du tartre de gibbsite. L'adsorption des molécules utilisées sur les supports modèles a été étudiée par le biais d'une technique faisant appel à la chromatographie liquide. La mesure de constantes de Henry permet une comparaison des forces d'adsorption à faible concentration de molécules pouvant présenter un caractère inhibiteur face à la formation du tartre de gibbsite. Les matériaux utilisés sont l'acier et la gibbsite, afin de comprendre les phénomènes d'entartrage pouvant avoir lieu dans le procédé Bayer. Les molécules choisies possèdent toutes un cycle aromatique portant un groupement alcool et un halogénure en position ortho. Les mesures d'isothermes d'adsorption montrent une tendance de la force d'adsorption en fonction de la nature du substituant. Une étude comparative d'entartrage sur l'acier doux en présence ou en absence d'inhibiteurs a été menée, afin de mieux comprendre l'influence de ces molécules. De plus, des études de précipitation ont complété ces travaux afin de s'assurer que les molécules prévenant l'entartrage n'influencent pas de manière négative les rendements de précipitation de la gibbsite.
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Plagnieux, Virginie. "Influence des conditions d'agglomération sur la morphologie de la gibbsite et les propriétés d'usage de l'alumine." Vandoeuvre-les-Nancy, INPL, 2003. http://www.theses.fr/2003INPL088N.

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L'@amélioration de la solidité de l'alumine utilisée pour la production d'aluminium et la réductionde la génération de particules fines qui résulte des chocs lors de la calcination et des transports sont des points essentiels pour les producteurs des usines Bayer. Le but de cette étude est de montrer les liens qui existent entre les conditions opératoires de précipitation de la gibbsite et sa morphologie, et de vérifier leur impact sur la solidité de l'alumine. Des analyses sur produits industriels et sur produits élaborés en laboratoire ont été effectuées. Nous avons focalisé notre attention sur le rôle de l'étape d'agglomération. La procédure expérimentale a été choisie pour respecter au mieux les conditions industrielles. La morphologie des cristaux de gibbsite a été quantifiée en utilisant trois modes de visualisation (microscope optique avec des liquides d'immersion, microscope électronique à balayage sur poudre et sur section polie) et un ensemble de paramètres de forme. Cinq paramètres de forme ont été utilisés pour décrire la forme bidimensionnelle des cristaux du point de vue de leur rugosité, de leur allongement et de leur tortuosité. L’analyse en composantes principales a permis de synthétiser l'information pour une meilleure précision des résultats et une interprétation plus fine. Le microscope électronique à balayage permet de visualiser les facettes des cristaux. Des paramètres pseudo-tridimensionnels ont été calculés pour décrire le réseau de facettes. Sur section polie, le contour des cristaux est bien défini et permet de calculer des tàilles de côtés assimilées aux tailles des facettes. La solidité de l'alumine a été évaluée à l'aide d'un lit fluidisé standardisé et de deux indices. !. . :indice d'attrition mesure la proportion de particules de taille inférieure à 45 ~m créées lors du test. !. . :indice de brisure quantifie l'évolution globale de la distribution de taille après le passage en lit fluidisé
The@improvement of the solidity of alumina which is produced for aluminium refinery and the reduction of fine particles generation which result of shocks during calcination and transport are essential points for the Bayer producers. The aim of this study is to link the gibbsite precipitation conditions to the morphology of the crystals and to verity their impact on alumina solidity. Analysis on industrial and lab-made products was done. We have focused our attention on the role of the agglomeration step. The experimental procedure was chosen to be as close as possible to the industrial process. Gibbsite morphology was quantified by using three visualization methods (optical microscopy with different immersion liquids, scanning electron microscopy on free powder and on polished section) and a setof different shape parameters. Five shape parameters quantify the two-dimensional shape of the crystals from the point of view of their roughness, elongation and concavity. Principal component analysis have enabled an information simplification for a better precision of the results and a better interpretation. The scanning electron microscope on free powder enables the tacet network visualization. Pseudo three dimensional parameters were calculated to describe the tacet network. On polished section, the crystal frames are weil defined and enable the sizing of the crystal sides related to the tacet sides. Alumina solidity was evaluated with a standardized fluidized bed and two indices. The attrition index quantifies the proportion of particles of size less than 45 1-1m which have been created du ring the test. The breakage index quantifies the evolution of the size distribution after the test
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Lee, Mei-yin. "The mechanism of gibbsite crystal growth in Bayer liquor." Curtin University of Technology, School of Applied Chemistry, 1998. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=10719.

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Although the precipitation of aluminium trihydroxide as gibbsite, via the Bayer process has been widely studied, the mechanism of crystal growth is poorly understood. This work focus on the morphology of gibbsite and the relative growth rates of individual crystal faces.Initial work was carried out to characterize aluminium trihydroxide and it was found that bayerite, another polymorph, precipitated at temperatures below 50 [degrees] C and its morphology depended on the method of precipitation. Gibbsite however, precipitated above this temperature and its morphology depended on the type of alkali aluminate solutions used. The method of precipitation does not affect the morphology, only the size of the precipitate formed. The morphology of gibbsite can be altered by the addition of organic compounds which are known to inhibit gibbsite precipitation. Some of these compounds were found to selectively inhibit the growth of individual crystal faces, thus altering the overall morphology of gibbsite. Boehmite, a polymorph of aluminium hydroxide, can be produced by partial dehydration of gibbsite at 300T. The morphology of boehmite consisted of diamond shaped crystals.The influence of cation incorporation on the morphology of gibbsite was studied experimentally and computationally (molecular modelling). These studies showed that there is a linear relationship between the amount of cation incorporated and atomic radii and between the amount of cation incorporated and the defect energy calculated. The equilibrium morphology of gibbsite predicted in the absence of media matched the morphology of gibbsite grown slowly from sodium aluminate, implying that the amount of sodium incorporation is low in these crystals.The growth rates of individual crystal faces were measured in situ, and found to be a function of supersaturation squared for the prismatic faces, possibly indicating ++
that E growth occurs by spiral growth mechanism. The growth of the basal face was found to follow the spiral growth mechanism below a relative supersaturation of 0.815 and the birth and spread mechanism above this level. The activation energies and kinetic coefficients for the individual prismatic faces were also determined.Growth rate dispersion was observed in these microscopic studies, but the question of size dependency remains unanswered.The overall growth rates of gibbsite crystal, determined using rapid dynamic light scattering, was found to be an exponential function of supersaturation indicative of a birth and spread growth mechanism.
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Fitzpatrick, Alexander John. "Adsorption of arsenate and phosphate on gibbsite from artificial seawater." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21552.

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Anomalously high concentrations of arsenic and phosphate are found in the sediments of the Saguenay Fjord in comparison to those of the Gulf and St. Lawrence Estuary. The source of arsenic is unclear. It could be supplied to the Fjord by the marine waters which enter from the St. Lawrence Estuary or may have accumulated as a result of historically high levels of effluent input.
The waters of the Saguenay Fjord are also characterized by anomalously high particulate aluminum concentrations (i.e., [Al]tot/[Al] diss > 1), introduced as a result of the aluminum refining activity along the shores of its tributaries. Gibbsite (Al(OH)3), a by-product of this activity, is known to strongly adsorb phosphate and arsenate from low ionic strength aqueous solutions, and may act as a vector for these two elements to sediments of the Saguenay Fjord.
The small amount of arsenate and phosphate adsorbed onto gibbsite from seawater indicates that their adsorption to particulate aluminum in the water column cannot account for the elevated levels of arsenic and phosphate in the sediments of the Saguenay Fjord. (Abstract shortened by UMI.)
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Fitzpatrick, Alexander John. "Adsorption of arsenate and phosphate on gibbsite from artificial seawater." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0023/MQ50768.pdf.

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Li, Tian Siong. "Modelling and kinetics estimation in gibbsite precipitation from caustic aluminate solutions." Curtin University of Technology, School of Applied Chemistry, 2000. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=13672.

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Precipitation of gibbsite from supersaturated caustic aluminate solutions has been investigated extensively due to its central role in the commercial Bayer plant, for extracting the alumina compound from bauxite. The primary focus of Bayer process simulation and optimisation is to help maximise the product recovery and the production of a product crystal size distribution (CSD) that meets the product specification and improves downstream process performance. The product CSD is essentially determined by the nucleation, growth and agglomeration kinetics, which occur simultaneously during the precipitation process. These processes are still poorly understood, owing to the high complexity of their mechanisms and of the structure of the caustic aluminate solutions. This research focuses on the modelling and kinetics estimation aspects of simulating gibbsite precipitation. Population balance theory was used to derive different laboratory gibbsite precipitator models, and the discretised population balance models of Hounslow, Ryall & Marshall (1988) and Litster, Smit & Hounslow (1995) were employed to solve the resulting partial integro-differential equations. Gibbsite kinetics rates were determined from literature correlation models and also estimated from the CSD data using the, so-called, differential method. Modelling of nonstationary gibbsite precipitation systems showed that error propagated with the precipitation time scale. The main contribution to the observed error was found to be from the uncertainties in the kinetic parameter estimates, which are estimated from experimental data and used in the simulation. This result showed that care is required when simulating the CSD of non-stationary precipitators over longer time scales, and methods that produce precise estimates of the kinetics rates from the experimental data need to be used.
Kinetics estimation study from repeated batch gibbsite precipitation data showed that the uncertainty in the experimental data coupled with the error incurred from the kinetic parameter estimation procedure used, resulted in large uncertainties in the kinetics estimates. The influences of the experimental design and the kinetics estimation technique on the accuracy and precision of estimates of the nucleation, growth and agglomeration kinetics for the gibbsite precipitation system were investigated. It was found that the operating conditions have a greater impact on the uncertainties in the estimated kinetics than does the precipitator configuration. The kinetics estimates from the integral method, i.e. non-linear parameter optimisation method, describe the gibbsite precipitation data better than those obtained by the differential method. However, both kinetics estimation techniques incurred significant uncertainties in the kinetics estimates, particularly toward the end of the precipitation runs where the kinetics rates are slow. The uncertainties in the kinetics estimates are strongly correlated to the magnitude of kinetics values and are dependent on the change in total crystal numbers and total crystal volume. Batch gibbsite precipitation data from an inhomogeneously-mixed precipitator were compared to a well-mixed precipitation system operated under the same operating conditions, i.e. supersaturation, seed charge, seed type, mean shear rate and temperature.
It was found that the gibbsite agglomeration kinetic estimates were significantly different, and hence, the product CSD, but the gibbsite growth rates were similar. It was also found that a compartmental model approach cannot fully account for the differences in suspension hydrodynamics, and resulted in unsatisfactorily CSD predictions of the inhomogeneously-mixed precipitator. This is attributed to the coupled effects of local energy dissipation rate and solids phase mixing on agglomeration process.
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Books on the topic "Gibbsite"

1

A, Dzombak David, ed. Surface complexation modeling: Gibbsite. Hoboken, N.J: Wiley, 2010.

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Apps, J. A. Thermochemical properties of gibbsite, bayerite, boehmite, diaspore, and the aluminate ion between 0 and 350C. Washington, DC: Division of Waste Management, Office of Nuclear Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, 1989.

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Reyhani, M. M. Investigations at the atomic level of interactions between gibbsite and sodium oxalate in the Bayer process. East Perth, WA: Minerals and Energy Research Institute of Western Australia, 2000.

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Dzombak, David A., and Athanasios K. Karamalidis. Surface Complexation Modeling: Gibbsite. Wiley & Sons, Incorporated, John, 2010.

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Dzombak, David A., and Athanasios K. Karamalidis. Surface Complexation Modeling: Gibbsite. Wiley & Sons, Incorporated, John, 2011.

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Dzombak, David A., and Athanasios K. Karamalidis. Surface Complexation Modeling: Gibbsite. Wiley & Sons, Incorporated, John, 2011.

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Book chapters on the topic "Gibbsite"

1

Gooch, Jan W. "Gibbsite." In Encyclopedic Dictionary of Polymers, 340. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_5493.

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Harato, T., T. Ishida, and K. Yamada. "Autoprecipitation of Gibbsite and Boehmite." In Essential Readings in Light Metals, 141–47. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118647868.ch18.

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Harato, T., T. Ishida, and K. Yamada. "Autoprecipitation of Gibbsite and Boehmite." In Essential Readings in Light Metals, 141–47. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48176-0_18.

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Futia, A., H. M. Ang, and Dean Ilievski. "Yield Model of a Batch Gibbsite Precipitator." In Mixing and Crystallization, 215–26. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-017-2290-2_19.

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Li, Tian, Dean Ilievski, and Iztok Livk. "Compartmental Modelling of an Aggregating Batch Gibbsite Precipitator." In Electrometallurgy and Environmental Hydrometallurgy, 1783–91. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118804407.ch53.

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Zheng-gen, Liu, Chu Man-sheng, Tang Jue, Han Yuan-ting, and Wu Xiang-long. "Appropriate Reduction and Fe-Al Separation of High Iron Gibbsite." In Light Metals 2013, 223–27. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118663189.ch39.

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Langa, J. M. "The Heat of Dissolution of Gibbsite at Bayer Digestion Temperatures." In Essential Readings in Light Metals, 170–75. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48176-0_22.

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Zheng-gen, Liu, Chu Man-sheng, Tang Jue, Han Yuan-ting, and Wu Xiang-long. "Appropriate Reduction and Fe-Al Separation of High Iron Gibbsite." In Light Metals 2013, 223–27. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-65136-1_39.

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Yamada, K., T. Harato, S. Hamano, and K. Horinouchi. "Dehydration Products of Gibbsite by Rotary Kiln and Stational Calciner." In Essential Readings in Light Metals, 717–26. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118647868.ch100.

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Langa, J. M. "The Heat of Dissolution of Gibbsite at Bayer Digestion Temperatures." In Essential Readings in Light Metals, 170–75. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118647868.ch22.

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Conference papers on the topic "Gibbsite"

1

Legg, Benjamin A., and James J. DeYoreo. "ENERGY LANDSCAPE FOR GIBBSITE NUCLEATION AT THE MICA-WATER INTERFACE." In GSA Annual Meeting in Phoenix, Arizona, USA - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019am-341436.

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Lu, Yi, Xu Zhang, Yanfeng Gao, Xin Wang, Shuochao Fan, Yuan Chen, Yan Li, et al. "Characterization of Gibbsite Filler in HTV Silicone Rubber by Thermogravimetric Analysis." In 2019 IEEE 3rd International Electrical and Energy Conference (CIEEC). IEEE, 2019. http://dx.doi.org/10.1109/cieec47146.2019.cieec-2019207.

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Lumetta, Gregg J., Brian M. Rapko, and Herman M. Cho. "Studies of the Fundamental Chemistry of Hanford Tank Sludges." In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4633.

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Abstract:
The U.S. Department of Energy has embarked on an effort to retrieve, immobilize, and dispose of the 2.1 × 105 m3 of radioactive tank wastes that were generated during weapons production and other operations at the Hanford Site in Washington State. One of the major challenges associated with this effort is the processing of the 4.2 × 104 m3 of high-level waste sludges. These sludges consist of a complex mixture of amorphous and crystalline mineral phases. The current plan for processing the sludge solids consists of leaching with aqueous NaOH, washing out the NaOH and dissolved components, then vitrifying the solids in borosilicate glass. The purpose of the NaOH leaching step is to remove components such as Al, Cr, and P that can lead to the production of an unacceptable quantity of high-level waste glass. In this paper, we will discuss the chemistry underlying the leaching and washing processes, focusing on the specific mineral phases present in the sludge solids and how these phases respond to the leaching process. The chemical phases present in the Hanford tank sludge solids have been identified through microscopy coupled with electron diffraction and through powder X-ray diffraction. We have also recently been applying nuclear magnetic resonance spectroscopy to characterize chemical species in tank sludge solids. Numerous chemical species have been identified including the aluminum oxy/hydroxides gibbsite and boehmite, aluminosilicates, iron oxy/hydroxides, and mixed Cr/Fe oxyhydroxides. Identification of these phases has led to a more fundamental understanding of the behavior of the various sludge components during leaching; in turn, this understanding will allow for improved process flow sheets. For example, we have shown that certain tank sludges are high in boehmite, Υ-AIOOH. This mineral phase is much more refractory than other AI phases such as gibbsite. Thus, more severe leaching conditions (e.g., increased temperature, NaOH concentration, and leaching duration) are required to remove AI from wastes high in boehmite.
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Sowards, Kimberly F., Stephen T. Nelson, Stephen T. Nelson, John McBride, John McBride, David Tingey, David Tingey, Kevin A. Rey, and Kevin A. Rey. "INVESTIGATING SMECTITE AS AN IMPORTANT INTERMEDIATE PRODUCT BETWEEN IGNEOUS MINEROLOGY AND A MATURE ASSEMBLAGE OF KAOLINITE-GROUP CLAYS, GIBBSITE, AND FE-OXIDES." In GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-283454.

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Cortez, L. A., J. Marques Júnior, R. G. Peluco, G. T. Pareira, and L. A. Camargo. "Relações Espaciais entre Caulinita e Gibbsita e a Estabilidade dos Agregados de Latossolo." In I Simpósio de Geoestatística Aplicada em Ciências Agrárias. Botucatu, São Paulo, Brasil: FCA/UNESP, 2009. http://dx.doi.org/10.12702/i-sgea-a32.

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Jacovitti, Giovanni, Alessandro Neri, and Alberto Laurenti. "Tomographic reconstruction from partial angular views using Gibbsian models." In San Diego '92, edited by Michael A. Fiddy. SPIE, 1992. http://dx.doi.org/10.1117/12.139030.

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Chang, Michael M., A. Murat Tekalp, and M. Ibrahim Sezan. "Bayesian segmentation of MR images using 3D Gibbsian priors." In IS&T/SPIE's Symposium on Electronic Imaging: Science and Technology, edited by Majid Rabbani, M. Ibrahim Sezan, and A. Murat Tekalp. SPIE, 1993. http://dx.doi.org/10.1117/12.143137.

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Qiu, H., S. N. Srivastava, J. C. Anderson, and D. N. Ruzic. "Gibbsian segregating alloys: a potential solution to minimize collector degradation." In Advanced Lithography, edited by Michael J. Lercel. SPIE, 2007. http://dx.doi.org/10.1117/12.712465.

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Heesch, D., and M. Petrou. "Non-Gibbsian Markov random field models for contextual labelling of structured scenes." In British Machine Vision Conference 2007. British Machine Vision Association, 2007. http://dx.doi.org/10.5244/c.21.88.

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Potamianos, G., and J. Goutsias. "An analysis of Monte Carlo methods for likelihood estimation of Gibbsian images." In Proceedings of ICASSP '93. IEEE, 1993. http://dx.doi.org/10.1109/icassp.1993.319863.

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Reports on the topic "Gibbsite"

1

Martino, C. J. Gibbsite/Bayerite and Uranium in Tank 41H. Office of Scientific and Technical Information (OSTI), January 2003. http://dx.doi.org/10.2172/807384.

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Duff, M. C. Uranium Sorption on Sodium Aluminosilicates and Gibbsite. Office of Scientific and Technical Information (OSTI), February 2003. http://dx.doi.org/10.2172/807916.

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Russell, Renee L., Harry D. Smith, Donald E. Rinehart, and Reid A. Peterson. Development and Characterization of Gibbsite Component Simulant. Office of Scientific and Technical Information (OSTI), January 2009. http://dx.doi.org/10.2172/967006.

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Herting, Daniel L. Effect of Phosphate, Fluoride, and Nitrate on Gibbsite Dissolution Rate and Solubility. Office of Scientific and Technical Information (OSTI), January 2014. http://dx.doi.org/10.2172/1119691.

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Poirier, M., and P. Burket. Impact Of Sodium Oxalate, Sodium Aluminosilicate, and Gibbsite/Boehmite on ARP Filter Performance. Office of Scientific and Technical Information (OSTI), November 2015. http://dx.doi.org/10.2172/1235439.

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Hay, M., K. Kofi Adu-Wusu, and D. Daniel McCabe. DETERMINATION OF THE FRACTION OF GIBBSITE AND BOEHMITE FORMS OF ALUMINUM IN TANK 51H SLUDGE. Office of Scientific and Technical Information (OSTI), August 2008. http://dx.doi.org/10.2172/939428.

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Apps, J. A., J. M. Neil, and C. H. Jun. Thermochemical properties of gibbsite, bayerite, boehmite, diaspore, and the aluminate ion between 0 and 350/degree/C. Office of Scientific and Technical Information (OSTI), January 1989. http://dx.doi.org/10.2172/6481805.

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