Dissertations / Theses: 'Kaolin Kaolin'

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Branco, Marta Sofia de Pinho. "Electrophoretic deposition of kaolin." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22591.

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Mestrado em Engenharia de Materiais
A deposição eletroforética (EPD) é uma técnica interessante do ponto de vista de processamento de materiais permitindo a formação de filmes dos mais variados materiais em diferentes substratos condutores. É uma técnica simples, versátil e de baixo custo associado. No presente trabalho, conduziram-se estudos que permitiram estabelecer as condições apropriadas para a produção de filmes espessos de caulino por EPD. Depositaram-se filmes de caulino em verde, com cerca de 5 mg, em três tipos de substrato: aço inoxidável, folha de platina e silício platinizado. Para a identificação das condições de deposição, contribuiu o estudo sistemático das condições de preparação da suspensão de caulino que incluíram a avaliação do potencial zeta de suspensões com o pH da mesma, do efeito da composição do meio suspensor (água, etanol, ou mistura de ambos), do recurso ao iodo como aditivo, e da variação com o tempo da transmitância da luz UV por parte dos diferentes meios suspensores, com ou sem iodo. Os resultados obtidos permitiram concluir que as melhores condições de deposição são as que combinam a adição de alguma água ao etanol, enquanto meio suspensor, e o uso de iodo como aditivo. Os filmes preparados por EPD foram sinterizados a 1200 e 1300 oC, durante 2 h. A microestrutura dos filmes, antes e após sinterização, observada por microscopia eletrónica de varrimento (SEM) permitiu concluir que as partículas de caulino tendem a depositar de uma forma orientada em que as suas superfícies basais se alinham paralelamente ao substrato. Os filmes de caulino sinterizados foram submetidos a ensaios de nanoindentação e determinou-se a sua dureza Vickers e módulo de Young para os quais se obtiveram, respetivamente, 300 MPa e 40 GPa. Este trabalho contribuiu para identificar condições para obter filmes espessos de caulino de cuja a microestrutura anisotrópica se aponta a possibilidade de aceder a propriedades maximizadas segundo determinadas direções o que do ponto de vista das suas aplicações pode abrir novas oportunidades.
Electrophoretic deposition (EPD) is an interesting technique from the point of view of materials processing. The technique allows the formation of films of many different materials on different conductive substrates. Besides that, EPD is a simple, versatile and low cost technique. The studies conducted, in the present work, allowed the establishment of appropriate conditions to produce kaolin thick films by EPD. Green kaolin films with around 5 mg were deposited on three types of substrate: stainless steel, platinum foil and platinized silicon. A systematic study about the preparation conditions of the kaolin suspension contributed to identify the deposition conditions. This study included the assessment of the pH dependence of zeta potential of the suspension and the effect of the suspension media (water, ethanol or a mixture of both) as well as the use of iodine as additive. Transmittance variation of the UV light with time was also assessed for the different suspension media with and without iodine. The obtained results allowed to conclude that the best deposition conditions are those that combine the use some water in the ethanol based suspension media added also with iodine. The kaolin films produced by EPD were sintered at 1200 and 1300 oC for 2 h. The observation of the films microstructure by scanning electron microscopy (SEM), before and after sintering, allowed to conclude that the kaolin particles tend to deposit in an oriented way in which their basal surfaces align parallel to the substrate. The sintered kaolin films were submitted to nanoindentation tests and their Vickers hardness and Young’s modulus was determined as 300 MPa and 40 GPa, respectively. This work contributed to identify the conditions to obtain kaolin thick films of which the anisotropic microstructure is expected the possibility of assessing maximized properties under certain directions. From the point of view of applications, this can open new possibilities

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Li, Qiang, and 李强. "Time effects on artificially cemented kaolin." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/208034.

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With the aim to achieve a better understanding of the time-dependent behaviour of structured clays, especially cemented clay, a critical review of the literature and a programme of laboratory testing have been carried out. In order to investigate the time effects on different structured clays, a series of advanced triaxial and oedometer tests were conducted on reconstituted pure kaolin (PK), artificially cemented kaolin (ACK) with different curing periods, and remoulded artificially cemented kaolin (RACK). Strain rate effects were examined in pure kaolin with different degrees of over-consolidation in both undrained and drained shearing. The influence of bond structure on the monotonic stress-strain behaviour of cemented kaolin was investigated on specimens prepared with two different curing stress and curing periods. Tests on pure kaolin and remoulded cemented kaolin were also performed. Strain rate effects on long cured cemented kaolin under low and high confining stresses, with constant rate of straining in pre-peak stage and step-wise change rate of straining in post-peak stage were examined. This was completed by a study of the microstructure of pure kaolin and cemented kaolin specimens before and after tests via scanning electronic microscope. The coupling between stress or strain rate and curing time effects was investigated on cemented kaolin cured for shorter periods. The results have added significant data to the existing database and addressed the relationship between bond structure and time effect. The main conclusions are: ••The viscous type of PK determined is characterized as decaying positive isotache and General TESRA in undrained and drained shearing repectively. The strain rate history does not affect the critical state in both q-p’ and v-ln p’ spaces. ••The addition of cement not only creates new inter-particle bonds but also affects new fabric. The shear strength is dominated by bond structure under low confining stress, and by volume change under high confining stress. ••The viscous type of long-term cured ACK is dependent on the degree of bond structure. It is almost insensitive to strain rate changes when the specimen is stiff, and the apparent “aging” effect dominates resulting in a “negative” rate effect when bond structure is destroyed. A special rate phenomenon called stick-slip seems to occur under the lowest strain rate (0.01%/h) during the pre-peak stage. The RACK shows a TESRA type of viscosity in undrained shearing. ••The short-term cured ACK, in which structuring and rate effects are combined, shows negative rate effects due to the curing under low confining stress and apparent aging under high confining stress. Stick-slip occurs both in pre-peak and post-peak stages, due to different reasons.
published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy

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Schultz, Hillary S. "The Effects of Kaolin Particle Film on the Viburnum Leaf Beetle During Container Production of Viburnum Dentatum under Different Levels of Applied Nitrogen." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/SchultzHS2006.pdf.

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Celes, Josepha D. "Transformation of processed kaolin by plasma magmavication." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/21643.

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Haghighi, Ali. "Thermo-hydro-mechanical behaviour of Kaolin clay." Thesis, Heriot-Watt University, 2011. http://hdl.handle.net/10399/2479.

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The need for an improved understanding of the effects of temperature on the hydro-mechanical behaviour of compacted clays is important in many applications, such as disposal of high level nuclear wastes, burial of high voltage cables, drilling of deep offshore wells, and clay liners used on landfills. In this thesis, a study of the thermo-hydro-mechanical (THM) behaviour of kaolin clay under different conditions is presented. A series of experimental unsaturated tests was carried out, including temperature and suction controlled oedometer tests, and suction measurements to obtain the soil water retention curves at different temperatures. In order to describe the dependency of the soil water retention curves on temperature, the influences of temperature on the contact angle of menisci and the microstructure of the soil samples were studied. Moreover, Environmental Scanning Electron Microscopy was employed for studying the microstructure of the soil at certain conditions of interest. A new suction and temperature controlled oedometer cell was designed, developed and calibrated for investigating THM behaviour of kaolin clay. The oedometer was used to examine the combined effects of suction and temperature on compressibility and collapse behaviour of the soil. In this thesis, special attention was given to the filter paper methodology for suction measurements at different temperatures. The calibration curve of Whatman No. 42 filter paper was determined at 10, 25 and 50ºC using the vapour equilibrium technique with sodium chloride solutions at different concentrations and the axis translation technique. Based on the experimental data, a unique calibration equation was proposed; taking into account the effect of temperature. The experimental results showed that temperature has a relevant influence on filter paper suction measurement and that misleading results can be obtained if temperature is not taken into account in the calibration equation.

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Le, Grange Monique. "Effect of kaolin applications on pome fruit." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52255.

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Thesis (MScAgric)--Stellenbosch University, 2001.
ENGLISH ABSTRACT: Sunburn is a major problem in the apple industry worldwide. A kaolin product, M-97- 009 (100% kaolin), originally developed for insect control, was evaluated for its efficacy in controlling sunburn on pome fruit. Trials were conducted over two seasons in two different areas of the Western Cape, South Africa. During the first season, 'Royal Gala', 'Fuji' and 'Granny Smith' apples were evaluated in the Koue Bokkeveld. The kaolin was mixed with water and applied to the trees by means of a hand-gun regularly throughout the season. In addition to the effect on sunburn, effects on yield, colour development, snout beetle damage and other defects were determined. Sunburn was reduced on all the cultivars tested, although not significantly on 'Granny Smith'. Inconsistent effects on yield parameters were observed. The applications significantly reduced red colour on 'Fuji', but this problem was rectified by an improved application technique the following season. During the second season, additional apple cultivars and 'Rosemarie' pears were included in the trials. The apple trials were conducted in the Elgin area, and the 'Rosemarie' trial in the Koue Bokkeveld. Surround™ (95% kaolin) was applied to the trees by means of a commercial "blower". The effects on sunburn, yield, colour development and fruit maturity were determined. In contrast to the previous season, sunburn was not reduced on any of the cultivars examined. Yield parameters were not affected except in the case of 'Royal Gala' where the number of fruit was increased, and 'Cripps' Pink' where the number of fruit was reduced. Fruit colour was not affected in the apple cultivars, but chroma of 'Rosemarie' pears was reduced, indicating a less intense colour. The kaolin applications had a variable effect on fruit maturity. The effect of the foliar applications on photosynthetic photon flux density (PPFD), photosynthetic rate, stomatal conductance and transpiration rate was determined. In addition to these spot measurements, photosynthetic light response curves were determined. Measurements were taken on both the inner and outer canopies The applications significantly reduced photosynthetic rates in the inner canopy and reduced the apparent quantum efficiency of leaves on the outer canopy. No significant effect on PPFD was found. It appears that the white coating reflects light and allows less light to penetrate the leaf, thus reducing photosynthesis. Surround™ treatments could not counteract the damaging effects of the high temperatures experienced in the Western Cape during this season and was not effective as a control measure for sunburn. This does not appear to be a commercially viable solution for the sunburn problem and it would be worthwhile to investigate the use of alternative options, such as evaporative cooling.
AFRIKAANSE OPSOMMING: Sonbrand is een van die grootste probleme wat wêreldwyd in die appelbedryf ondervind word. 'n Nuwe produk, M-97-009 (100% kaolien), is oorspronklik ontwikkel vir insekbeheer in geïntegreerde plaagbeheer, maar daar is beweer dat dit moontlik sonbrand op kemvrugte kan verminder. Proewe is oor twee seisoene uitgevoer in die Koue Bokkeveld en ook in die Grabouw-omgewing in die Wes-Kaap. Tydens die eerste seisoen is die effek van M-97-009 op 'Royal Gala', 'Fuji' en 'Granny Smith' appels beoordeel. Die kaolien is met water gemeng en deur die loop van die seisoen met 'n handspuit op die bome gespuit. Die effek van die produk op sonbrand, oesgrootte, vruggrootte, kleurontwikkeling, kalanderskade en ander defekte is bepaal. Sonbrand is op alle kultivars verminder, alhoewel nie betekenisvolop 'Granny Smith' nie. Die effek van kaolien op oesparameters was rue konsekwent nie. kleurontwikkeling op 'Fuji' benadeel, heel moontlik Die toedienings het as gevolg van die toedieningstegniek. Met verbeterde toedieningsmetodes die volgende seisoen, is kleurontwikkeling van 'Fuji' nie benadeel nie. Tydens die tweede seisoen is die effek van kaolien op nog appelkultivars en 'Rosemarie' pere ge-evalueer. Die appelproewe is in Elgin uitgevoer, terwyl die 'Rosemarie'-proefin die Koue Bokkeveld uitgelê is. Surround™ (95% kaolien) is met kommersiële spuitpompe toegedien. Weereens is die effek van die produk op sonbrand, oesgrootte, vruggrootte, kleurontwikkeling en vrugrypheid bepaal. Sonbrand is nie verminder nie. Vruglading tydens oes is nie betekenisvol beïnvloed nie, behalwe in die geval van 'Royal Gala' waar die vruglading verhoog is, en 'Cripps' Pink' waar daar minder vrugte op die gespuite bome was. Die Surround™ toedienings het geen uitwerking op kleur van appels gehad nie, maar het die chromawaarde van 'Rosemarie' pere verlaag, d.w.s die vrugkleur was minder intens. Die kaolienspuite het 'n uiteenlopende effek op vrugrypheid gehad. Fotosintetiese foton vloeddigtheid (FFV), fotosintesetempo, huidmondjieweerstand en transpirasietempo is gemeet en ligreponskurwes van beide die buitenste en binneste blaardak is bepaal. Die Surround™ toedienings het fotosintese van blare ill die binneste gedeelte van die blaardak verminder en die kwantumdoeltreffendheid van blare op die buitenste deel van die blaardak verminder. Geen betekenisvolle effek is op FFV gekry nie. Dit wil voorkom asof die wit laag kaolien op die bome lig weerkaats en veroorsaak dat minder lig na die blaar deurdring. Dit verminder dan die fotsintesetempo. Met die baie warm weer wat in die Wes-Kaap gedurende die tweede seisoen ervaar is, kon die SUITound™behandelings nie sonbrand verhoed nie. Dit wil voorkom asof Surround™ nie 'n baie doeltreffende oplossing in kommersiële boorde sal wees nie. Alternatiewe oplossings, soos byvoorbeeld evaporatiewe verkoeling, saloorweeg moet word.

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Elmes, D. R. "Creep and viscosity in two kaolin clays." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372627.

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Heß, Viola, and Wolfram Heidenfelder. "Schätze im Geopark: Kaolin – das weiße Gold." Geopark „Porphyrland. Steinreich in Sachsen“ e.V, 2015. https://slub.qucosa.de/id/qucosa%3A36066.

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McKeown, Ian Patrick. "Adsorption of surfactants from solution onto kaolin." Thesis, Liverpool John Moores University, 1990. http://researchonline.ljmu.ac.uk/4988/.

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Aguilar-Mamani, Wilson. "Crystallization of NBA-ZSM-5 from kaolin." Doctoral thesis, Luleå tekniska universitet, Kemiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63169.

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ZSM-5 is an aluminosilicate zeolite with high Si/Al ratio with suitable properties for catalysis, ion exchange, adsorption and membrane applications. The main goal of this thesis was to study the growth of ZSM-5 zeolite crystals from inexpensive natural sources of silica and alumina, as well as n-butylamine (NBA) as a low-cost structure directing agent. The first objective of this work was to develop pathways to synthesize ZSM-5 crystals from kaolin clay or diatomaceous earth, two inexpensive natural sources of silica and alumina (Paper I). In the case of kaolin, a heat treatment was used in order to form amorphous metakaolinite. Subsequently, dealumination of the raw materials by acid leaching made it possible to reach appropriate Si/Al ratios and to reduce the amount of impurities. Finally, leached metakaolinite or diatomaceous earth was reacted with sodium hydroxide and NBA. After synthesis optimization, both sources of aluminosilicates were found to behave differently during the course of synthesis and to lead to slightly different reaction products. The final products exhibited Si/Al ratios in the range 10-20. The use of leached diatomaceous earth allowed to reach higher yield of ZSM-5 crystals within comparable synthesis times. However, low amounts of mordenite were inevitably formed as a by-product, which was related to the high calcium content of diatomaceous earth. Therefore, the rest of the thesis focused on the kaolin system. In order to study the growth mechanism of ZSM-5 from leached metakaolinite, a proper methodology to gain local compositional data by energy dispersive spectroscopy (EDS) on aluminosilicates was developed (Paper II). Zeolite A was used as a model system that could be ion-exchanged with various elements. In order to evaluate the reliability of the measurements, inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) and EDS were compared. The EDS method developed in this work resulted in molar ratios very close to theoretical values and was therefore found more reliable than ICP-SFMS. Therefore, the method developed for zeolite A was applied in the rest of the thesis work to study the formation and growth of ZSM-5 crystals. The second part of this work focused on the kaolin system in order to understand the nucleation and growth processes of the ZSM-5 crystals. This system was heterogeneous, due to the formation of a gel upon heating of the synthesis mixture. First, the internal structure of the gel was investigated (Paper III). Second, a kinetic study was performed and compared with microstructural observations (Paper IV). Finally, the mechanisms leading to Al-zoning and dendritical growth of the zeolite crystals were investigated (Paper V). The characterization of the intermediate phases during the different stages of the hydrothermal synthesis were analyzed by different analytical techniques, such as inductively coupled plasma-sector field mass spectrometry (ICP-SFMS), dynamic light scattering (DLS), extreme high resolution-scanning electron microscopy (XHR-SEM), energy dispersive spectroscopy (EDS), high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) and nitrogen gas adsorption. These investigations led to several important conclusions: 1) The walls of the gel were shown for the first time to be inhomogeneous and to possess a biphasic internal structure consisting of a mesoporous skeleton of aluminosilicate nanoparticles embedded in a silicate-rich soluble matrix of soft matter. 2) The kinetic study and microstructural evidences indicated that the early crystals were fully embedded inside the gel phase and that crystal growth was retarded, as the formation of the gel occurred simultaneously with the early growth of the crystals. Hence, nucleation and growth appeared to be solution mediated. 3) Finally, the Al zoning of the crystals was related to the biphasic internal structure of the gel, since the silicate-rich matrix was preferentially consumed first. 4) The dendrites present at the surface of the crystals during most of the growth process were shown to be caused by the presence of a web of nanoparticles, most likely originating from the mesoporous skeleton inside the gel. In the future, these findings are expected to lead to optimized synthesis pathways of catalysts with homogeneous properties and to contribute to the development of poor regions in Bolivia.

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Benetytė, Kristina. "Leucito susidarymas kaoline ir kristalizacija iš stiklų." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2006. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2006~D_20060613_202043-76292.

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Kali aluminium silikate mineral leucite is a component of odotic porcelain. Porcelain is used in stomatology, producing unnatural teeth and renewing tooth structure. Purpose of this work was to get leucite by crystallizing modified alumosilicate glasses and by synthesizing kaolin in a high temperature. In synthesis of glasses were used these compounds: SiO2, AI2O3, K2CO3, CaCO3, TiO2, ZnO, Li2CO3, Na2CO3. Getting leucite from kaolin, as stock was used: kaolin, Al2(SO4)3, K2SO4. Crystallization of glasses was processed in 900˚C - 1100˚C and the time of exposition was from 2 till 15 hours.

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Palomino, Angelica Maria. "Fabric formation and control in fine-grained materials." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-06072004-131309/unrestricted/palomino%5Fangelica%5Fm%5F200405%5Fphd.pdf.

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Thesis (Ph. D.)--School of Civil and Environmental Engineering, Georgia Institute of Technology, 2004. Directed by J. Carlos Santamarina.
Vita. Includes bibliographical references (leaves 183-192).

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Al-Tabbaa, A. "Permeability and stress-strain response of speswhite kaolin." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382516.

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Iqbal, Zubera. "Recovery of lithium from kaolin mining waste material." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6373/.

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Lithium is considered a borderline strategically important metal for the UK due to the limited availability of primary deposits, of sufficient grade, for economic processing (Naden, 2012). The rising demand, of approximately 10% yearly, has promulgated investigations for the development of secondary sources of lithium in order to secure long term reserves for the UK and Europe (Jaskula, 2015). The British Geological Survey (1987) estimated that the St Austell granite contained up to 3.3 million tonnes of recoverable lithium. Imerys Ltd also identified lithium-bearing mineral in their kaolin waste material in Beauvoir, containing up to 0.89 wt.% Li2O. The lithium-bearing minerals identified were; lepidolite (K(Li,Al)3(Si,Al)4O10(F,OH)2) and zinnwaldite (KLiFeAl(AlSi3)O10(F,OH)2), which can contain between 3.0 to 7.7 wt.% Li2O and 2.0 to 5.0 wt.% Li2O, respectively (Garrett, 2004). Lithium flotation concentrates containing up to 5.0 wt.% Li2O were optimised for the Beauvoir waste material with up to 80% lithium recoveries, whereas a lower flotation grade of 0.5 wt.% Li2O was found for the St Austell material. The St Austell waste materials did not prove viable to process via conventional flotation routes hence a novel process route for the bio-recovery of lithium from lithium rich micas was developed. Extraction of lithium by bioleaching has demonstrated the ability of fungi, of Aspergillus niger group, to leach lithium from the lepidolite in significant quantity, achieving 125mg/L of lithium in solution after twelve weeks of bio-leaching, at a recovery of 45%. Following this research, Imerys are applying to build a pilot plant, securing funding through the Innovative UK grant.

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Kerns, David L., and Glenn C. Wright. "Protective and Yield Enhancement Qualities of Kaolin on Lemons." College of Agriculture, University of Arizona (Tucson, AZ), 2000. http://hdl.handle.net/10150/223852.

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Kaolin (Surround) was highly effective at preventing citrus thrips populations from reaching damaging levels in Arizona lemons. Applications should be initiated before thrips become numerous. Applying the material before petal fall may offer protection of early set fruit, but may not be necessary if thrips densities are low. However, since kaolin should be applied in advance of thrips populations increase, determining the benefits of pre-petal fall applications of kaolin is difficult. Kaolin applied on a maintenance schedule offers continual suppression of thrips populations, whereas traditional standard insecticides offer temporary population knockdown. Kaolin did not interfere with photosynthesis or stomatal conductance, and may possess yield enhancement qualities.

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Hamidon, AbuBakar. "Some laboratory studies of anisotropy of permeability of kaolin." Thesis, University of Glasgow, 1994. http://theses.gla.ac.uk/6338/.

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This thesis is concerned with an investigation into some aspects of the permeability measurement and permeability characteristics of reconstituted saturated supreme kaolin clay. Development of permeability anisotropy is investigated when the sample has experienced: (1) anisotropic consolidation, and (2) undrained shear. Conventional step-loaded consolidation tests, constant flow rate and some constant head permeability tests were conducted on the kaolin slurry and block samples. For every conduct of testing, a pair of identical samples were tested: one underwent vertical drainage and the other radial drainage conditions. Both, however, were subjected to one dimensional deformation in the vertical direction. Permeability of the clay was evaluated both directly and indirectly, from results of the permeability tests and consolidation tests, respectively. Data from the constant flow rate and constant head permeability tests yield the same values of permeability for both cases of vertical or radial flow (kv not necessarily equal to Kh). Theoretical considerations of the transient phase of the experimental record of the constant flow rate permeability test are found to be applicable to form the basis of evaluation of permeability, coefficient of consolidation, and coefficient of volume compressibility of the clay sample. Experimental results showed that during the progress of anisotropic consolidation of the kaolin slurry, the clay's vertical and horizontal permeability exhibited unique relationships with the void ratio which are linear on the logarithmic-linear scale [linear (lg k vs e) plot ]. These relationships were found to be independent of the overconsolidation ratio. A lack of permeability anisotropy was observed in the early part of compression or at the initial void ratio, e = 3.1, but as the compression proceeds, development of permeability anisotropy was observed to reach a value of up to 2.1 which correspond to a void ratio of 1.30, where the corresponding vertical effective stress was 530kPa. Experimental results for the block samples that had experienced undrained shear also showed the unique relationships of the clay's vertical and horizontal permeability with void ratio. Development of permeability anisotropy, however, was somewhat in opposition with that of the slurry sample observed during anisotropic consolidation. For samples sheared to vertical strains of 7.9 to 11.5%, an initial permeability anisotropy of 1.3 at a void ratio of 1.66 was observed to decrease with compression and developed into isotropic condition at a void ratio of 1.50, where the corresponding vertical effective stress was 120kPa. For samples sheared to vertical strains of 2.0 to 5.0%, an initial permeability anisotropy of 2.5 at a void ratio of 1.30 was observed to decrease very little with compression and the degree of anisotropy remained to a value xiv of 2.3 at a void ratio 1.05, where the corresponding vertical effective stress was 480kPa. Solutions from both the Terzaghi's and Biot's consolidation theories were used to evaluate the experimental data of the axisymmetric problem of consolidation with radial drainage to inner and outer fixed boundaries. Compared with measured values, permeabilities of the samples calculated from both the Terzaghi's and the Biot's solutions and using the Taylor'S square root of time method, are underestimated by a factor of 10 to 100 (ie. kcal/km = 1110 to 11100). Furthermore, the calculated permeabilities are less orderly in the l9.k vs e plot while the variation is more ordered and linear for the measured values.

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Jüttner, Thomas [Verfasser]. "Keramikschäume auf Basis von Kaolin und Aluminiumoxid / Thomas Jüttner." München : Verlag Dr. Hut, 2017. http://d-nb.info/1147674531/34.

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Austin, James Clifton. "Ultrasonic compression wave propagation in flocculating aqueous kaolin suspensions." Thesis, Keele University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337001.

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Furling, Olivier. "Procédés d'élaboration et rhéologie des suspensions concentrées de kaolin." Vandoeuvre-les-Nancy, INPL, 2002. http://www.theses.fr/2002INPL071N.

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Le procédé de dispersion de pigment dans une phase aqueuse est une opération commune dans l'industrie. Aucune étude n'est disponible dans la littérature pour des volumes se rapprochant d'une échelle semi-industrielle pour la réalisation de suspensions concentrées. Le présent travail compare différents procédés d'élaboration de suspensions concentrées de kaolin. La préparation s'effectue dans un premier temps en mode batch avec trois types de turbine: une turbine Cowles et deux turbines spécifiques, respectivement la turbine Défloculeuse et la turbine Sevin de la compagnie VMI-Rayneri. L'influence du débit d'incorporation de poudre sur la consommation énergétique, le temps de dispersion et la finesse de dispersion sont évalués en fonction du type de kaolin utilisé. La mesure de la qualité de la dispersion s'effectue par le suivi du couple consommé par la turbine et par des mesures rhéologiques off-line. Dans une deuxième temps, des mélangeurs statiques Sulzer de type SMX sont employés en mode semi-continu et en ligne afin de démontrer leurs capacités de dispersion solide- liquide pour la réalisation de suspensions concentrées de kaolin. Le nombre de mélangeurs statiques pour une réalisation en ligne varie de 12 à 24 selon les conditions opératoires. L'énergie totale est moindre par rapport à une préparation en batch pour une même qualité de suspension. D'autre part, l'utilisation d'une géométrie de procédé spéciale accouplé à un rhéomètre a permis le suivi en ligne de la viscosité de la suspension lors de l'incorporation des pigments pour une préparation à l'échelle laboratoire. L'évolution du couple de la turbine et de la viscosité de la suspension sont évaluées en fonction du débit d'incorporation de la poudre, la vitesse de rotation de la turbine et du type de kaolin utilisé. Le comportement rhéologique des suspensions concentrées de kaolin a été modélisé de façon satisfaisante avec un modèle de Quémada.

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Tremblay, Michel. "Étude de l'hétérogénéite du gisement de kaolin de Château-Richer et de son incidence sur les propriétés des mousses d'argile /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1986. http://theses.uqac.ca.

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Kaloga, Bokar. "Le manteau kaolinique des plaines du centre-Sud de la Haute-Volta : dynamique et relation avec le manteau smectitique /." Paris : Ed. de l'ORSTOM, 1987. http://catalogue.bnf.fr/ark:/12148/cb349545910.

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22

Alali, Jamal. "Evaluation and beneficiation of silica sand and kaolinitic sandstone in south of Jordan." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394750.

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Silica sand (SS) samples from the Hanout area of Late Cambrian-Early Ordovician sandstone and the kaolinitic sandstone (KS) samples from the Wadi Es Siq-Rakyia area of Lower Cretaceous in south of Jordan were studied and assessed as a source of glass sand. A detailed mineralogical, geochemical, and grain size distribution analysis was carried out using XRD, XRF, SEM, and binocular microscopy. Heavy mineral separation was conducted using heavy liquids and spirals. Attrition scrubbing trials were performed on various size fractions to assess the benefit of attrition scrubbing in upgrading the silica sand. Upgrading the silica sand included removing or reducing the content of the contaminant oxides (i.e., Al2O3, Fe2O3, TiO2, CaO, and MgO) and the heavy minerals. The aim of this project was to achieve this upgrading through the use of inexpensive and relatively simple processing techniques. Kaolin was also concentrated in the fine fraction after attrition scrubbing and wet screening of the kaolinitic sandstone sample. Following the initial sample characterisation at “bench scale”, a pilot plant study was performed on bulk samples of both the silica sand and the kaolinitic sandstone. A high-grade glass sand product of 500-125μm size fraction was produced from both samples by dry and wet screening, attrition scrubbing and the separation of heavy minerals using spirals. Due to the relatively low level of impurities in the raw material, a high silica sand recovery was produced with a high silica grade when the middling fraction was combined with that of the product fraction. The mass flowrate of the feeds and the products in the spiral was calculated for both SS and KS samples as well as in the hydrocyclones for the – 125μm fraction of the KS sample. The amount of water required to operate the pilot plant was calculated. The high quality glass sand produced compared well with the Grade A British Standard for glass sand. The silica sand product was clearly capable of being used in the high quality glass industry and in many other applications where pure silica is required. A kaolin-enriched product was produced from the –125μm wet screened fraction of the kaolinitic sandstone following the use of small diameter hydrocyclones. A moderate quality of kaolin with low recovery was produced from the KS sample, which could be used in the ceramic industry for tableware and sanitaryware.

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Bartošík, Jan. "Zvyšování bělosti kaolinu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-316237.

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The thesis deals with the issue of increasing the whiteness index of kaolin raw material. The research was focused on floating the kaolin suspension and the subsequent processes related to increasing the whiteness index. Increasing the whiteness of the kaolin raw material took place on the basis of acid leaching. The eluents were based on sulfuric acid, phosphoric acid, oxalic acid and sodium bisulfite. The leaching process was influenced by the temperature and concentration of the leaching agent. Floated and leached kaolin samples were characterized by several methods. The XRD method investigated the mineralogical composition and the kaolinite structure order. The distribution of chromogenic components was monitored by SEM-EDS. Residues of organic matter was determined by COD test and the concentration of chromogenic components in the extract was monitored by the ICP-OES method. Last but not least, the index of whiteness was measured, the increase of which is the aim of the diploma thesis, using a UV-VIS spectrometer with reflective extension.

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Zhang, Yan. "Dispersions of kaolin particles in non-aqueous solvents and polymers." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492510.

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The stability of particles plays an essential role in manipulating the properties of their suspensions. Alkyl silanes and amines were applied to modify the kaolin surface in order to render the particles hydrophobic and dispersible in non-polar solvents. A Hammett indicator shows the surface of kaolin has strong acidic groups and the silanes, such as isobutyltrimethoxysilane (IBTMS), did not neutralise them, whereas the amines, such as hydrogenated tallow (HT) and a polyisobutyl chain based stabiliser (SAP), reacted with them.

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Gregory, Peter. "Analysis of sedimenting Kaolin suspensions by miniaturised Electrical Resistance Tomography." Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302456.

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Kovo, Abdulsalami Sanni. "Development of zeolites and zeolite membranes from Ahoko Nigerian kaolin." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/development-of-zeolites-and-zeolite-membranes-from-ahoko-nigerian-kaolin(3496e1fa-ece8-4781-be3f-a27a103f4c4a).html.

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Zeolites and zeolite membranes are two important advanced chemical materials which are widely used in chemical processes. The manufacture of these materials usually involves the use of expensive chemicals. This study involves the use of Ahoko Nigerian kaolin (ANK) as precursor material for the development of zeolites and zeolite membranes. The synthesis of zeolite A, Y and ZSM-5 was successfully obtained following a sequence, collection of the raw clay from Nigeria, metakaolinization, dealumination and actual hydrothermal synthesis of the zeolites. Raw ANK was refined using sedimentation technique and about 97% kaolin was recovered from the raw sample. A novel metakaolinization technique was developed to convert kaolin into a reactive metastable phase. Amorphous metakaolin was obtained at a temperature of 600°C and exposure time of 10 min. This is a significant result because previous studies use higher temperatures and longer exposure times for the metakaolinization step. The metakaolin was used to prepare a number of different zeolites under various conditions. Highly crystalline zeolite A was obtained at an ageing time of 12 h, crystallization time of 6 h and crystallization temperature of 100oC. Zeolite Y was obtained at an ageing time of 3 h, crystallization time of 9 h and crystallization temperature of 100oC. Zeolite Y was also synthesised by using a dealuminated kaolin and highly crystallized zeolite Y with Si/Al ratio of 1.56 and BET surface area was obtained of 630 m2/g. ZSM-5 was synthesised using an ageing period of 36 h, crystallization time of 48 h and temperature of 140oC. The results obtained from zeolite powder synthesis from ANK were then used as guide to prepare supported zeolite films and membranes by a hydrothermal method. The effect of the support surface (stainless steel) was investigated using two synthesis methods namely modified in-situ and secondary (seeded) growth. Zeolite A, Y and ZSM-5 films were successfully prepared from ANK for the first time and on two modified supports, etched and oxidised. The zeolite films and membranes developed showed complete coverage on the two supports with the oxidised showing better adhesion and intergrowth. The separation performance of the three developed zeolite membrane was tested by pervaporation of water/ethanol mixture. The results of pervaporation of ethanol/water mixture showed that zeolite A membrane is highly selective towards water mainly because of hydrophilic properties occasioned by the high aluminium content. Zeolite Y membrane show a similar response when their separation performance was evaluated but with less selectivity because of reduced aluminium content. ZSM-5 showed selectivity towards ethanol because of it hydrophobicity allowing only ethanol to permeate. In all the zeolite membranes, the flux is lower in comparison to commercial zeolite membranes due mainly to the thickness of the zeolite layer. Oxidised support membranes showed better performance because of their better interaction between the oxide surface and the aluminosilicate gel. The results show that ANK can successfully be used to prepare zeolites and zeolite membrane.

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27

Bombrowski, Martin. "Viskoelastisches Verhalten und Struktur konzentrierter Kaolinsuspensionen mit negativer Normalspannung." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-201880.

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In Abhängigkeit von der Suspensionszusammensetzung und der jeweiligen Scherrate können konzentrierte Kaolinsuspensionen ungewöhnliche rheologische Phänomene wie Oszillationen der scheinbaren Viskosität oder eine negative 1.~Normalspannungsdifferenz zeigen. In dieser Arbeit wurde die Abhängigkeit der 1.~Normalspannungsdifferenz, des Speicher- und des Verlustmoduls im linear-viskoelastischen Bereich sowie der Fließgrenze von der Oberflächenbeladung des Kaolins, von der Kaolinfeststoffkonzentration, vom pH-Wert und von der Ionenstärke untersucht. Weiterhin wurde eine Methode entwickelt, die die Fixierung der scherinduzierten Mikrostruktur der Suspensionen und deren anschließende Charakterisierung mittels Röntgenbeugung gestattet. Außerdem wurde ein rheologisches Modell abgeleitet, das den Zusammenhang zwischen den Aussagen zur scherinduzierten Mikrostruktur und dem Auftreten negativer 1.~Normalspannungsdifferenzen herstellt.

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Yu, Chun Ying. "Structure effects on the mechanical responses of kaolinite and pore-size evolution at different states /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202007%20YU.

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Siu, Wai Kwan. "Effects of soil structure on the mechanical properties of kaolinite clay /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20SIU.

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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.
Includes bibliographical references (leaves 154-164). Also available in electronic version. Access restricted to campus users.

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30

ORTIZ, NILCE. "Determinacao de ferro estrutural e na forma de compostos em caulins." reponame:Repositório Institucional do IPEN, 1993. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10346.

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Made available in DSpace on 2014-10-09T12:37:37Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:03:18Z (GMT). No. of bitstreams: 1 05334.pdf: 3065832 bytes, checksum: b253ceacd6573f2f6568c4ff97566548 (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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31

Martin-Calle, Serge. "Pouzzolanicite d'argiles thermiquement activées : influence de la minéralogie et des conditions de calcination." Lyon, INSA, 1989. http://www.theses.fr/1989ISAL0077.

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La chaux d'hydratation des ciments est incompatible avec une bonne durabilité des bétons et composites du Génie Civil. Un moyen d'éliminer cet inconvénient réside dans les propriétés pouzzolaniques de certaines argiles calcinées, notamment les métakaolins. Ce travail fait le point sur l'influence de la nature du kaolin de départ et de son mode de calcination sur l'activité pouzzolanique obtenue, au moyen de différentes techniques de caractérisation (Diffraction X, analyses thermiques, analyse chimique, spectrométrie infra-rouge, granulométrie, porosimétrie, etc. . ) Des liants ciment-argile kaolinique calcinée variés sont étudiés. Il apparaît qu'il faut distinguer une réactivité pouzzolanique à court terme (3-7 jours) sensible à l'état de surface de la pouzzolane et une réactivité à moyen terme à relier préférentiellement au degré d'amorphisation et à la proportion de minéraux inertes. Un kaolin désordonné pur contenant du fer apparaît comme un bon compromis;cependant des argiles kaoliniques modérément actives parviennent à des résultats · intéressants sous certaines formulations. L'étude des liants ciment-métakaolin montre qu'outre la consommation de la chaux, l'incorporation de métakaolin dans les ciments permet une meilleure hydratation des anhydres du ciment et provoque l'apparition d'une porosité fermée favorable à la durabilité de ces matrices cimentaire
Cement hydratation lime is incompatible with a good durability of concrete and composites. Pozzolantic properties of some calcined clays, particularly metakoalin, allows to avoid this drawback. This work deals with the influence of the kind of raw several characterisation technics (x-ray diffraction, thermic analysis, chemical analysis, infra-red spectroscopy, granulometry, porositemtry, etc. ). Various calcined kaolinic clays-cement binders are investigated. It is possible ti distinguish a short time pozzolinic activity (3-7 days) which is influenced by the surface state of pozzolana and a mid-time activity wich is preferentially linked to the amorphization degree and the inert minerals proportion. A disordered pure kaolin enclosing a significant amount of iron appears to be a good compromise meanwhile kaolinic clays with moderate pozzolanic activity reach some interesting results in fitted proportions. The study of cement-metakaolin binders show that, beyond-lime consumption, metakaloin incorporation in cements leads to a better hydration of cement anhydrous components and also induces a close porosity appearance witch emphasizes the durability of these cement pastes

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Mihoubi, Daoued. "Deshydratation d'argile par compression et séchage. : Aspects de modélisation et de simulation." Pau, 2004. http://www.theses.fr/2004PAUU3016.

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Ce travail s'inscrit dans un contexte général qui concerne les procédés de Séparation Liquide Solide (SLS) et plus particulièrement : la filtration/compression et le séchage. L'objectif de ce travail est de modéliser ces deux procédés en tenant compte du comportement mécanique du produit étudié. Dans la première partie du travail, une caractérisation expérimentale des argiles utilisées (kaolin et bentonite), en rapport avec le séchage, est présentée. Dans un deuxième temps, un modèle thermo-hydro-mécanique général est développé. Le modèle est ensuite testé dans deux situations différentes : unidirectionnelle et bidirectionnelle. La deuxième partie de l'étude est consacrée à l'étude et la modélisation des procédés de filtration/compression. Le modèle développé dans ce travail décrit uniquement la phase de compression, et tente, comme précédemment, de fournir un modèle hydromécanique. Des simulations issues de la résolution numérique du modèle, permettent en partie de valider la démarche entreprise
This work falls under a general context which is related to the processes of Solid Liquid Separation (SLS) and more particularly to filtration/compression and drying. The objective of this work is to propose a model of these two processes by taking in account the mechanical behaviour of the studied product. In the first part of work, an experimental characterization of used clays (kaolin and bentonite), in relation with drying, is presented. Then, a thermo-hydro-mechanical general model is developed. The model is then tested in two different cases: one dimension and two dimensions. The second part of the investigation is devoted to the study and the modelling of filtration/compression processes. The model developed in this work describes only the phase of compression, and attempts, as previously, to propose a hydro-mechanical model. Simulations resulting from the numerical resolution of the model partly allow to validate the undertaken approach

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Li, Ying. "Investigation of aqueous kaolin suspensions : a rheological and sedimentation volume study." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ64069.pdf.

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34

Torshage, Erik. "Reduktion av stoftutsläpp från närvärmepanna genom tillsats av kaolin som bränsleadditiv." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-105981.

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Hörnefors är en tätort belägen strax söder om Umeå. Orten har ett fjärrvärmenät som ägs och drivs av Umeå Energi AB där två pelletseldade pannor står för den huvudsakliga produktionen. Det finns en risk att fjärrvärmeproduktionen i Hörnefors blir satt under hårdare utsläppskrav genom ett nytt direktiv som eventuellt kommer att införlivas under 2015. Direktivet kommer troligen att sätta ett gränsvärde för stoftutsläpp på 45 mg/Nm3 vid 6% O2 från och med år 2030 vilket är så lågt att pannorna Hörnefors inte kommer klara av det. I detta arbete har därför metoden att minska stoftutsläpp genom additivtillsats undersökts. Det bestämdes att proveldningar skulle utföras med kaolin som tillsatsmedel. Kaolin är ett lermineral som fångar upp kalium vilket är ett problematiskt ämne när det kommer till stoftutsläpp. Testerna utfördes genom att blanda in kaolin i pelletsströmmen på väg in i pannan, stoftutsläpp och storleksfördelning på stoftet mättes i utgående rökgaskanal innan skorstenen. Driftfallen vid testerna delades in i hög och låg last samt 0.3 eller 1 vikt-% inblandning av kaolin. I tillägg till detta så gjordes referenstester utan inblandning av kaolin också vid hög och låg last. Resultatet av proveldningarna på låg last visar att en signifikant reduktion av stoftutsläpp erhölls redan vid 0.3 vikt-% kaolin och att utsläppet minskade ytterligare vid 1 vikt-% kaolin. Detta gjorde att pannan med god marginal skulle klara sig under den föreslagna gränsen med endast 0.3 vikt-% kaolin inblandat. Vid hög last gav proveldningarna inte ett signifikant resultat och det gick därmed inte att se någon skillnad mellan proverna med och utan kaolininblandning. Pannan skulle därmed inte klara den föreslagna gränsen på 45 mg/Nm3. Anledningen till detta är troligen för hög hastighet på gasflödet genom bädden vilket orsakat medryckning av partiklar. Slutsaten av arbetet är att stoftreduktion genom tillsats av kaolin fungerar bra vid låg last men ger ingen skillnad vid hög last. Kaolintillsats skulle vara det absolut bästa alternativet för stoftreduktion om det skulle fungera vid även vid hög last på grund av det relativt låga priset. Önskas en snabb lösning rekommenderas spärrfilter eftersom det ger ett garanterat stoftutsläpp under gränsvärdet. Beräkningarna på ekonomi för de olika reningsmetoderna utvärderades också med nuvärdes- metoden och en kalkylränta på 8%. Ekonomiberäkningarna visade att det billigaste alternativet är kaolintillsats, därefter kommer spärrfilter och dyrast är elfilter. Metoden med additivtillsats i den berörda anläggningen kan troligen förbättras avsevärt. Som ett steg rekommenderas att undersöka möjligheterna att bygga om bränslematningen så att bränslet inte sönderdelas innan det når pannan. Nya tester bör också genomföras med ändrad lufttillförsel där mindre primärluft tidigt på rosten skulle vara önskvärt.

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CUNHA, FABIOLA OLIVEIRA DA. "STUDY OF PRADO REGION KAOLIN PULP RHEOLOGY FOR THE PAPER INDUSTRY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5926@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CENTRO DE TECNOLOGIA MINERAL
Polpas concentradas de caulim (70 por cento em peso de sólidos) são utilizadas na Indústria de Papel como cobertura. Durante a aplicação da polpa são alcançadas altas taxas de cisalhamento que, associadas às altas viscosidades de polpas concentradas, provocam dificuldades no movimento da lâmina acarretando riscos, bolhas ou até mesmo rasgando o papel. Para minimizar esse efeito, são adicionados agentes dispersantes que causam a redução nos valores da viscosidade. O presente trabalho teve por finalidade caracterizar fisicamente as amostras beneficiadas do caulim da região do Prado/BA e, utilizando-se da Teoria DLVO Clássica, contribuir para uma melhor compreensão sobre os aspectos fundamentais que norteiam a reologia de polpas concentradas de caulim a partir dos fundamentos de química coloidal. A caracterização tecnológica das amostras foi efetuada pelas técnicas de difratometria de raios-X, medição de alvura, análise granulométrica e análise morfológica (MEV e MET). As amostras analisadas revelaram ser, predominantemente, de caulinita; de alvura adequada a Indústria Papeleira para as amostras Coat 90 e Coat 87; de distribuição bimodal para as amostras Coat 90 e Coat 87 e de formato lamelar de perfil irregular, tendo sido encontradas partículas de perfil hexagonal. Posteriormente, foram apreciadas as propriedades eletrocinéticas das amostras. Foi medido o potencial zeta das amostras na ausência e na presença do dispersante hexametafosfato de sódio em função do pH e da concentração do dispersante em força iônica constante. A análise dos resultados revelou: que as amostras Coat 90 e Coat 87 possuem ponto isoelétrico de 3,5, enquanto o caulim Extra Fino possui ponto isoelétrico de 3,2; que o potencial zeta assume valores mais negativos com o aumento do pH e com o aumento da concentração de dispersante e que o ânion proveniente da dissociação do hexametafosfato de sódio adsorve quimicamente à superfície das amostras. De posse dos dados de potencial zeta, utilizou-se a Teoria DLVO para calcular a energia de interação total existente entre as partículas da amostra de caulim Coat 90. Após a análise dos resultados, ficou evidente que, para valores de pH maiores ou iguais a 5, existe uma barreira energética que aumenta de intensidade com o aumento do pH e da concentração de dispersante onde, com o aumento do pH, houve uma tendência à estabilização e, no caso da concentração, foi obtido um valor máximo em 3kg/t de dispersante (após este valor não houve aumento da barreira energética). Nessas curvas também foi observada a existência de um mínimo secundário que, embora pequeno (~2kT), revelou a possibilidade de adesão reversível. A análise reológica da amostra de caulim Coat 90 foi realizada a partir da comparação das viscosidades aparentes encontradas para taxas de cisalhamento constantes (100s-1 ou 1000s-1) e após a mesma quantidade de tempo (280s) já que as polpas eram tixotrópicas. Esses dados revelaram que, com o aumento do pH, as polpas atingem valores mínimos de viscosidade, onde para cada concentração de dispersante foi atingido um patamar diferente. O menor valor de viscosidade foi obtido em 3kg/t de dispersante, onde a partir desse ponto a viscosidade passou a aumentar levemente. Finalmente, os dados reológicos foram confrontados com os calculados pela Teoria DLVO Clássica, onde foi revelada a existência de um valor de energia de interação total (~400kT) comum a todas as concentrações de dispersante que indica um grau máximo de estabilidade da polpa, isto é, as partículas encontram-se tão afastadas umas das outras que o movimento relativo entre elas durante o cisalhamento não é mais afetado. Concluiu-se que, apesar das interações interparticulares serem de natureza microscópica e a viscosidade uma medida macroscópica, a Teoria DLVO foi capaz de explicar qualitativamente o compor
Concentrated kaolin pulps (70 percent solid weight) are utilized as coatings in the paper industry. During the pulp application, high shear rates are obtained. Shear rates associated to high viscosities incite difficulties on the lamina movement generating risks, bubbles or even tearing the paper. To minimize this effect dispersant agents are added. The aim of the present work was to characterize physically the Prado region (Bahia State) kaolin particles and, using the DLVO theory, contribute for a better understanding about the fundamental aspects of kaolin concentrated pulps rheology via colloidal chemistry. Sample technological characterization was carried out with X-Ray difractometry technique, brightness measurements, size measurements, particle distribution and morphological analysis (MEV and MET). Samples were, predominantly, of kaolinite; samples Coat 90 and Coat 87 were of adequate brightness for Paper Industry and presented two peaks and all samples were platelike with irregular edges where hexagonal particles were found. Sample electrokinetic properties were appreciated afterwards. Zeta potential measurements were taken in the absence and in the presence of sodium hexametaphosphate dispersing agent as a function of pH and dispersant concentration using constant ionic strength. Result analysis revealed: Coat 90 and Coat 87 samples had 3,5 of isoelectric point, while Extra Fino sample had 3,2 of isoelectric point; zeta potential values became more negative with pH and dispersant concentration rising and the anion of sodium hexametaphosphate dissolution chemically adsorbs to sample surfaces. Zeta potential values were used to obtain total interparticular interaction energy by means of DLVO theory. These procedures were done only for Coat 90 sample. It became clear that, for pH values equals or higher than 5, exists an energy barrier whose values rise as pH and dispersant concentration increases. It has been noted that for pH increase, the tendency of energy barrier was to stabilize. In the case of dispersant concentration increase, was obtained maximum value (3kg/t). By data observation, a secondary minimum was noted. However the secondary minimum is low (~2kT), it revealed the possibility of reversible adhesion. The rheological analysis of Coat 90 kaolin sample was realized by comparison of apparent viscosities found on constant shear rates (100s-1 and 1000s- 1) and after the same time (280s) because pulps were thixotropic. The investigation showed that with pH increase, pulps had their viscosity reduced. Each dispersant concentration value generates a different viscosity, where the smallest viscosities were achieved in 3kg/t. Within the increase of dispersant concentration, viscosity had its values improved. Finally, rheological data were coordinated with those calculated from DLVO theory. It was observed that there is a total interaction energy value (~400kT) common to all dispersant concentrations. This point means that pulp stability is maximum, in other words, particles are so far from each other that relative movement among them is not affected anymore. The conclusion of this work is that, however interparticular forces are of microscopic nature and viscosity is a macroscopic measure, DLVO theory was able to explain qualitatively the rheological behavior of kaolin concentrated pulps.

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36

Ileme, Ogechi Chinonye Mary. "Experimental study on thermo-hydro-mechanical behaviour of compacted kaolin clay." Thesis, Heriot-Watt University, 2017. http://hdl.handle.net/10399/3332.

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Several engineering problems are associated with unsaturated soils that are subjected to high temperature due to the environments where they are located or activities around them. Typical examples include upper layers of soils in tropical regions, soils around geothermal structures, landfill liners and clay barriers around nuclear waste repository systems. Previous researchers have reported that variations in stress, suction and temperature affect the mechanical behaviour of unsaturated soils. Notwithstanding already existing studies, the influence of temperature on some unsaturated soils is still a challenge relative to saturated soils, as the results from these existing studies are soil specific and cannot be inferred as the behaviour of all unsaturated soils. A sound understanding of the behaviour of unsaturated kaolin clay without a hydraulic history under temperature and suction variation is still required. The main objective of this study was to investigate the influence of temperature variations on the volumetric and water retention behaviours of statically compacted kaolin clay. Statically compacted samples at a dry side of optimum were tested at different temperatures, using standard and suction controlled oedometer cells, to investigate the influence of temperature on volumetric behaviours. The tests were carried out considering various stress paths. Additionally, pressure plate and vapour equilibrium tests were carried out following a drying path at two temperatures and void ratios to investigate the influence of temperature and densities on the water retention of statically compacted kaolin clay. Complimentary tests were carried out to investigate the effect of temperature variation on overall volume and suction, through the filter paper method. Either collapse or expansion occurred on wetting, depending on the density of the sample. Compressibility was found to increase with an increase in temperature. For tests at constant suction, increase in temperature was found to increase compressibility at low suction, but compressibility was unaffected by temperature at high suction. The results when presented in the light of LC model, indicated a shift of the LC curve to the left at high temperature. The study demonstrated that temperature variation alone was sufficient to vary suction and volume. Features captured on other soils were also identified; for example, yield stress was found to increase with suction. Water retention was observed to decrease with an increase in temperature and increase with void ratio (along the capillary fringe). Good fits were observed, when pertinent soil water retention models were fitted to the obtained water retention data. The study noted that the hydro-mechanical behaviour of a sample prepared at the wet of optimum water content is significantly different from dry of optimum sample and this should be considered when predicting soil behaviour. The study also demonstrated that increase in temperature will affect samples without hydraulic history differently. Further work is still required on an extended range of temperature and suction.

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37

Illes, Jane. "Organic complexes of unrefined and milled kaolin : an infrared spectroscopic study." Thesis, Sheffield Hallam University, 2000. http://shura.shu.ac.uk/19856/.

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Aim: to characterise the surface sites present on unrefined and ball milled Cornish kaolin, with a view to ultimately determining the mode of interaction between the mineral and industrially significant organic molecules. Milling and temperature were found to affect the structure of kaolin and types of surface sites present. These changes were monitored primarily by variable temperature diffuse reflectance infrared Fourier transform spectroscopy (VT DRIFTS) and other complementary techniques including XRD and TGA. Curve fitting of the VT DRIFT spectra was used to aid characterisation of the types of water present on the mineral surface. The diagnostic probe molecule pyridine was used to identify the changes in reactive acid sites present as temperature increased both before and after milling, and oleic acid was used as a representative adsorbate to analyse the effects of carboxylic acid treatment. As ball milling time increased, so did the kaolin agglomerate size and the amount of surface sorbed water. The types of water present on the surface of unrefined and ball milled Cornish kaolin have been characterised, and grouped into four main types -strongly hydrogen bonded, moderately strongly hydrogen bonded, weakly hydrogen bonded and very weakly hydrogen bonded. The different water environments were observed using DRIFTS in the bending and stretching regions of the spectrum. Changes in the stretching region were generally less distinct, since the bands were broader than in the bending region. However, changes in both regions were elucidated by curve fitting of the VT DRIFT spectra, and certain bands appeared to have similar thermal behaviour. Freshly milled samples had a greater proportion of strongly hydrogen bonded water compared with the other, more weakly bonded types. Aged samples had less total surface sorbed water, and relatively less strongly hydrogen bonded water compared with the more weakly bonded species. Pyridine displaced the more strongly hydrogen bonded water (an effect similar to ageing). A dehydrated halloysite impurity was found which intercalated pyridine. VT XRD showed that deintercalation occurred at c 100 °C. The hydrogen bonding nature of the halloysite-pyridine interactions became less pronounced as milling increased. Pyridine adsorption to kaolin was via Bronsted sites in the unmilled kaolin. As milling time increased the mineral surface took on Lewis acid character and less hydrogen bonding occurred. Bronsted associations were present in all the milled (and unmilled) samples and became more significant as milling time increased (as more surface water was present). In addition to the intercalation reaction between halloysite and pyridine, this probe molecule is likely to bind to exposed (broken) edge sites on kaolin and/or halloysite, or to sorb between the slightly expanded mineral layers at the edges of the mineral stacks. Oleic acid adsorption onto kaolin at pH 3, was via surface adsorption of monodentate. Acid precipitate was loosely associated with the surface via hydrocarbon chain interactions with the adsorbed salt. At pH 9, total surface adsorption was low. Adsorbed species were monodentate in character. Mono- and dioleate were present as loosely bound surface precipitates. At pH 12 the salt was associated with the surface in the bridged bidentate form. Adsorption was high due to hydrocarbon chain associations with micelles, containing some trapped acid species. The precipitate at pH 12 was strongly held, and there was no significant reduction in intensity after washing.

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38

Schwerdtner, Günter, Heidrun Anger, and Manfred Störr. "Die Kaolinlagerstätten des Kemmlitzer Reviers." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-78905.

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Das Kemmlitzer Kaolinrevier liegt ca. 60 km nordwestlich der sächsischen Hauptstadt Dresden zwischen den Flüssen Elbe und Mulde. Die bisher bergbaulich genutzten Lagerstätten sind durch tiefgründige Verwitterung im Zeitraum Oberkreide bis Miozän aus verschiedenen permischen Vulkaniten, vorwiegend quarzreichen Porphyren, hervorgegangen. Die Kaoline enthalten neben verwitterungsresistentem Quarz an Tonmineralen vor allem Kaolinit und in wechselnden Anteilen Illit-Montmorillonit-Mixed-Layer-Minerale. Die Mächtigkeit der Verwitterungskruste beträgt 10 bis 40 m, gelegentlich auch mehr. Haupteinflüsse auf den Erhaltungsgrad haben eine junge Bruchtektonik und pleistozäne Erosionsvorgänge. Die Deckschichten der Kaoline werden überwiegend von verschiedenen pleistozänen und untergeordnet tertiären Sedimenten gebildet. Die Kaoline um Kemmlitz wurden Anfang des 19. Jahrhunderts entdeckt und seit 1883 intensiv bergbaulich genutzt. Der Abbau der Lagerstätten erfolgte zunächst im Tiefbau, verstärkt ab 1953 und gegenwärtig ausschließlich im Tagebaubetrieb. Durch nassmechanische Aufbereitung der Rohkaoline wird in mehreren Klassierstufen der Quarz weitestgehend abgetrennt und der Wertstoff Tonmineral angereichert. Die Schlämmkaoline finden aufgrund äußerst geringer Schadstoffgehalte (Fe, Ti) und günstiger Verarbeitungseigenschaften vor allem bei der Herstellung von Geschirr- und Elektroporzellan, Sanitärkeramik und Fliesen Verwendung. Im Kemmlitzer Revier wurden bis Ende 2004 ca. 31 Mio. t Kaolin abgebaut, die Vorratsbasis der nächsten 50 Jahre ist gesichert und weitere Ressourcen sind bekannt.

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39

Kirabira, John Baptist. "Characterisation of Ugandan raw-minerals for firebricks -before and after sintering." Licentiate thesis, KTH, Materials Science and Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1704.

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Development of products which can be produced from acountry's natural resources is very important as far as theindustrialization of a nation and saving foreign exchange isconcerned. Presently, industries in Uganda and the other statesin the Lake Victoria region import allrefractory-related-consumables, as the demand cannot be metlocally. Based on the abundance of ceramic raw materials forhigh temperature applications in the region and the demand forrefractories by industries it is pertinent to develop andmanufacture firebricks by exploiting the locally available rawmaterials.

This thesis thus, concerns the characterisation of ceramicraw mineral powders from in the Lake Victoria region, moreparticularly, Uganda, with the aim of developing firebrickrefractories from the minerals. Two main deposits of kaolin anda fireclay deposit, located in the Lake Victoria Region,Uganda, were investigated to assess their potential in themanufacture of refractory bricks. Raw- and processed samplepowders were investigated by means of x-ray diffraction (XRD),thermal analysis (DTA-TG) and Scanning Electron Microscopy(SEM). In addition, the chemical composition, particle sizedistribution, density, and surface area of the powders weredetermined.

A general production process scheme for manufacture offirebricks starting with raw powder minerals (Mutaka kaolin andMukono ball clay) was used to make six groups of samplefirebrick. Experimental results from the characterization offormulated sample bricks indeed reveal the viability ofmanufacturing firebricks from the raw minerals.Characterization of the sample bricks has been done fordetermination of physical and mechanical properties; density,shrinkage, porosity, water absorption, and phaseidentification. Formation of mullite, which is a principalcompound for aluminous refractories, is evidenced in thepowders with DTA tests and for the fired samples with XRD; thefired samples are dominated by mullite peaks.

Keywords: kaolin; clay; powders characterization; ceramics;mullite; Lake Victoria region;

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40

Bich, Christelle Pera Jean. "Contribution à l'étude de l'activation thermique du kaolin évolution de la structure cristallographique et activité pouzzolanique /." Villeurbanne : Doc'INSA, 2005. http://docinsa.insa-lyon.fr/these/pont.php?id=bich.

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41

GONCALVES, PAULO S. "Influencia do caulim nas caracteristicas reologicas de esmaltes ceramicos." reponame:Repositório Institucional do IPEN, 2003. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11094.

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Made available in DSpace on 2014-10-09T12:48:14Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T13:57:04Z (GMT). No. of bitstreams: 1 09458.pdf: 5565544 bytes, checksum: 4fb384d317386b05f7e92b3e9eaa9b58 (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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42

Mornard-Pochet, Bernadette. "Adsorption et rétention des tensio-actifs anioniques par une argile kaolinique : application à la récupération assistée du pétrole." Vandoeuvre-les-Nancy, INPL, 1987. http://www.theses.fr/1987NAN10102.

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L'étude est réalisée avec de l'argile provenant de Guizengeard (Charentes) et deux agents de surface : l'octylbenzènesulfonate de sodium (OBSNa) et le 4-dodécylbenzènesulfonate de sodium (4 DBS Na). Les résultats expérimentaux sont utilisés pour développer un modèle et déterminer la valeur de la constante de sélectivité à retenir pour calculer les quantités de cations échangées en fonction des conditions expérimentales. Ce modèle est également utilisé pour interpréter les isothermes de rétention du 4 DBS Na et de l'OBS Na sur la kaolinite

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43

Nico, Pierre. "Etude du mécanisme d'interaction des polysaccharides avec la kaolinite en milieu aqueux." Mulhouse, 1985. http://www.theses.fr/1985MULH0A07.

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44

Bich, Christelle. "Contribution à l'étude de l'activation thermique du kaolin : évolution de la structure cristallographique et activité pouzzolanique." Lyon, INSA, 2005. http://theses.insa-lyon.fr/publication/2005ISAL0009/these.pdf.

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La métakaolinite est une pouzzolane de synthèse couramment utilisée dans le domaine du génie civil. Elle est le résultat de la calcination de la kaolinite. Ce travail permet de compléter les études sur le comportement thermique de la kaolinite, notamment celui de la déshydroxylation. Cette transformation est suivie par plusieurs méthodes analytiques (Analyses thermiques, IRTF, RMN-MAS, DRX), ainsi ceci permet d'étudier l'évolution de la formation de la métakaolinite, des structures cristallographiques et d'appréhender la cinétique de déshydroxylation. Une kaolinite désordonnée se déshydroxyle plus rapidement qu'une kaolinite ordonnée. Les observations en RMN-MAS nous conduisent à définir la métakaolinite par un désordre local important. Elle conserve dans sa structure minéralogique des traces de la structure de la kaolinite mère. L'activité pouzzolanique a pu être déterminée par la quantification de l'hydroxyde de calcium consommé par les métakaolins de l'étude. Une calcination incomplète de kaolin synthétise des pouzzolanes très réactives. L'étude de corrélation multiple a permis de montrer que l'activité pouzzolanique à 7 jours est essentiellement liée à la structure minéralogique des atomes d'aluminium, de silicium et à la présence de défauts de surface. La substitution de 25% de ciment par des métakaolins hautement déshydroxylés, entraîne une amélioration des résistances mécaniques à 28 et 90 jours. Les paramètres agissant sur le développement des résistances mécaniques sont la quantité de grains inférieurs à 10 μm, la quantité d'atomes de silicium Q3 organisé et la teneur en atomes d'aluminium hexacoordonné
The utilisation of calcined clay (metakaolin) as a pozzolanic material for mortar and concrete has received considerable attention in recent years. This work deals with the influence of the calcination conditions of kaolinite and the characterisation of dehydroxylation. The mechanism of thermal dehydroxylation has been investigated by means of kinectics description and characterisation of structural modifications occurring during the transformation into metakaolinite (thermical analysis, infra-red spectrometry, MAS-NMR, X-Ray diffraction). Clearly, the kinetic of kaolinite dehydroxylation is depends upon the degree of disorder of kaolinite crystals. The dehydroxylation of disordered kaolinite is easier than the dehydroxylation of well ordered kaolinite. Metakaolinite is the subsequent of the structural breakdown of kaolinite. 29Si and 27Al RMN-MAS show that metakaolin contains Al in octahedral, pentahedral, tetrahedral coordination and differents sites of Si. Metakaolin contains small amounts of the original structure of kaolinite. Metakaolin partially dehydroxylated is highly pozzolanic. Flash calciner produces very reactive métakaolin. Pozzolanic activity (at 7 days) depends on the mineralogical structure of Al, Si and surface state. Blended cements containing 25% metakaolin, exhibit interesting mechanical properties at 28 and 90 days. The compressive strength of blended cement depends on physical parameters like particule size distribution

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45

Duteil, Marie-Laure. "Influence de deux argiles sur la synthèse microbienne de substances para-humiques." Toulouse, INPT, 1998. http://www.theses.fr/1998INPT017A.

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Un modele de laboratoire a ete utilise pour examiner l'influence de l'argile sur la formation des substances humiques (sph). Des sph ont ete fabriquees par des microorganismes en absence et en presence de deux argiles : la montmorillonite et la kaolinite. Les composes formes ont ete etudies par : microanalyse centesimale, spectroscopie infra-rouge, dosages de groupements fonctionnels, chromatographie de permeation sur gel (c. Pe. G. ), isoelectrofocalisation (i. E. F. ). L'influence de l'argile est prouvee car les sph formees ne sont pas identiques ; elle s'exerce sur les sph fixees et aussi sur les sph solubles en presence d'argile. Les differences portent sur deux points. 1- l'encombrement moleculaire des sph adsorbees est tres superieur a celui des composes solubles. Parmi ces derniers, l'encombrement sterique le plus bas est celui des composes formes en presence d'argile. 2- la composition chimique. Les sph les plus fortement fixees sont les plus pauvres en azote et les plus riches en noyaux aromatiques. La c. Pe. G. Et l'i. E. F. Ont montre que la nature du mineral n'est pas toujours un point important. Quelle que soit l'argile, les profils de fractionnement des sph restees solubles sont identiques. Ceci est confirme par l'i. E. F. . Cette technique montre egalement que, les sph provenant de l'extraction de meme rang (1#e#r ou 2#e#m#e) ont plus de similitudes que les sph extraites successivement de la meme argile.

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46

Said, Mansour Mohamed. "Influence du métakaolin sur le comportement rhéologique et mécanique des bétons à hautes performances." Thesis, Cergy-Pontoise, 2010. http://www.theses.fr/2010CERG0496.

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L'utilisation du kaolin calciné, sous forme de métakaolin, comme matériau pouzzolanique pour le mortier et le béton a suscité une attention considérable ces dernières années. Le travail actuel décrit les résultats d'un projet de recherche lancé pour étudier la calcination d'un kaolin local sous diverses températures (650-950°C) et durées (2, 3 et 4 heures) qui ont produit le métakaolin avec une activité pouzzolanique élevée. L'activité pouzzolanique a été évaluée par des méthodes de la chaleur d'hydratation et la résistance à la compression à 28 jours. L'activité maximale a été obtenue à une température de 850°C pendant 3 heures. Les résultats observés établissent qu'une augmentation de la chaleur d'hydratation et de la résistance à la compression a été obtenue lorsque le ciment Portland Ordinaire a été remplacé par 10% de métakaolin. L'utilisation du ciment ternaire améliore la résistance au jeune âge et à long terme. La durabilité a été également améliorée où une meilleure résistance des mortiers à l'attaque des acides a été observée
The utilisation of calcined clay, in the form of metakaolin as a pozzolanic material for mortar and concrete has received considerable attention in recent years. The present work describes the results of a research project initiated to study the calcination of a local kaolin at various temperatures (650-950°C) and durations (2, 3 and 4 hours) to produced a metakaolin with a high pozzolanic activity. The pozzolanic activity was assessed by 28-days compressive strength and hydration heat methods. The maximum identified activity was obtained at 850°C for 3 hours duration. The observed results establish that an increase of both hydration heat and compressive strength was obtained when ordinary Portland cement was replaced by 10% metakaolin. The use of ternary blended cement improves the early age and the long-term compressive strength. The durability was also enhanced as better acidic resistance was observed

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47

Houta, Nadia. "Dispersion de phyllosilicates et processus de frittage de céramiques silicatées." Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0075/document.

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Ces travaux de thèse visent à améliorer la densification et la résistance à la rupture de céramiques silicatées élaborées principalement à partir de kaolin. Cette amélioration est effectuée en substituant une partie du kaolin par de l’halloysite. En effet, cette voie permet également de mettre en évidence l’influence de la morphologie et de l’organisation des particules sur les propriétés microstructurales. Premièrement, la dispersion des suspensions contenant soit du kaolin soit un mélange de kaolin et d’halloysite, a été optimisée en réduisant la taille des agglomérats et en augmentant la valeur absolue du potentiel zêta. Deuxièmement, les paramètres (broyage, rapport liant/plastifiant…) contrôlant le procédé de mise en forme de coulage en bande ont également été optimisés. Enfin, l’influence de deux types de traitement thermique à 1200°C (frittage conventionnel et par voie micro-ondes) sur les propriétés mécaniques (contrainte à la rupture en flexion biaxiale) des matériaux finis a été mise en évidence. Les résultats obtenus montrent que plusieurs compromis entre le taux de porosité, l’organisation de la microstructure et les propriétés mécaniques ont été obtenus i) soit avec un taux d’halloysite de 10 % en masse associée à un traitement thermique par voie micro-ondes à 1200°C ii) soit avec un taux de substitution d’halloysite égal à 50 % en masse associé à un frittage conventionnel à la même température
This thesis is devoted to improve both densification and stress to rupture values of silicate ceramics mainly elaborated from kaolin. This improvement is achieved by replacing a proportion of kaolin by halloysite. Indeed, this way also allows to highlight the influence of the shape of particles and their organization on microstructural properties. First, the dispersion of suspensions containing only kaolin or a mixture of kaolin and halloysite was optimized by reducing the size of agglomerates and by increasing the absolute value of zeta potential. Second, parameters (milling, ratio binder/plasticizer...) controlling the tape casting shaping process were also optimized. Finally, the influence of two types of thermal treatment at 1200°C (conventional and micro-waves sintering) mechanical properties (stress to rupture determined by bixial bending tests) of final products was studied. Results obtained show that several compromises regarding porosity, the organization of microstructure and mechanical properties i) a proportion equals to 10 mass % of halloysite combined with a micro-waves thermal treatment at 1200°C ii) a substitution content equals to 50 mass % of halloysite combined with a conventional thermal treatment at the same temperature

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48

Carrier, Michelle Bridget. "Dielectric measurements over a wide frequency range in E-grade kaolin clay." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621740.

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49

Bessa, Raquel de Andrade. "Synthesis and characterization of composite magnetic zeolites using kaolin for softening water." Universidade Federal do CearÃ, 2016. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=17007.

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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
The present work deals about the synthesis and characterization of magnetic zeolites obtained by hydrothermal route using kaolin from Brazilian Northeast as silicon and aluminum source. By means of the X-ray diffraction technique it was possible to identify zeolite LTA and zeolite P1 as major crystalline phases for each synthesis, with low intensity peaks referent to unreacted quartz present in the kaolin used, which is in accordance to the. FTIR spectra; the nanoparticles were identified as magnetite, with low intensity peaks referent to goethite. In scanning electron microscopy, however, it was not possible to morphologically identify these minor components, while the zeolites showed well defined morphologies, presenting unchanged morphology when in the composites form, but with nanoparticles dispersed over their surface, as expected. From transmission electron microscopy it was observed that the nanoparticles were of ca. 50 nm. Magnetic measurements indicated magnetite presence with superior diameter to critical diameter to superparamagnetic particles and remanent magnetization. Thermogravimetric analyses showed for the composites, lower mass loss than compared to the pure zeolites what may be associated to the improvement of its thermal stability. Granulometric distribution indicated nanoparticles agglomeration in variable sizes, while zeolites formed agglomerates of ca. 10 Âm. Water softening was accomplished by using both zeolites, with high efficiency on Ca2+ removal and similar behavior between the zeolite and its respective composite, being the best result observed for zeolite A, with efficiency of 97,95%, reaching equilibrium in the first contact minutes. The dependence on mass studies also showed that zeolite A and its composite presented the best efficiency, whereas zeolite P achieved the same removal levels using corresponding zeolite masses (45 mg). This way, the proposed method for zeolites synthesis proved to be efficient, so that the use of a magnet is capable to attract them, leading their excellent separation from the aqueous medium with its ionic exchange capacity unaffected.
O presente trabalho trata da sÃntese e caracterizaÃÃo de zeÃlitas magnÃticas obtidas por impregnaÃÃo de nanopartÃculas de magnetita a zeÃlitas A e P, sintetizadas por mÃtodo hidrotÃrmico utilizando caulim branco do Nordeste brasileiro como fonte de silÃcio e alumÃnio. Por meio da tÃcnica de difraÃÃo de raios-X foi possÃvel identificar como fases cristalinas majoritÃrias a zeÃlita LTA e P1 para cada sÃntese, com picos de baixa intensidade referentes a quartzo, resistente ao processo tÃrmico de tratamento prÃvio do caulim, bem como nos espectros de infravermelho; as nanopartÃculas foram identificadas como magnetita, havendo ainda indÃcios da presenÃa de goethita em pequena quantidade. Nas anÃlises de microscopia eletrÃnica de varredura, entretanto, nÃo foi possÃvel identificar esses componentes minoritÃrios morfologicamente; enquanto que a morfologia das zeÃlitas mostrou-se bem definida, sem alteraÃÃes apÃs a formaÃÃo dos compÃsitos, apenas com nanopartÃculas espalhadas em sua superfÃcie, como desejado. A partir da microscopia eletrÃnica de transmissÃo, pÃde-se observar melhor a variaÃÃo de tamanho das nanopartÃculas, em mÃdia de 50 nm. Medidas magnÃticas das amostras com essa propriedade indicaram a presenÃa de magnetita com diÃmetro superior ao diÃmetro crÃtico para partÃculas superparamagnÃticas e magnetizaÃÃo remanente. As anÃlises termogravimÃtricas mostraram que a adiÃÃo das nanopartÃculas Ãs zeÃlitas diminuiu sua perda de massa diante do aumento de temperatura e as anÃlises de distribuiÃÃo granulomÃtrica indicaram a aglomeraÃÃo das nanopartÃculas em tamanhos variÃveis, enquanto que as zeÃlitas formaram aglomerados de aproximadamente 10 Âm. Os ensaios de abrandamento de Ãguas mostraram alta eficiÃncia das zeÃlitas em remover Ca2+, com comportamento similar entre a zeÃlita e o seu respectivo compÃsito, encontrando para a zeÃlita A o maior percentual de remoÃÃo, de 97,95 %, atingindo equilÃbrio nos primeiros minutos de aplicaÃÃo. Os estudos de massa tambÃm mostraram a eficiÃncia da zeÃlita A e de seu compÃsito, tendo a zeÃlita P se aproximado dos mesmos nÃveis de remoÃÃo em massas referentes a 45 mg de zeÃlita. Assim, o mÃtodo proposto para sÃntese das zeÃlitas magnÃticas mostrou-se eficiente, de modo que a utilizaÃÃo de um ÃmÃ Ã capaz de atraÃ-las facilitando a separaÃÃo do meio apÃs a aplicaÃÃo em meio aquoso e sua capacidade de troca iÃnica nÃo foi afetada.

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50

Sousa, Daniel José Lima de. "Étude pétrologique et cristallochimique du kaolin de la rivière Capim - Pará, Brésil." Vandoeuvre-les-Nancy, INPL, 2005. http://www.theses.fr/2005INPL041N.

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Le District kaolinitique du Rio Capim, localisé dans le nord du Brésil, dans la région Amazonienne, constitue un des plus importants dépôts de kaolin du monde. Connu par sa blancheur élevée, ses applications concernent l'industrie de papier. Le kaolin s'est développé à partir des sédiments crétacés argilo-gréseux de la Formation Ipixuna où un intense processus latéritique ont eu lieu dés le Mesozoic au le Cenozoic. Le but de ce travail est de traœr l'évolution des faciès du kaolin du Rio Capim en considérant les aspects macro-morphologiques, minéralogiques, micro-morphologiques, texturaux cristallochimiques et chimiques. Ces études ont été réalisées sur les profils levés aux fronts de tailles de l'exploitation à ciel ouvert de la Société Imerys Rio Capim Caulim (IRCC) et les matériaux ont été analysées par chimie (ICP-MS, ICP- EAS), diffraction des rayons-X, analyses thermiques et gravi métrique (A TD-A TG), microscopie optique, microscopie électronique à balayage (MEB-EDS) et à transmission (MET -EDS), des analyses texturales par volumétrie d'adsorption d'azote, granulométrie par diffusion laser, des mesures de la capacité d'échange cationique cationique (CEC), spectroscopies UV visible, spectroscopie infrarouge (IR), spectroscopie Mossbauer. L'ensemble des données a été repris dans une étude statistiques par analyse en composantes principales (ACP) et enfin, des datations de monocristaux de zircons ont été effectuées par la méthode Pb-Pb. Six faciès ont été définis (faciès grès, faciès soft, faciès de transition inférieur, faciès ferrugineux, faciès de transition supérieure, faciès flint) et reliés aux différentes étapes du processus supergénène. Les faciès des transitions et ferrugineux sont les témoins d'un processus de ferruginisation qui a engendré la formation d'une épaisse cuirasse sur le faciès soft. Le faciès soft a été formé à partir du sédiment grès- argileux de la Formation Ipixuna (faciès grés). Le processus de ferruginisation a été suivi d'un processus de déferruginisation à l'origine de la différenciation. La même assemblage de minéraux denses dans les différents faciès montre que les sédiments ont une origine commune. Cette constatations a été corroboré par les études de provenanœs effectués sur les zircons des faciès flint et soft par la méthode de vaporisation Pb- Pb
The Capim Kaolinic District, located in the eastem Brazilian Amazon, constitutes one of the most important kaolin deposits in the world. Known for its high whiteness, its noble application is in the paper industry. The kaolin developed at the expense of Cretaceous sandy-clayey sediments of the Ipixuna Formation, on which intense lateritic processes took place from the Mesozoic to the Cenozoic. This work aims at tracing the evolution of the Capim kaolin faciès, taking into consideration macromorphological, mineralogical, micromorphological, textural, chrystallo-chemical and geochemical studies. These studies, based on the description of profiles in the exploration fronts of the open pit of the Imerys Rio Capim Caulim mine (IRCC), encompassed X-ray diffraction analysis (XRD), differential and gravimetric thermal analysis (DTA-GTA) , optical analysis of thin sections, chemical analysis, scanning (SEM) and transmission electron microscopy (TEM), both equipped with an energy dispersive X-ray detector (EDS), porosity and surface specific determinations, cationic exchange capacity (CEC) measurements, UV-visible determination, infrared and Mossbauer spectroscopies, statistical analysis and the Pb-Pb isotopic analysis using single zircon vaporization. Six facies (sand kaolin, soft kaolin, lower transition facies, ferruginous crust, upper transition facies and flint kaolin) are defined and related to different stages of the supergenic proœss. The transition facies and the ferruginous crust represent relicts of a ferruginization process that led to the formation of a thick ferruginous duricrust on the soft kaolin, which in turn evolved from sandy-clayey sediments of the Ipixuna Formation (sand facies). A subsequent deferruginization event caused the degradation of the duricrust, resulting in the flint kaolin facies. The chemical analyses corroborate to the lateritic processes, characterized by the ferruginization and deferruginization mechanisms that led to the distinction of the different facies. Even if ferruginization and deferruginization mechanisms led to the individualization of different Capim River kaolin facies, the sa me heavy mineraI assembly persists in ail facies, evidencing that these minerais originated from the same basal sediments. Provenance studies carried out on the soft and flint faciès allowed to trace the possible sources of sediments that host the ore. The Pb-Pb vaporization method was applied to four predominant morphologic classes of detrital zircons and the ages obtained were compared to the main age intervals of the rocks surrounding the Capim Kaolin District (CKD). Four major plateau ages (2. 15,2. 02,1. 87 and 1. 51 Ga) were defined for both soft and flint facies, indicating a common source for the kaolin

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