Navegando por Assunto "Caulim - Amazônia"

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Acesso aberto (Open Access)
Atividade pozolânica dos resíduos cauliníticos das indústrias de mineração de caulim da Amazônia
(2011) BARATA, Márcio Santos; ANGÉLICA, Rômulo Simões
The Capim and Jari regions, northern Brazil, are the main Kaolin mining areas in the Amazon region. They encompass the biggest high-grade (high whiteness) kaolin reserves for the paper coating industry. During the beneficiation of this kaolin, different kinds of processed and non-processed wastes are generated. The main objective of this work was to evaluate the reactivity of pozolans produced after calcinations and milling of such residues, by the comparison of the mineralogical composition and the type of kaolinite from the two regions (different kinds of structural order/disorder). The heating temperature to produce the pozolans was evaluated in order to obtain the better reactivity with lower energy consumption. The results showed that the pozolans obtained from both residues exhibited high reactivity, also better than those commercially available. Those obtained from kaolinites with high structural defects needed lower temperatures in comparison with low-defects kaolinites. The use of the former kaolinites reduces the production costs to obtain pozolans without losing quality in terms of reactivity.
Acesso aberto (Open Access)
Caracterização dos resíduos cauliníticos das indústrias de mineração de caulim da Amazônia como matéria-prima para produção de pozolanas de alta reatividade
(2012-03) BARATA, Márcio Santos; ANGÉLICA, Rômulo Simões
Capim and Jari are the two most important kaolin mining districts of the Brazilian Amazon region. They encompass the major Brazilian reserves of high quality kaolin for the paper coating industry. The kaolin is mined and processed by three major companies responsible for about 500,000 ton of a residue mainly composed of kaolinite. The wastes come mainly from the centrifugation phase of the kaolin beneficiation process and their final destinations are huge sedimentation basins that occupy large areas. The main purpose of this work is to evaluate the physical, chemical and mineralogical characteristics of the kaolin wastes processed from the Capim and Jari region, in order to obtain metakaolinite, a high reactive pozzolan for the cement industry. When incorporated to ordinary Portland cement such pozzolans increases the concrete and mortars performance. All the residues studied in this work were characterized by means of: X-ray diffraction analysis, differential thermal analysis, infrared spectroscopy, scanning electron microscopy, X-ray fluorescence spectrometry and laser diffraction. Both residues are mainly constitutes by at least 92% of low granulometry kaolinite with specific surface area above 8 m2/g and mean diameter below 1 µm. Free silica (quartz) contents are below 3%. The high concentration of kaolinite in these residues dispenses rigid control parameters for removal of impurities usually employed in pozzolan production. The Jari kaolin exhibits high disordered kaolinite in comparison with the high ordered kaolinite of the Capim region and gives rise to higher desidroxilation degree at lower temperatures. It points to energy saving and reducing costs during the production of a pozzolan. The results are satisfactory and reveal that both kaolin wastes are excellent raw material for the production of high reactive metakaolin.
Acesso aberto (Open Access)
Caulins amazônicos: possíveis materiais de referência
(2013-09) SANTOS, Suzianny Cristina Arimatéa; ROCHA JUNIOR, Carlos Augusto Ferreira da; SILVA, Liliane Nogueira da; ANGÉLICA, Rômulo Simões; NEVES, Roberto de Freitas
Kaolin is a product originated by the weathering action of aluminum silicates, such as feldspars, which in the Amazon region is favored by warm and humid climate. Used in fabrication of refractory, cement, pharmaceuticals, catalysts, paper coating and filler and other several purposes. This study aims to characterization and comparison of kaolins for paper coating and in natura from different regions in Pará ( Rio Capim, Jarí and Vila do Conde) of sedimentary origin with kaolins used as reference materials (IPT-28, IPT-32, IPT-42, KGa-1b e KGa-2). The characterizations were carried out by methods of chemical, physical and mineralogical analyses: Particle size distribution, X-Ray Diffraction, X-Ray Fluorescence, Scanning Electron Microscopy, Differential Thermal Analysis. The results showed as main mineral phase in all kaolin studied the kaolinite, with different degrees of "crystallinity". The Amazon kaolins presented high and low degree of structural order as well as reference materials. With respect to the properties of chemical composition, both materials showed levels of SiO2 + Al2O3 above 90%, low levels of Na2O and TiO2, with average of 0.6% and 1.92%, respectively for the reference materials, and for amazon kaolins were 0.3% and 1.62% to TiO2. The particle size analysis showed variances of the D50 from 0.7 to 9 µm to the amazon kaolins and from 1.7 to 6 µm to the reference materials. The sedimentary amazon kaolins, with low levels of impurities and found in large quantities, suggest a strong potential for use as reference kaolins.
Acesso aberto (Open Access)
Desenvolvimento de processos de síntese de sodalita a partir de rejeitos de caulins da região Amazônica
(Universidade Federal do Pará, 2013-01-17) SILVA, Liliane Nogueira da; NEVES, Roberto de Freitas; http://lattes.cnpq.br/9559386620588673
In the study of the Sodalite synthesis used two wastes kaolins from two kaolin processing industries for paper coating, located in the Amazon region, operating in the region of Rio Capim (CRC) and Rio Jari (CRJ). Besides this, was also used as a source of silica and alumina to metakaolin, obtained by calcination of kaolin (MRC and MRJ, respectively). Preliminary chemical and mineralogical characterization of kaolin was performed to obtain information of its characteristics. The Sodalite synthesis was performed varying some parameters, such as starting material: kaolinite was used directly as starting material at temperatures of 80, 100, 120 and 150 °C, and, starting with metakaolinite at 95 °C. In order to observe the influence of ions OH, Cl- and CO32-, as well as Na2O/Al2O3 ratio, the syntheses were carried out varying the basic solutions, set temperature at 95 °C for the starting material MRC. Furthermore, the Na2O/Al2O3 ratio were maintained constant and temperature were varied in the reaction mixture to determine the ideal conditions for Sodalite synthesis. The starting materials and the synthesis products were identified and characterized by using XRay Diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis, Thermal Methods (DTA/DTG) and Fourier Transform Infrared Spectrometry (FTIR). The method of synthesis that show best results were used as starting material metakaolin, with NaOH + Na2CO3 solution having Na2O/Al2O3 ratio of 3.89 conducted under stirring at 95 °C, atmospheric pressure and a time of 4 hours, for the two types of kaolin (CRC and CRJ). Using the MRC metakaolin, kaolin from the Rio Capim, under the above conditions was obtained by conversion of 86.5% by weight of sodalite and MRJ metakaolin, kaolin of the Rio Jari, the conversion was 73.6% in sodalite. All products were characterized as mesoporous materials, but starting from the product of metakaolin Rio Jari showed higher specific area.
Acesso aberto (Open Access)
Efeito do tempo de síntese de zeólita A a partir de caulim amazônico, conformação por extrusão e verificação desta na eficiência de adsorção de NH4 +
(Universidade Federal do Pará, 2015-04-24) SANTOS, Suzianny Cristina Arimatéa; NEVES, Roberto de Freitas; http://lattes.cnpq.br/9559386620588673
Kaolin is widely used in the field of materials (ceramics, pozzolans, fillers and manufacture of paints) as much as the waste and the product received. Currently the most exploited use has been in zeolite synthesis, as it presents the most noble applications. Zeolites are synthesized from silicon and aluminum sources, a fact that justifies the use of kaolin, because it is formed essentially by the clay mineral kaolinite (Al2Si2O5 (OH) 4). In this work we made a kaolin comparison of Grass River region with kaolin mineralogical / chemical and other Amazon kaolin reference to see if you can make it a reference material. The comparison was carried out by size analysis, X-ray diffraction, X-ray fluorescence, scanning electron microscopy, differential thermal analysis and infrared spectroscopy and crystallinity calculations. Moreover, the kaolin of the Rio Capim region was used as a source of silicon and aluminum to obtain the zeolite in order to determine the effect of time on the synthesis. Assays were performed in a time of 30 min, 1 h, 2 h and 24 h applied in these zeolites ammonia adsorption. From the synthesized zeolite was carried out the forming process by extrusion, evaluating various ligands (sodium silicate, bentonite, kaolin and CMC) and firing temperatures (500, 700 and 800 ° C). Later, these were extruded applied also in ammonium adsorption to check its efficiency. It was observed that it is possible to use kaolin Grass River as mineralogical reference material (high degree of structural order) and/or chemical, because it showed performance equal or close to the reference kaolin compared in this work. The zeolite A was synthesized from Amazon kaolin and this presented an excellent silicon and aluminum source. All synthesis times gave zeolite A zeolite in amounts of ~ 600 g. All zeolites showed a high degree of structural view to XRD and SEM. It was also found that synthetic zeolite A in 30 minutes time can be performed without loss in its application, since it presented below only 3% difference in adsorption efficiency compared to 24 h. The shaping by extrusion tests proved promising, 5 out of 10 trials were successful in obtaining granulated with physical strength. However, only the granules containing sodium silicate and CMC as a binder showed a high ammonia adsorption efficiency. With values of ~ 95,5% efficiency in 24 hours of contact.