Navegando por Autor "CASTRO, Elton Anderson Santos de"

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Caracterização mineralógica e geoquímica e estudo das transformações de fase do caulim duro da região do Rio Capim, Pará
(2003-12) CARNEIRO, Bruno Santana; ANGÉLICA, Rômulo Simões; SCHELLER, Thomas; CASTRO, Elton Anderson Santos de; NEVES, Roberto de Freitas
The Capim region (Pará State, northern Brazil) is the most important kaolin district in the Amazon region, with the largest Brazilian reserves of high whiteness kaolin for the paper coating industry. The main ore (soft kaolin horizon) is located at a depth of about 20 m, being covered by a hard, iron-rich kaolin level, also called flint or semi-flint kaolin, besides a sandy-clay overburden. The beneficiation of this kaolin produces large volumes of wastes, composed mainly of coarse-grained kaolinite, deposited in basins that occupy extensive areas. The main objective of this work is to carry out mineralogical and geochemical studies of the hard kaolin, and to evaluate its thermal transformations through calcination up to 1500 oC. The results show a mineralogical composition dominated kaolinite. The evaluated thermal transformations allows us to describe a series of chemical reactions from kaolinite to metakaolinite and further development of spinel, cristobalite and mullite. For the two analyzed samples, such transformations can start at different temperatures as a result of the different chemical compositions, mainly the iron contents.
Acesso aberto (Open Access)
Síntese, caracterização físico-química e aplicação de alumínossilicatos como adsorventes
(Universidade Federal do Pará, 2003-05) CASTRO, Elton Anderson Santos de; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
In this work three differente aluminosilicates were used for evaluation of the index of recovery of the coloring monovalent metilene blue. The no-porous clay mineral, Kaolinite, from Capim river area in Pará, Brazil, was treated with hydrochloric acid 5N in order to increase the specific area. The microporous molecular sieve, zeolite NaP, was synthesized through the hidrotermal method, with the kaolinite of Capim river area being used as source of Si and Al. The hidrotermal method was also used for the synthesis of the mesoporous molecular sieve Al-MCM-48, wich received thermal treatment (calcination) at 540ºC under flow of N2 and air for 7h to removal of the agent director (surfactant). The porous and no-porous materials were characterized by X-ray diffraction, infrared spectrophotometry, thermodifferential and termogravimetric analyses and adsorption and desorption methods with N2. Chemical analysis for the clay mineral has been performed and scanning electronic microscopy was used for the microporous aluminosilicate. These materials were tested as adsorbents in the recovery of the metilene blue at concentration of 6ppm, in different times (20, 40, 60 and 120min) with the contact method being used. The concentration, separation method of phases and the more appropriate wave length were studied. The determination of the recovery index for the organic coloring, using the three materials, was performed through visible spectrophotometry. XRD and chemical analysis results revealed the high purity of the clay mineral kaolinite. The specific surface area increased by 31,23% after acid activation. The specific area obtained for Al-MCM-48, was of 1219m2g-1, which is a characteristic value for this kind of materials. The results of XRD indicate that the zeolita NaP was formed, but traces of the feldspatoid hidroxysodalite are also present, what could be confirmed by the SEM images. The values of the recovery index for the metilene blue demonstrated that the kaolinite under acid activation was the most effective (100% of recovery), followed by the zeolite NaP (97,89% of recovery) and Al-MCM-48 (97,35% of recovery). The results indicate the viability of use of these materials as agents for pre-concentration in cromatographic analyses.