Luiz Carlos Bertolino

Ore Dressing and Technological Characterization of Palygorskite from Piauí/Brazil for Application as Adsorbent of Heavy Metals

Palygorskite (Mg,Al)5Si8O20(OH)2(OH2)4.4H2O, is a lamellar mineral with a fibrous morphology. The micropores and canals in the structure give a high specific surface and sorption capacity of various kinds of species. Guadalupe’s palygorskite (Piaui/Brazil) run of mine (ROM) was prepared (PA) and characterized by XRD and XRF. PA is composed by palygorskite, kaolinite, quartz and goethite and has 15.8, 58.0, 4.2 and 7.6% of SiO2, Al2O3, MgO and Fe2O3, respectively. Wet magnetic separation tests were conducted with PA obtaining the magnetic and non-magnetic fractions (PAM and PANM, respectively). PANM was characterized by XRD and XRF and the results of the XRF indicated that the iron content in the PA decreased 8.0% in the non-magnetic product. A new wet sieving was conducted with PANM to obtain a purer fraction (−20 μm) (PANMP) which was characterized by XRD, XRF, CEC, Zeta potential, SEM, TG/DTG. The result showed that this mineral could be used as adsorbent of heavy metals.

Synthesis and Characterization of Sodalite and Cancrinite from Kaolin

Cancrinite and sodalite are characterized by high capacity of adsorption due to its porous structure. The aim of this work was to use kaolin from Borborema-Serido/Brazil as a source of aluminium and silicon to hydrothermal synthesis of sodalite and cancrinite and to evaluate the best conditions to the formation of these phases. Therefore, kaolin was heated at 700 and 900 °C for 2 h in order to transform kaolinite in metakaolin. Thereafter, experiments with the calcined kaolin’s were carried out between 150 and 230 °C for 30–270 min on a stainless steel pressure vessel using NaOH, Na2CO3 and H2O. The samples were characterized by X-ray diffraction, nuclear magnetic resonance, scanning electronic microscopy, thermogravimetry, and Zeta potential. The most pure sodalite phase was obtained at 230 °C, with the kaolin/NaOH ratio of 1:1, low concentration of Na2CO3 and smaller time of synthesis (30 min). On the other hand, for the synthesis of cancrinite phase at 230 °C, it was necessary to use kaolin heated at 900 °C, a longer time of synthesis (270 min) and a higher concentration of Na2CO3.

Avaliação do risco ambiental e comportamento geoquímico de metais em área impactada por resíduos industriais em Queimados (RJ).

Areas contaminadas por metais podem configurar serio risco a saude publica e ao meio ambiente. No final da decada de 1980 foi instalado um patio de estocagem provisoria de residuos industriais perigosos na area da empresa Centro Tecnologico de Residuos (CENTRES), no municipio de Queimados, RJ. A gestao inadequada destes residuos proporcionou um grande impacto ambiental ao solo da regiao. Entao, em 2009 foram amostrados solos desta empresa para que fossem avaliadas a mobilidade, toxicidade, biodisponibilidade e risco ambiental de Cd, Cr, Cu, Ni, Pb e Zn utilizando extracao sequencial para o fracionamento geoquimico (BCR), determinando-se as concentracoes destes metais por ICP OES. A soma de todas as fracoes geoquimicas mostraram que a amostra P1 e severamente contaminada por Zn, que as amostras P5 e P5.1 sao contaminadas por Cu, Ni, Pb e Zn, que a amostra P5.2 e contaminada por Ni, Pb e Zn e que a amostra P6 possui concentracoes de Ni que ultrapassam o valor de investigacao industrial preconizado pela legislacao brasileira. Geralmente, o Cd, o Ni e o Zn se mostraram como os metais mais moveis, devido ao enriquecimento das suas concentracoes na fracao soluvel e trocavel do solo (F1). O Pb so se mostrou altamente soluvel e trocavel em amostras de solos que foram severamente contaminadas com este metal. Por outro lado, o Cu e o Cr se mostraram pouco moveis, preferindo estar adsorvidos a fracao oxidavel do solo (F3) ou ao residuo (R) que contem a matriz silicatica e oxi-hidroxidos de alta cristalinidade. Finalmente, o codigo de avaliacao de risco (RAC) se mostrou uma ferramenta limitada ao superestimar o risco ambiental do Cd e do Ni e subestimar o do Cu.

Characterization and Ore Dressing of Bauxite from Brazil

The Bauxite from North Brazil is characterized by a geological profile with different layers. The differences among these layers are percentage of bauxite constituents (gibbsite, kaolinite and hematite). Nowadays, only one layer is used for alumina production by Bayer process, the commercial or crystallized bauxite. This work intended to characterize and to ore dress crystallized bauxite (CB), amorphous crystallized (MB) and nodular bauxite (MNB) from Para to make them usable in the Bayer process. The ore dressing was developed by mechanochemical activation with an alkaline reagent in different concentrations and conditioning time. After ore dressing, the samples were submitted to characterization by X-ray diffraction (XRD), X-ray fluorescence (XFR) and rheological characterization. CB and MB ore dressing products were characterized by an increase of mass ratio Al2O3available/SiO2reactive and it was observed that the total silica of MNB, after ore dressing, decreased around 13%. These results were a strong indication that these bauxites could be used in the Bayer process.

Caracterização tecnológica e mineralógica dos caulins Belmiro Braga e São Miguel do Anta, Minas Gerais

The study aimed the technological and mineralogical characterization of the kaolins Belmiro Braga (BB) and Sao Miguel do Anta (SMA), through X ray diffraction (XRD), scanning electron microscopy (SEM-EDS), X ray fluorescence and electron spin resonance (ESP) as well as the physical and chemical beneficiation to eliminate the ion Fe+3 and upgrade their whiteness levels. Both kaolins are fine grained; the BB kaolin has kaolinite in its mineralogy, and the SMA kaolin has quartz. After chemical bleaching, the whiteness reached 81.0% ISO to the BB sample, and 71.2% ISO to the SMA sample.