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ResumoA exploração desordenada ao longo dos anos das argilas bentoníticas do município de Boa Vista, PB, resultou no esgotamento das variedades nobres. Assim, o que existe atualmente são bentonitas com elevado percentual de minerais acessórios, elementos contaminantes a exemplo do quartzo, os quais influem negativamente nas propriedades reológicas das dispersões. O presente trabalho propõe concentrar dispersões dessas argilas pouco nobres pela operação de hidrociclonagem e posterior secagem por spray dryer, visando à obtenção de amostras com valores de reologia de acordo com norma EP-1EP-00011-A da Petrobrás. Assim, preparou-se dispersões de três composições com as argilas Bofe, Chocolate, Verde-Lodo, Chocobofe e Sortida previamente selecionadas por planejamento experimental com concentrações de 4% em massa de argila para serem concentradas por hidrociclonagem. Os concentrados foram secos por spray dryer em duas condições de secagem. Os resultados evidenciaram a eficiência das operações de hidrociclonagem e secagem por spray dryer das misturas com notável melhoria nas propriedades reológicas.

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A wide variety of synthesis methods have been proposed for obtaining mullite, however, some techniques produce powders with heterogeneous morphology and a large amount of glassy phase, forming large clusters making it difficult to obtain nanopowders. The microwave synthesis offers advantages over conventional methods, the heating is rapid and uniform, avoiding an undesirable grain growth. The aim of this work was the synthesis of nanoscale mullites powders from delaminated bentonites. For the process of delamination samples were initially treated, then rehydrated, frozen and deagglomeration in ball mill and subsequently subjected to centrifugation, in order to produce a nanosized precursor for the synthesis of mullite. The powders obtained after peeling were characterized chemical and mineralogical. The synthesis of mullite was performed in a microwave oven and the powders were characterized by XRD and SEM. The results showed that the delamination of the bentonite and microwave synthesis were essential in obtaining nanopowders mullite.

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Tailing incorporation into mortars has been the subject of much research in recent years. Despite this, most of these studies did not investigate the harmful effects resulting from the exposure of such mortars to an environment containing aggressive agents. This work investigated the effects of perlite tailing addition into mortars containing cement CP V-ARI MAX and hydrated lime. The raw materials were subjected to chemical characterization (X-ray fluorescence (XRF)) and mineralogical (X-ray diffraction (XRD)), while the samples immersed in 1 N NaOH solution were characterized by XRD, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and compression strength (CS). The results showed the harmful effects of incorporating perlite tailings into the mortar investigated. Such a degradation was proven by linear expansion and compressive strength experiments accomplished in the samples after the test of resistance to an alkali–silicate reaction.

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In the ceramic industry, the firing is one of the main stages of the production process. There are two heating rates prevailing at this stage: low heating rate (long residence time) and high heating rate (fast residence time), the low rate is more used in traditional ceramics. This study aims to evaluate the influence of firing conditions on technological properties of three compositions of clay, used in the manufacture of red ceramic products. Initially, the mixtures were characterized subsequently were extruded, dried and submitted to firing at temperatures at 900 and 1000 °C with heating rates of 1, 2, 5, 15, 20 and 30 °C/min. The crystalline evolution of the different samples was analyzed using X-ray diffraction and the technological properties were determined. For the mechanical resistance, it was not observed significant change with the increase of the temperature and heat rate