Materials Science Forum Vol. 820

Abstract: The northern region of the state of Rio de Janeiro, Brazil, has a significant participation in the country ceramic production for civil construction owing to the abundance of raw materials, mainly kaolinitic clays. Each municipality in that region has ceramic industries using raw materials mined from its own deposits. Products such as bricks and tiles may lack the required quality due to the limited know-how on the applied raw material. The present work conducted a technological evaluation of the clayey raw material used in the municipality of São José de Ubá including its potential for ceramic processing at firing temperatures of 700, 850 and 950oC. The results indicated that only the ceramic fired at 950oC conforms to the specifications for water absorption and mechanical strength.

Abstract: The municipal area of Campos dos Goytacazes in the northern region of the state of Rio de Janeiro, Brazil, is the state’s major industrial pole for red ceramic fabrication. The extensive clay deposits and easy to mine conditions have attracted more than one hundred ceramic industries to operate in the area. In particular, the district of São Sebastião contributes to the production of red bricks and tiles but the characterization of the existing clay and the quality of ceramic pieces has not yet been evaluated. Therefore the present work carried out an investigation of a typical clay body used in São Sebastião by means of its physical and chemical characteristics. The technological properties of red ceramics fabricated from this clay body and fired at temperatures of 700, 850 and 1100oC indicate that they comply with the mechanical strength requirements for masonry bricks. However water absorption is not satisfactory due to the excess of sand and lack of fluxing elements.

Abstract: The physical, chemical and mineralogical characterization of a precursor clay body before firing is of relevance for understanding the technological performance of the fired clay ceramic. In particular, structural clay ceramic blocks used in building construction need to attend standard properties specified by the norms. In the present work the precursor clay body, typically used to fabricate structural blocks in Campos dos Goytacazes, state of Rio de Janeiro, Brazil, was characterized in terms of particle size distribution, X-ray diffraction, chemical composition and Atterberg limits. In addition, the performance of structural ceramic blocks, fabricated from the extruded clay body and fired at 850oC, was evaluated. The results indicated that the ceramic mechanical strength complies with the Brazilian norm but the water absorption is higher than the maximum specified by the norm. The characteristic of the clay body contribute to justify the structural blocks performance.

Abstract: The proposal to obtain a new route for exploitation of tailings from pegmatite emerged from the need of many companies that showed to reuse of these tailings as raw materials ceramics. The pegmatites represent a large part of available industrial minerals. These can be classified into: kaolin, feldspar, mica, quartz and metallic minerals such as tantalite / columbite and others. The consumer markets for these minerals are glassmaking, ceramic industries, paper, pulp, metallurgy, etc. Order for the product is fit for sale ceramics and metals companies must be of high purity of this raw material. Therefore, the process of separation of these minerals must be carried out as effectively as possible. In this study, surveys have been made to the development of a new process route which facilitates, an optimized manner, separation from pegmatite, concentrated in the waste process of extracting companies, so that a better product shall be passed through the ceramic industry.

Abstract: Structural ceramic quality is particularly related to the quality of the clays. Our aim is to characterize the common clay called Batinga used in the ceramic industry in Colatina - ES, which has a ceramic pole with about twenty companies. Batinga samples were tested for chemical and mineralogical composition, particle size distribution characterization, thermal behavior, optical microscopy, SEM and Atterberg limits. The specimens were shaped, dried at 110oC, burned in industrial furnace and submitted to ceramic test. The results show that the clay presents typical chemical composition of raw clay with significant amount of silica and alumina, besides adequate particle size distribution and mineralogical composition. The high plasticity shown may require high water content in the molding of ceramic roof tiles. The tests yielded results that showed that the clay meets the requirements of the Brazilian standard for structural ceramic.

Abstract: Bentonite clays, after treated with surfactants, are called organofilic clays. The objective of this work is the development of organofilic clays, using ionic surfactants, based on a variety of smectite from Cubati, PB, for application in organic media. The following materials were used: Superior Gray bentonite clay from the town of Cubati, PB, Brazil, and the ionic surfactants Praepagen WB® and Praepagen HY®. The clay was characterized with basis on the granulometric analysis by laser diffraction (AG), chemical composition by X-ray fluorescence (EDX), X-ray diffraction (XRD), thermogravimetric analysis (TG) and thermal differential (DTA). The clay was processed and then turned into sodic and later into organofilic clays. The results prove that there was intercalation of the ionic surfactant into the clay fraction, and that the process variables did not affect the organofilization process, but the surfactant type has influence on the process.

Abstract: Vermiculite has a structure consisting of layered silicates surfaces interspersed with layers of water. When the expansion occurs intra lamellar clay water is removed. This paper aims to characterize the Vermiculite clay of Santa Luzia, Paraíba (Brazil) in their natural form, and after thermogravimetric treatments by classic X-ray diffraction analysis, thermal analysis and scanning electron microscopy. The results show that the method of expansion, using the technique of microwave energy is possible, however, the expansion factor is lower when compared to the indirect heating by the thermal expansion of the clay.

Abstract: The use of natural resources for sustainable development is becoming a relevant issue in modern societies. In particular, building materials composed of local soil or available residues are considered sustainable solutions for housing construction in relatively small urban areas. In the present work a preliminary study was conducted on a typical soil in the municipal area of Miracema, state of Rio de Janeiro, Brazil. The study comprised the characterization of the particle size distribution and particle density of the soil. In addition, the application of the soil by combining with Portland cement was investigated to produce concrete blocks specified as soil-cement bricks by the Brazilian norm. The results indicated that a trace of 14 parts of soil, 6 parts of local gravel and 4 parts of cement/water produced concrete blocks that comply with the compression strength specified by the norm.

Abstract: Clays are very important raw materials in the manufacturing of traditional ceramic products. The present study was intended to study the phase transformations of smectites submitted to thermal treatment in conventional stove, applying slow and fast cycles. We used three clays, two national and one imported, which were beneficiated and characterized by mineralogical analysis. Later, they were submitted to a thermal treatment at 1100, 1200 and 1250°C, with heating rate of 5 and 30°C/min, remaining under the maximum temperature for 60 minutes. We observed the presence of mullite peaks starting at 1100°C for all samples. It was verified that the sample with the highest alumina/silica ratio presented more intense mullite peaks, and the sample with the high MgO content, besides the mullite phase, also formed cordierite.