Lisiane Navarro de Lima Santana

Utilization of kaolin processing waste for the production of porous ceramic bodies

The kaolin processing industry generates large amounts of waste in producing countries such as Brazil. The aim of this study was to characterize kaolin processing waste and evaluate its suitability as an alternative ceramic raw material for the production of porous technical ceramic bodies. The waste material was physically and chemically characterized and its thermal behaviour is described. Several formulations were prepared and sintered at different temperatures. The sintered samples were characterized to determine their porosity, water absorption, firing shrinkage and mechanical strength. Fired samples were microstructurally analysed by X-ray diffraction and scanning electron microscopy. The results indicated that the waste consisted of quartz, kaolinite, and mica, and that ceramic formulations containing up to 66% of waste can be used for the production of ceramics with porosities higher than 40% and strength of about 70 MPa.

Statistical design for recycling kaolin processing waste in the manufacturing of mullite-based ceramics

Mineral extraction and processing industries have been cited as sources of environmental contamination and pollution. However, waste recycling represents an alternative recovery option, which is interesting from an environmental and economic standpoint. In this work, recycling of kaolin processing waste in the manufacture of mullite-based ceramics was investigated based on the statistical design of mixture experiments methodology. Ten formulations using kaolin processing waste, alumina and ball clay were used in the experiment design. Test specimens were fired and characterized to determine their water absorption and modulus of rupture. Regression models were calculated, relating the properties with the composition. The significance and validity of the models were confirmed through statistical analysis and verification experiments. The regression models were used to analyze the influence of waste content on the properties of the fired bodies. The results indicated that the statistical design of mixture experiments methodology can be successfully used to optimize formulations containing large amount of wastes.

Kaolin processing waste applied in the manufacturing of ceramic tiles and mullite bodies

In the last few years, mineral extraction and processing industries have been identified as sources of environmental contamination and pollution. The kaolin processing industry around the world generates large amounts of waste materials. The present study evaluated the suitability of kaolin processing waste as an alternative source of ceramic raw material for the production of ceramic tiles and dense mullite bodies. Several formulations were prepared and sintered at different temperatures. The sintered samples were characterized to determine their porosity, water absorption, firing shrinkage and mechanical strength. The fired samples were microstructurally analysed by X-ray diffraction. The results indicated that ceramic tile formulations containing up to 60% of waste could be used for the production of tiles with low water absorption (~ 0.5%) and low sintering temperature (1150 °C). Mullite formulations with more than 40% of kaolin waste could be used in the production of bodies with high strength, of about 75 MPa, which can be used as refractory materials.

Argilas bentoníticas de Cubati, Paraíba, Brasil: Caracterização física-mineralógica

O Estado da Paraiba possui jazidas de bentonitas utilizadas comercialmente em uma vasta gama de setores tecnologicos. No entanto, esses jazimentos estao se exaurindo apos dezenas de anos de exploracao. Assim, este trabalho tem por objetivo a caracterizacao fisico-mineralogica de bentonitas recentemente descobertas no municipio de Cubati, PB. As amostras estudadas foram secas a 60 oC e caracterizadas por meio de fluorescencia de raios X, picnometria de He, determinacao da distribuicao de tamanho de particulas, difracao de raios X, analise termica diferencial e gravimetrica e microscopia eletronica de varredura. Os resultados evidenciaram que as amostras sao bentonitas policationicas, apresentando teores de MgO, CaO e K2O semelhantes aos de outras bentonitas sul-americanas e que sao constituidas por argilomineral esmectitico e por quartzo e caulinita. As amostras apresentaram fracoes de particulas abaixo a 2 μm variando entre 31 e 41%, estando, no entanto, em elevado estado de aglomeracao.

Comportamento de expansão de argilas bentoníticas organofílicas do estado da Paraíba

Organoclays are used in a wide range of industrial applications, from the petroleum to the pharmaceutical and cosmetic industry, reaching the waste adsorption applications and production of polymer-clay nanocomposites. This work has as aim study the influence of the amount of quaternary ammonium salts in the organophilization of bentonite clays. The used clays were characterized by chemical composition, particle size distribution and cation exchange capacity determination. The organoclays were prepared using two quaternary ammonium salts: alkyl dimethyl benzyl ammonium chloride (Dodigen) and cetyl trimethyl ammonium bromide (Cetremide). The organoclays were characterized by X-ray diffraction and IR spectroscopy. The results showed that the interlayer spacing increase with the rise in the amount of salt used for the organophilization, and that this behavior varied according to the salt and clay used, the interlayer spacing increasing behavior is linear when the Dodigen salt was used and varied according to the bentonite clay when the Cetremide salt was used.

Mullite Preparation from Kaolin Residue

In the process of kaolin improvement to types of residue are generated and dispose in the environment. The first residue, about 70%wt, generated from the washing of the kaolin and the second generated residue from the improvement in sieve 200 mesh (0.074mm), of the remaining of the washed kaolin 30%. These residues can present excellent qualities to be used as raw materials rich in kaolinite. Kaolinite when is submitted to heat give two stable phases: mullite and crystobalite. The properties of mullite, such as, low thermal expansion, low dielectric constant and high mechanical resistance, make this material as a good candidate to be applied in electronic products and in structural high temperature uses. In this work, compositions with residue from kaolin, alumina and ball-clay were studied to obtain mullite. The compositions were established starting from proportion between silica and alumina to obtain mullite (2SiO 2 .3Al 2 O 3 ). The samples were made by pressing processing with 27 MPa and sintering at temperatures of 1350 and 1500°C, with heating rate of 10°C/min. Through the results from chemical analysis of the formulated masses, it can be verified that the proportions of the oxides were close to the stoichiometric of the mullite and that the sintering, at studied temperatures, give the formation of mullite, and confirmed by the DRX analysis. The preliminary results showed that the compositions with low alumina content and submitted to a high temperatures, presented the best results.

Planejamento experimental no estudo da maximização do teor de resíduos em blocos e revestimentos cerâmicos

The use of experimental design to the study of mixtures has found a wide range of applications, even in laboratory scale or in industrial development works. Thus, this work has as aim apply the experimental design used in the study of mixtures to evaluate the suitability of use kaolin processing waste and granite sawing waste together for the production of ceramic bricks and tiles. Based on the raw materials, specific formulations were developed using the experimental design. The raw materials were mixed and sample bodies were produced using extrusion and uniaxial pressing. The sample bodies were fired and characterized in terms of water absorption and mechanical strength. Regression models were adjusted relating the water absorption and mechanical strength with the amount of raw materials. The results showed that the methodology of experimental design maximize the content of wastes incorporated in ceramic bricks and tiles formulations. Formulations containing up to 50% waste can be used for the production of ceramic bricks, and formulations, which contained up to 40% of waste can be used for the production of ceramic tiles.

Utilização do resíduo do beneficiamento do caulim para a produção de corpos mulíticos

In the last few years, mineral extraction and processing industries have been mentioned as sources of environmental contamination and pollution. The kaolin processing industry around the world generates large amounts of wastes. This work evaluated the kaolin processing waste suitability as alternative ceramic raw material for the production of mullite bodies. Several formulations composed of kaolin waste and alumina were prepared and homogenized in a ball mill. Test specimens were obtained by uniaxial pressing and sintering at different temperatures. Fired samples were microstructurally analyzed by X-ray diffraction. Sintered samples were characterized to determine their water absorption, apparent density, firing shrinkage and modulus of rupture. The results indicated that the amount of waste in the composition dictates the firing temperature, and that extremely high firing temperatures may lead to overfiring. Mullite formulations with more than 40% of kaolin waste could be used for the production of bodies with high strength, of about 75MPa.

Influence of Firing Conditions on Properties of Red Ceramic

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

Use of Kaolin Processing Waste for the Production of Mullite Bodies

Mullite is a versatile material used in traditional and advanced ceramic, due to low thermal expansion, high thermal shock and creep resistance. The production of waste from ore industry is a problem that is increasing nowadays. The kaolin processing industry produces residue rich in Al2O3 and SiO2. These oxides are good precursors to produce mullite. The aim of this work is to use the residue from kaolin industry to produce mullite ceramic bodies. It was studied alumina, clay and residue from kaolin processing as raw materials. The material was dried and pressing in uniaxial press (30MPa). The samples were sintered at temperatures of 1450oC, 1500oC, 1550oC and 1600oC. The ceramic bodies were characterized by X-ray diffraction. The density was measured by Archimedes method and the flexural strength by the three point bending technique. The results showed that is possible to produce mullite with high amount of waste from kaolin processing.