Liszandra Fernanda Araújo Campos

Influência das variáveis de processo na obtenção de argilas organofílicas

As argilas bentoniticas, usadas como agente viscosificante e nanocompositos, nao podem ser usadas sem um previo tratamento orgânico para que suas superficies se tornem hidrofobicas e possam ser dispersas em meios orgânicos. Estas argilas depois de tratadas sao chamadas de argilas organofilicas, e sao geralmente obtidas atraves da adicao, em meio aquoso, de um agente organofilizante, geralmente um tensoativo, ionico, anfotero ou nao ionico. O processo de organofilizacao, composto de varias etapas, nem sempre garante a obtencao de argilas organofilicas de boa qualidade, sendo importante destacar as variaveis de processo bem como a escolha das materias-primas a serem utilizadas. Propoe-se entao um estudo detalhado das variaveis envolvidas no processo de dispersao das argilas bentoniticas, e tambem no processo de organofilizacao procurando relacionar as viscosidades aparente e plastica das dispersoes argilosas com a eficiencia do processo de organofilizacao. O processo de organofilizacao sera controlado pelos resultados de difracao de raios X e termogravimetria. As variaveis de processo tanto envolvidas na dispersao das argilas quanto na organofilizacao, do ponto de vista da caracterizacao, nao tem grande influencia na incorporacao do tensoativo as argilas bentoniticas, sendo influentes o tipo de argila e tensoativo e a presenca de sodio como agente defloculante, o que e muito importante de vista industrial pela melhor operacionalidade das condicoes de processamento.

Study of the Effect of Feldspar Replacement from a Mixture of Glass / Syenite in Technological Properties of Ceramic Coatings

Obtaining new raw materials for the production of ceramic coating is increasingly highlighted, however, it is desirable to maintain or improve the technological properties of the formed product. Thinking about it, and aiming at the environmental context, the aim of this work is to study the mixing recycled glass effect with syenite, an alternative melting often used in the production of ceramic tiles, in replacing to feldspar. The raw materials were characterized and subsequently the technological properties were determined for the standard formulation and the formulations with 5, 10, 15 and 20% mixing glass / syenite, in replacing to feldspar. The test bodies were prepared by wet, and sintered at different temperatures, with a rate of 30 °C /min and a level of 20 minutes. The results indicate that the mixing glass / syenite has the potential to be used as melting material in the composition of the ceramic mass.

The Incorporation of the Ceramic Industry Firewood Ash into Clayey Ceramic

Much industrial waste has mineralogical, chemical and physical characteristics similar to clays used in ceramic materials, enabling the reuse of these as raw materials in the ceramic industry. The ashes are a type of waste containing metals, which can cause air pollution, responsible for serious respiratory problems in the affected population. This study investigate the use of waste derived from the carbonization of a solid fuel (wood) in ceramic paste used for the manufacture of rustic floors, aiming its incorporation into the mix, partially replacing (lessening the environmental problem) the usage of raw material (saving clay), enabling the analysis of certain variables of sample preparation (characterization and formulation) and their influence on the final properties of the material. Results indicate that the partial replacement of clay by ash is feasible in the chemical and mineralogical aspects in the formulation of ceramic paste in the manufacturing of rustic floors.

Estudo da incorporação de pó de concha de marisco em massa de porcelanato

The fishing of shellfish is one of the most important commercial activities of the fishing community of the municipality of Cabedelo (Paraíba, Brazil). The step of processing, after the extraction of the mollusk, generates a large amount of shells, whose discharge, in considerable volume, causes silting of large areas and consequent environmental imbalance. In the search for the use of these residues (mollusk shells) and aiming at reducing the environmental problems caused, this work had the aim of studying the incorporation of mollusk shell powder in the mass of porcelain tile. Ceramic compositions were formulated from an industrial standard mass and mollusk shell powder or commercial CaCO3 ranging from 0 to 7% by weight. Samples prepared by uniaxial pressing had their technological properties evaluated as a function of the sintering temperature. The results indicated that the use of up to 7 wt% of the mollusk shell powder maintains the technological properties within the standards required by the ABNT (Brazil) for classification as BIa type porcelain tiles.

Modelagem de propriedades reológicas de argilas esmectitas do estado da Paraíba para uso em fluidos de perfuração de poços de petróleo

Atualmente mais de 79% das argilas bentoniticas industrializadas sao oriundas das jazidas de Boa Vista, PB. Estes jazimentos vem sendo minerados de forma desordenada ha mais de 40 anos, resultando no esgotamento das variedades mais nobres, havendo serio prejuizo para qualidade do produto final. As empresas mineradoras impoem rigidas condicoes de comercializacao para os produtores, condicionando a aquisicao das variedades menos nobres junto as variedades que ainda apresentam propriedades mais adequadas e frequentemente as variedades menos nobres sao descartadas no processo produtivo. Este trabalho teve o objetivo otimizar as propriedades reologicas das novas ocorrencias de argilas bentoniticas do estado da Paraiba, utilizando a tecnica de planejamento experimental de misturas, a fim de adequa-las as exigencias da Petrobras e da industria nacional. As argilas utilizadas foram provenientes dos municipios de Olivedos e Boa Vista, PB. As amostras de argilas foram misturadas utilizando a tecnica mencionada e caracterizadas fisica, quimica, termica e mineralogicamente. Apos caracterizacao as argilas foram transformadas em sodicas e foram determinadas suas propriedades reologicas para uso em perfuracao de pocos de petroleo de acordo com a norma da Petrobras. As variaveis respostas, viscosidade aparente, viscosidade plastica e volume de filtrado, foram avaliadas mediante analises das superficies de respostas. Os resultados obtidos evidenciaram que as argilas estudadas sao promissoras para usos em fluidos de perfuracao. Observaram-se ainda melhoras significativas de suas reologias apos mistura com as argilas de Boa Vista, PB.

Synthesis of Alpha Alumina Using Microwave Energy

This work investigated the synthesis of α-alumina using dissolution and re-precipitation of aluminum nitrate and microwave heating. The synthesized powders were characterized by X-ray diffraction, thermal analysis (TGA and DTA) and surface are by BET. The dissolution process was carried out using acid solution and heat treatment. Results depicted the efficiency of the process to accelerating the synthesis of alpha alumina. The results showed that the powders have the microwave structure of α-alumina with specific areas ranging between 3 and 15m2/g and pore diameters between 190 to 485nm.

Improvement of Rheological Properties of Little Noble Varieties from Boa Vista Bentonites - Part I: Experimental Design

The noble variety of the Boa Vista bentonites became scarce, originating fluids which do not answer the Petrobras specifications. The utilization of a blending with available samples have been used in industry successfully. Thus, the present work aims to use the mixture modeling methodology with design in simplex-centroid network and further purification by hydrocycloning, trying to optimize rheological properties of dispersions prepared with little noble clays, obtaining drilling fluids that attend the normative requirements. Initially, the rheological behavior of dispersions on each of the five clays, activating them in proportions of 50, 75, 100, 125 e 150 meq of Na2CO3/100 g of dry clay. After result analyzing, the mixtures were formulated, using experimental planning with the five clays, but with activation in proportions of 100 and 125 meq of Na2CO3/100 g of dry clay.

Synthesis of Alumina Using Aluminum Acetate

Alumina is a material used in a wide range of applications, including refractories, structural materials, sensors, catalysts, etc. Several synthesis methods are available for the production of submicrometric and nanometric alpha alumina. However, there is few studies on the use of acetate for the synthesis of alumina. Thus, the present work has as aim the synthesis of alumina powders using aluminum acetate. The precursors were obtained from the decomposition of aluminum acetate under temperatures of 650oC and 850oC, resulting in an amorphous precursors and gamma-alumina. These materials were submitted to dissolution and calcination. Based on the results, it is observed a reduced in the temperature formation of alpha phase, at around 900oC, when using the adopted methodology of synthesis. Amorphous precursor was more susceptible to the synthesis procedure used and generated alpha alumina in lower temperatures.

Influência da expansão por umidade no comportamento mecânico de argilas para uso em blocos de cerâmica vermelha - revisão

Moisture expansion (ME) phenomenon results from the action of water and water vapors causing the expansion of ceramic materials, which may damage the material damage and jeopardize its useful life. In literature there is much emphasis on problems generated by the ME and the tensions resulting from this expansion, but until now there is a lack of data on mechanical behavior of ceramics after ME. Recent works in UFCG specifically deal with this problem in ceramic bricks. Initially it was found that in the case of ceramic bodies for use in red ceramic burned at different temperatures, ranging from 700 to 1100 oC with ME induced by soaking, boiling and autoclaving, the ME correlated with the mechanical behavior of burned bodies, and a reduction in modulus of rupture with the rising of ME was observed. Researches undertaken with compositions developed using clay and calcium carbonate and magnesium carbonate as adds for red ceramic, burned from 850 to 1000 °C, showed the beneficial effect of calcium carbonate in reducing moisture expansion and rise modulus of rupture. Correlations between ME and modulus of rupture, was observed when calcium carbonate was used as additive. However, this associations was noted when magnesium carbonate was used as additive. Works carried out using fine quartz as additive of red ceramic compositions and aiming glassy phases development not observed well defined correlations between ME and modulus of rupture. The addition of 10 and 20% of fine quartz improve the mechanical strength of ceramic bodies after autoclaving and that the addition of 30% of quartz decreases its mechanical strength.

Composição de argilas organofílicas obtida com tensoativo não-iônico para fluidos de perfuração base orgânica

INTRODUCAOAs argilas organofilicas foram introduzidas nos fluidos de perfuracao na decada de cinquenta do seculo passado, atuando como controladores da reologia do sistema [1]. Essas argilas sao produzidas, em geral, a partir da reacao de troca cationica de uma argila (hidrofilica) com sais quaternarios de amina ou de amonio [2]. As argilas organofilicas quando dispersa no meio oleofilico promove a capacidade de gelificacao do fluido de perfuracao, em virtude da caracteristica tixotropica da argila [3], sendo utilizadas em concentracoes de 2,0 a 15 lb/bbl (0,0057 a 0,0427 g/mL), dependendo da densidade do fluido formulado [1]. Os fluidos de perfuracao consistem em uma fase liquida continua, tratada quimicamente de forma a adequar suas propriedades as operacoes de perfuracao [4-6]. Suas propriedades principais sao massa especifica (na pratica de fluidos de perfuracao, ha certa imprecisao na nomenclatura, como por exemplo: os termos densidade, massa especifica e peso especifico. Que serao utilizados indistintamente neste texto com o significado de massa especifica), viscosidade, homogeneidade, reatividade, filtrado e salinidade. Os fluidos de perfuracao em relacao ao meio dispersante liquido podem ser de dois tipos: fluidos base de agua e fluidos base orgânica. Os fluidos base orgânica sao formados por uma emulsao na qual a fase continua e um liquido nao aquoso e agua saturada com NaCl, tendo como fase solida argilas organofilicas. Dentre o grande numero de composicoes de argilas organofilicas (argila mais componente orgânico) pesquisadas, as de maior importância industrial sao as