H. S. Ferreira

The use of granite wastes as ceramic raw materials

The granite industry generates a large quantity of wastes that pollute and damage the environment. This work aim to characterize and evaluate the possibilities of the use of granite sawing wastes, generated by the industries from Northeast region, as alternative ceramic raw materials for production of ceramic bricks and tiles. Samples of granite sawing wastes were collected from industries located at Paraiba, Ceara and Pernambuco states, and afterwards were characterized for the determination of their particle size distribution, specific mass, surface area (BET) and chemical analyses, differential thermal analysis, GTA, X-ray diffraction, and scanning electron microscopy. After characterization, technological tests were performed in ceramic compositions with the objective of evaluation of the possibilities of the addition of wastes in ceramic masses for the production of ceramic bricks and tiles. The main results show that the wastes have physical and mineralogical characteristics similar to the conventional ceramic raw materials and ceramic bodies. Moreover, the ceramic pieces prepared using the wastes have technical characteristics according to the Brazilian standards for ceramic bricks and tiles.

Studies of new occurrences of bentonite clays in the State of Paraíba for use in water based drilling fluids

New bentonite clay deposits have recently been discovered in the state of Paraiba, mainly in the municipalities of Cubati and Pedra Lavrada, creating great expectations in view of the possibility of expanding industrial production using these new reserves. The aim of this study was to study the new occurrences of bentonite clay in Paraiba, particularly in the municipality of Pedra Lavrada, for use in water based drilling fluids. The mineralogical properties of the clays were characterized by particle size analysis using laser diffraction, and thermogravimetric and differential thermal analysis, and its chemical composition was analyzed by X-ray fluorescence, X-ray diffraction, cation exchange capacity and specific surface area. The bentonite clays were treated with sodium carbonate at concentrations of 75, 100, 125, 150 and 175mEq/100g of dry clay, to transform them from polycationic to sodium form. For the technological characterization, drilling fluids were prepared according to the standards of Petrobras. The results indicated that the mineralogical composition of the samples consisted of montmorillonite, kaolinite and quartz. As for their rheological properties, the samples were found to partially meet the rheological requirements of the Petrobras standard.

Sais solúveis e eflorescência em blocos cerâmicos e outros materiais de construção - revisão

Eflorescencias sao depositos salinos que se formam na superficie de materiais cerâmicos, resultantes da migracao e posterior evaporacao de solucoes aquosas salinizadas. As eflorescencias trazem em si um problema mais de ordem estetica do que estrutural, no entanto, por se tratar de um fenomeno complexo e com reflexos economicos preocupa fabricantes e construtores. Os sais soluveis que dao origem as eflorescencias podem ter varias origens, dentre elas as materias-primas, os materiais de construcao, a agua existente no subsolo, etc. Assim, este trabalho tem por objetivo o estudo dos sais soluveis e eflorescencias em materiais de construcao cerâmicos e nao cerâmicos, com enfase nos trabalhos experimentais que foram recentemente desenvolvidos na Universidade Federal de Campina Grande, PB. Foram utilizadas amostras de argilas, tijolos, britas, areias e massames oriundas de varias regioes do Estado da Paraiba. A quantidade de sais soluveis nos materiais foi determinada utilizando-se a condutividade eletrica de seus extratos. Os ensaios de eflorescencia foram conduzidos segundo a metodologia da ASTM. Pode-se observar que nao ha uma correlacao bem definida entre o teor de sais soluveis das materias-primas e o nivel de eflorescencia das pecas cerâmicas. O teor de 0,025% de sais soluveis nos corpos cerâmicos aparenta ser um limite adequado para avaliar a aptidao, ou nao, das pecas para apresentarem eflorescencias.The deposition of salts on the surface of ceramic materials is called efflorescence. It is resulted from the migration and evaporation of aqueous saline solutions. The efflorescence is basically an aesthetic problem, but due to be a complex phenomenon with economical consequences it worries manufactures and building constructors. Raw materials, building materials, subsoil water, can be the source of soluble salts, which generate the efflorescence. This work is based on studies recently developed at the Federal University of Campina Grande, and has as aim analyze the soluble salts and efflorescence characteristics of ceramic and non-ceramic building materials. Samples of clays, bricks, and other building materials, from several parts from the State of Paraiba, were used in the study. The amount of soluble salts in the materials was determined using the electrical conductivity of its extracts. The efflorescence test was conducted according to the ASTM methodology. Based on the results was not observed a well-defined correlation between the amount of soluble salts of the raw materials and the efflorescence level. The content of 0.025% of soluble salts is a limit that offers a good indication of the materials susceptibility to efflorescence.

Análise da expansão por umidade e absorção de água de pisos cerâmicos comerciais em relação à composição química e à quantidade estimada de fase vítrea

Moisture expansion is the size increase of the ceramic body due to water adsorption and can have a great influence in the ceramic material service life. This work aims to relate the moisture expansion and water absorption of commercial ceramic tiles with their chemical composition and estimated glassy phase content, calculated from the phase equilibrium diagram of the system SiO2.Al2O3.K2 O using the lever rule. Samples of twenty three commercial ceramic tiles were studied. The chemical composition of the samples was obtained (wet route) and their moisture expansion and water absorption were determined (according to the Brazilian standard NBR 13818). The specific surface area of some samples was also determined, using the nitrogen adsorption methodology (BET). The results obtained generally show an inverse proportionality between the moisture expansion and the water absorption, for the majority of the samples. The analysis using the phase diagram suggests an inverse proportionality between the water absorption and the estimated glassy phase content and a direct proportionality between the moisture expansion and the quantity of glassy phase.

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.

Development of Organoclays for Use in Oil-Based Drilling Fluids

The organoclays are derived from bentonite clays treated in aqueous solution with surfactants, which are incorporated into the interlayer surface of clays, covering them with an organic layer; so, the naturally hydrophilic clay becomes hydrophobic. This paper proposes a study to find the dispersant media (diesel, paraffin or ester) which is more suitable for use in fluids, using the bentonite clay Cloisite Na +, treated with ionic surfactants Praepagen HY and Praepagen WB. The organoclay obtained was characterized by X-ray diffraction, and we measured the apparent viscosity and plastic dispersions. We observed the importance of the type of surfactant and dispersant amid to obtain organoclays for non-aqueous drilling fluids with the dispersants that meet existing specifications for drilling oil wells.

Estudo da durabilidade de argamassas alternativas contendo resíduos

O interesse pela preservacao dos recursos naturais e a busca pelo desenvolvimento sustentavel tem despertado interesse de um grande numero de pesquisadores visando obter materiais de construcao nao convencionais. Dentre essas possibilidades, destacam-se os residuos produzidos pela construcao civil e pela industria de beneficiamento de granito, em virtude do volume gerado e os impactos ambientais do seu descarte inadequado. Este trabalho tem como objetivo estudar a durabilidade das argamassas alternativas incorporadas com residuos de construcao civil e da serragem do granito. Para quantificar a durabilidade dos materiais estudados, foram realizados ensaios de envelhecimento natural e ensaios de envelhecimento acelerado atraves de ciclos de molhagem e secagem, visando simular condicoes de utilizacao e avaliar sua degradacao. Nos estudos da durabilidade foram utilizados tracos de argamassas para alvenaria de elevacao, com percentagens de substituicao, em peso, da cal por residuo de 30% e 50%. Os resultados para o envelhecimento natural evidenciaram o comprometimento da durabilidade do material apos 60 dias com reducao no comportamento mecânico, sendo os melhores resultados para os corpos-de-prova com 30% e 50% de residuo de construcao. No envelhecimento acelerado, para os tratamentos adotados, os resultados evidenciaram a acao da formacao de silicoaluminatos de calcio e potassio que favoreceram um aumento do comportamento mecânico e, alem disso, nao foi observado o comprometimento da sua durabilidade.

Estudo da sorção de tensoativos orgânicos em argilas bentoníticas

Techniques for obtaining organoclays have been studied by many researchers, intending to optimize the preparation process and to ensure a good quality product. These studies are based on the fact that such clays present a wide range of applications in engineering. However, works that emphasize the chemical study of these processes are less frequent. Thus, the main objective of this work was to study the sorption of ionic and non-ionic surfactants in bentonite clays. In organophilization process the Brasgel clay was used, with two surfactants, TA 50 (with 100% active matter) and WB (with 81.26% active matter). In dispersions five different concentrations (%w/w) of clay from 3.16% to 7.16% were used. Each clay concentration was organophilized with four different concentrations of surfactant. The sorption isotherms were constructed using the thermogravimetry data, and adjusted to the linear and Freundlich models. From the isotherms, it was inferred that the mechanisms involved in the sorption are multilayer adsorption (for two surfactants used) and cooperative adsorption (for WB); and the clay content of 3.16% had the higher sorption capacity.

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.

Organofilização de argilas bentoníticas com tensoativos não- iônicos visando seu uso em fluidos de perfuração base óleo

Resumo O uso de tensoativos nao ionicos vem substituindo os tradicionais tensoativos ionicos dentre outros motivos pelo seu elevado potencial de resistencia a degradacao termica. Assim, este trabalho tem por objetivo o desenvolvimento de argilas organofilicas atraves da incorporacao de tensoativos nao ionicos visando seu uso em fluidos de perfuracao de pocos de petroleo base oleo. Argilas bentoniticas natural, industrializadas e organofilizadas foram caracterizadas por analise quimica, difracao de raios X e analises termicas. Apos a organofilizacao foi realizado o inchamento de Foster, visando a escolha dos tensoativos mais adequados aos meios liquidos orgânicos dispersantes: ester, diesel e parafina. Com as dispersoes obtidas foram determinadas as propriedades reologicas atraves de viscosidades aparente e plastica. Os resultados evidenciaram que as argilas organofilicas apresentaram um aumento do espacamento interlamelar e que as dispersoes apresentaram propriedades reologicas dentro das especificacoes da Petrobras, para uso como argilas organofilicas em fluidos de perfuracao em base oleo. Palavras-chave: organofilizacao, argilas bentoniticas, tensoativos nao ionicos.