Dissertações em Engenharia Química (Mestrado) - PPGEQ/ITEC

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2309

O Mestrado Acadêmico iniciou-se em 1992 e pertence ao Programa de Pós-Graduação em Engenharia Química (PPGEQ) do Instituto de Tecnologia (ITEC) da Universidade Federal do Pará (UFPA).

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Acesso aberto (Open Access)
Influência da granulometria e de aditivos no comportamento reológico do rejeito de lavagem da bauxita
(Universidade Federal do Pará, 2014-03-13) GONÇALVES, Silvane Gonçalves e; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; FELIPE, Augusta Maria Paulain Ferreira; http://lattes.cnpq.br/8871741271063047
In the bauxite mining in Parogominas-PA city, tailings are discarded in the processing with 33,5% of solids content and small granulometry with D50 below 5 μm. These factors contribute to this suspension basically formed by sílico aluminates, with high concentrations of kaolinite clay, have high viscosity and high initial tension flow. It was performed granulometric analysis and determined the chemical and mineralogical composition of the material. The granulometric analysis was made by wet sieving and the small particles were determined by laser diffraction. The determination of the chemical composition was made by Fluorescence Spectrometry X-ray, identifying considerable amounts of alumina available, 21,28%. The mineralogical composition was determined by X-ray diffraction (XRD), obtaining gibbsite, hematite, quartz and kaolinite. It was performed the determination of the friction factors pulp, using equation to fluids that have Herschel-Bulkley behavior and using the Dodge and Metzner correlations. It was used VT550 viscosimeter, with coaxial cylinder sensorSV1, to make defloculation and flocculation test using different rheological additives. The additives used were: sodium hexametaphosphate, hydroxamate, aluminum sulphate, sodium polyacrylate and 25% anionic polyacrylamide. The trials were realized in shear rate of 100 s-1, time 20s and temperature of 32ºC.It was performed also, analysis of viscosity of pulps with different pH and in samples less 38μm (400# Tyler), with the objective of evaluate how the particle size and pH influenced in the behavior of additives. The study showed that particle size and pH influence on the behavior of additives, because if the particle size is very small better is the behavior of the additive. The behaviors of the additives as flocculation or defloculation depend of the pH.
Acesso aberto (Open Access)
Influência do teor de cinza volante na reologia de argamassa de assentamento: fabricado com reciclagem de resíduos
(Universidade Federal do Pará, 2014-02-05) CARDOSO, Dilson Nazareno Pereira; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; FELIPE, Augusta Maria Paulain Ferreira; http://lattes.cnpq.br/8871741271063047
The mortars may be considered as a set of solid suspended particles (aggregate), water and binders (cement slurry). Thus, rheological behavior during cure can be influenced by factors such as particle size, composition and content of corporate water. This study investigated the rheological properties of six mortars, depending on the content of fly ash as a pozzolanic activity material, partial replacement of cement. This type of cement used as an aggregate base construction of the residue (RCC) which was characterized by diffraction and fluorescence X- rays. Were formulated for the mortars with addition of rheological tests residue construction (RCC) in proportions of 95, 90, 85, 80, 75 and 70% fly ash (CV) 0, 5, 10, 15, 20 and 25 % to 5 % of ordinary Portland Cement (PC - II and 32), and in each sample was incorporated 35 % water. We used the model VT 550 viscometer with sensor type coaxial cylinders SV1 - Haake temperature of 28 ºC. To evaluate the curing time of the material has scheduled a constant shear rate 53.4 s-1 for 1h and 45 min, with rated torque at intervals of 15min. For the development of flow curves and hysteresis curves, we used the shear rate between 0 and 600 s-1 in the time interval of 120 s. The results showed that the incorporation of fly ash is the main factor for increased torque on the curing time of mortar and behavior change reópetico for thixotropic, the traits analyzed. The experimental data of the proposed formulations are adjusted to the rheological model of Herschel - Bulkley.

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