Navegando por Assunto "Transformation of natural resources"

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Acesso aberto (Open Access)
Desenvolvimento de unidade piloto de transferência de massa gás/líquido: redução da reatividade do resíduo da indústria de alumina através da reação com gases de combustão
(Universidade Federal do Pará, 2013-02) VENANCIO, Luis Carlos Alves; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
The bauxite refining using the Bayer process produces 0.7 to 2.0 tons of the residue known as red mud and about 1.0 ton of CO2 for each ton of alumina produced. The bauxite residue, although not particularly toxic, poses risks to the environment due to its large volume and reactivity. According to the latest technology, part of the moisture is removed and it is stacked on sealed areas specially constructed. More than 95% of the bauxite residue that has been produced (2.6 Bt until 2007) was discarded, especially in ponds on land. This thesis shows the design, construction and operation of a pilot scale gas liquid mass transfer unity with the objective of testing the reduction of the reactivity of the bauxite residue through a reaction with flue gas. As an additional gain, there is a reduction of carbon dioxide and sulfur dioxide emissions. This unity, with three reactors, was designed in order to consume minimal power, process the effluent as efficiently as possible and minimize the investment cost. Twenty-five experiments were realized with duration from 80 to 520 minutes each. The gases were analyzed at the entry and exit with electrochemical cells and non-dispersive infrared sensors. The pH was monitored during and after the reaction in order to evaluate the short and long-term results as well as the stability of the reactions. It was demonstrated the viability of reacting the bauxite residue with the flue gas from the refinery without previous processing with the stabilization pH reaching 10.5.
Acesso aberto (Open Access)
Estudo da magnetohidrodinâmica em dutos usando transformadas integrais
(Universidade Federal do Pará, 2015-11-27) LOBATO, Benedito; SOUZA, Marcelo José Raiol; http://lattes.cnpq.br/2980566423137880; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
The present work presents the study of magnetohydrodinamics for the outflow of fluids in ducts with different geometric shapes. The integral transforms technics, in this case GITT, were used to obtain solutions of the momentum and energy transfer equations. In each case a hybrid (analytical-numerical) solution was obtained, and they were treated with computational codes that allowed the analysis of the velocity, temperature and entropy fields. The results were compared with the results obtained in classic situations of the literature and also with the actual results, showing the efficiency and capacity of the utilized technique.
Acesso aberto (Open Access)
Estudo e avaliação do uso de resíduos do processo Bayer como matéria-prima na produção de agregados sintéticos para a construção civil
(Universidade Federal do Pará, 2010-03) SOUZA, José Antônio da Silva; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785
The large amount of solid waste coming from mines and metallurgical industries became a serious social-environmental problem. The physical and chemical features of this material can raise a great interest in other industries. The ceramic industry might be a great costumer for most of this material, since it can supply the current lack of raw material. The red mud, main industrial residue of the alumina manufacturing, has been a very interesting input for several kinds of aggregates manufacturing used for the concrete production in civil engineering. In this context, this paper deals with studies concerning the red mud recycling to be applied as raw material for the synthetic light aggregate production to be used as an alternative material in the civil construction industry. This is because of its physical-chemical features and the large amount annually produced (around 10 million tons within two factories in the North of Brazil). The studies completed in this work show the feasibility of aggregates manufacturing, with different properties and possibilities. These properties depend on the parameters control such as content of free silica and clay, and the sintering temperature. Such variables allow to perfectly controlling the glassy phase formation which is responsible for the aggregate properties such as: porosity, mechanical resistance and density. This material can be used for conventional or special concretes to supply the civil engineering needs.
Acesso aberto (Open Access)
Obtenção e caracterização de ligas de ouro aplicadas ao setor joalheiro no estado do Pará
(Universidade Federal do Pará, 2014-06) MAIA, Raimunda Figueiredo da Silva; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; SÁ, Fernando Antonio de; http://lattes.cnpq.br/8275621144223544
Gold has main application as adornment in jewelry pieces but in its pure state doesn’t have the hardness required for this use, being generally fused with other metals to form alloys. The aim of this research was to elaborate and characterize optical, structural and mechanical properties of gold alloys and introduce the use of intermetallic Au-20% Al, seeking to improve the production of jewelry industry. Four (4) gold alloys were prepared: one (1) intermetallic Au-20% Al violet colored and three (3) with usual coloration in jewelry manufacture (Au-25% Ag - light green, Au-12,5% Cu - red, Au-12,5% Ag-12,5% Cu - yellow). Au-20% Al alloy was produced in microproducers of the state of Pará workshops, while the others were fused in Materials Laboratory of Chemical Engineering School in Federal University of Pará (UFPA). The structural properties were analyzed by optical microscopy (OM) and scanning electron microscopy (SEM). The results revealed dendritic cell structure for Au-25% Ag and Au-12,5% Cu alloys, dendritic structure for Au-12,5% Ag-12,5% Cu alloy and cellular structure for Au-20% Al alloy. The mechanical properties were obtained through Vickers microhardness tests, evidencing the highest hardness for Au-20% Al alloy, intermetallic of AX2 type. The optical properties evaluated by colorimetric tests showed visible light spectrum in the range from violet color (Au-20% Al), greenish yellow (Au-25% Ag), red (Au-12,5% Cu) and yellow (Au-12,5% Ag-12,5% Cu).
Acesso aberto (Open Access)
Solução de equações de balanço populacional usando a técnica da transformada de Laplace e filtro de partículas
(Universidade Federal do Pará, 2011-12) BATISTA, Clauderino da Silva; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785
The evolution of particle size distribution in many fields of applied science, such as crystallization, aerosols, colloids, and polymer processing, can be obtained by solving population balance equation (PBE). The Laplace transform technique with numerical inversion was used to solve an integro-partial-differential equation related to the mathematical modeling of the physical problem to study convective processes with birth and death rates of particles or aerosols. Such model is governed by the population balance equation (PBE), in which is taken into account the nucleation, growth and coagulation processes. A Bayesian method was employed to solve the hyperbolic and non-linear inverse problem and estimate the size distribution density function, thus predicting the dynamic behavior of the physical system. Specifically the particle filter with sampling Importance Resampling (SIR) has been applied as a method of solving the problem. From these solutions, numerical results were obtained and compared with those in the literature for particulate systems permitting a critical evaluation of the present solution methodology.