Navegando por Assunto "Carbonatação"

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Acesso aberto (Open Access)
Captura de carbono em placas de concreto permeável
(Universidade Federal do Pará, 2020-06-12) SANTOS, Caio José Bastos Marques; CORDEIRO, Luciana de Nazaré Pinheiro; http://lattes.cnpq.br/9126233381230999; https://orcid.org/0000-0001-7931-4042
The production of cement has an impact on the environment from the release of co2 where carbon dioxide acts directly on the phenomenon of "greenhouse effect". Although cement production generates high rates of carbon dioxide, cement hydration products have the ability to reabsorb carbon dioxide from a physical-chemical phenomenon called carbonation. This research related this physical-chemical phenomenon to a material considered sustainable, such as permeable concrete. This type of concrete can be used on non-reinforced floors. The research focuses on analyzing the ability to capture co2in permeable concrete slabs. As for carbonation, mixtures produced with two granulometric bands of pebble and CP II F agglomerate with a/c ratios of 0.33 and 0.37 were analyzed in protected and unprotected environments, and in an accelerated environment in a co2 chamber. A chemical phenolphthalein indicator was used to assess the occurrence of carbonation in five ages of reading and image analysis software to study the carbonated surfaces. The material showed satisfactory results in terms of mechanical, water and carbonation depth parameters, having reabsorbed the atmosphere gas from the cement paste that surrounds the aggregate grains of the material's granular skeleton.
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.