Navegando por Assunto "Kaolin waste"

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Acesso aberto (Open Access)
Cimentos de baixo impacto ambiental (LC3 ) a partir dos resíduos cauliníticos da Amazônia
(Universidade Federal do Pará, 2020-02-02) ARRUDA JUNIOR, Euler Santos; BARATA, Márcio Santos; http://lattes.cnpq.br/7450171369766897; https://orcid.org/0000-0002-0012-3778
The use of mineral additions as a partial replacement of clinker in Portland cement has been one of the main strategies for reducing CO2 emissions by the global cement industry. However, the availability of blast furnaces and fly ash does not meet demand. In the Amazon, the kaolin processing industries as a cover for paper have already deposited around 70 million tons of waste consisting essentially of extremely fine kaolinite. An alternative for the region would be the use of Portland cement with mineral additions of limestone and calcined clay for the production of a low CO2 cement - LC3 (limestone calcined clay cement). The objective of this work was to evaluate the properties of these LC3 cements with high incorporations of limestone and metakaolin from the kaolin processing residue. The levels of substitution of mineral additions on the common Portland cement mass were 45% and 60%. The investigated variables were specific mass, specific surface area Blaine, water of consistency and time of initial and final setting of the cement, in addition to the resistance to mortar compression. The incorporations of the metakaolin-lime mixtures increased the water demand and reduced the setting times due to the high fineness of the kaolinite. However, there were significant increases in compressive strength compared to common and compound Portland cements, demonstrating the high efficiency of this binder which reached compressive strength of up to 62.3 MPa at 91 days. As for the carbon footprint produced by LC3 cements. The results showed a 20% to 38% reduction in CO2 emissions compared to CPII F 40. Furthermore, the wide applicability of the LCA tool to the construction sector was evidenced. The results are promising, but require further studies, especially with regard to the aspects of rheology, durability in view of the high water demand of these cements, high tendency to retraction and low alkalinity and, mainly, regarding economic viability when combined with other actions to mitigate emissions such as increasing energy efficiency combined with the use of alternative fuels.
Acesso aberto (Open Access)
Desenvolvimento de processo de zeólita A utilizando o caulim da Amazônia e aplicação na adsorção de Cu+2
(Universidade Federal do Pará, 2014-08-22) MORAES, Cristiane Gomes; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
Around the world millions of tons of inorganic waste are produced every day in mining and mineral processing. These wastes are stored in sedimentation basins or discarded in landfills, and very often are thrown directly into the environment without any treatment process. However, alternative recycling and/or reuse should be investigated and, where possible. This work shows studies in order to reuse the kaolin waste from Amazon, from a kaolin processing company for paper covering. For the synthesis of the zeolite in static and dynamic hydrothermal processes, was used as the silicon source and the aluminum kaolin waste, which passed through the calcination procedure in a muffle at 600°C to obtain metakaolin; and as sodium source chose to 5M sodium hydroxide solution. In the static method was used stainless steel autoclaves, in an oven at 110°C, using 1,75g of metakaolin, varying the time of synthesis and the mass of sodium hydroxide and the dynamic process, we used 100g of metakaolin, mass 34,5g sodium hydroxide; at 95°C under stirring system, varying the time of synthesis, in order to determine the optimal conditions in the synthesis of the zeolite in the process. Matches materials and zeolitic products obtained in the syntheses were characterized by: X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis and thermogravimetric (DTA/TG), X-ray fluorescence (XRF) and particle size analysis. There is the possibility of scale-up, since the zeolite obtained, the dynamic process in time of 30 min. Data from adsorption experiments determined by iodometric technique copper alloys and metal and minerals, adjusted by Langmuir and Freundlich suggest that the static and dynamic zeolitic materials have good adsorptive capacity reached 95% efficiency for concentrations in the range of 50 to 100mg/L, thereby demonstrating that these materials are efficient and cost effective alternative when used for the removal of heavy metals, in the case of copper, the treatment of industrial effluents.