Título: | DRI CARBURIZATION IN THE TRANSITION AND COOLING ZONES OF MIDREX TYPE REACTORS | |||||||
Autor: |
FERRY SABEL BELISARIO BENIQUE |
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Colaborador(es): |
JOSE CARLOS D ABREU - Orientador |
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Catalogação: | 03/NOV/2021 | Língua(s): | PORTUGUESE - BRAZIL |
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Tipo: | TEXT | Subtipo: | THESIS | |||||
Notas: |
[pt] Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio. [en] All data contained in the documents are the sole responsibility of the authors. The data used in the descriptions of the documents are in conformity with the systems of the administration of PUC-Rio. |
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Referência(s): |
[pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=55598&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=55598&idi=2 |
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DOI: | https://doi.org/10.17771/PUCRio.acad.55598 | |||||||
Resumo: | ||||||||
In later years efforts are being made aiming at the increase in the carbon content in the DRI, this to enable it to act as energy source and reducing agent for the residual oxides in the operation of the electric arc furnaces – EAFs. The present work, product of a cooperative project between the Samarco Mining Co. and the Iron and Steelmaking Group from the University PUC-Rio, presents the obtained results for the experiments on DRI carburization, made at the laboratories of both institutions, under simulated conditions occurring in MIDREX reactors. To mimic the reactor operation, it was divided in three zones, quoting: Reduction, Transition and Cooling. For each of these zones a set of experiments were conceived and statistically planned to permit the carburization kinetic determination. It must be also added that fluidynamic scale similarity were respected in those same experiments. Further, a special chemical method was successfully employed to access the graphitic and free carbon DRI contents for the carburization tests performed for the Transition and Cooling zones. Based on the obtained results, sets of curves for carburization versus time were composed and kinetic equations, for various temperatures and gaseous atmospheres, were proposed. For the Transition zone the carburizing agent was the methane gas, being its injection made under the temperatures of 300, 600, 700 e 850oC. The kinetic model utilized for the carburization in this zone was that of a mass flux linear equation. From this formalism, an apparent activation energy of 12.3 kJ/mol was calculated indicating a difusional control. The total DRI carburization in this zone ranged from 0.1 per cent C (300oC) to 3 per cent C (850oC) for a typical residence time of 0.7 hours. In the Cooling Zone there was a temperature dependency ruling the carburizing agent role, above 400oC the gas methane is the main carburizing gas, but below 500oC the CO act as such. In this zone, the DRI carburization was fitted with a kinetic equation of the first order with respect to carbon. The obtained result for the apparent activation energy for this equation rated 5.31 kJ/mol, consistent with a difusional mechanism. Considering the experimental results for a residence time of 2.15 hours, the final carburization for the DRI in the Cooling Zone ranged from 2.0 per centC ( furnace peripheral conditions / 600oC ) to 3.0 per cent C ( core conditions / 250oC ).
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