Título: | CONTRIBUTION TO THE STUDY OF THE FORMATION AND REDUCTION OF ZINC FERRITE | |||||||
Autor: |
MERY CECILIA GOMEZ MARROQUIN |
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Colaborador(es): |
JOSE CARLOS D ABREU - Orientador |
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Catalogação: | 28/MAI/2004 | 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=4943&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=4943&idi=2 |
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DOI: | https://doi.org/10.17771/PUCRio.acad.4943 | |||||||
Resumo: | ||||||||
The present work includes initially a bibliographical
revision on the formation and reduction of the zinc
ferrite. Further a thermodynamic and kinetic study was made,
focusing its formation from an equimolar mixture of pure
iron oxide Fe2O3, and pure zinc oxide ZnO, due to the fact
that this substance is often the major constituent in the
electric arc furnace dust. The zinc ferrite that is formed
during the operation of the electric arc furnaces doesn t
necessarily results from an equimolar mixture; it could be
produced from a wide range of constituents compositions.
Initially the equimolar mixture was characterized thermally
(DTA-TGA) and structurally (XRD). The temperature where
this compound began its formation and the quantitative
results regarding the zinc ferrite synthesis conversion
were calculated by the software Topas 2,1 Difracc Plus,
using the Reitveld XRD method. The following experimental
results from the kinetic analysis of the zinc ferrite
formation were obtained: at low temperatures (650-730 Celsius Degree)
the phenomena fitted the interface reaction model, or
topochemical model, being the chemical reaction the control
mechanism. The obtained data in this case was: Ea equal 65,6
kcal / mol and k equal 2,32 x 10-3 K-1. On the other hand, at
high temperatures (750-1000 Celsius Degree) the modified population
growth formalism showed the best fit, being the diffusional
mechanism the controlling process. Again the obtained data
was: Ea equal 16,1 kcal / mol and k equal 570 K-1. Finally a
transition between the two mechanisms was found to happen
at approximate 744 Celsius Degree (mixed control). Several DOPF (phase
predominance operational diagrams) were obtained based
upon the thermodynamic analysis of the Fe2O3 - ZnO mixtures
reduction driven by CO and H2 reducing gases, focusing the
formation and reduction of zinc ferrite compound. For that
purpose the softwares HSC 5,0 and MathCAD 6,0 were
utilized. The DOPF for the systems: Zn-C-O, Zn-H-O, Zn-C-H-
O, Fe-C-H-O and Zn-Fe-C-H-O, considering the activities of
their metallic and their oxides phases, were generated and
discussed.
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