Logo PUC-Rio Logo Maxwell
ETDs @PUC-Rio
Estatística
Título: CONTRIBUTION AT CARBOTHERMIC SELF-REDUCTION OF AGGLOMERATES OF MANGANESE OXIDES
Autor: FERRY SABEL BELISARIO BENIQUE
Colaborador(es): JOSE CARLOS D ABREU - Orientador
Catalogação: 13/DEZ/2007 Língua(s): PORTUGUESE - BRAZIL
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.
Referência(s): [pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=11024&idi=1
[en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=11024&idi=2
DOI: https://doi.org/10.17771/PUCRio.acad.11024
Resumo:
In this work, aiming at the investigation on the reduction process of manganese dioxide to manganese oxide, experiments were made using selfreducing briquettes containing manganese oxides and charcoal, at temperatures ranging from 900 to 1300oC. A general overview of the manganese is presented, indicating its principal products such as, the farming usage of MnO and the steelmaking application of the FeMn alloys, also emphasizing the thermodynamical and kinectical aspects of their productions. It is worthwhile to emphasize that MnO is an intermediary product in the production of the FeMn alloy. Experimental details concerning materials characterization and discussion on the obtained results, are also presented. In the determination of the MnO conversion the complexometric titration with EDTA chemical procedure was applied. From these determinations a model was proposed for the calculation of the kinectic parameters. The experimental results of reduction, from Mn+4 towards Mn+2 , it was possible to identify two stages for the reactions in the temperature range from 900 to 1300 C. An onset stage was marked by high reaction rates, lasting for the first 10 minutes, achieving high MnO conversions. In the experiments carried out in the range of 1000 to 1200oC, for instance, a 0,94 conversion was attained within just 10 minutes. As for the second stage, beginning after 10 minutes, the conversion showed a decrease, suggesting that the product of the first stage, the MnO, could be suffering a transformation, generating an other substance - probably Mn3C. Being this a new process, out of the scope of this work, its elucidation is left here as a suggestion for later works. Wrapping up the kinetic model, a time frontier between the two processes, around 10 minutes, was considered . Below this limit, i.e., in the temperatures - 1000, 1100, 1150 and 1200oC -, the process exhibited an apparent activation energy of 11.50 kJ x mol -1 and a pre-exponential frequency factor of 57 µHz, inferring a diffusion control. As for times beyond 10 minutes, in experiments at 900, 1000, 1100, 1150, 1200 e 1300°C, though the nature of a new compound was not probed - possibly a manganese carbide - it was possible to measure a new apparent activation energy, 46.10 kJ x mol -1 , with a pre- exponential frequency factor of 48 Hz, values coherent with a mixed control, i.e., between the diffusional and the chemical mechanisms.
Descrição: Arquivo:   
COVER, ACKNOWLEDGEMENTS, RESUMO, ABSTRACT, SUMMARY AND LISTS PDF    
CHAPTER 1 PDF    
CHAPTER 2 PDF    
CHAPTER 3 PDF    
CHAPTER 4 PDF    
CHAPTER 5 PDF    
CHAPTER 6 PDF    
CHAPTER 7 PDF    
CHAPTER 8 PDF    
CHAPTER 9 PDF    
REFERENCES AND APPENDICES PDF