Título: | RECYCLING OF LD DRY DUSTS AND BLAST FURNACE C-CONTAINED RESIDUES IN STEEL BATH AND SELF-REDUCTION PROCESSES | ||||||||||||
Autor: |
JERSON EDWIN ALVARADO QUINTANILLA |
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Colaborador(es): |
JOSE CARLOS D ABREU - Orientador |
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Catalogação: | 27/MAR/2018 | 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=33403&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=33403&idi=2 |
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DOI: | https://doi.org/10.17771/PUCRio.acad.33403 | ||||||||||||
Resumo: | |||||||||||||
The steel dusts (fine-F and coarse-G fractions) generated in the dry dedusting equipment of the LD converter exhaust system, and in the blast furnace-AF dust collector, play a relevant role among secondary materials generated in the various steps of the integrated steelmaking chain, either by the quantities produced and their compositions. Because they mainly contain iron and carbon units and sometimes zinc in their compositions, actually these wastes are being the target of several technological initiatives, aiming to recover or recycle them. Moreover, the particulate materials generated by the LD dry dedusting system, unlike those collected in the wet system of the same LD processes, still lack in-depth studies for recycling. Nowadays briquetting is increasing in importance among agglomeration processes, mainly due to its feature in treat particulate materials with a wide range of size. This thesis studied, in a first stage, the feasibility of manufacturing the so-called simple F-G briquettes, in the proportions of 50-50 and 70-30, respectively, as well as their theoretically and experimentally possibilities to be charged as a ferrous burden in reduction processes and as an alternative material to the scrap and pellets, when used to control the liquid steel temperature in LD converters. In the manufacture of the simple F-G briquettes, was also tested the binders ARI cement and sugarcane molasses, alone or when mixed, taking into account the water / cement ratio of 0,5 and the water / molasses ratio of 0,7. For the briquettes studied in this research, all cure operations lasted for up to 28 days and the compressive strength parameter obtained to evaluate the mechanical quality of the briquettes. The experimental methodology involved the technique of factorial planning, 2(k) levels (minimum and maximum), with three variables (residues, agglomerates and water). The results showed that the compressive strengths of the simple F-G briquettes, when using the cement-molasses mixture, always achieved higher values than that for
briquettes using the cement or molasses separately. Moreover, the higher content of coarser fraction (briquettes 50-50) always leads to higher mechanical resistance than the finer one (70-30). On the other hand, the energy balances showed that the simple F-G briquettes 70-30, have presented the better cooling indexes for the liquid steel temperature control than the 50-50 briquettes. Regarding the second part of the thesis, two types of F-G self-reducing briquettes were also produced, containing stoichiometric and 10 percent excess of BF-collector dusts. After curing, they were tested on compression and reduced in temperatures of 1100 Celsius degrees and 1150 Celsius degrees. The kinetic study of the self-reducing briquettes was carried out evaluating the metallic iron conversion and the metallic iron phenomenology and morphology formation. The results showed: a) that the iron conversion increased as higher the temperature and amount of carbon; b) that the iron metallization presented a shell-layer type morphology and, c) that the continuous-reaction type kinetic model, adjusted very well the experimental reduction results, with a correlation factor above 99 percent. Additionally, in order to better understand the experiment results, the metallurgical coke reactivity was obtained using the ASTM D5341-99 test and the Differential Thermogravimetric analyzes (DTG), as well as confirmed the hydrated water amount in the passivated F and G dusts, also using the DTG methodology. Finally, considering the manufacturing feasibility of the both, simple and self-reducing F-G briquettes, the following could be also marked: I) The use of both briquettes type for liquid steel temperature control in LD converters, as effective alternative materials to scraps and pellets, considering the following comparative cooling indexes: a) 2,1 and 2,4 times the scrap, for the self-reducing briquettes 50-50 and 70-30, respectively, both with 10 percent excess; b) 1,7 and 1,9 times the scrap, for the simple briquettes, 50-50 and 70-30 respectively. II) The effective use of the self-reducing briquettes as an alternative ferrous burden in ironmaking processes, particularly those demanding fast metallization, such as the emergent ITmk3 and Tecnored processes.
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