REMOÇÃO DE ZINCO DE SUCATA DE AÇO GALVANIZADO PARA VIABILIZAR A RECICLAGEM DA LAMA FINA DE ACIARIA LD
REMOVING ZINC FROM GALVANIZED STEEL SCRAP TO FEASIBLE THE BOF SLUDGE RECYCLING
Lima, Monica Marques Caetano de; Salimani, Luciana Cerqueira S.; Quintela, Marco Antonio
http://dx.doi.org/10.4322/tmm.2013.016
Tecnol. Metal. Mater. Min., vol.10, n2, p.112-119, 2013
Resumo
A sucata de aço galvanizado gerada na Usiminas é totalmente reciclada nos convertedores das aciarias da Usina de Ipatinga. Essa sucata contém quantidade significativa de zinco que, devido à sua alta pressão de vapor, é liberada durante o sopro no convertedor. O zinco na forma gasosa, juntamente com outros gases e pós, são captados pelo sistema de limpeza de gás, compondo a lama de aciaria. Devido à presença de zinco, a lama fina de aciaria é disposta em aterros controlados. Para permitir a reciclagem dessa lama, este trabalho estuda a remoção do zinco dessa sucata, por meio de tratamento térmico. Foi desenvolvido um forno rotativo e avaliada a capacidade de remoção de diferentes tipos de sucata das linhas de galvanização, em ambiente inerte, variando a massa de camada de zinco entre 20 g/m2 e 150 g/m2, temperatura entre 700°C e 900°C e tempo entre 3 min e 10 min. Nas condições avaliadas, sob temperatura de 700°C e tempo de 10 min, a remoção de zinco é acima de 70%. Mais de 60% do pó de zinco recolhido é na forma de zinco metálico e o restante, como óxido. Diante disso, a metodologia proposta torna viável a reciclagem desta lama na sinterização.
Palavras-chave
Lama de aciaria, Zinco, Sucata, Tratamento térmico
Abstract
Galvanized steel scraps generated at Usiminas Ipatinga are recycled in BOF converters. Although they are noble products, they contain a significant quantity of zinc that escapes from the bath due to its high vapor pressure and is captured by the gas control system, appearing in BOF sludge. As BOF sludge contains high iron content, it could be recycled to the process, but due to its zinc content, it is disposed in landfills. For this reason, this study aimed to treat these scraps to remove zinc layer using a thermal treatment process. The samples were fed to a rotative furnace in an inert ambient. It was tested the hot dip galvanized and eletrogalvanized scraps, varying the zinc coating weight between 20g/m2 and 150g/m2, temperature between 700°C and 900°C and time between 3 minutes and 10 minutes. Considering these conditions, it is verified that more than 70% of the zinc layer is removed at 700°C, in 10 minutes. Dust captured is about 60% of metallic zinc and 40% as zinc oxide. Based on these results, the recycling of BOF sludge can be feasible to the ironmaking process.
Keywords
BOF sludge, Zinc, Scrap, Thermal treatment
Referências
1 Lima MMC, Solimani LCS, Campolina EA. Comportamento do zinco da lama de aciaria gerada em convertedor. In: Anais do 41. Seminário Internacional de Aciaria; 2010; Resende, Brasil. São Paulo: ABM; 2010. p. 1-11.
2 Koros PJ, Hellickson DA, Dudek FJ. Issues recycling galvanized scrap. In: Proceedings of the Galvatech Conference; 1995; Chicago, USA. London: Iron and Steel Society; 1995, p. 535-542.
3 Janjua RA. Optimisation of electric arc furnace dust recycling and zinc recovery by scrap de-zincing [doutorado]. Freiberg: Fakultät für Werkstoffwissenschaft und Werkstofftechnologie der Technischen Universität Bergakademie Freiberg; 2008.
4 Franzen A, Pluschkell W. Removal of zinc layers from coated steel strip by thermal and mechanical processing. Steel Res. 1999;70:141-146.
5 Tee J, Fray D. Removing impurities from steel scrap using air and chlorine mixtures. JOM. 1999;51: 24-27. http:// dx.doi.org/10.1007/s11837-999-0237-x
6 Herter CJ, inventors. Herter CJ, assignee. Method for preparing a low residual alloy steel charge from scrap metal. United States patent. US4517016. 1985 May 14.
7 Hegewaldt F. Recycling of zinc coated steel sheets. In: International Scientific Colloquium Modelling for Saving Resources; 2001, Riga, Letonia. [S.n.t.]. p. 164-168.
8 Cadarso C, Losada L. Melting of zinc coated scrap. Foundry Trade J. 2003;177:7-11.
9 Saotome Y, Nakazawa Y, Yokoyama Y. Vacuum aided recycling systems technology (VARS Tech) as a restoration systems technology of ecofactory. Vacuum. 1996;47:833-836. http://dx.doi.org/10.1016/0042-207X(96)00077-2
10 Dudek F, Daniels E, Morgan W. Dezincing technology. In: Proceedings of Aise Annual Convention & Iron And Steel Exposition. 1997; Cleveland, United States. Washington: Assistant Secretary for Energy Efficiancy and Renewable Energy; [s.d.].
11 Ozturk B, Fruehan R. Vaporization of zinc from steel scrap. ISIJ Int. 1996;36:239-242. http://dx.doi.org/10.2355/ isijinternational.36.Suppl_S239
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