Tecnologia em Metalurgia, Materiais e Mineração
https://tecnologiammm.com.br/article/doi/10.4322/tmm.2013.016
Tecnologia em Metalurgia, Materiais e Mineração
Artigo Original

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

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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



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