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Electric Arc Furnace Dust (EAFD) is a solid waste originated from electric steelmaking furnaces. Currently, according to some authors, there is an estimated generation of 15 to 25 kg of dust per ton of steel produced. The formation of the dust is related to the following steps of the process: furnace charge, metal volatilization, iron vaporization under the arc, drag of solid particles and, mainly by the collapse of CO bubbles from metallic bath decarburation. The dust has metals that are harmful to the environment. Otherwise, it is mostly composed of the elements iron, zinc and oxygen. Due to increasing costs for disposal and because it is considered a hazardous waste, industry is looking at the possibility of returning the dust to the steelmaking process. One of the alternatives is by reintroducing the waste in an electric melting shop using self-reducing agglomerates as part of the furnace burden. In this study, self-reducing mixtures are prepared with EAFD and petroleum coke (PET), presenting chemical and physical characterizations. An evaluation about the behavior of the mixtures is carried out in thermobalance, regarding the possibility of use in measuring accurate PET content in self-reducing pellets. As results it could be stated that the elements of economic interest, Zn and Fe, represent, respectively, 34.23 and 22.80%, in weight. These elements are present in chemical species frankilinite, zincite and magnetite and the reducible oxygen was estimated as 17.90%. Also, it was concluded the optimal content of petroleum coke in the mixtures varies from 10 to 15%, in weight. Therefore, the utilization potential of the thermogravimetric technique in the industrial field for adjustment of carbon content in batches of self-reducing pellets is satisfactory.

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ResumoA produção siderúrgica em usinas semi-integradas gera vários tipos de resíduos dentre os quais as carepas. No presente trabalho estuda-se o comportamento físico-químico em altas temperaturas de briquetes autorredutores elaborados com carepa e finos de carvão vegetal produzidos no Rio Grande do Sul, objetivando sua introdução no processo produtivo de aciaria elétrica. Ensaios realizados em laboratório com briquetes industriais confeccionados com estes resíduos demonstraram a potencialidade de utilização destes briquetes autorredutores em processos siderúrgicos via forno elétrico a arco (FEA). Palavras-chave: Carepa; Finos carvão vegetal; Briquetes autorredutores. SELF-REDUCING BRIQUETTES FROM STEELMAKING MILL SCALE FOR USE IN ELECTRIC ARC FURNACE AbstractThe steelmaking industry in semi-integrated plants generates several wastes, among which mill scale. In this paper it was studied self-reducing briquettes made with mill scale and charcoal fines produced in Rio Grande do Sul State and its physicochemical behavior at high temperatures. The objective is its reintroduction in electric steelmaking process. Laboratory tests with industrial briquettes made with these residues had demonstrated the potential use of these briquettes in steelmaking processes through electric arc furnace (EAF).

Resumo A resistência mecânica do coque metalúrgico está intimamente relacionada com a sua microestrutura, de forma que a posse de uma ferramenta metodologica para realizar a caracterização microestrutural é de grande valia. Nesse trabalho foi desenvolvido um algoritmo de análise de imagem que possibilite a obtenção dos parâmetros microestruturais de interesse do coque. Devido a heterogeneidade microestrutural do coque as melhores condições de granulometria das partículas de coque, número de amostras analisadas (plugs) e área de campo analisada de cada plug foram definidas. Coques laboratoriais produzidos com carvões de propriedades distintas foram caracterizados a partir da metodologia desenvolvida nesse trabalho. As propriedades dos carvões foram relacionadas com a microestrutura dos coques.A metodologia desenvolvida nesse trabalho possibilita a obtenção de parâmetros que podem ser relacionados com a resistência mecânica do coque em ensaio de tambor, para coques com composição não saturados em materiais inertes. Palavras-chave:Coque metalúrgico; Microestrutura; Porosidade; Resistência mecânica.

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