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.

The amount of Electric Arc Furnace Dust (EAFD) is continuously increasing in mini-mill steel plants. This dust is considered a hazardous waste because of the presence of elements like lead, cadmium and chromium. Among many different treatment processes for this issue, there is the possibility of returning the EAFD back to the Electric Arc Furnace. This article presents a study of the compressive strength of selfreducing cold bonded pellets as well as their zinc removal, in an agglomerate containing EAFD, petroleum coke (PET) and Portland cement. The effects of the reductant and binder employed were discussed. Moreover, an apparatus was built to prevent zinc gas reoxidation inside an electric vertical laboratory furnace. Thus, the fraction of weight loss complemented the result of a previous study indicating the optimal content of PET source usage between 10 to 15%, in mass. Zinc removal and additional X Ray Diffraction outcomes are shown and discussed, concluding that 80% of zinc removal for this system could indicate the possibility of the EAFD reuse.

The continuous casting tundish is the last metallurgical reactor where molten metal flows before solidifying in the continuous casting mold. A tundish covering powder can be used for improving steel cleanliness; in this case it is named 'active tundish slag'. The objective of this work is to evaluate, in laboratory, the effect of three kinds of tundish covering powders on cleanliness for a SAE 1055 modified steel -a Ca-aluminate, a Ca-Mg-aluminate, and an Al-silicate powder, analysing their interaction with rice hull ash. The forementioned materials were molten on liquid steel, representing different kinds of tundish covering powders which are used in the steel industry: a Ca-Mg-aluminate, an Al-silicate, and a Ca-aluminate. Experiments were performed with and without a top layer of rice hull ash, simulating industrial conditions. Distribution, density, and mean diameter of inclusions were measured through automated inclusion analyses. Through computational thermodynamics it was possible to evaluate deviation from saturation (considering Al 2 O 3 and MgO from refractory) and slag viscosity. It can be stated that the Ca-aluminate tundish covering powder gives better results regarding cleanliness for the SAE 1055 modified steel under laboratory conditions.

ResumoA geração de resíduos siderúrgicos é um problema que abrange dois cenários: o ambiental, no que diz respeito ao descarte de resíduos no meio ambiente e também tange o econômico, pois trata-se de material não reaproveitado que deve ser destinado a aterros industriais, gerando custos. Tendo isto em vista, a reciclagem desses possíveis coprodutos para a reutilização como matéria-prima do processo torna-se uma alternativa pertinente. Uma das formas de recuperação do pó de aciaria elétrica (PAE), resíduo abordado neste trabalho, é através da pelotização. Para o reaproveitamento de metais de interesse do pó foi utilizado um agente redutor, o coque de petróleo. No entanto, para formação das pelotas um aglomerante se faz necessário. Este, em associação com as partículas do óxido, tem como objetivo conferir resistência mecânica adequada às solicitações que o processo de fabricação do aço exige. Neste trabalho, são feitas considerações acerca do uso de seis composições diferentes de aglomerantes com o objetivo de avaliar o desempenho destes, através de ensaios de resistência a compressão, testes de queda e tamboramento. Como resultado, pode-se verificar o melhor desempenho da combinação da cal com cinza de casca de arroz. Palavras-chave: Resistência mecânica; Pelotização; PAE; Aglomerantes. EVALUATION OF THE UTILIZATION OF BINDERS IN THE MECHANICAL PROPERTIES OF SELF-REDUCING PELLETS FROM EAF DUST AbstractThe production of siderurgical residues is a problem that covers two main scenarios: the environmental, regarding the residues' disposal on soil and also the economic field, because it's a non reused material that must be send to industrials landfills, generating costs. Thus, recycling these possible co-products to use as raw material of the process becomes a relevant option. One of the ways to recover the EAF dust, residue approached in this paper, is through pelletization. For the reutilization of the metals of interest in the dust a reducer agent was used, the petroleum coke. Nevertheless, for the pellets' formation, a binder is needed and in association with the oxides particles aims to give mechanical strength suitable for the iron making process. In this paper six different binders' composition are tested, aiming evaluate their performance through compressive strength testing, drop shatter test and tumbler test. As result it was possible to verify the efficiency of the combination hydrated lime with rice rusk ash for the three tests.

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