Utilização de métodos de análise na caracterização química e estrutural de compostos de zinco em resíduos de forno elétrico a arco em processo siderúrgico

Abstract

Nowadays, developing environmentally friendly new methods of disposing industrial waste is a global priority. Efforts have been made to reduce the use of natural resources and also the production of tailings. In a preventive aspect, various sectors of the industry have been dealing with the challenge of finding new strategies for cleaner production with minimal wastes. The increase in steel production in a worldwide scope implies higher consumption of energy and of renewable and non-renewable natural resources, creating more industrial waste, mainly: sludge, dust, slag and gases. Several of these aforementioned wastes are already expressively exploited, either as a source of energy or raw material. However, the dust and sludge from the gases generated by the cleaning systems of the electric arc furnaces, while possessing high iron content, are among the less recycled materials, mainly due to their high content of zinc and other heavy metals. In the researched steel mill, the occurrence of zinc is mainly due to the use of galvanized scrap as raw material for production of steel in the electric arc furnace. Thus, the use of sludge derived from steelwork would impair the reutilization of this waste in steel production, once the presence of this material would entail several operational problems, such as corrosion, reduction of the refractorys life, obstruction of the collecting ducts, among others. In this study, we investigated waste samples from an electric arc furnace gas cleaning system of a semi-integrated steel mill provided by Ecosteel Indústria de Beneficiamento Ltda. These samples were submitted to analysis for chemical and structural characterization of the observed zinc compounds. The methods of analysis utilized for this chemical and structural characterization reveal irregular and spherical particle shapes as well as dendritic structures. The presence of zincite and franklinite was also observed and these phases are diffuse in the sample and the results compatible with those observed in the literature. It was observed a predominance of magnetite and presence of other oxides, such as wustita, hematite, calcite, dolomite, periclase, among others.