Fundamentos e roteiro da caracterização de materiais por DRX/MEV-EDS e aplicação destas técnicas em um estudo de caso: finos de uma liga FeCrAC e os produtos do seu processamento químico.

Abstract

Every metallurgical process is associated with the production of wastes. These, for environmental and economic reasons must be recycled. For example, the production of FeCr alloys, which are relevant for the stainless steel industry, results in a significant amount of fine sized particles containing significant quantities of Cr and C. A possible route for the recycling of such industrial waste consists in using combined pyro and hydrometallurgical processes for Cr extraction. The present work focuses on presenting a guide of the methodology used to perform the characterization of the mentioned powder residue, by X-ray diffraction (XRD) for phase determination by Rietveld Method, scanning electron microscopy (SEM) for the study of particle morphology, as well as the semiquantitative evaluation of the major elements composition through energy dispersive spectroscopy (EDS). Moreover, in order to illustrate the applicability of the diverse characterization techniques used for giving support to a pyro and hydrometallurgical Cr extraction process design, both intermediate, as well as final material produced were studied. The results show that the raw material consists mainly of carbides (42.5% Cr7C3 and 20.4% Fe7C3), the intermediate material (filtered) by Fe and Mn oxides (33.96% Fe2O3, 12.56% FeO and 34.06% MnO2), and the final material by clusters of spherical geometry entirely composed of a single phase (100% Cr2O3), that give support to the high selectivity achieved during extraction, thereby resulting in a final product of high purity.