Currently the Brazilian stainless steel production is around of 350,000 tons per year. At the same time, the stainless steel industries generate more than 7,000 tons of dusts with high content of chromium, nickel, iron and lead. The amount of sludge generated during stainless steel production is very inconstant. These wastes represent a problem to stainless steel industries due to their high content of chromium, nickel, iron and lead. The waste characterization is an essential step in a recycling process definition. One kind of dust and one kind of sludge, generated in the stainless steel production process, were studied in this work. The techniques used to characterize the waste were chemical analyses, size separation tests, density measurements, X-ray diffraction analyses, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) microanalysis. The biggest portion of the dust and sludge particles had a spherical shape. This kind of particle was composed mainly of iron and chromium in the form of a spinel or oxides. Precipitation of a second phase was identified in some particles. Three briquettes were prepared with each waste, Fe-Si alloy and CaO. The studied wastes were RESA and RESB. The briquettes were introduced in a ASTM 1020 liquid steel at three different temperatures 1570º, 1600 and 1635ºC. In this study, it was utilized a bench-scale equipment to melt the reactants. This study showed that besides the high recovery of chromium (98%) and nickel (100%) from the wastes, the new waste generated in the experiment (slag) is less aggressive to the environment than the initial wastes used for the production of the briquettes because it contains a smaller amount of heavy metals.
recycling; chromium; dust; sludge; stainless steel
