Eduardo Junca

EVALUATION OF CAST IRON DESULFURIZATION WITH SYNTHETIC SLAGS

The aim of this work was to study the use of slags to desulfurization of cast iron. It was proposed to use alumina instead fluorspar. In addition, marble waste was used instead lime. Simulations applying Thermo-Calc software were performed in order to obtain the theoretical phases thermodynamic data. Then, a comparison between theoretical data and experimental tests were performed. The cast iron was melting in induction furnace at 1550°C. Slags composed mainly for CaO and Al2O3 were used to cast iron desulphurization. It was observed that increasing liquid phase, the desulphurization reaction was favored. Besides, it was found that cast iron desulfurization occurs by top slag mechanism.

RESÍDUO DO CORTE DE GRANITO: INOVAÇÃO TECNOLÓGICA PARA A DESTINAÇÃO FINAL

The granite processing market is one of the most promising business areas of the mineral sector, with an average growth of the world production of about 6% per year. The granite extraction generates residues in the form of powder rock of 20-25 wt.% of the total benefited. The granite dust must be carefully managed since it can cause siltation of rivers and human health risks. This paper presents two routes for the final destination of this waste: the vitrification process aiming the production of fibers for thermo-acoustic insulation, and the magnetic separation in order to recover the steel grit. Results showed that the forms of treatments presented are economically and ecologically viable since they represent a cost reduction in the waste disposal, and also provide the production of new materials with commercial value.

ESTUDO CINÉTICOS DA REDUÇÃO DE PELOTAS DE POEIRA DE ACIARIA LD POR HIDROGÊNIO

The generation of basic oxygen furnace dust is a problem that companies found in the steel industry. In this way, studies are important to obtain, or at least indicate a way to recycle this waste. The direct reduction can be an alternative, once this method produces rich in iron. Thus, the goal of this paper is study the kinetic of reduction of basic oxygen furnace dust pellet using a mixture containing hydrogen and argon. Thereby, the mechanism and apparent activation energy that involve the reduction can be found out. The kinetic analysis was carried out applying the Forced Stepwise Isothermal Analysis method. The temperatures used in the test were between 500°C to 1,100°C. The results showed that reduction occurred in three steps. In the first step, nucleation was the control mechanism. It was found an apparent activation energy about 24kJ/mol in this step. In the second and third stage, the control mechanism was diffusion. In the second step, the apparent activation energy was 54.9 kJ/mol, while in the third step the apparent activation energy was 80.7 kJ/mol

Briquetagem da granalha de aço recuperada do resíduo de rochas ornamentais

This paper presents the results obtained with the production of briquettes from the steel grit found in the residue of ornamental rocks. The grit recovered by magnetic separation was characterized by titrimetric analysis, EDS (Electron Dispersive Spectroscopy) and X-ray diffraction for the analysis of iron concentration in the residue. The size and distribution of particles were obtained by the granulometric analysis method and scanning electron microscopy (SEM). The process resulted in a concentrate containing 93% metallic iron. The maximum load before fracture of the green briquettes was 1.02kN and of the dry briquettes was 3.59kN.