Reduction of electric arc furnace dust pellets by simulated reformed natural gas

The purpose of this paper is to study the kinetic reaction of electric arc furnace dust pellets using a reducing gas simulating the reformed natural gas. The kinetic investigation was accomplished via forced stepwise isothermal analysis method. The tests were programmed in the range of 500-1000 degrees C. It was used a reducing gas contained 25 % of CO and 75 % of H-2. X-ray patterns were analyzed in order to understand the reduction process. The results show the reduction of electric arc furnace dust pellet occurs in three steps. At 550-650 degrees C, the zinc ferrite is reduced to magnetite and zinc oxide, followed by the reduction of magnetite to wustite. Carbon deposition on the pellet surface was detected in this step, which impairs the kinetic analysis. In the range of 700-800 degrees C, wustite is reduced to iron. It was determined a mixed control between nucleation and diffusion with Ea of 89.2 kJ mol(-1). At 850-950 degrees C, the main reaction is zinc oxide reduction to gaseous zinc. However, wustite reduction is also observed. The Ea of 135.5 kJ mol(-1) with a mixed control between diffusion and chemical reaction was detected.