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

Abstract

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 °C. It was used a reducing gas contained 25 % of CO and 75 % of H2. 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 °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 °C, wustite is reduced to iron. It was determined a mixed control between nucleation and diffusion with E a of 89.2 kJ mol−1. At 850–950 °C, the main reaction is zinc oxide reduction to gaseous zinc. However, wustite reduction is also observed. The E a of 135.5 kJ mol−1 with a mixed control between diffusion and chemical reaction was detected.