Direct Conversion of Electric Arc Furnace Dust to Zinc Ferrite by Roasting: Effect of Roasting Temperature

The direct conversion of electric arc furnace (EAF) dust into zinc ferrite by roasting with a small amount of Fe2O3 was explored with a focus on the influence of roasting temperature on zinc conversion, phase transformation, microstructural evolution, and product magnetic property. The results showed that the zinc compounds in the dust preferentially reacted with iron components to form zinc ferrite in the temperature range up to 1000 & DEG;C due to the low Gibbs free energy changes of the relevant reactions and high contents of Fe2O3 and Fe3O4 in the dust, increasing the percentage of zinc conversion of EAF dust to 91.36% after roasting at 1000 & DEG;C. When the temperature exceeded 1000 & DEG;C, however, the percentage of zinc conversion dropped to 90.26% due to the consumption of zinc for generating zinc-containing impurity phases, mainly Ca2ZnSi2O7 and slag, and to the loss of zinc caused by volatilization of the metal. After roasting of EAF dust at the optimal temperature of 1000 & DEG;C for 2 h, 94.13% of total zinc existed in the form of insoluble zinc in the roasting product with the saturation magnetization (M-S) of 47.9 emu/g and coercivity (H-C) of 65.8 Oe. The product can serve as a good precursor for producing high-quality ferrite powders.

Automated summary

This study explores the direct conversion of electric arc furnace (EAF) dust into zinc ferrite through roasting with a small amount of Fe2O3, focusing on the influence of roasting temperature on zinc conversion, phase transformation, microstructural evolution, and product magnetic property. The results show that zinc compounds in the dust react with iron components to form zinc ferrite at temperatures up to 1000°C due to favorable thermodynamics and high iron content. However, at temperatures above 1000°C, zinc conversion decreases due to the formation of zinc-containing impurity phases and the volatilization of zinc. After roasting at the optimal temperature of 1000°C for 2 hours, 94.13% of total zinc exists as insoluble zinc in the product, which exhibits good magnetic properties and can be used as a precursor for high-quality ferrite powders.