Thermodynamic Investigation of the Sulphation Roasting of Electric Arc Furnace Dust

During the remelting of automobile scrap in the electric arc furnace steelmaking process, a dust is generated. This dust contains significant amounts of zinc, iron, and lead and in some cases, copper and nickel. However, the recovery of these metals is difficult, because of the complex chemical and physical characteristics of the dust. Numerous pyrometallurgical, hydrometallurgical and hybrid processes have been devised and tested for metal recovery, but only the Waelz rotary kiln process has achieved significant commercialisation. One potential process, which has received little attention in the literature, is the pyrometallurgical sulphation of the dust. In the present research, a high temperature thermodynamic model has been developed using HSC (R) Chemistry 7.1, to investigate the sulphation of the dust. The effects of process parameters on the conversion of the various metals into sulphates were studied. At a temperature of 600 degrees C, almost one hundred percent of the zinc could be converted into zinc sulphate, while about ninety-five percent of the iron could be retained as hematite. In addition, several low cost, potential sulphating reagents were evaluated.