Optimization of leaching process of electric arc furnace dust to obtain the maximum recovery of Fe/Ca ratio in leaching solution

This work aimed to obtain a solution rich in iron, calcium, and magnesium from electric arc furnace dust of steelmaking. Raw materials characterization was performed by several techniques, including X-ray fluorescence (XRF), X-ray diffraction (XRD), inductively coupled plasma-optical emission spectrometry (ICP-OES), and field emission scanning electron microscopy (FESEM). Calcium and iron are the two main constituents of arc furnace dust, but their dissolution conditions vary at different temperatures and concentrations of sulfuric acid. Since the amount of calcium in the initial chemical composition of the electric arc furnace dust is much higher than iron, it is necessary to remove some calcium along with other undesirable elements. The response surface methodology (RSM) was used as the experimental design to maximize the total ratio of iron to calcium recovery (F/C) and evaluate the effective parameters, including sulfuric acid concentration and temperature. Recovery of iron from electric arc furnace dust reached to its maximum value via a two-stage leaching process: 0.1 M and 1 M H2SO4, respectively, in 1 hour at the temperature of 85 °C and liquid to solid ratio of 50. Under the above experimental conditions, the F/C ratio was almost 4, which is eight times higher than that of in the initial electric arc furnace dust.