Selection of leaching media for metal dissolution from electric arc furnace dust

This study focuses on selective zinc and lead leaching from Electric Arc Furnace (EAF) dust in order to turn this major source of steel plant pollution into a recyclable Fe-rich feed material for the steel manufacturing process. The raw material investigated comprises of engineering steel plant EAF dust that contains zinc 33.2%, iron 17.9%, manganese 2.5%, lead 1.6% and chromium 0.2%. The 16 different leaching media investigated include: (i) acids, - nitric, sulfuric, hydrochloric, aqua regia, citric, acetic, formic, phosphoric, and oxalic; (ii) alkalines - sodium potassium and ammonium hydroxide and (iii) other lixiviants like distilled water, ethanol, ethylene glycol and acetone. The study shows that four media - 10% aqua regia, 1.2 M hydrochloric, 0.94 M citric and 1.5 M nitric acids - resulted in high (>75%) zinc extraction with good Fe selectivity (iron extraction <6% in 1.2 M hydrochloric acid, 10% aqua regia and <15% with 0.94 M citric and 1.5 M nitric acids). Furthermore, these four leaching media showed partial dissolution of manganese (21–35%), chromium (36–65%) and lead (18–60%), although the highest lead removal was achieved with 1.75 M acetic acid. In terms of zinc selectivity, it was found that ammonium outperformed both sodium and potassium hydroxide.