Leaching of Electric Arc Furnace Slag for Selective Recovery of Iron: Effect of Temperature, H2SO4/HCl Acid, and Oxidant Concentration

Abstract

A significant amount of electric arc furnace slag (EAFS) is generated as a by-product from the steelmaking industry. Acid leaching was carried out with both the presence and absence of oxidants to intensify the iron recovery from EAFS in the final product. Oxidative leaching refers to the process whereby the oxidant helps in removing one or more electrons in a chemical reaction. In contrast, non-oxidative leaching means there is no transfer of electrons during the process. In this study, hydrogen peroxide and potassium permanganate were used as the oxidants in the leaching process. The influences of the leaching factors, such as the concentration of leaching reagent (0.5–8 M), leaching temperature (323–363 K), EAFS particle size (50–300 μm) and concentration of the oxidants (0.5–2 M), were also studied. The findings revealed that the particle size, acid dosage and type of oxidants significantly influenced iron recovery. Smaller particle sizes greatly improved the recovery of iron. İn the non-oxidative leaching environment, sulphuric acid exhibited a higher iron recovery than hydrochloric acid. The recovery efficiency was 21.47% higher. For oxidative leaching, the leaching efficiency of iron was more favourable at lower concentrations of hydrogen peroxide in both sulphuric and hydrochloric acid, and the opposite was the case for potassium permanganate. An overdose of hydrogen peroxide can cause radical quenching, which will reduce oxidant utilisation. Oxidative leaching resulted in better iron recovery at optimum leaching conditions with a temperature of 50°C, 5 M H2SO4, 1 M hydrogen peroxide, a leaching time of 60 minutes, a solid to liquid ratio of 1:20 and a stirring rate of 300 rpm.