Leaching Kinetics of Iron from Electric Arc Furnace Slag (EAFS)

The steelmaking process produces a substantial amount of electric arc furnace slag (EAFS). Therefore, this present study conducted acid leaching, with and without the use of oxidants such as hydrogen peroxide (H₂O₂) and potassium permanganate (KMnO₄), to increase the amount of iron (Fe) recovered from the EAFS. The effect that reagent concentration of 0.5-8.0 M, leaching temperatures of 50-90 °C, and oxidant concentrations of 0.1-2.0 M had on leaching activities were investigated. A temperature of 50 °C, a 5 M sulphuric acid (H₂SO₄) concentration, a 1 M hydrogen peroxide concentration, a leaching duration of 60 minutes, a 1:20 solid: liquid (S: L) ratio, and a 300-rpm stirring rate was found to yield the highest iron. recovery. Three kinetics models; diffusion-controlled, chemical reaction-controlled and mixed-controlled model; were also investigated. The reaction was found to follow the chemical-reaction model as it yielded the highest square of the correlation coefficient (R², 0.9998). The activation energy of the chemical reaction-controlled model was +16.95 kJ/mol. During the cyclic voltammetry (CV) study, 0.1 M sodium chloride (NaCl) was added to the iron-rich leaching solution to act as a supporting electrolyte. Tests were then conducted at potential ranges of -1-1 V at a scan rate of 100 mV/s using screen printed carbon electrode (SPCE). The CV indicated that there were two distinct oxidation peaks (-1.5 and .5 V) and two distinct reduction (0.9 and -0.9 V) peaks occurred at all temperatures.