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.