Abstract:
In this study, the leaching kinetics of manganese oxide powder supplied from spent alkaline batteries was investigated in H2SO4 solutions including molasses. Waste battery powder containing manganese oxides was prepared by separating manually from the other components of the collected waste alkaline batteries. The leaching experiments were carried out in a batch reactor. The effects of H2SO4 concentration, stirring speed, solid-to-liquid ratio, reaction temperature, particle size, and amount of molasses on the leaching rate of manganese were studied. It was determined that molasses used as the reducing agent had an important effect on the leaching rate. By adding molasses to the leaching media, it was found that almost all manganese in waste battery powder transferred to the solution. It was observed that the leaching rate increased with an increase in the solution concentration, stirring speed, reaction temperature, and amount of molasses, and with a decrease in the particle size and solid-to-liquid ratio. While the concentration of H2SO4, stirring speed, solid-to-liquid ratio, reaction temperature, particle size, amount of molasses, and reaction time were 1 M, 500 rpm, 2/500 g/mL, 60 °C, 0.348 mm, 2 g, and 120 min, respectively, the amount of the dissolved manganese was found to be approximately 98%. A mathematical model represented that the leaching kinetics was elaborated. It was determined that the leaching kinetics followed the mixed kinetic model. The activation energy value for the process was calculated to be 52.31 kJ/mol. After the leaching treatment, Mn (II) ions in the solution were recovered in the form of MnCO3 using NaHCO3 solution. MnCO3 was calcined isothermally at 400 °C for 4 h, and MnO2 was produced. Graphical Abstract: [Figure not available: see fulltext.] © 2022, The Minerals, Metals & Materials Society.