Dissolution and precipitation of zinc and manganese obtained from spent zinc-carbon and alkaline battery powder

The aim of this study was to investigate manganese and zinc recoveries from spent zinc-carbon and alkaline battery powder. The effect of sulfuric acid concentration, ascorbic acid dosage, reaction temperature and leaching time on zinc and manganese dissolutions was investigated. The optimum reductive acid leaching conditions were determined as: 3 hours, 70 °C, 0.5 M of sulfuric acid concentration, 13 g/dm3 of ascorbic acid dosage, 1/20 g/cm3 of solid/liquid ratio and 200 rpm of stirring speed. Under these conditions, dissolution efficiencies were 99.99% for Zn and 99.25% for Mn. In addition, dissolution kinetics of manganese was undertaken, and the activation energy was found to be 7.04 kJ/mol. Using 3 M NaOH as precipitating agent at room temperature, 95.35% of Zn (at pH 8) and 93.66% of Mn (at pH 10) were precipitated from the leaching solution. Under the same conditions, using 3 M KOH, precipitations of Zn and Mn were 91.63% and 96.39%, respectively. Based on the experimental results, a flowsheet of zinc and manganese recovery was proposed.