Sulfur dioxide leaching of spent zinc–carbon-battery scrap

Recovery of manganese and zinc from spent Zn-C and alkaline batteries in acidic medium

“…These results are in agreement with composition data found in the literature. 2,3,12,13 After drying the anode + internal paste at 40 ºC the mass was reduced from 10.00 to 7.98 g for Zn-C batteries (loss of mass 20.2 ± 0.5 wt %) and from 10.06 to 8.26 g for alkaline ones (loss of mass 17.9 ± 1.1 wt %). This last result is consistent with previous studies on moisture content in the components processed in this study.…”

“…2,15 However, this is only true if manganese is solubilized via conversion to Mn(II) by adding a reducing agent. 1,7,13,16,17 Otherwise, manganese leaching is partial. In separate experiments leaching was performed under the conditions described in the experimental section, except that no hydrogen peroxide was added.…”

“…Leaching of all other metals was also lower in the experiments without hydrogen peroxide, as already shown in the literature. 13 Under these circumstances neither the leachate nor the solid residue can be regarded as raw material for zinc and manganese recoveries, respectively. Other metals are present, requiring further separation (precipitation) steps.…”

“…These processes require more steps and consumption of chemicals and also generate final liquid effluents. 2,7,13 Sulfuric acid is the most employed leachant. It has been demonstrated that this acid is more efficient than hydrochloric acid.…”

“…Zinc is solubilized to a considerable extent (80-90 wt %), whereas manganese remains in the solid residue together with other metal impurities and some zinc. 3,13 Alternatively, the whole battery may be worked in a process called vitrification: 18 spent alkaline batteries are transformed into inert substances. This process allows recovery of iron, manganese and zinc.…”