Preparation and characterization of EMD from manganese cake — A byproduct of manganese nodule processing

Electrolytic manganese dioxide (EMD) was prepared from manganese cake, which is an oxide material and byproduct obtained during processing of manganese nodules. Manganese cake dissolution was carried out in sulfuric acid media using waste newspaper as a reductant. In the two-stage purification of leach liquor iron was initially removed by pH adjustment using lime slurry followed by sulfide precipitation using sodium sulfide. Effects of current density, Mn(II) and sulfuric acid concentrations were studied during the electrodeposition of EMD from purified solution. The EMD obtained was characterized by XRD, SEM and its discharge capacity was determined. The XRD pattern demonstrated that EMD was a mixture of γ- and ε-variety. The EMD produced from manganese cake showed a discharge capacity of 290 mAh/g, which is industrially acceptable.

► Electrolytic manganese dioxide prepared from a waste manganese oxide source.
► EMD obtained was a mixture of γ-MnO2 and ε-MnO2 forms.
► Prepared EMD showed high discharge capacity of 290 mAh/g.
► Current density had a strong influence on EMD particle size.