Production of electrolytic zinc powder from zinc anode casing of spent dry cell batteries

Abstract

This paper aims to study experimentally the packed bed electrolysis of anode particles obtained from zinc casing of spent secondary batteries, by which electrolytic zinc powder can be produced. Zinc casings of the exhausted zinc–carbon type dry cell batteries were separated from both the internal carbon rods and MnO2 paste materials and from the external covers then fed into cuboids anode basket made from graphite or titanium. Two stainless steel permanent cathode sheets together with the anode basket were immersed in a basic solution containing 230g/L NaOH. Electrolytic zinc powders in the form of nanorods, dendritic and/or a dispersed shape with a purity of about 99.8% Zn and with an apparent density of 1203.1 to 2085.2kg/m3 were obtained. The results indicated that, the graphite basket is better than the titanium one for all studied parameters except for the specific energy demand factor. The deposited zinc powders are contaminated with about 0.0053% Ti when using titanium basket. The process was enhanced with increasing current density, electrolyte temperature, electrolyte stirring rate, and the use of an old electrolyte. The electrolysis process was carried out with cathodic current efficiency up to 94.85%, anodic current efficiency up to 98.97% and specific energy demand in the range between 0.808 and 2.518kWh/kg Zn with powder productivity up to 1.150g/A.h.