Characterizing industrially electrowon sticky zinc deposits

Physical, chemical, and microscopic characterization of industrially electrowon zinc was performed with a focus on cataloguing morphological differences between sticky and non-sticky zinc deposits. Preferred crystal deposition plane orientations were analyzed by XRD. The crystal orientations for the sticky samples reveal small angle growth (~ 25°) to the cathode surface. In non-sticky samples, the crystals were oriented at an average of ~ 44° to the cathode surface. Deposit microstructures were studied by SEM and optical microscopy. These revealed flat or basal zinc platelets with a number of pores for the sticky deposits whereas the non-sticky deposits were compact, sharp-edged and featured continuous grains with angular crystal plane depositions. No differences in deposit impurity contents were observed by elemental (ICP) and EDX analyses. Microhardness studies of the deposit cross-sections revealed that the sticky samples were, on average, softer than the non-sticky samples particularly at locations closer to the Al cathode.