TRANSMISSION ELECTRON MICROSCOPY (TEM) INVESTIGATION OF INDUSTRIAL MINERALOGY OF ANODIC BATTERY WASTE

U.S. citizens use approximately 8 disposable alkaline batteries per year, creating a waste stream of an estimated 2.4 billion batteries; much of this waste stream is landfilled. Identifying economically and environmentally viable methods for recycling is critical for reducing this waste stream. Industrial mineralogical approaches to the study of battery recycling are needed. One portion of the spent alkaline battery waste stream that has received little attention is the anodic zinc-rich portion. Anodic components from Duracell D-type batteries were investigated to assess the mineralogical nature of these materials using Transmission Electron Microscopy (TEM). For TEM, the <2 μm size fraction from deionized water suspensions was investigated from an unwashed separate and a separate that had been washed with deionized water repeatedly until the pH of the supernatant was approximately 7.0 . Bright field imaging was carried out using a JEOL JEM-2100 transmission electron microscope fitted with a Bruker Silicon drift XEDS detector. TEM indicates a range of textures exist. Near euhedral zincite crystals are dominant with dimensions varying from approximately 100 nm x 300 nm to 200 nm x 600 nm. Other textures indicate progressive corrosion from single anhedral zincite crystals to nearly amorphous aggregates of zinc oxide-rich material. Potassium-rich amorphous particles are commonly associated with corroded textures of zinc oxides. Two textures of Zn-Mn-oxides were observed as well, a spherical aggregate texture and a rhomboid texture. Spherical textures were approximately 100 nm in diameter and rhomboid particles are approximately 400 nm in diameter. Recycling technologies for batteries exist, however these methods have been found to be technically successful but not lucrative; the Batenus process requires large energy inputs, while the Recytec process is chemically demanding. The TEM results of this study provide constraints on the mineralogy of the anodic portion of this universal battery type for direct recycling purposes and may provide insight into mineralogy of batteries in landfill systems.