ENVIRONMENTAL MINERALOGICAL INVESTIGATION OF ANODIC PORTIONS OF SOME SPENT ALKALINE BATTERIES

On average U.S. citizens use 8 disposable batteries per year; with a population of approximately 300 million people, this translates into an estimate of 2.4 billion batteries. There are geologic connections to spent alkaline batteries because these compounds are originally derived from minerals, are synthetic clay-sized mineral analogs in their spent form and may be a significant contributor to the heavy metals in landfill leachate. Mineralogical approaches to the study of batteries are therefore warranted and can provide new information about this critically important waste stream. One portion of spent alkaline batteries that has received little attention is the anodic zinc-rich portion. Several anodic components from Duracell D-type batteries were investigated to assess the mineralogical nature of these materials. The mineralogy of anodic portions of spent Duracell alkaline batteries that had been equilibrated in air for approximately 3 months was investigated. Powder X-ray diffraction (XRD) identified the bulk of the anodic material as zincite (ZnO) using PDF card #036-1451. Scanning electron microscopy (SEM) indicates a variety of textures of zincite are present with elongated hexagonal crystals being most common as well as box and lattice-shaped aggregates, some euhedral crystals and anhedral aggregates. Energy dispersive spectroscopy (EDS) analysis (detection limit = approximately 0.1 wt%) indicates that although the zincite is in a Mn-rich environment, there are no trace amounts of Mn within the ZnO. This differs for many natural zincites which have a few weight percent MnO. XRD and SEM data also indicate a consistent presence of an unidentified K –rich phase and SEM investigation identified trace amounts of Ni and Al. Recycling technologies for batteries exist such as the Batenus process and the Recytec process. These two methods have been successful, but the Batenus process is energy intensive, while the Recytec process is chemically intensive. Results of this investigation provide constraints on the mineralogy of the anodic portion of this common battery type for direct recycling purposes and provide insight into mineralogy of batteries in landfill systems. Clay mineralogical approaches to the investigation of battery wastes may be effective for elucidating new recycling methods.