Paper No. 32
Presentation Time: 9:00 AM-6:00 PM
INDUSTRIAL MINERALOGICAL INVESTIGATIONS OF ELECTROLYTIC MANGANESE OXIDE (EMD) FOR POTENTIAL ENVIRONMENTAL APPLICATIONS
Electrolytic manganese dioxide (EMD) is an industrial mineral stock material that is used as the cathode for disposable alkaline batteries. This material is dominated by synthetic ramsdellite and akhtenskite, polymorphs of MnO2. The market for EMD is expected to gradually decline as rechargeable battery types dominate the market. Finding new uses for EMD that are more environmentally beneficial are desired by manufacturers. The purpose of this study is to characterize the mineralogy of EMD and screen for materials of environmental concern using electron microscopy techniques to determine if EMD has any potential as a reactive media for environmental remediation. Representative EMD material from Tronox was investigated using variable pressure back scatter field emission scanning electron microscopy to search for environmentally relevant particulate impurities (i.e., heavy metals) and bright field transmission electron microscopy was used to characterize microtextures. Energy dispersive spectroscopy was used for elemental chemical analysis.
Two populations of particles are present in the EMD material with one population consisting of angular aggregates that are commonly 20 to 100 micrometers in diameter and a second population of smaller discrete mineral aggregates exists that are less than a few micrometers in diameter. TEM imaging indicates the smaller particles are composed of irregular inter-grown crystals approximately 50 to 300 nm in diameter. Electron microscopy imaging did not find any examples of heavy metal particulate, however trace amounts of sulfur at a level of approximately 0.1 wt% were consistently observed using energy dispersive spectroscopy in both SEM and TEM. The fine particle size and textures observed suggest that EMD should be a reactive environmental media. Whether or not other sources of EMD share similar qualities is unknown but results for Tronox material is encouraging for potential environmental applications.