Abstract:The main mineral occurrence and mineral dissemination characteristics of the elements such as C，Na，Al，Fe in the spent cathode of aluminum electrolysis are analyzed by means of SEM and TEM. Results show that the main components of the spent cathode carbon block are carbon and fluoride. Carbon is mainly graphite with high degree of graphitization，but the crystal size is only tens of nanometers to a few micrometers. Fluoride is mainly sodium fluoride，cryolite and calcium fluoride. Aluminum is mainly occurred asalumina and cryolite. Iron is mainly occurred asmetallic iron. Minerals are disseminated closely and intermingled universally，the particle size of minerals is between tens of nanometers and tens of micrometers.