High-Temperature Vacuum Treatment of Aluminum Electrolytic Spent Carbon Cathode

摘要

The spent carbon cathode (SCC) produced in the aluminum electrolysis process has been listed as hazardous waste due to excessive soluble fluoride and cyanide. In a high-temperature vacuum environment, the soluble fluoride and cyanide in SCC can be evaporated and decomposed, respectively. As a result, its impact on the environment can be eliminated. The remains and volatiles can be collected for resource use. Based on the analysis of SCC chemical composition and phase structure, thermodynamic parameters of evaporation reactions were calculated by FactSage. The effects of treatment temperature and particle size of SCC on the removal of soluble fluoride and cyanide were further investigated by experiment. A suitable treatment condition, in which SCC particle size is 1.000-3.000 mm, at 1000 degrees C for 2 h at vacuum conditions of 10 Pa, was obtained. The removal rate of soluble fluoride and cyanide in treated SCC reached 91.10 and 99.33, and carbon content reached 89.89. Combined with the analysis of TG-DSC and particle profile scan, the evaporation reaction mechanism by high-temperature vacuum treatment (HTVT) was analyzed. The work will be helpful for the development of new SCC treatment process.