Abstract:Techniques to extract alumina from fly ash with predesilication and soda-lime sintering process, hydrochloric acid leaching process, and sulfuric acid roasting process were introduced. The theoretical energy consumption of each process was calculated. The results indicate that energy consumption of predesilication-soda-lime sintering process is 1 707 kgce (for one ton Al2O3) and 53.67% of the whole energy consumption concentrates in sintering process. Hydrochloric acid leaching process and sulfuric acid roasting process consume less energy, with energy consumption of 1 396 kgce and 1 476 kgce respectively, which drops by 18.3% and 13.5% respectively compared to predesilication-soda-lime sintering process. In hydrochloric acid leaching process, pyrolysis energy consumption of aluminum chloride accounts for 42.57% of the total energy consumption, while dehydration process of aluminum sulfate takes up 51.38% of the whole energy consumption in sulfuric acid roasting process.