Abstract:Preparation of metallurgical alumina from coal ash in circulating fluidized bed with sulfuric acid method was studied. The results show that the Al2O3 leaching rate reaches 93.1% under the optimum conditions including temperature of 180 ℃, time of 5 h, initial sulfuric acid mass concentration of 30%, and acid excess coefficient of 1.5. The iron removal rate from crude aluminum sulfate solution is 91.7% by KMnO4 oxidation-precipitation method with coal ash calcined at 500~600 ℃ for 40 min as alkaline agent. The refined aluminum sulfate solution is concentrated, crystallized, and calcined at 1 100 ℃ for 4 h to produce metallurgical alumina which meets YS/T 274-1998 standards, level 1.