Effect of aluminum-containing additives on the reactivity in air and CO_2 of carbon anode for aluminum electrolysis

摘要

Airburn reaction and carboxy reaction result in the excess consumption of carbon anode in aluminum electrolysis. To reduce the excess carbon consumption, carbon anode was doped with aluminum-containing additives, such as Al, Al_4C_3, AlF_3 and Al_2O_3. Their reactivity in air and CO_2 was determined with an isothermal-gravimetric method to study the effect of aluminum-containing additives on the reactivity in air and CO_2 of carbon anode. Results shown that the airburn reactivity at 450℃ and carboxy reactivity at 970℃ of carbon anode both decreased with Al-containing additives adding, while shown a minimum with the amount of Al_4C_3, AlF_3 and Al_2O_3 increasing. However, all Al-containing additives increase the airburn reactivity at 550? of carbon anodes. Coke yield measurement and XRD examination with aluminum containing additives doped pitch cokes revealed that the effect of Al-containing additives on the airburn reactivity and carboxy reactivity of carbon anode would result from chemical factors and structural factors.