Sustainable Mining and Metallurgy

Carbon dross is a hazardous solid waste produced in aluminum electrolytic cell production. A combustion test of carbon dross in Muffle furnace has been conducted. The test results show that when no covering material is added, carbon dross is barely combustible at the temperature of below 500℃; at 500℃, carbon dross starts to be combusted; at 600℃, it takes 5h for full combustion of carbon dross; at the temperature of above 700℃, only 2h is needed for full combustion of carbon dross, and the electrolyte in carbon dross is molten and becomes coked after cooling. In case of adding covering material, both carbon dross and covering material have no change at the temperature of below 500℃; at 550℃ with the combustion lasting 8h, carbon dross takes on grey white and is completely combusted; at the temperature of above 600℃, carbon dross speeds up combustion and is fully combusted after 5h; at the temperature of above 700℃ with the combustion lasting for more than 3h, carbon dross and covering material are molten and bond with each other, resulting in lower oxygen concentration and hindering carbon combustion. The pre-baked anode of electrolytic cell can provide the temperature and oxygen conditions required for carbon dross combustion. Carbon dross on the replaced anode can be combusted completely by using the heat energy released by the anode. The practical application in high and low lithium salt electrolyte system aluminum electrolysis series has proved that zero discharge of carbon dross can be realized by carbon dross combustion.