China Nonferrous Metallurgy

Quite a large quantity of carbon dross is produced in aluminum electrolysis, about 5~15kg/t of Al. At present, the main methods for treating carbon dross are flotation process and crucible furnace smelting process, and these two methods have their respective advantages and disadvantages in disposal cost and electrolyte purity, but all have the issue of producing carbon slime (hazardous waste) in the disposal process. On the basis of the DSC-TG data analysis for carbon dross, the carbon dross low temperature circulating roasting process is put forward to recover electrolyte and avoid producing carbon slime at the same time. The roasting test result shows that using this process to recover electrolyte from carbon dross is technically feasible, after two times of circulating roasting under the roasting temperature of 750℃, the comprehensive carbon removal rate can be as high as 97.6%, the main component of the carbon dross after circulating roasting is electrolyte (cryolite). This process can successfully avoid producing carbon slime, which provides a new idea for the reduction and resourceoriented disposal of carbon dross. However, the production capacity of aluminum electrolysis is subjected to limitation, the future needs for electrolyte for the startup of electrolytic cell will be less and less, the development and use of the recovered electrolyte will be the next step issue to be contemplated by research fellows in aluminum industry.