Footprint of harmful substances in spent pot lining of aluminum reduction cell

Abstract Spent pot lining (SPL) from aluminum reduction cells is considered to be hazardous materials due to containing a large amount of soluble fluoride salts and trace toxic cyanides. The distribution of fluorides and cyanide in a 350 kA cell operated for 2396 days was analyzed and the footprint and corrosion mechanism of the harmful substances in SPL were also studied. It is found that the fluorides are mainly concentrated in the cathode carbon block and the layer of dry barrier under the cathodes, which is closely related to permeability of the cathodes and dry barrier the fluorides penetrate in. Cyanide has a low concentration in the cell center and a high concentration in the sidewall, which is positively related to the air amount entering into the areas in the cells.