Cement kiln co-processing of spent pot liner generated in aluminum industry

The aluminium manufacturing industry uses high temperature electrolytic process to produce aluminium from alumina. This process is carried out in an electrolytic pot. This pot tends to have a production life of about 3–10 years. After the pot becomes disfunctional, the carbon and refractory lining of the pot is removed which is called as Spent Pot Liner (SPL). After removing the SPL, the pot is relined and put back in the production process.
Cement kiln co-processing is an ideal option for the management of the SPL. However, fluorine and cyanide content present in SPL pose safety and process concern to the cement industry because of the possibility of leaching of these constituents in water or release into the atmosphere. To evaluate these concerns, a study was undertaken to determine the leachability of fluorine and cyanide in water at different pH conditions from pH 4 to 12.
This evaluation suggests that for safe handling and co-processing of SPL, the contact of SPL with water and acidic environment needs to be avoided.