Recovery of fluoride from spent cathode carbon block by combustion combined with water leaching process

Spent cathode carbon blocks (SCCBs) is a kind of hazardous waste that can be harmful to the environment. In this study, a process of high-temperature combustion combined with water leaching was explored to dissociate toxic substances from SCCB and recover valuable components. Combustible components in SCCB can be converted into useable heat energy. The combustion parameters and water leaching process were optimized, and the transformation trend of important components was explained. According to the experimental findings, under optimal conditions, the combustion weight loss rate of SCCB reaches 81.5%, and the defluorination rate reached 88.2%. The toxic leaching concentration of fluoride from the treated residue was reduced to 49 mg L−1, in line with the safe discharge standard. The characterization results showed that the final recovered product was highly similar to its analytical reagent counterpart. This treatment process has the environmental benefits of secondary resource recycling and can effectively reduce the negative impact of SCCB on the environment.