Recovery of the majority of resources from hazardous was 2025 Environmental

Carbon dross, a hazardous waste from aluminum electrolysis, poses a challenge to the global aluminum industry. This paper proposes a combined flotation-leaching (CFL) method to recover valuable resources from carbon dross, achieving a total recovery yield of 95.9%. This included 17.35% carbon powder (95.67 wt% purity) and 78.55% electrolytes (99.65 wt% purity). Kinetics results showed that the carbon dross flotation processes followed the classical first-order model, while fluoride ion leaching followed the shrinking core model, controlled by internal diffusion. Thermodynamic calculations indicated that Na3AlF6 was the main impurity removed. DFT calculations showed that the higher surface energy of the Al exposed surface and the lower binding energy with NaOH resulted in a higher reaction rate for alkaline leaching compared to acid leaching, but with poorer leaching efficiency. Treating one ton of carbon dross with CFL reduces at least 539 kg of CO2 emissions, aiding carbon reduction in the aluminum industry.