Efficient recovery of metallic aluminum from hazardous secondary aluminum dross via ball-milling and supergravity-enhanced separation

Secondary aluminum dross (SAD), a by-product of aluminum extraction from primary aluminum dross, contains metallic aluminum particles coated with dense oxidized films, complicating the recovery of metallic aluminum using traditional methods. Ball-milling was employed to break and alter the structure of these oxidized films. The results indicated that the films became thinner and stripped away, exposing the aluminum surface. Based on the in-situ observation of the structure evolution of milled SAD particles with temperature, the metallic aluminum liquid was efficiently recovered from SAD at 680 °C via supergravity-enhanced separation, where the recovery ratio and mass fraction of Al in the separated aluminum phase were up to 95.72% and 99.10 wt.%, respectively. Moreover, the tailings can be harmlessly utilized in refractory, cement and ceramic fields with subsequent treatment, such as denitrification, dechlorination, and fluoride fixation.