Simultaneous extraction of Al, Fe, Si to prepare aluminum-based intermediate alloys from secondary aluminum dross by a high temperature electrochemical reduction method

A short-process technology integrating hydrolysis-calcination and molten salt electrolysis was developed to recover Al, Si, and Fe from secondary aluminum dross (SAD). Thermodynamic and characterization studies elucidated the reaction pathways, phase transformations during pretreatment, and the dissolution behavior, electrolytic mechanism, and element migration (Al, Si, Fe) of pretreated SAD (P-SAD) in cryolite molten salts, overcoming its poor solubility. The research results show that the presence of Al₂O₃ can promote the recovery of the Si element, and optimized electrolysis (30 wt.% P-SAD, 1000 °C, 1 A/cm², 3 h) produced an Al-alloy containing 1.2 wt. % Si and 0.9 wt. % Fe with 76.7 % current efficiency. Microstructural analysis showed an Al matrix with Al-Si and Al-Si-Fe intermetallic phases, exhibiting uniform Si distribution and localized Fe enrichment. This study provides systematic insights into the electrolytic recovery process for high-value SAD utilization.