automotive aluminium recycling: a comparative review of alloy chemistry, thermodynamic barriers, and emerging circular recovery technologies

The rapid expansion of lightweight vehicles and battery electric vehicle production has intensified global demand for aluminium alloys while increasing the strategic importance of end-of-life vehicle (elv) aluminium recycling. although secondary aluminium production requires substantially less energy and generates significantly lower greenhouse gas emissions than primary smelting, achieving high-value closed-loop recycling remains fundamentally constrained by alloy contamination, inefficient alloy-specific separation, tramp element accumulation, and the thermodynamics of melt purification. these challenges are particularly critical for modern wrought automotive alloys, whose mechanical and corrosion properties depend on strict compositional tolerances for fe, cu, si, zn, and mg. this review critically examines automotive aluminium recycling through an integrated chemical, metallurgical, thermodynamic, technological, environmental, and circular economy perspective. a structured analysis of 81 publications published between 2010 and 2025 was conducted using scopus, web of science, engineering village, and google scholar databases. particular emphasis is placed on two systemic barriers that remain insufficiently addressed in the literature, including the thermodynamic limitations governing tramp element removal during remelting and the absence of alloy-grade traceability throughout the automotive lifecycle. key chemical phenomena, such as partition equilibria, oxide stability, and the formation of brittle fe–al intermetallic phases, are analyzed related to secondary alloy quality and recyclability. established and emerging recycling technologies are comparatively evaluated, including pyrolysis, hydrometallurgical extraction, solid-state recycling, solid-state electrolysis, laser-induced breakdown spectroscopy (libs), x-ray transmission (xrt), and ai-assisted sensor-fusion sorting systems. the review concludes with a future research roadmap spanning alloy design, electrochemical purification, intelligent sorting, digital traceability, and circular metallurgy integration.