Metallic aluminum in aluminum dross is recovered in Japan generally by physical separation, using the so-called Metal Reclamate Machine (MRM). A large amount of the residue containing oxides, metallic aluminum, nitrides and salts is unavoidably generated as a by-product of the MRM process. Since the metallic aluminum is much more viscous than the relatively brittle oxides and nitrides, it remains larger after crushing in the MRM. Using of an easier separation process for the recovery of metallic aluminum from the residue would promote sustainable recycling. The relationship between the composition and the grain size of the residue was investigated to develop an easier technique for upgrading aluminum dross residue. The mean sizes of studied residues were 100–200 µm. The residues larger than about 200 µm had higher metallic aluminum content, whereas their aluminum nitride and chlorine contents were lower. It was confirmed that the metallic aluminum content of the residue could be easily increased by the proposed screening process.
- Metal recovery
- Screening technique