Grade-preserving recycling of highly polluted Al-Mg-Si alloys scrap: Continuous filtration under supergravity-induced

Abstract

The development of low-cost and efficient recovery technologies for highly polluted alloys scrap is generally considered very essential, because it is difficult to remove the large number of non-metallic inclusions and polluting elements from the scrap simultaneously by conventional methods. Therefore, a new process was proposed in this study for direct recovery of forging alloys meeting production standards from highly polluted Al-Mg-Si alloys scrap under supergravity-induced field in combination with microporous Al2O3 CFF. Under the action of gravity deposition and inertial collision mechanisms enhanced by super-gravity, non-metallic particles were all intercepted in the top region of Al2O3 CFF, while large amounts of intermetallic inclusions were trapped in the complex channels inside CFF and precipitated prematurely near the inner walls and impurity particles. At d = 150 μm, G = 200 and T = 650 °C, the content of hazardous elements such as Fe was rapidly reduced from 1.67 wt% to 0.48 wt% and could be further reduced by using Al2O3 CFF with smaller pore size. In addition, a continuous centrifugation device was successfully applied to industrial-scale recovery of Al-Mg-Si alloys scrap. The results show that this method has successfully achieved continuous and effective recovery of highly polluting aluminum alloys scrap on a low-cost and clean basis with high economic benefits.