De-Ironing of Aluminium Alloy Melts by High Shear Melt Conditioning Technology: An Overview

Abstract

The main problem of recycling aluminium scrap is the gradual accumulation of impurities, especially iron, which tend to form undesired intermetallic compounds that affect the integrity and the mechanical performance of the castings. In this paper, we aim to provide an overview on the topic of iron removal from aluminium melts through primary intermetallic precipitation and the progress made during the LiME Hub project to understand the process and to develop a more efficient procedure. We cover both thermodynamic analysis and experimental validation. We found that high shear melt conditioning technology enhances the typically slow nucleation and growth of the dense primary intermetallics, speeding up their sedimentation and allowing a faster removal of Fe from the melt by simple gravity sedimentation. It also promotes the formation of smaller and more compact Fe-rich intermetallics, allowing an increased volume fraction recovery and mitigating their effect of being present in the final castings. The technology is not limited to batch processing, with a 90% efficiency, but can also be applied to continuous melt treatment of aluminium scrap, with currently 60% efficiency, and could be combined with other solid–liquid separation techniques to increase the purification efficiency even more.

Synergistic effect of Mg addition on the enhancement of the mechanical properties and evaluation of corrosion behaviors in 3.5 wt % NaCl of aluminum alloys

“…Just because a metal is sensitized by precipitation at grain boundaries does not necessarily mean that corrosion will occur, be it intergranular corrosion or stress corrosion cracking. The likelihood of corrosion would also depend on the surrounding environment [ [6] , [7] , [8] ]. According to research, silicon and magnesium can be added to aluminum alloys to increase their thermal conductivity and heat resistance.…”

Numerical Studies of Batch and Inline High Shear Melt Conditioning Technology Using Different Rotors

“…These beneficial effects and the concomitant improvement of thermomechanical properties all occur without chemical inoculation, thereby increasing the recyclability of the cast or wrought alloy. A successful application of HSMC is the deironing of highly contaminated aluminum alloy melts, where intensive shearing reduces the sedimentation time and leads to faster iron removal [16][17][18].…”