Upcycling of scrap aluminum to pure aluminum through molten salt electrolysis

The amount of scrap aluminum has increased continuously in recent years such that the widely adopted method of remelting no longer meets the demands of high-quality recycled secondary aluminum. Molten salt electrolysis is a method of upcycling scrap aluminum to pure aluminum. In this study, pure aluminum was recovered from scrap aluminum through the electrolysis of a 56 mol%LiCl-36 mol%KCl-8 mol%NaCl molten salt system. The electrochemical dissolution behavior of scrap aluminum was studied adopting an anodic polarization curve. The results show that Al dissolved preferentially compared with Si and Fe in scrap aluminum. The effects of electrolysis parameters, such as the AlCl 3 concentration, electrolysis temperature, and current density, on the current efficiency and cathode products were studied along with the process of purifying scrap aluminum. The results show that the adoption of a suitable current density, electrolysis temperature and AlCl 3 concentration increases the current efficiency and improves the morphology of the cathode products. Pure aluminum of industrial grade with purity of 99.8 % can be obtained on the cathode at an electrolysis temperature of 550 °C, AlCl 3 concentration of 10 mol%, electrolysis time of 3 h, and current density controlled below 0.15 A/cm 2 .