Novel and efficient purification of scrap Al-Mg alloys using supergravity technology

Supergravity technology is an efficient method for the separation of trace elements from Al-Mg alloys made of their scraps. This study investigated the enrichment and separation behavior of impurities from Al-Mg alloy using supergravity technology under various conditions. After supergravity enrichment, nonmetallic inclusions and precipitated intermetallic compounds were concentrated at the bottom of the samples, and the enrichment degree positively correlated with the gravity coefficient. High-purity Al-Mg alloys was obtained with efficient impurity removal from the alloy melt of the scraps by filtration in supergravity fields. Improving the gravity coefficient benefited the recoveries of the Al and Mg but had little influence on the purity of the obtained Al-Mg alloy. Although the recoveries of the Al and Mg increased slightly with increasing the separation temperature, the removal rates of the metallic impurities were relatively low at elevated temperatures. At the temperature of 500 °C, gravity coefficient of 600, and separation time of 1 min, 91.6% and 90.1% of Al and Mg were recovered, respectively. Their corresponding mass fractions in the filtered Al-Mg alloy were 99.2 wt%. An amplified experimental centrifugal separation apparatus was also designed for purifying the alloys on an engineering scale. The results indicate that supergravity technology is feasible on an industrial scale and that it can be potentially employed as a separation and purification process.