Aren't the periphery products just seperated away during the molting process of aluminum recycling? I'm not a chemist, but I have a friend who works in a metal

Aren't the periphery products just seperated away during the molting process of aluminum recycling? I'm not a chemist, but I have a friend who works in a metal recycling plant and he described the process to me once. It seems like aluminum can recycling is a pretty well built out process. Getting rid of the impurities from an aluminum can (paint and plastic liner) don't seem like an issue, especially compared to refining ne aluminum.