Not being an engineer, I read a few articles (not written by engineers) that said that reclycled aluminium goes into articles of less quality, i.e. it goes from aircraft, then scrapped, then to cans, or consumer products or wires aso.
If my memory is correct, I lately read that you can use now reclycled aluminium also for aircraft again. I guess because of sophisticated melting technology, allowing higher metal purity. Maybe they mix new and old alu together.
Dani