On Fri, 16 Oct 2015 06:59:00 -0700 (PDT), Tim
wrote:

Now metals are fed into huge shredders to fill export containers

https://m.youtube.com/watch?v=lXfitusZ9qY

That is mixed scrap, not near as valuable as sorted (clean) metals.
I assume that waste stream goes through magnetic separation at least
but you still need a way to separate aluminum and copper from the
plastic and glass.
That is easier done in a 3d world plant where labor cost, worker
safety and environmental concerns are not as important.
.......
Greg, that's true, but with modern techniques, thee are easier ways to separate metals then ever, so mixed becomes in-mixed in better fashion than say 20 years ago