Recycling of old wire - this is how it works.

In the old days they used to shove the whole lot into a fire, let it
burn and when cool recover the copper, or whatever metals were left
behind.

This was deemed not very responsible so now wire is recycled like
this.

It is cut into small pieces. It is shaken, thrown around one hell of
a lot and generally agitated until the metal part (copper or other)
falls out. I know it seems hard to believe but apparently it does
just work its way out.

Then they separate the two, recycle the copper and are left with a
load of plastic insulation to deal with. There is no market for
recycling the insulation so what happens next seems to be known
already.