Many years ago, my parent's house burned down and I went in and cut, jerked and stripped all the copper wiring out of it. I took a whole pickup bed full of wire home, set it on fire and burned the plastic off. Two things happened.
1. I was paid a visit by the local authorities for burning in city limits without a permit ($50.00) fine and had to extinguish the left-over blaze.
2. When I finally get all the plastic stripped off, I haul it to the salvage yard and the worker tells me he can't take it because it's been burned? I finally get the owner, and he agreed to take the stuff off my hands "just this one time."
I think the plastic has to be stripped off and not burned off? That's my one and only experience dealing with copper. I don't know a whole lot about it - it was too much trouble for me...
Good Luck, Tim