they have a tumbler im told?it strips the wire clean and runs an eddy current or some #$%* to separate ferrous?burning copper wastes it!you get half the price for "burnt copper"includes any pieces with soldered parts,sometimes ill separate the copper pipe from brass fittings if I think its worthwhile,theyll only pay brass price for it otherwise,i aint greedy its free #$%* anyway but make the most with little effort,i strip the foam insulation from copper pipe used in aircon units though,its too easy,that way you end up with good clean copper,i don't bother with soft aluminium you need too much of it,or steel,its $100 per metric ton!you get about 5 or 6 bucks for a big truck battery so I don't bother too much with them either,dont like the acid fumes attacking #$%* around the place,plus they are always greasy filthy things for 5 bloody bucks if that?