Even then it’s a little dicey.

That’s only half the story they told you. After you dice, grind and melt the original material. You have to use some virgin materials as binder to get all that stuff together. The amount of virgin materials can sometimes surpass even the amount of old stuff and render the whole recycling process moot for those nasty material. That’s why you should have better just burn them all in a furnace or just bury them back in the ground where they belong.