[pjc50]

> You can recover about 25% of the copper in a device

This is surprising to me, because it's all on the surface of the PCBs? Where does the other 75% "go"? I'd have thought if you incinerate the thing you'll get a puddle of gold-copper mix running out the bottom, and the rest of the rare elements and aluminium as oxides in the slag.

[Nasrudith]

It goes into things that are uneconomical to extract without vastly different conditions. Technically one could breakdown and separate everything by element and isotope but that would be an incredibly inefficient way of doing so.