I wonder if you could take the lid off and put a weed burner somehow across the top or, maybe, a little into the top? Sort of an afterburner to burn those nasty pyrolysis gases.
I think this is what happens with pyrolysis. Correct me if I'm wrong. As everyone knows, it takes oxygen to burn most anything. When you get organic materials hot enough, with not enough oxygen present to make them burn, the volatile ingredients will vaporize, leaving behind carbon, mainly. This is called pyrolysis. If these very combustible off-gases are too confined and too concentrated and, if any oxygen (air) is allowed to co-mingle with them, the temperature will increase dramatically and an explosion can occur.
These explosions occur mainly when people are trying to confine the off-gases and condense them to produce an oil. When circuit boards were phenolic and, I heard, contained 40% phenol oil ($40/gallon at the time), I remember people talking (never heard of anyone actually doing it) about using pyrolysis. I knew a guy in Oregon that was pyrolyzing tires. In between explosions, he got a drum of oil (and a lot of fine steel wire and carbon black) from a ton of tires. These systems must be 100% sealed, with zero possibility of air entry.
We're not after any oil, so we can use an afterburner and burn these nasty, toxic, stinking off-gases.
To pyrolyze openly, the parts must be somewhat confined in preferably a steel box. There must be holes large enough to let the off-gases freely escape into the afterburner, yet not so small that the off-gases can build up in the box. Keep in mind that, the higher the temperature, the faster the generation of off-gases.
After everything that's going to vaporize has vaporized, you can remove the box lid and burn the carbon to white ash. This will allow you to get to the metals.
