Re:Down on the farm that harvests metal from plants
by hinkley on Monday March 02, 2020 @01:53PM
(#22467480)
We know that lead is airborne. Is that what you meant by reducing the volume?
Dessication is probably a safer way to reduce volume. I don't think lead is pernicious enough to warrant the cost of supercritical oxidation.
Re:Down on the farm that harvests metal from plants
by samatman on Monday March 02, 2020 @04:33PM
(#22469275)
Unquestionably safer to dessicate. I mean to say the lead could be leached if one were of a mind to; I did indicate it's probably not a good idea.
No supercritical anything was sketched out however; just a reducing pyrolysis (making charcoal) and leaching it once or twice with nitric acid. Some lead would undoubtedly escape during pyrolysis unless the fumes were washed, which is tractable (just bubble it through the nitric acid and reuse it for the leachate) but this just adds to the already considerable expense.
Not necessarily. The char could be ground and leached with nitric acid, producing soluble lead(II) nitrite from metallic lead (which you'd most likely have after a reducing pyrolysis of the stalks).
Nitric acid is cheap as chips, but this would be somewhat labor-intensive and you're not going to get much lead out of it. Just charring the stalks before burial would reduce the volume of lead which needs to be sequestered, in comparison to the stalks themselves, and it would be carbon negative for much longer.