Decarboxylation
Pyrolysis

https://en.nncup.org/2607-ash-as-a-fertilizer-benefits-composition-use-in-the-g.html

https://en.m.wikipedia.org/wiki/Decarboxylation

https://en.m.wikipedia.org/wiki/Carbonylation

https://en.m.wikipedia.org/wiki/Pyrolysis

..

i suspect the pyrolysis process will lock zinc into the nitrogen & sulfur with ionic bonds, leaving the larger particles & heavy metals behind, along with charcoal.

https://en.m.wikipedia.org/wiki/Gasotransmitter

https://en.m.wikipedia.org/wiki/Disulfide

https://en.m.wikipedia.org/wiki/Oxidative_folding

https://en.m.wikipedia.org/wiki/Redox

https://en.m.wikipedia.org/wiki/Electron_acceptor

https://en.m.wikipedia.org/wiki/Zinc_finger