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Lurker_IV t1_irqmf93 wrote

Reply to comment by I2ichmond in Why, when you continue to burn ash, do the ashes eventually change from black to white? by genitalwaffles

Charcoal is pure carbon. The heat of fire without any available oxygen in the mound vaporizes any volatile compounds and burns them off leaving the carbon.

Charcoal fires can burn up to 100-degrees hotter than wood fires, iirc, which is why it is needed for metalworking.

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malastare- t1_irr13hd wrote

>Charcoal is pure carbon.

Not really. It still has some of those metals that end up as white oxides when you completely burn the charcoal, and it still has a decent amount of bound oxygen. The volatile compounds are mostly gone (with a bunch of the carbon) but all the trace metals are still there too. Some processes are able to remove some of them, with the goal being a result that retains as much carbon as possible, but burning even the best charcoal still results in non-carbon ash.

Coke (a slightly different process) has a notably higher carbon content, but even that isn't nearly close enough to "pure carbon" to be considered chemically pure carbon. It's better as a carbon source for steel and more expensive that charcoal as a heat source, but from what I can find, its still just shy of 90% carbon.

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