Linked from
The 10 pages that link to Iron smelting, each with the reason it gives.
CharcoalRelated: Charcoal historically supplied both heat and carbon monoxide for reducing iron ore.
Nok cultureRelated: Furnace remains at Nok sites provide evidence of iron production.
BlacksmithRelated: Smelting supplied the raw metal that smiths refined and shaped.
FayaliteRelated: Iron-rich silicate phases related to fayalite occur in smelting slags.