The “Primitive Technology” channel shows how to process iron from river sand. The level of effort and the raw materials needed in order to produce a *tiny* amount of iron are impressive, but the results show that it can be done at a very low tech level. A bit of refinement and a useful amount of workable iron could be produced on a fairly regular basis by a small family, tribe or village. Why you’d want to go to the bother *today* I’m not so sure, but maybe this sort of thing would be useful for those of a prepper mindset, or planning on colonizing new worlds or time traveling. I’m not here to judge.
A couple months back the same guy showed how to make an iron knife – admitted a bad one, but an iron knife nonetheless – from bacteria. I was *certain* that I’d posted this video, but a concentrated, detailed search of the blog for more than ten seconds did not turn it up. Shrug.