I'm not sure what refractory cement is made out of but I don't think it's that easy to find in a riverbed or such. Also it has a high R-value by design, so makes it a poor material for a heat exchanger. Ordinary clay will crack well below the temperatures you need.
I tend to think you want a big column filled with coal, lime, and iron ore, and then some way to blow a ton of air through it.
Or more realistically, if teleported back 5000 years, you primarily focus on staying alive and accept that technology doesn't tend to speed-run, even if you know in theory what's supposed to be done.
Caleb James DeLisle /
npub1mh…q233h
2025-05-14 08:28:44
in reply to nevent1q…d5mk
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npub1mh5a6mhm4u78glqxhltq7uexv6kddphycthlguvn0ux8ch72tc8q6q233hSeen on
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2025-05-14 08:28:44Event JSON
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