Gra, I had a go at smelting copper from ore which I burned to the oxide and it was a royal pain.
You can do a thermite reaction, where you mix the metal oxide with aluminium powder and then set alight to it with a sparkler.
This has the added bonus of "reducing" everything to it's elemental form. The snag is when you are smelting stuff that you lose a lot of it, assuming you are using a mega blast of air.
I found it quite difficult to get a satisfactory result. Nevertheless, I obtained a nugget of cornish copper. The yield from wet ore to metal was about 4.5%