How did Drogo melt gold?

[CFdS]

To clear up the bigger fire = hotter flame debate: A big (enough) fire creates a chimney like effect: the hot, oxygen depleted air rises and cold, oxygen-rich air flows into the fire. The fire has its own bellows, in a matter of speaking. So a bigger fire as a higher chance to reach the maximum flame temperature for the given fuel but it is not guaranteed to. That does not invalidate any of Fearsome Fred's points:

-If you have to cook for many people you use MORE and BIGGER fires, not hotter ones. Professional pizza bakers do not have hotter ovens than amateurs.

-The pot has to be as hot as the gold on the inside, hotter on the bottom. The handle will be cooler than the inside but the difference will be smaller the longer it is on the fire. While oven mitts protect against typical temperatures one encounters in a kitchen (100°C to 250°C) they provide little protection against temperatures encountered in metal working.

But perhaps the dothraki used microwaves, perfectly matched to the resonance frequency of gold. That way they could melt the gold nearly instantaneous without heating the pot too much. This is not supported by the book, though....