As soon as Eisen finished properly extracting all of the metallic parts from the ground-down ore, which in itself took a few hours, he filled those metallic parts into large crucibles made with his element, added some ground-down limestone, and then some ground-down charcoal, using the charcoal that he created out of the trees grown within this Dungeon.
Once everything was in place in the right proportions to one another, Eisen properly made the crucibles heat up as much as possible to melt everything down, of course also trying to use his mana to properly help with the metal extraction process a little more.