Gloom'rel in BRD teaches how to smelt after you bring him 20 Gold Bars, 2 Star Rubies and 10 Truesilver bars.
After you exit the bar, head down the steps and take the first left, which is Flamelash's room. Contine on past him and through the next room until you come to a tomb with 7 ghost. Gloom'rel is one of the ghosts.
The black forge (which you need to smelt) is the next area, look to the left of the bridge that leads across to Molten Core.
The black anvil (which you need to make anything from the bars) is in another part of the instance,where incendius is.