I’ve never dealt with the hobgoblins directly but they seem to be the only ones who can do it:
From FTB wiki:
Hobgoblins are the only way to obtain the valuable resource of Koboldite. They are the only ones who know how to turn Koboldite dust into Koboldite Nuggets [and nuggets] into Koboldite Ingots. They are also the only ones who can find the dust when digging.
You would need to trade a dust for a nugget and a nugget for an ingot, along with some sort of price if I read that correctly. Seems someone needs to teach these b******s a lesson for hoarding information.