Advanced Iron Smelting (includes steel and copper smelting) Even more advanced Iron Smelting with the mod dependencies (quartz for copper, lime for iron + steel, possibility to cast high steel)
Mods introducing new content into the game.
Iron Smelting is a mod that tries to squeeze itself between some larger mods. Its functionality is to smelt iron and steel with an increased yield, at the price of more byproducts to handle. Dependencies to many other mods. This can be seen as an mod pack too...