Smelting was what had been previously known as Mining; the Kingdoms of Camelot Staff changed the name of the research because apparently it confused some players. Smelting must have confused them more, because they subsequently changed the name back to Mining.
Mining is a technology that can be researched at an Alchemy Lab. Every upgrade of mining increases your Ore production by 10%. Each level requires that the Alchemy Lab and Mine level are the same or higher than the level to be researched e.g. Level 9 mining requires at least a level 9 Mine and level 9 Alchemy Lab.