What are you actually even doing here? What are you trying to accomplish?Great! Let's get into the details:
- Where? Can you provide references/page numbers/quotations of what is actually said in the book?
- What are they smelting? This is important if you're trying to establish a particular level of human technology has been attained.
- Who is doing the smelting? Are they supernatural/magical beings (or people working for them) or people from "fairy-land" or a "lost" superior culture, or are they normal people like hobbits or Men of Bree, Laketown/Dale, Dunland, or Rohan? I think this is important for determining whether one might expect the activities of such people to conform to what has been established as "typical" by reference to the archaeological record.
- What actual physical processes are being described, keeping in mind that what we have is a "translation" and that the terminology for a given process in Westron might be untranslatable into English? Also, that the translation appears to have been originally written in English (because it actually was) so is unlikely to be all that faithful to the original Westron.