In a medieval-ish world (Or any other pre-20th century earth), how long could you keep using the same metal? As in, you have very little territory, and what metal was available, has been mined from the ground. If you somehow recovered all metal (Arms, armor, fittings and nails, screws and bolts, forks and sporks) from their use, picking all up from burned down buildings and looting all corpses, from a metallurgical standpoint, how long could you remelt the scrap iron and steel, to make "new" metal? Plenty of territory to grow trees and make charcoal with, but there is no new metal.
If you're careful, you can keep recycling the metal more or less forever, though you can expect some small loss over time as fine metal-rich dust gets blown away, but the amount is very low.
The issue is that the remelting and reforging process will inevitably introduce a small amount of impurities each time, effectively making the input to the recycling process a very high grade ore. During the refining process, you'll be generating a small amount of slag. That slag will have some proportion of metal bound up in it.
You can re-smelt the slag, of course, though that obviously requires you to provide more energy. If you're happy to keep growing enough trees, then you'll be OK.
Not all metals are create equal, of course. Iron in slag is more or less indistinguishable from useful iron ore... iron oxide, mostly, and standard iron smelting processes work on that so iron could effectively be recycled forever even with relatively primitive technology. Copper is also easily recyclable in this way, as are many other metals. Aluminium on the other hand is more problematic, because aluminium oxides are quite refractory, and are impractical to refine if you're trying to use charcoal to do so.