Originally posted by Hatsune Neko Gaming:

its best to build smelters where your mining, then move it back to your main base of operations.
i use mods that let me move ore thru portals, but i still build smelters where i mine because its easier. plus gives me another base to operate out of with the ability to repair my items.

Why is it easier to smelt at the mining site? Ores or ingots none can go trough portals. I'm not sure what.is the difference between smelting there or at your base.