There's some cheese methods (world hopping being the easiest)

Non-cheese early game:
Build a portal at the ore deposit and another at your base. Mine the ore into a chest and use the portal to repair, rest, and store the huge amount of stone you will also mine. I recommend saving the stone because you will need an enormous amount of it to build with later.

Once the deposit is mined out switch to leather armor (if you aren't using it already), build a cart at your ore deposit (nails can go through portals), load your ore into it (not too much though or it will become impossible to pull up hills, especially with low run skill), pop Eikthyr power and run it back to your base.

Unload your cart, hit it with an axe until it's destroyed, pick up the materials, go back through portal while Eikthyr is still up, repeat until all your ore is moved. Don't start refining until Eikthyr fades or you return it all.

The game gives you all the tools you need to hump a bunch of metal around but you have to think about how you're going to get the ore back ahead of time of it will become frustrating very quickly.