[kortex]

Iron oxide is completely inert. You can store it in piles, under the elements. Iron powder less so, you need to keep it dry, but again you can just pile it up. The only tricky part is moving dense dry solids around at the huge scales required.

Edit: wait I forgot that direct reduced iron powder exothermically reacts with oxygen and water in the air, that's how single-use instant hand warmers work. So yeah you gotta isolate the iron powder a bit more than stick it under a tarp.

I've been playing too much Factorio lately so of course my mind goes towards rail systems (could repurpose coal plants) in combination with pneumatics.

[kragen]

single-use instant hand warmers are catalyzed by salt and a little water. iron powder is indeed hazardous by itself but not like that