That or slag is much lighter per lb of refined product, reducing the transit cost. Iron ores are incredibly common, but they’re also very heavy, what with them being literally rocks.
of course I can't find the original video I was watching, but since the slag is directly outside the steel mill, transit is about as low as it could get.
If you search on YouTube for "deskulling slag pot", you'll find a bunch of videos showing slag trains going maybe a couple miles from the mill to a pit to deskull?
