...There's nothing that says all the ore processed there came from Bajor either, some unprocessed ore could have come from other systems to be processed there en route to a final destination...
This is my take on it too.
When the Cardassians took over Bajor, they not only took over the planet, but
the entire Bajoran system, and all the resources that system had to offer.
So yeah, I don't think much of the ore came from the planet at all, but from the various planets, asteroids and moons neighboring Bajor.
I think Terok Nor was built in close proximity to Bajor not because of it's convenient location to the planet, but because of its convenient access to
free and expendable slave labor.
Of course the first order of business was to build such a station
to take advantage of all those resources in the system, and who better to build it than Bajoran slaves?
Why build a station with so many docking ports and pylons? Not because they wanted a transportation hub for all those other species, the Cardassians were too xenophobic and certainly not altruistic enough to do that.
No, I think the reason was to support all the Cardassian mining transport vessels that brought in raw ore from
around the system. Otherwise, why not just set up some industrial transporters and beam it up from the surface as needed?
Of course it was stated multiple times that Bajor was strip-mined, but I think that many of those Bajoran labor camps on the surface served in both extracting and processing most of the ore that was mined there.
Lastly, there's Empok Nor, which is the exact design as it's sister station - but it's just sitting there, not orbiting a planet at all, which further makes me think that the Cardassians would build these stations for the purpose of processing ore found in space.
Just my 20¢.