[amluto]

I don’t know anything about geology in particular, but: vaporized rock is vaporized rock, not air. It’s going to cool off as it travels up a relatively cool shaft, and some or all of it will condense and/or solidify into something that will be, in the best case, fine dust. The gasses in the shaft will need to be moving upward faster than the terminal velocity of the removed material for the material to continue moving upward.

In the worst case, I can imagine the vaporized rock depositing (directly in the strict chemistry sense or indirectly via a liquid intermediate) into the walls of the shaft higher up.

[lazide]

Additionally, keeping the vapor from cooling/depositing will also require keeping it above the vapor point of rock - which is well above any metals they might make anything from.