No, you have to buy a new mine.But right now, I can't really suggest to buy a private mine. We will rework them a bit, as soon as we got time again.
Well since you are going to rework mines I would like to ask you if you are considering to add some HQ materials to private mines?Resources could even depleted after some time, so the price for private mine is mostly price for safety and comfort. Also there could be different prices for different kind of mines depending on quantity and quality of resources.
BTW, what do you think about the idea of using dynamite at mining? (more resources at once)
It should go to suggestions after implementing explosive level 3 (or mayby wiki is out of date)
You can make dynamite with demo 2. and yes I agree, gives explosives more use than just blowing up bluesuits in NCR.