The heating of the metal would result in an energy expenditure
that would make mining copper counterproductive
The expenditure of the process is comparative to how much material (rock, dirt, whatever) you have to process. The more will be the material to be route, the larger will be the equipment, or the longer you have to run it, and the more power and other other materials you need. so that is why its expensive to extract copper from contaminated lanhope it helpshope it helps