Why is it expensive to extract copper from a contaminated land where the percentage of copper is low, using the traditional method?

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 lan

hope it helps

hope it helps

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)