I am somewhat cynical about the techniques called bioleaching and phytomining in order to recover low levels of less reactive metals from mines and areas with low levels of metals in order to recycle metals. My issue would be that the low levels of metal recovered would be far too low to be useable in an industrial set up, and what could you do with a few hundred kg of metal from a given site, bearing in mind the time taken for plants to take up metal minerals.
I have to teach this at GCSE level:
The future of copperhttp://www.bbc.co.uk/schools/gcsebitesize/science/aqa/metalsanduses/extractingmetalsrev5.shtml
We are running out of copper-rich ores. Research is being carried out to find new ways to extract copper from the remaining low-grade ores, without harming the environment too much. This research is very important, as traditional mining involves huge open-cast mines that produce a lot of waste rock.
Phytomining, bioleaching and scrap iron
Some plants absorb copper compounds through their roots. They concentrate these compounds as a result of this. The plants can be burned to produce an ash that contains the copper compounds. This method of extraction is called phytomining.
Some bacteria absorb copper compounds. They then produce solutions called leachates, which contain copper compounds. This method of extraction is called bioleaching.
Copper can also be extracted from solutions of copper salts using scrap iron. Iron is more reactive than copper, so it can displace copper from copper salts. For example:
iron + copper sulfate → iron sulfate + copper