AIUI you grow the plants, then process them to get the metals. Then you have plant matter with 'no' metals ... so using that to make bio-diesel seems possible?

AIUI you grow the plants, then process them to get the metals. Then you have plant matter with 'no' metals ... so using that to make bio-diesel seems possible? Depending on the details it might be possible to use the burning of the plants to extract the metals - similar effect (in that you get an energy crop and mineral extraction in one). You raise a valid concern though, thank you.