Is there any industry that extracts heavy metals from coal ashes?
First you need to know what is in coal ash before it become economical to extract it. You also need a source of coal ash. Fly ash with water is exothermic, where the reaction is so rapid that the heat can melt an Aluminium dump truck. See cite below on waste. Contact your local power company on additional material, they are happy to help students and they see such help as good PR.