An interesting discussion about how burning coal concentrates trace amounts of uranium and thorium in coal and leaves it in fly ash (the remaining particulates).
It makes me wonder how much of each element you could extract by "mining" fly ash dump sites.
People have already looked into extracting rare earth elements from fly ash.
>Average total REE content (defined as the sum of the lanthanides, yttrium, and scandium) for ashes derived from Appalachian sources was 591 mg kg–1 and significantly greater than in ashes from Illinois and Powder River basin coals (403 and 337 mg kg–1, respectively). The fraction of critical REEs (Nd, Eu, Tb, Dy, Y, and Er) in the fly ashes was 34–38% of the total and considerably higher than in conventional ores (typically less than 15%).
It makes me wonder how much of each element you could extract by "mining" fly ash dump sites.