Re:Don't they use it for concrete. (Score 1)

Yes. Coal fired plants have huge electro-static precipitators which capture almost all particulates. The captured fly-ash is so fine you can blow it through pipes to the hoppers. They either add water and dump it back into the coal pits, or sell it for filler in concrete (don't confuse it with pot-ash which is also used in concrete).

One irony of collecting fly ash is that the sulfer dioxide leaves the plume more acidic than if the fly ash were left in. But personally, I prefer that to seeing the area around a coal fired plant looking like a moon scape. You should see what the area around a smelter looks like.