Nuts in a bad way. They even have a sign stating that they don't take spent cartridge casings. I'm wondering who does since I know of a few gun ranges that collect their's in 50 gallon drums and then sell them. I think I better ask them when I get around to it.
I think it has something to do with un-burnt powder residue and the heat from the smelter. There is also the possibility of a un-fired shell in the pile of brass. That would not be a good thing, hot molten brass a live ammo.