I spread some foam-stinking sand out on a baking tray and bbq'd it on high stirring occasionally for about an hour, bucketing it once it stopped smoking and putting some more on there to continue... The bucket I put the cooked sand in had zero foam stench afterwards. It was maybe 1/4 of my entire supply of sand. I haven't used it enough since to be able to say if it made a differnence. I used it as 'facing sand' thinking it would help the foam gas off at least a little before I had to worry about more sand float. Pour failed but not because of that, so I can't say if it would have worked. But at least it got some the stink out of a portion of my sand... I think it would have worked, but I could probably pay for another half a bag of clean new super fine glass blasting beads (what I use for lost foam sand) for the price of the propane I burned doing it. Residual furnace heat might be a cheaper way to go as evlwht-guy suggested to me.