If it has gone acid, I'd burn it. If it is fast burning, don't make the mistake of having your face above it when you light it. I had some spilled 231 or bullseye, about a cup, put up a 10 foot flame and toast the bottom of the bball net - I barely got my face out of the way. A rifle powder can be hard to light, not so with pistol propellents.
If you just spill something and it is not gone south, it makes a great fertilizer. Just don't dump it all on one plant, that's a LOT of NITROGEN there!