dig a huge hole around the edge of the mound, very quickly scoop up the mound, fling aforementioned mound over fence to neighbors house ..
just kidding...but ants wont cross some things...
not sure about fire ants but supposidly cornmeal, grits and cream of what kills ants, they eat it and cant digest it and die.
ants also despise peppermint
Ants will not walk through baby powder.
Sprinkling dry Maxwell House Coffee grounds on a fire ant nest kills the ants.
Black pepper, chili powder, and ground cinnamon are all good for getting rid of ants. Both the pepper and chili powder repel ants, and the little beasties won't cross a line of cinnamon.
uncooked Minute Rice around the base of an anthill or wherever ants are a problem. The ants take the rice back to their nest for the colony to devour. When the ants eat it, the rice swells in their stomachs, killing them.