Anything can be used as a fuel. If ants can make fire then I don't see why dinosaurs can't.
When do ants make fire?!?!?!
If ants are able to create vast tunnels and dungeons, it is not unlikely that their massive prehistoric ancestors were capable of rubbing two sticks together. Furthermore, it could have been used as a sort of warfare against other ants. This and scaring wild dinosaurs away from their tunnels, it would have been very beneficial for ants to use fire.
Furthermore, if ants were able create fire, then they most likely would have been able to heat clay or metals to make basic utensils or tools. In fact, since they have more limbs and thus more dexterity than humans, their tools would have been even more advanced and intricate than anything that our ancestors were capable of making.
Ants very well could have been the equivalent of the modern day blacksmith.