If you have an unlimited supply of energy, you can pretty much recover whatever. The only elements hopelessly lost are those that involve nuclear reactions.
Well, while you can in principle do something, an accelerator is a pretty blunt instrument. You're unlikely to have practical success putting Krypton, Barium and a few neutrons together into a Uranium nucleus even if it's theoretically possible. The phase space for the reaction is just not there. Chemistry has a lot more tricks for synthesizing molecules than just shooting them at each other.
