andhow it work with the Al powder
If your idea is to make the conversion in solution, then it's not possible. My idea refers to a solid sulfate of something, let's say solid magnesium sulfate, for example. You reduce the sulfate to fine powder, you dry it (heating it, if necessary) the you mix it perfectly with Al powder in stoichometric amounts according to the reaction:
CaO + Al2
then you start the reaction in a point with a gas torch and go away because the reaction is higly exothermic.