The only ion that is going to precipitate is calcium (which is, of course, a pretty important ion). It precipitates as apatite (a phosphate) and the amount that does depends on how much you put in, how much phosphate the particular malt you are using contains and how much of that phosphate is available to react with the calcium and mash pH. Another big factor would be whether phosphoric acid was used to set the mash pH.
If you were foolish enough to go through the whole process of duplicating a water profile or if you are brewing with a carbonaceous water and did not decarbonate it prior to mashing then calcium carbonate will also precipitate when the water/mash is heated.
Thus without knowing a lot of particulars and making a lot of assumptions it would be difficult to estimate the amount of calcium that would be removed beyond the broad observtion that probably at least 1 mEq/L would remain (20 mg/L).
Sulfate, chloride, sodium, potassium and to a lesser extent magnesium (some magnesium will precipitate) will all stay in solution.