I'm sorry, but I do not understand your post. If you could please rephrase your question, I may be able to comment.

Ok,We had repair of our concrete block walls where a lot of mortar joints were drilled out and redone. Fine grit is everywhere in the basement. Tried picking it up with a dry vac, but the blowing and the filter just seem to move the dust around. Tried mopping a small square of the floor. but it takes at least 5 moppings to get rid of the grit. I didn't want to hose it down as there's too much in storage to do more than 1/3 of the foor (1000 sq ft) at a time. Maybe I'm just too fussy-- maybe a fine coating of grit on the foor won't effect the paint job. We used TSP on the walls, but the floor doesn't appear oily or anything(last painted 8 years ago). So, how do I get the floor clean enough to paint?

I honestly cannot figure out why a shop vac will not pick it up. Did you try replacing the filter? Maybe your vac is not strong enough to pick up finer granules.....I don't know. I go through 5 shop vacs a year and only buy 6HP and up models.

I know from experience that once you start rolling paint on the floor, the roller will start picking up the grit. Floor prep is crucial in order to ensure a successful bond.

I do not recommend adding water to a basement to two reasons. One is that you can activate mold spores, the second reason is you may leave moisture in/on your floor which would lead to failure if you try to cover it with paint/epoxy.

You could also try to scrape, sweep, vacuum, then use a rag with denatured alcohol to pick up the rest. Wear gloves and respirator.