Can I use dye on a concrete floor that has been primed

If the floor has primer on it, I would think that it would prevent the dye from soaking into the floor properly and evenly. It may be better to consider using a paint instead, unless you are able to remove the primer somehow.

Yes, I believe so. Tho you may want to put another preservative on top of the dye, when you get it done, just to keep it longer. J.

Can't stain a painted concrete floor. Stain will not get absorbed into the concrete. You can paint the concrete to make it look stained.

http://www.hometalk.com/search/posts?filter=paint%20concrete%20floor

If it's been primed with a paint primer, you'll have to use concrete paint. The primer had formed a barrier that won't hold a stain or dye.

You will have to have them sanded/buffed to get off the primer if you want to come te stain.

When I stained my first floor, I was sold a bonding agent that they said I needed for the stain to 'stick' to the floor. (Only used it once) I would think this agent would do the same over primer, but would be much easier to just do what W Burbank said & paint to look like stain...