[rance]

Wow, that looks way too much like real work. I try to stay away from that sorta thing. Understand that a mop could tend to round over the high spots. My suggestion would be to attack it chemically.

 

[rance]

I've revised my suggestion. Why not bead blast them. I'm sure you have all the tools at your place and just don't know it. 20ga shotgun from about 10 yards should just about do it. If it needs more, then drag it behind the truck for about 5 miles and call it "done".