I have a new concrete countertop for a BBQ that I would like to sand to a very smooth finish. I have an orbital sander that uses the Hook & Loop to attach sandpaper to it. Can you recommend a type of sandpaper and the grit sequences to use. 
The only suitable products we have with a Hook & Loop back are paper products, and therefore may not last as long as a cloth backed item would. However, if you would like to try, we would recommend our PS11 which is a wet dry silicon carbide paper. As for the grit range, that is a hard call for me to make not seeing the surface, but I would think if you started at 80 and went to 150 or so, you should end up with a fairly nice looking top. You can always sand finer if you decide you want more sheen to the concrete.