Is there an easy way to remove steel wool dust from a marble floor after I recrystallize?

You can use what is called a magnetic broom. This is a long magnetic with two wheels on each side that are attached to a broom handle. Since steel wool is a magnetic metal the magnetic will effectively pick up the steel wool fibers. These brooms can be purchased at Stonecarecentralpro.com.

TIP It is very easy to make your own magnetic broom. Cut a 1x2 about 24 to 36 inches long. Next purchase two side mount wheels(available at most hardware stores) and attach them to each side of the 1x2. Purchase several square magnets and super glue them to the bottom of the 1x2. Attach a handle and you now have a magnetic broom.