A centrifugal system would certainly separate the mercury assuming you could maintain a fluidized bed and that there were not large differences in the sizes of the particles in the slurry. Depending on the volume involved, a vibratory table might be better. There are many other methods, but I would need to know the relative size / volume / solidliquid ratio information in order to make a useful recommendation. You need to take special precautions in any case to preclude the release of mercury into the environment.    _{Your Comment}