Abstract: A drum is supported for rotation between two shafts having gears thereon engaging a ring gear around the outer periphery of the drum. A crushing and milling cylinder is journalled for rotation upon a vertically adjustable shaft extending freely through the entrance and exit apertures in the side plates of the drum and this shaft is supported within stationary bearings one upon each side of the drum. The sludge comprising finely crushed rock and water is discharged through the exit in one side wall and into a hopper where it is conveyed by a conveyor system over and through a bed of mercury which extracts the gold in the form of an amalgam. The sludge is then discharged from the other side of the mercury bed.