Abstract: Apparatus for use with extremely low-grade aggregate ore, for deriving a concentrate comprised of metal-bearing ore particles having densities within a predetermined range. The apparatus is in the form of a mobile, self-sustained system including a vehicle trailer for horizontal transport and elevated operational support, plus an integral power system capable of supplying the total energy requirements of the apparatus. Two types of particle size separation are applied, followed by compaction and particle density separation. Two density separation areas are provided to effect both coarse and fine gravitational shaving actions, and dual adjustment controls are also provided to vary the shaving force intensity to derive the concentrate independently of changes in the particular characteristics of the aggregate being processed. The apparatus includes outer and inner cylindrical chambers concentrically mounted on the trailer so as to be tiltable and rotatable.