Abstract: A double skin trommel having an inner drum and an outer drum joined together to rotate. Material is fed into one end of the inner drum, where some passes through apertures therein and the rest moves to the opening at the opposite end and is discharged as oversize material to a stockpile. Material that passes through the apertures is received in the outer drum which has roller mesh screen panels around a helical discharge spiral. Material that is smaller than the opening in the mesh passes through onto a conveyor and that fines grade material is stockpiled. The material that is retained in the outer drum is moved by the spiral to the discharge end of the drum and that middle grade material is conveyed to a stockpile. The apparatus is transportable being mounted on a chassis.