Abstract: An outer cylindrical drum has an inner drum concentrically mounted therein in spaced relationship, to form coextensive outer and inner drying chambers that are connected to a common source of hot exhaust gases from a sugar factory boiler. Raw bagasse is first passed through the outer annular chamber to effect primary drying thereof, and then a portion of the primary dried bagasse is divided from the remainder and is passed through the inner chamber to produce secondary dried bagasse. The conveyance path between the point where the primary bagasse is divided and the inlet of the inner chamber is short in both time and distance to preserve heat in the divided portion, and an entrainment unit is utilized to preheat the divided portion before it enters the inner chamber.