Shredded tobacco is blended with expanded tobacco on the foraminous bottom wall of an elongated vibratory conveyor which receives overlapping streams of shredded and expanded tobacco at one end of the bottom wall in such quantities that the ratio of shredded tobacco to expanded tobacco remains constant. Blowers are provided to supply compressed hot and cool air against the underside of the bottom wall whereby streamlets of air pass through the perforations of the bottom wall and travel across the particles of tobacco in the vibratory conveyor to convert such particles into a fluidized bed of substantially constant height which advances toward the other end of the bottom wall. The speed of streamlets is reduced above the fluidized bed to prevent the ascending streamlets from entraining appreciable quantities of particles from the bed. The particles which form the fluidized bed are intimately mixed with each other before they leave the conveyor. A nozzle is provided to sprinkle atomized casing or top flavor onto the fluidized bed above the bottom wall.