Abstract: Upper and lower vortex chambers are disposed immediately below a calcining furnace for calcining powdery raw materials. The scattering clinker particles from a fluidized-bed burning furnace are trapped in the lower vortex chamber and are returned to the fluidized-bed burning furnace so that the scattering clinker particles are positively prevented from flowing into the upper vortex chamber and the calcining furnace.

Abstract: A dual shaft pan mixer comprises a mixing vessel (1) having a first and a second pan section (3 and 4), a pair of paddle assemblies (10) having drive shafts (13) which are disposed horizontally and in paralllel relationship with each other within the mixing vessel (1) and adapted to rotate in mutually opposite directions, and a drive source (20) for synchronously driving the pair of paddle assemblies (10). The mixing vessel (1) includes a substantially triangular space (22) below an area intermediate the first and the second pan section and displaced out of the loci of rotation of the paddle assemblies (10), and also includes a discharge port (5) which is disposed adjacent to the space (22). The mixer also comprises a rod-shaped vibration generator (30) disposed within the space (22) and extending in a direction parallel to the drive shafts (13).