Abstract: A method and apparatus for the introduction of second cohesive powders into an improved fluidized bed blender containing UO.sub.2 powder, and for blending such second cohesive powders with the UO.sub.2 powder in the fluidized bed blender. The apparatus comprises an eductor, an improved pressurized vortec mill, a pneumatic conveying system that operates in turbulent flow, and an improved fluidized bed blender. The method and apparatus provide for injection and uniform dispersion of a second cohesive powdered ingredient or ingredients having hydrophobic, hydrophilic or hygroscopic properties in the fluid bed blender adjacent the bottom of the fluidized bed therein during the blending operation, thereby minimizing entrainment of the second powder mixture and providing a homogeneous blend of powders.

Abstract: A metering method and apparatus is provided for the controlled discharge of powder from a fluidized-bed blender to a material container, which gives accurate material weights while separating powder from fluidizing gas. In this method the material container is filled with a series of short duration discharges at a reduced powder flow rate. This method enables the apparatus to more precisely measure the weight of the container and maintain homogeneity of the blended material in both the bed and the container. The apparatus for carrying out this method includes a flexible pressure-tight sleeve connecting the fluidized bed to the container. When a ball valve located at the bottom of the fluidized bed opens to discharge powder, the sleeve retains the high pressure fluidizing gas inside the sleeve and the container. This causes the pressure to build at the outlet of the valve thus preventing the gas from rapidly exhausting and forcing powder through the outlet.

Abstract: A mixture of fine and cohesive powders is blended to complete homogeneity in a nuclear-safe bubbling-bed fluidized bed blender having an improved fluidizing grid. The blender includes a generally vertically-oriented slab-shaped, nuclear-safe mixing vessel having a fluidizing grid disposed at one end of the vessel. The fluidizing grid comprises a linear array of generally downwardly-directed, pyramidal-shaped hoppers each having walls converging into a conically-shaped opening. A plurality of ball valves are employed, one such valve being disposed at the bottom of each hopper. The rotary closure member of each of the ball valves includes a first set of gas orifices for directing a flow of fluidizing gas upwardly in a divergent swirl-shaped pattern along the walls of each of the hoppers. In one embodiment a second set of fluidizing gas orifices for directing a flow of fluidizing gas downwardly into the apex of each of the hoppers is also provided.