Gravity-Flow Blenders

As the name implies, the only motive force in gravity blenders is the flow of a solid moving under its own weight. Mixing occurs as a result of differential blender retention times as solids exit the blender outlet. Gravity-flow blenders are especially useful when large quantities of solids must be mixed and stored.
Different types of gravity-flow blenders include tube blenders, cone-in-cone blenders and diamondback blenders.

Tube blenders derive their name from the many tubes inside a bin with entry points into the tubes at multiple elevations in the arrangement. These tubes deliver their contents from multiple elevations simultaneously to the blender outlet, thus providing the differential bin retention time required for mixing.

Cone-in-cone blenders consist of a bin with a conical hopper that houses another smaller and steeper conical hopper inside. These designs are most effective when interior cylinders above the interior cone lock in the differential flow velocities and extend that effect to the top of the outer cylinder.

The diamondback blender works the same way as a cone-in-cone blender. It derives its differential retention time from the cylinder that protrudes into the upper hopper portion of the blender, thereby producing a varying gap between the cylinder and the hopper wall. Velocity is controlled in proportion to the gap created between the cylinder and the diamondback blender.