A diffusion mixer, also known as a tumbler mixer, is a mixing device for solids and powders. The mixer consists of a closed metal container that is rotated around an axis at optimum speed by an electric motor.
The powder particles must first be set in motion by external action, so diffusion is the main mechanism in these types of mixers. The powdered material to be mixed is loaded into the vessel and the movement of the powdered particles is achieved by tilting the material beyond the angle of repose and using gravity to drive the flow.
The results that can be achieved with a tumble mixer depend mainly on the tilt angle of the mixer, the filling volume, the speed, the residence time, and the filling method.
There are several subcategories of tumble mixers: