Agitator Mixer. These mixers are devices that employ one or more impellers, mounted to a center shaft, and driven by a motor. The shaft and impellers are placed into the media to be mixed by the rotating impellers, much like a top-fed home blender. Sizes range from small hand-held mixers to large permanently mounted units used in heavy industries, such as mining, pulp and paper, and heavy chemical processes. Design types and materials used depend upon the media being blended.