Solids mixing is the mixing of one or more solid components such as powders or granulates (bulk materials). The process is frequently used in the ceramics, raw materials, building materials, pharmaceutical, cosmetics, animal feed and food industries. Examples include the production of tea blends, dry soups, muesli, fertilizers or pigments.

Mixing solids is not a matter of converting substances. Rather, the aim is to produce a previously defined mixing quality. In addition to the mixing quality, it is important to keep the mixing process as short as possible for energy and cost reasons. To achieve this, values from the laboratory test must be transferred to larger production plants (scale-up). Tests are also fundamentally useful because the properties of the bulk materials vary greatly and can be influenced by many factors.