Vacuum Mixer

A vacuum mixer is a piece of process equipment in which bulk materials, pastes or liquids are mixed under reduced pressure. The pressure in the mixing chamber is below atmospheric pressure and is set and controlled using vacuum pumps. Vacuum operation lowers the boiling point of liquids, enabling gentle processing at low temperatures. At the same time, oxygen is removed, thereby reducing oxidation, hydrolysis and undesirable side reactions.

Vacuum mixers are used for homogenisation, degassing, impregnation, reaction and drying. In vacuum contact drying, heat is supplied via heated vessel walls or mixing tools, whilst water or solvents evaporate and are removed. The mixing ensures an even distribution of temperature and moisture throughout the entire product volume, thereby preventing localised overheating or residual moisture.

If the vacuum mixer is to be used for drying, the materials being mixed must be heated. All surfaces within the process chamber must be temperature-controlled to prevent condensation. Cold surfaces lead to the recondensation of vapour and reduce drying efficiency. A uniformly temperature-controlled vessel geometry is therefore an essential design feature of vacuum dryers and mixers.

Vacuum mixers are used in the chemical, food, pharmaceutical, battery and plastics industries. They are particularly suitable for temperature-sensitive, hygroscopic or oxidation-prone products, as well as for processes involving solvents. Modern vacuum mixers are often designed to be dead-space-free, which enables hygienic cleaning and reproducible processes.