A colloid mill is a machine that is used to reduce the particle size of a

solid Solid is a state of matter where molecules are closely packed and can not slide past each other. Solids resist compression, expansion, or external forces that would alter its shape, with the degree to which they are resisted dependent upon the ...

suspension Suspension or suspended may refer to: Science and engineering * Car suspension * Cell suspension or suspension culture, in biology * Guarded suspension, a software design pattern in concurrent programming suspending a method call and the calling ...

in a

liquid Liquid is a state of matter with a definite volume but no fixed shape. Liquids adapt to the shape of their container and are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to th ...

, or to reduce the droplet size in emulsions. Colloid mills work on the rotor-stator principle: a rotor turns at high speeds (2000–18000

RPM Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or r⋅min−1) is a unit of rotational speed (or rotational frequency) for rotating machines. One revolution per minute is equivalent to hertz. Standards ISO 80000-3:2019 def ...

). A high level of stress is applied on the fluid which results in disrupting and breaking down the structure. Colloid mills are frequently used to increase the stability of suspensions and

emulsion An emulsion is a mixture of two or more liquids that are normally Miscibility, immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloi ...

s, but can also be used to reduce the particle size of solids in suspensions. Higher shear rates lead to smaller droplets, down to approximately 1

μm The micrometre (Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a unit of length in the International System ...

which are more resistant to emulsion separation. Schematic diagram of colloid mill

Application suitability

Colloid mills are used in the following industries: * Pharmaceutical * Cosmetic * Paint * Soap * Textile * Paper * Food *Grease

Rotor - stator construction

A colloidal mill consist of a high speed rotor and stator with a conical milling surfaces * 1 stage toothed * 3 stage toothed

Execution

* fix gap * adjustable gap

Application suitability

Rotor - stator construction

Execution

References

See also