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

solid Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structura ...

suspension Suspension or suspended may refer to: Science and engineering * Suspension (topology), in mathematics * Suspension (dynamical systems), in mathematics * Suspension of a ring, in mathematics * Suspension (chemistry), small solid particles suspen ...

in a

liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, an ...

, 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 with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimension ...

). 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 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 colloids. Althou ...

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 ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Uni ...

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