Dispersion is an important process in many industries: the production of sauces, jams, and medicines often needs dispersing raw ingredients; the preparation of shampoo, adhesive, paints requires dispersion to blend different chemicals; furthermore, in advanced industries like batteries and nano-materials, a step of dispersion on materials such as carbon or ceramic is also necessary before further processing. So, what exactly is the principle of dispersion, and how do contemporary dispersing machines operate in those industries?

The process of dispersion involves bringing one or more states of matter (liquid, solid, or gas), known as the dispersing phase, into another state of matter (usually liquid), known as the continuous phase, in an even, rapid, and efficient way; normally, each phase is immiscible with the other, but when strong external energy is acted on these phases, they can be mixed into a homogenized phase.

When a dispersing machine operates, its rapidly spinning rotor generates strong momentum with its high tangential speed and frequent mechanical impacts; within the narrow gap between the rotor and stator, raw materials receive combined forces from the mechanical & hydraulic shear, centrifugal extrusion, physical impact and tearing, liquid turbulence, and more; this process then produces suspensions (solid/liquid), emulsion (liquid/liquid), and foams (gas/liquid). As a result of dispersion, the immiscible solid, liquid, and gas phases are instantly changed into a unified, stable mixture. If necessary, the dispersion process can be repeated in cycles to obtain even finer and higher-quality products.

Process of Inline High-Shear Dispersion

1. When the raw material is fed into the inlet, it is suctioned into the disperser’s working chamber under the centrifugal force generated by the rapidly spinning rotor.

2. The strong centrifugal force radially draws raw material into the narrow gap between the rotor and stator; the centrifugal force, extrusion, impact, and more forces act jointly and simultaneously on the material, causing it to be crushed and dispersed at the first stage.

3. As the outer edge of the rotor spins at the linear speed of at least 15m/s and at most 40m/s, strong mechanical and hydraulic shearing, hydraulic friction, impact, and tearing forces act simultaneously on the material, causing it to be adequately dispersed. As the particle size of material is reduced, it is discharged radially from the gap, and after one or more times of cyclical processing, the process of dispersion, emulsification, and homogenization is finally completed.

4. Alternatively, the machine might contain a second group of rotor-stator set operating simultaneously, so after the material is discharged from the first set, it immediately enters the second set to be sheared again; there may as well be a third rotor-stator set that serves for the same purpose: to disperse, emulsify, homogenize the material once more. Such a machine containing three stages of rotor and stator is able to effectively complete the dispersion process within shortest amount of time.

Factors that may influence results of dispersion:

-Work form (batched or continuous);

-Stages, and shear rates of work head;

-Tooth structure of the work head (e.g. coarse, moderate, fine, ultra-fine, etc.);

-Material’s dwelling and dispersing time inside the working chamber;

-Number of cycles.