A suspension is a heterogeneous mixture of a liquid and solids distributed in it. Suspending is the process of bringing these two together. An agitator, usually together with a dispersing agent, slurries the solids and keeps them in suspension.
Coarse, fine or colloidal
This solid-liquid mixture is a type of dispersion. Depending on the size of the solids, there are three groups:
Coarse suspension
For example chalk slurry. Coarsely dispersed systems tend strongly to settle.
Fine suspension
For example milk of lime. The particles are much smaller.
Colloidal dispersion
Particles below about 1 µm. It lies between a true solution and a suspension. Gels also belong to this group.
Applications
Many everyday liquids are suspensions, such as orange juice, cocoa or wheat beer. Mortar and concrete are mineral suspensions. In the photovoltaic and semiconductor industry, suspensions of silicon carbide and polyethylene glycol cut wafers. Examples from our field:
What matters when suspending
The goal is a mixture that is as even as possible, even though it will never be truly homogeneous. The solid phase remains as particles and does not dissolve.
- Breaking up agglomerates and finely distributing stabilising additives
- Homogenising technology with high flow speed in all areas of the vessel
- Sufficient energy input for good quality and efficient production
- Finely dispersing particles and stabilising them with wetting and dispersing agents
- Structuring the liquid phase with thickeners such as xanthan, carbomer or cellulose derivatives
As a result, the particles hardly settle and can easily be shaken up again if needed. We are happy to advise you, including on used homogenising mixers.
Our innovative dosing station ensures efficient weighing and dosing of liquid raw materials.
Other processes
Frequently Asked Questions about suspension
What is a suspension?
A heterogeneous mixture of a liquid and solid particles distributed in it. Depending on particle size, coarse and fine suspensions are distinguished; with very small particles one speaks of (colloidal) dispersions.
Why do suspensions tend to sediment?
The solid particles do not dissolve and settle due to their density. Dispersants, stabilizers and fine distribution keep them suspended longer.
What matters when suspending?
Agglomerates must be broken up and stabilizing additives finely distributed. The homogenizing equipment should provide high flow velocities throughout the vessel and sufficient energy input.
Where are suspensions produced?
For example in pharma (suspensions, dietary supplements), food, building materials and the semiconductor industry.