Classic agitation is not always enough to mix solids and liquids. Agglomerates often form, air enters the product, dust develops or solvents escape. Solid-liquid mixing prevents these side effects: it wets the solids and then combines mixing, homogenising and dispersing in a single pass.
Typical problems when agitating solids
This agitation task is called suspension. The solids can be soluble or insoluble. With a simple agitator, the following often occur:
- Agglomerates and air entrainment
- Heavy dust formation or solvent emissions
- Solids sticking to the agitator tool
- Quality deviations and raw material losses
Physics of solid-liquid mixing
Physically, solid-liquid mixing is a three-phase system of solid, surrounding gas phase and liquid. When a liquid meets a moving solids mixture, its quantity and spreadability determine how well the individual particles are wetted. Spreadability depends mainly on:
Applications
Incorporating powders, granules or bulk materials into liquids is a complex process in many industries. In the pharmaceutical industry, for example, tablet coatings are made from solids and aqueous solutions. Suspensions of colour pigments are typical in dye production. Further examples:
What matters
- The entire amount of solids gets completely into the liquid
- No residues remain in feed containers and lines
- The solid does not swirl up or stick to the lid
- The suspended solid is evenly distributed, without agglomerates or sedimentation
- Powder induction with a premixing section and no rewetting of the solids
- Agitators that reach every point in the vessel with sufficient flow
Here too, precise design in advance is necessary, depending on raw materials and process. This usually takes place in homogenising mixers. We are happy to advise you, including on used plants.
You can dose liquid raw materials efficiently with our new dosing station.
Other processes
Frequently Asked Questions about solid-liquid mixing
What is solid-liquid mixing?
A process in which solids such as powders or granules are wetted and mixed, homogenized and dispersed in one passage. It avoids typical problems of conventional agitation.
Which problems does the process avoid?
Agglomerates, air intake, dust, solvent emissions, sticking to the agitator, quality deviations and raw material losses. This saves time as well as personnel, cleaning, disposal and energy costs.
What does wetting of the solid depend on?
On surface tension and viscosity of the liquid, porosity of the solid, affinity of the phases (lipophilic/hydrophilic) and the efficiency of material distribution.
How can powder be incorporated dust-free?
For example via powder induction with a pre-mixing section without re-wetting, combined with agitators that provide sufficient flow throughout the vessel – matched to raw materials and process.