In bulk powder processing, dispersion is the process of achieving even particle distribution of heterogeneous materials.
Some powders, however, are poorly dispersible and have a tendency to clump together. In order to create a homogenous blend of such materials, many dispersion processes include intensive deagglomeration as part of the dispersion process.
Deagglomeration is one means of overcoming the binding mechanisms that cause dry materials to clump together so they can be evenly dispersed into other ingredients. These unwanted agglomerates of powder, also known as “fish-eyes,” are non-material bonds that can arise due to conditions such as residual moisture, electrostatic, or particle size.
Deagglomeration is a processing stage that uses a high energy input to generate centrifugal force, shearing, or friction. Under these conditions, the clumps break apart into smaller particles of more uniform size and shape. Once deagglomerated, the powders can then be dispersed evenly into heterogeneous ingredients.
amixon® custom-engineers a range of powder mixing equipment that can reliably deagglomerate and disperse even the most difficult powders into heterogeneous mixtures.
There are two main types of dispersion commonly used in material processing, and each method has its own unique benefits and limitations depending on the product and application.
Dry dispersion, the process which amixon® powder mixers can perform, involves using mechanical energy to overcome the binding mechanisms between agglomerated particles. Using a high energy input, the aggregate materials are brought into motion so that inertia acts to diminish the particle clusters.
Dry dispersion is the preferred method for powders that are cohesive but durable. Technically speaking, dry dispersion is a much simpler process than its counterpart, wet dispersion, especially if the end product is itself dry.
While wet dispersion is more complex, its results are often more precise and it is sometimes necessary in the case that particles are both cohesive and fragile. In order to avoid damaging the particle structures, the materials are added to a closed-loop liquid circulation system, either as a dry powder or as a suspension. The liquid medium breaks the surface tension of the agglomerates, and the inertia helps to disperse the particles evenly throughout.
amixon® powder mixing machines are outfitted with specially designed high-shear cutting rotors for the intensive deagglomeration of poorly dispersible powders. Even in the most challenging applications, our powder mixing equipment can successfully diminish clumps without damaging particle structures, thus creating ideal conditions for even dispersion.
High-Shear Cutting Rotors are installed on the side wall of the mixing vessel, near the bottom. As the powdery mixing goods are conveyed upwards along the periphery of the vessel, they pass by this high-shear mechanism and are deagglomerated. With a speed of up to 3.000 rpm, this relatively small installation can effectively deagglomerate lumps.
Furthermore, the cutting rotors can also be used to evenly disperse even highly viscous additives within dry ingredients, such as oils, fats, binding agents, or other liquid additives which are poorly dispersible in powders. A lance positioned near the cutting rotor injects the liquid into the mixing goods, ensuring that they first pass through the high-shear blades before entering the mixing flow.