Dispersing powders in liquids: air is the solution, not the problem

Vacuum expansion technology for powder dispersion

Powder contains air – a substantial amount of it. During loosening, conveying and fluidisation, the air content increases even further. When inducting powders into liquids, the goal is always to achieve an air-free dispersion of solid in liquid, where possible. Innovative powder-in-liquid dispersion technologies deliberately harness air’s expansive behaviour under vacuum to wet and disperse every single particle individually. Even agglomerates are effectively broken down using vacuum force combined with intense shearing at the same time.

Powder is essentially a dispersion of solid particles in air. Air fills the spaces between individual solid particles, and porous or hollow particles of powder contain air both between and within themselves. Depending on particle size, distribution and shape, powders can contain varying amounts of air. 

Compact powder flows poorly – or not at all. Particles touch one another in arrangements that enable the total volume to take up the least possible space. Irregularly shaped particles hook and wedge together in this way, while small particles fill the gaps between larger ones. When powder is mechanically fluidised, transferred, transported or dosed into vessels, moving particles space themselves further apart, enabling the loosened powder to take up a greater volume.

When powder is delivered in palletised sacks, the sacks at the bottom often contain more compacted and compressed powder due to transport stresses, so they contain less air than the sacks at the top. The situation is similar with powder in containers, big bags and silos – heavily compressed powder contains less air.

Mechanical movement such as fluidisation, transport or transfer loosens particle structures. The briefly agitated particles space themselves further apart, enabling the powder to take up greater bulk volumes…