The aim of this ZIM-funded project (KF2363847WO4), which was carried out in collaboration with Athena Technologie Beratung GmbH, was the development of a modular overall concept for a fine powder manipulator for dry ultrafine powders, comprising a storage hopper including a discharge module, a dosing unit, a transport section, a homogenisation unit and a dispersion module, which enables the user to carry out straightforward, process-specific powder extraction, dosing, component mixing, homogenisation and dispersion. To achieve these objectives, the aim was primarily to utilise the effects generated by the local application of high-frequency vibrations (ultrasonic technology).

When processing ultrafine powders with particle sizes of approximately 1 to 100 µm, severe agglomeration (the formation of particle clumps) causes particular problems during dosing (bridging, blockages), during mixing (inhomogeneous mixture due to agglomerates) and during transport (increased friction). For powder extraction and dosing, low-frequency vibrations were used in each case; these fluidise the agglomerated powder, thereby enabling it to flow through a sieve or a narrow hopper. Acoustic ultrasonic vibrations were employed in both the homogenisation unit and the dispersion module to break up the heavily agglomerated powder into individual particles (see Figure 1). In the homogenisation unit, a homogeneous powder mixture was produced from the atomised powders. The use of ultrasonic vibrations yielded entirely satisfactory results when flour, cocoa and other similar powders were used as test powders. In the transport module, a combination of low-frequency vibration for propulsion and high-frequency vibration for friction reduction was utilised.

The project resulted in a modular system capable of dosing, mixing, conveying and, ultimately, finely atomising ultra-fine powders. This system is shown in Figure 2.