VTT has purchased new ultra-fine milling equipment, which operates in a pilot-scale. The mill is called Ceren Miller DAU (Decompression, Air-flow, Ultra-fine milling), manufactured by Masuko Sangyo Co. Ltd., Japan. This is a brand-new model, the first one commercially available in the world.
The milling operation is based on five triturating principles: jet-trituration, impact-trituration, stone mill grinding, compression and high-frequency vibration. It can be run in a continuous mode to reach around 30-50 µm particle size. However, a so-called continuous batch mode enables the reduction of the particles down to 10-30 µm. The continuous batch mode means that the material is fed into the milling chamber in a short period of time (e.g. in 8 seconds). Then the feeding valve is closed and the material is subjected for a 1–3 min trituration. The longer the trituration time, the finer the particles become. After the trituration, the ultra-fine material is blown to a collecting cyclone with a high air-volume. After 30 seconds of blowing, new material is fed into the milling chamber and a new cycle is started. Computer controlled automation makes sure that all of the consecutive batches are processed similarly. The capacity of the continuous batch mode is around 5–10 kg/h.
The trituration unit (inside the milling chamber) consists of three stainless steel blades, three partition plates and a screening impeller in the end of the unit with two diamond stones against each other. All parts are mode of high-quality stainless steel, ensuring that it is easy to clean and fulfils the requirements for a hygienic food-grade processing.
In the new DAU-model ultra-fine particles are obtained with less discoloration and less deterioration of taste. To avoid the heating of the material, cooling water circulation is used during the milling. In addition, inert gas (such as nitrogen) can be fed under decompression to protect the materials towards oxygenation.
More information about the equipment: Juhani.Sibakov@vtt.fi
Picture. Representatives of Masuko Sangyo Co. Ltd. visiting VTT and giving the user training.