Eddy current mill
A vortex mill (also known as a whirlwind mill ) is a beater mill for fine and ultra- fine grinding in process engineering .
construction
Eddy current mills consist essentially of a mill cover, a stator, and a rotating located rotor , the U-shaped grinding elements is surrounded and mounted on two tool carrier rings. The rotor and stator are conical with about 12 °, which makes it possible to change the grinding gap in the range 0-8 mm in a simple manner by raising or lowering the stator. The rotor usually rotates in four planes in the lower mill housing, which is protected against wear by a corrugated grinding track. The inside of the mill cover is also lined with wear protection segments, which are designed in such a way that any "spray grain" is retained. The total air flow can be separated by a secondary air connection, i.e. the setting of the air flow for grinding is independent of the conveying air flow.
functionality
The ground material is fed into the mill via an inlet box, where it is pre-crushed when it hits the rotor. The beater bars of the rotor cause the material to be ground to be conveyed into the grinding chamber on the side of the rotor, where it is finely ground. The comminution takes place through a combination of impact grinding effects between the ground material and the grinding track, but primarily through the mutual impact of the grinding particles. This so-called jet milling effect is created by the intensive swirling of the product in the milling zone. The eddy current mill is suitable for the fine grinding of dry products down to a fineness of 10 to 20 micrometers . Grinding gap, air volume flow and rotor speed are important for setting the final particle size.
The main difference to conventionally known beater mills is that the comminution takes place through a combination of impact grinding effects between the particles and the grinding track and above all through the impact of particles against particles themselves. This so-called jet milling effect and thus the name giver for the eddy current mill is created by the intensive swirling of the product in the actual grinding zone itself and is one of the main reasons for the high efficiency of this process, which enables fine grinding of dry products down to fineness of 10-20 micrometers . Areas of application are powder coatings , minerals , spices , wheat flour , chemicals , waxes , food and animal feed, dyes , rubber and plastics .
Applications
Eddy current mills are mainly used for fine and ultra-fine grinding of soft to medium-hard materials. In addition, they can be used for grinding, coating , cryogenic grinding, grinding mixing and grinding drying of soft and medium-hard products, with the maximum grain size depending on the product. The eddy current mill can be found in various industries such as the chemical, plastics, building materials and food industries.
Eddy current mills are also widely used in the defibration of organic materials such as hemp or cellulose. The frayed material is used as a natural insulating material in the construction industry.
literature
- Patent EP1110615 : Published June 27, 2001 .
- Hans Rumpf: Symposium comminution , Verlag Chemie, Weinheim
Web links
- Pictures and graphics with explanations , Grenzebach.com