Hosokawa Micron B.V.

- Conical Screw Mixer



The Vrieco-Nauta conical screw mixer is a batch mixer specially designed for segregative, free-flowing powders and pastes. It’s named after Mr. J.E. Nauta, who developed the first conical Nauta-mixer more than 65 years ago. The Vrieco-Nauta is famous for its low-intensity mixing and is a pioneer in mixing technology. It especially suited to delicate products and processes where very accurate results are required and is synonymous with gentle mixing of large volumes of up to 100 000 litres.

The Vrieco-Nauta® conical mixer is a convective mixer with high mixing efficiency. It is gentle and guarantees the highest level of mixing accuracy without product distortion. The screw has an average speed of 70 rpm whilst the arm rotates at 1 to 2 rpm. The tip speed of the screw can fluctuate between 0.5 and 2 m/s, making it suitable for all ATEX zones.

The rotating cantilevered (free hanging) mixing screw conveys the product from bottom of the vessel to the product surface. The mixing screw is suspended from an orbital arm, which rotates the mixing screw along the conical inner vessel wall causing convective mixing of particles and shear.

The speed of particles in the downward massflow when recirculated by gravity in a conical vessel increases as the vessel diameter decreases. The result of these simultaneous actions is a fast and intensive mixing with low consumption of power together with high standards of mixing accuracy.

Convective mixing effect

The convective mixing effect is created by the following 3 factors:

  • Axial mixing by the screw
  • Radial mixing by shape of the cone
  • Tangential mixing by the arm

Wide variety of processes

Vrieco-Nauta® mixers are suitable for a wide range of processing activities in the pharmaceuticals, food, plastics, metals & minerals, nuclear, chemical, pigments and coatings industries. These include:

  • Gentle mixing of free-flowing and segregative powders, pastes, slurries and liquids
  • Moistening of powders
  • Coating
  • Granulation
  • Drying by means of heat input at atmospheric conditions or in combination with vacuum and possible liquid recovery
  • Coating of solids with liquids (with intensifier)

Key features Vrieco-Nauta mixer

  • Gentle mixing with minimum energy input or product distortion
  • Perfect mixing quality and accuracy
  • Constant mixing quality in charges from 10 to 100%
  • Heating, cooling, drying, mixing and moistening
  • Live hopper for sticky or segregative products
  • Agitated hopper to feed dryers like fluid beds with or without back mixing
  • Fast and full discharge with bottom discharge valve
  • Available from 2.5 liters up to 100 000 litres
  • ATEX approved

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