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Vrieco-Nauta® 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® conical screw mixer is famous for its low-intensity mixing and is a pioneer in mixing technology. It's especially suited for 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.

Product Support
Product Support

If you need more information about the Vrieco-Nauta® conical screw mixer, call us at +31 314 373 333 or fill out our contact form.


Working principle Vrieco-Nauta® conical screw mixer

Vrieco-Nauta mixer working principleThe Vrieco-Nauta® conical screw 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

    convective mixing effect Nauta mixer







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)

» Contact us for more information about batch mixing technologies.

Key features

  • 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

» Contact us for more information about batch mixing technologies.


Vrieco-Nauta® conical mixers are available in a range of net volumes from 2.5 litres up till 100 000 litres. We also have mixers available in our state-of-the-art test centre in Doetinchem, the Netherlands, should you wish to try out a particular product or process on a pilot scale.

Size [l] 500 1000 2000 5000 10 000 20 000 50 000 100 000
Vessel diameter [mm] 1450 1800 2100 2850 3550 4400 5700 7000
Vessel height [mm] 1750 2250 2800 3800 5000 6000 8250 9000
Height incl. motor [mm] 2250 2900 3500 4700 6200 7300 9650 10 300
Typical motor power [kW] 2.2 5.5 7.5 15 22 37 55 90

Vrieco-Nauta® Minimix

Vrieco-Nauta® Minimix

Following the concept of the famous classical Vrieco-Nauta® conical mixer, this small scale model has been made available for lab environment. Although small in size, the advantages remain: high mixing accuracy, gentle mixing, complete discharge and flexible filling range.

The Vrieco-Nauta® Minimix is able to provide reliable results from only 0.3 litres powder content.

» Contact us for more information about batch mixing technologies.


Our expert design and engineering team would happily help you specify the right ancillary equipment to compliment the Vrieco-Nauta® conical auger mixer. These ancillaries may include:

Intensifier Nauta mixer   Intensifier Rotor 
The conical auger mixer can be equipped with a high speed rotor for liquid addition or for de-lumping products. Rotating up to 20 m/s, this rotor creates a vortex effect and injects the liquid through the paddles directly into the product, resulting in an excellent dispersion or coating. By spraying the liquid into the mass in a vortex, you can avoid over-moistening the particles and sticking. This intensifier can replace several lump breakers. 
Isem ball segment valve   Outlet (ball segment valve)
We have various outlet valves to choose from including side outlets, slide gate bottom outlets and ball segment valves.
Sampler batch mixer   Sampler
A sampler can be placed in the vessel wall making it possible to take samples without disturbing the mixing process. Specially-designed seals can be installed to make the sampler suitable for abrasive products as well as suitable for CIP/SIP.
Side hatch Nauta mixer   Access door
Optimal dust and watertight closure on access door using FDA-approved seals.
Lump breaker   Lump breaker
A lump-beaker can be mounted in the lower part of the vessel. When the lump-breaker is not necessary a plug is provided to install instead (flush with the vessel wall).
    Liquid injection
Mounted through the hollow shaft, it can spray a liquid or oil just in front of the mixing screw, ensuring a good mixing.
    Dump hopper

» Contact us for more information about batch mixing technologies.


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