Nauta® conical screw mixer

The 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 in 1946.

The 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.

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The 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.

Nauta mixer working principle

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

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)

 

  • 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


The Nauta® conical screw mixer is available in many sizes. A few sizes with their typical characteristics are described below. Please note that these values are indicative only. Detailed information is available on request.

Size [m³] 0.5 1 2 5 10 20 50 100
Vessel diameter [cm] 145 180 210 285 355 440 570 700
Vessel height [cm] 175 225 280 380 500 600 825 900
Height incl. motor [cm] 225 290 350 470 620 730 965 1030
Typical motor power [kW] 2.2 5.5 7.5 15 22 37 55 90

 

Nauta® Minimix

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

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

Nauta® Minimix lab mixer


Our expert design and engineering team are happy to help you specify the right ancillary equipment to compliment the Nauta® conical screw mixer. These ancillaries may include:

Intensifier rotor

The conical screw 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.

Intensifier rotor

Outlet (ball segment valve)

Hosokawa Micron offers various outlet valves to choose from, including side outlets, slide gate bottom outlets and ball segment valves.

ISEM ball segment valve

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.

Hosokawa Micron Sampler

Access door

Optimal dust and watertight closure on access door using FDA-approved seals.

Mixing vessel access door

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).

Lump breaker

Charging hopper

Hosokawa mixers can be provided with a charging hopper for manual charging. It can be installed on the mixer cover and is available for single as well as dual person operation. The default model comes with a hinged access door, bolted grid and dust exhaust connection. 'Vibrating' grid and/or CIP nozzles are optional.

Charging hopper

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.