Industrial Double Screw Cone Mixer (Nauta Mixer) — Conical Cylinder with Double Screw Self-Rotation + Revolution, High-Precision Low-Energy Mixing for Extreme Ratio Materials

The Double Screw Cone Mixer (also known as conical mixer, double screw mixer, cantilever double screw cone mixer, or Nauta mixer) is a batch-type mixing equipment that uses two (or one) screw elevators inside a conical cylinder, which self-rotate while revolving, to lift material from the bottom to the top and then let it fall along the cone wall, forming circulating convection for uniform mixing. With high mixing precision, low energy consumption, no dead corners and large filling volume, it is especially suitable for mixing dry powders and granules with extreme ratios (up to 1:10000 or higher), large particle size differences and large density differences, widely used in chemical, pharmaceutical, food and building materials industries.

The conical cylinder (wide at top, narrow at bottom) is placed vertically. A revolution mechanism (planetary reducer) is installed at the top inside the cylinder, driving two (or one) screw elevators to revolve around the centerline of the conical cylinder, while the screw elevators self-rotate at high speed. Material is fed into the cylinder through the top feed inlet (typically filling 50% to 80% of cylinder volume). After starting the motor, the screw elevators self-rotate while revolving. When self-rotating, the screw elevators lift the surrounding material along the spiral blades from the bottom of the conical cylinder to the top. When revolving, the screw elevators move circularly along the inner wall of the conical cylinder, continuously changing the lifting position and sequentially lifting material from all parts of the cylinder. The material lifted to the top slides down along the inner wall of the conical cylinder (or the center of the cylinder) under gravity, returning to the bottom of the cylinder, and is lifted again by the screw elevators. This cycle repeats, producing strong up-down circulating convection and diffusion motion of the material inside the cylinder, with materials continuously exchanging positions and permeating each other. After a certain period of mixing, the material reaches a highly uniform mixed state. After mixing is complete, the material is discharged through the discharge valve at the bottom of the conical cylinder.

1. The conical cylinder is made of high-quality stainless steel (304/316L) plate rolled and welded, with mirror-polished inner wall, no dead corners, no residue, easy to clean; the cylinder can be designed as jacketed type for cooling water or hot water to meet temperature-controlled mixing needs;
2. The screw elevator is the core component, consisting of a screw shaft and spiral blades, with spiral blades made of stainless steel flat bar bent and welded; the upper end of the screw elevator is connected to the revolution mechanism through a bearing, and the lower end is suspended (cantilever type) without contacting the bottom of the cylinder, with no support bearing, avoiding material contamination and bearing wear;
3. The revolution mechanism uses a planetary reducer (or cycloidal pinwheel reducer + crank mechanism), installed at the top of the cylinder, driving the screw elevators to revolve around the cylinder centerline, with revolution speed typically 1 to 5 rpm; the self-rotation mechanism uses motor + reducer, driving the screw elevators to self-rotate at high speed, with self-rotation speed typically 50 to 150 rpm;
4. The feed inlet is located at the top (or side) of the cylinder, using a quick-open manhole/feed inlet with silicone sealing ring; the discharge outlet is located at the bottom (lowest end) of the conical cylinder, using a butterfly valve or ball valve for fast, clean and residue-free discharging;
5. The frame is welded from section steel with stable structure, with the transmission mechanism and motor installed at the top of the cylinder, equipped with a protective cover for operational safety;
6. Optional vacuum feeding system or screw feeder for dust-free feeding; optional vacuum suction or negative pressure discharge for dust-free discharging;
7. Optional time relay or PLC control to set mixing time and automatic shutdown; optional interlock protection device;
8. Optional spray device (liquid addition port) for liquid-added mixing; optional vacuum system for vacuum mixing or vacuum discharging; large models can adopt double-screw or triple-screw design to improve mixing efficiency.

• Extremely high mixing precision — the circulating convection motion of screw lifting + cone wall falling produces strong diffusion and convection, achieving mixing uniformity over 99.9%, especially suitable for mixing materials with extreme ratios (up to 1:10000 or higher), large particle size differences and large density differences;
• Low energy consumption — the screw elevators only need to lift part of the material (not all material), requiring much less power than rotary and ribbon mixers, with low operating cost;
• Large filling volume — filling volume can reach 50% to 80% of cylinder volume with high equipment utilization;
• No dead corners — the conical structure and cantilever screw design ensure no support bearings and no dead corners inside the cylinder, with no material residue and easy cleaning, meeting food and pharmaceutical hygiene requirements;
• Gentle mixing — material is mainly subjected to lifting and falling motions without strong shear and extrusion, suitable for mixing fragile and crystalline materials;
• Fully enclosed operation with no dust emission, improving operating environment;
• Optional temperature-controlled jacket, liquid spray, vacuum system and other devices to adapt to special process requirements;
• Stable operation with low noise and low maintenance.

• Widely used in chemical (pigments, dyes, plastic resins, pesticides, fertilizers, catalysts, detergents, cosmetic raw materials, ceramic powder, rare earth materials, lithium battery materials, 3D printing powder), pharmaceutical (APIs, pharmaceutical excipients, herbal powder, tablet granules, capsule filling materials, powders, granules, powder for injection), food (milk powder, protein powder, seasonings, flavors and fragrances, food additives, meal replacement powder, cereal flour, solid beverages, coffee powder, milk tea powder), feed (feed raw materials, feed additives, premix, concentrated feed, pet food), building materials (ceramic raw materials, glass powder, insulation materials, refractories, dry mortar, putty powder) and other (tobacco, gunpowder, metallurgical powder, environmental materials, pesticide intermediates) industries for high-precision mixing of dry powders and granules, especially suitable for mixing materials with extreme ratios and large particle size/density differences.