A vertical cone screw blender comprises a stationary conical vessel fitted with a screw that rotates on its own axis while simultaneously orbiting the vessel wall. This dual motion lifts material upward along the wall and returns it through the vessel centre under gravity, generating three-dimensional bulk recirculation with minimal particle shear. Used for large-scale gentle powder and granule blending across pharmaceutical, food, and chemical applications.
The orbiting screw sweeps the full conical wall during each precession cycle, lifting material upward via the screw flight. Material cascades back through the vessel centre under gravity, completing a full recirculation loop per orbit revolution. This gentle three-dimensional turnover achieves progressive homogenisation across the full vessel volume. An apex discharge valve allows gravity-assisted batch emptying at the end of the blending cycle.
Challenges
Long Blend Times at Large Scale
At low orbit speed, circulation rate in very large vessels is slow, extending blend times and limiting throughput in high-volume production environments.
Cohesive Powder Bridging
Materials with poor flow properties can bridge between the screw flights and vessel wall, creating stagnant zones that do not participate in the recirculation pattern and reducing blend uniformity.
Low Fill Level Performance
Below approximately 30% of vessel volume, the established recirculation pattern breaks down, reducing blending efficiency and increasing blend time significantly.
Mechanical Drive Complexity
The dual-motion drive system requires precision alignment and regular maintenance to sustain the correct geometric relationship between screw rotation and orbital precession throughout the service life.
Apex Seal Integrity Under Vacuum
The orbital screw shaft seal at the vessel apex is subjected to differential pressure during vacuum blending, increasing the risk of seal wear and leakage if not correctly specified and maintained.
Solutions
- Independent VFD Control of Screw and Orbit Speed: Separately controlling screw rotation and precession speed allows each to be optimised for the specific powder rheology and blend requirements of each product, improving blend efficiency without increasing particle shear.
- Variable-Pitch Screw Flight: Designing the screw with variable pitch along its length compensates for the velocity gradient introduced by the conical vessel geometry, ensuring consistent material lifting rate from apex to upper vessel diameter.
- Minimum Fill Level Interlock: Programming a PLC interlock that prevents blender operation below the validated minimum fill level protects blend quality and prevents equipment damage from operation with insufficient material in the vessel.
- Chopper Attachment on Screw Shaft: Mounting low-speed chopper pins on the screw shaft provides localised agglomerate disruption during blending without imposing full high-shear processing, extending the practical powder cohesiveness range of the blender.
- Pressure-Rated Apex Seal with Barrier Fluid: Specifying a double mechanical seal at the apex with barrier fluid circulation maintains vacuum integrity during nitrogen-blanketed or vacuum blending operations, protecting seal faces from differential pressure wear.
Applications
- Pharmaceutical: Large-scale API/excipient blending, direct compression homogenization, vacuum/nitrogen-blanketed moisture-sensitive processing.
- Food & Beverage: Bulk ingredient homogenization, flavouring premix preparation, powdered nutrition blending at industrial scale.
- Chemical: Large-volume specialty chemical powder homogenization, catalyst support blending, fine chemical premix.
- Cosmetics & Personal Care: Large-batch talc and clay-based formulation blending, pigment dispersion premixing.
Models & Capacities
| Standard Vertical Cone Screw Blender (Nauta Type) — Models & Capacities (10 L to 20,000 L) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Model | Scale | Net Vol. [L] | Gross Vol. [L] | Batch Size [kg] | Screw Speed [RPM] | Arm Orbit Speed [RPM] | Screw Motor [kW] | Arm Motor [kW] | Cone Ø (top) [mm] | Cone Ø (bottom) [mm] | Cone H [mm] | Overall H [mm] | Jacket Area [m²] | Weight [kg] |
| VCSB-010 | Lab | 7 | 10 | 2–5 | 30–300 VFD | 1–10 VFD | 0.25 | 0.06 | 380 | 80 | 500 | 1,200 | — | 85 |
| VCSB-025 | Lab | 17 | 25 | 5–12 | 30–300 VFD | 1–10 VFD | 0.37 | 0.09 | 520 | 110 | 680 | 1,550 | 0.12 | 150 |
| VCSB-050 | Lab/Pilot | 35 | 50 | 10–25 | 30–250 VFD | 1–8 VFD | 0.55 | 0.12 | 680 | 140 | 880 | 1,950 | 0.20 | 260 |
| VCSB-100 | Pilot | 70 | 100 | 20–50 | 20–200 VFD | 1–8 VFD | 0.75 | 0.18 | 860 | 180 | 1,100 | 2,400 | 0.35 | 420 |
| VCSB-200 | Pilot | 140 | 200 | 40–100 | 20–180 VFD | 1–6 VFD | 1.1 | 0.25 | 1,080 | 220 | 1,400 | 3,000 | 0.60 | 720 |
| VCSB-300 | Pilot | 210 | 300 | 60–150 | 20–160 VFD | 1–6 VFD | 1.5 | 0.37 | 1,260 | 260 | 1,620 | 3,450 | 0.82 | 1,050 |
| VCSB-500 | Production | 350 | 500 | 100–250 | 15–120 VFD | 1–5 VFD | 2.2 | 0.55 | 1,540 | 320 | 1,980 | 4,200 | 1.20 | 1,750 |
| VCSB-750 | Production | 525 | 750 | 150–375 | 15–100 VFD | 1–5 VFD | 3.0 | 0.75 | 1,800 | 380 | 2,300 | 4,900 | 1.65 | 2,600 |
| VCSB-1000 | Production | 700 | 1,000 | 200–500 | 15–100 VFD | 1–4 VFD | 4.0 | 1.1 | 2,000 | 420 | 2,600 | 5,500 | 2.10 | 3,600 |
| VCSB-1500 | Production | 1,050 | 1,500 | 300–750 | 12–80 VFD | 1–4 VFD | 5.5 | 1.5 | 2,340 | 490 | 3,020 | 6,400 | 2.90 | 5,200 |
| VCSB-2000 | Production | 1,400 | 2,000 | 400–1,000 | 12–80 VFD | 1–4 VFD | 7.5 | 2.2 | 2,640 | 550 | 3,400 | 7,200 | 3.70 | 7,200 |
| VCSB-3000 | Production | 2,100 | 3,000 | 600–1,500 | 10–60 VFD | 1–3 VFD | 11 | 3.0 | 3,100 | 650 | 4,000 | 8,500 | 5.20 | 10,500 |
| VCSB-5000 | Large Prod | 3,500 | 5,000 | 1,000–2,500 | 8–50 VFD | 1–3 VFD | 15 | 4.0 | 3,800 | 800 | 4,900 | 10,500 | 7.80 | 17,000 |
| VCSB-7500 | Large Prod | 5,250 | 7,500 | 1,500–3,750 | 8–40 VFD | 1–2 VFD | 22 | 5.5 | 4,500 | 950 | 5,800 | 12,400 | 11.0 | 26,000 |
| VCSB-10000 | Large Prod | 7,000 | 10,000 | 2,000–5,000 | 6–35 VFD | 1–2 VFD | 30 | 7.5 | 5,100 | 1,050 | 6,600 | 14,200 | 14.0 | 37,000 |
| VCSB-15000 | Large Prod | 10,500 | 15,000 | 3,000–7,500 | 6–30 VFD | 1–2 VFD | 45 | 11 | 6,100 | 1,250 | 7,900 | 17,000 | 19.0 | 58,000 |
| VCSB-20000 | Large Prod | 14,000 | 20,000 | 4,000–10,000 | 5–25 VFD | 0.5–1.5 VFD | 55 | 15 | 6,900 | 1,400 | 8,900 | 19,500 | 24.0 | 78,000 |