In essential oil and botanical extract production, the extractor is where yield is won or lost. A rotary extraction system addresses one of the oldest problems in solvent extraction: keeping plant material in constant, even contact with the solvent instead of letting it settle into a compacted bed at the bottom of the vessel.

What Is a Rotary Extraction System?

A rotary extraction system is a closed stainless steel vessel that turns during the extraction cycle. Instead of relying on an agitator to stir a static charge of material, the vessel itself rotates, tumbling the botanical charge through the solvent so that fresh surfaces are continuously exposed.

Dünder Machinery builds rotary extractors as the EKS-R series, alongside static extraction (EKS-S) and turbo extraction (EKS-T) systems. All three are delivered as complete lines sharing the same downstream equipment. What changes between them is how the solvent and the plant material are brought into contact, and that single difference drives cycle time, yield, running cost and maintenance load.

How the Process Works

1. Raw material preparation. Plant material is weighed and measured, dried or used fresh as required, then broken down or ground and loaded into the extraction tank. The solvent volume is calculated against the charge.
2. Mixing with solvent. Alcohol, hexane or ethanol is introduced, the rotating motion is started and the working temperature and pressure are set.
3. Settling. The mixture is rested so that solid and liquid fractions separate by gravity in the settling tank.
4. Filtration. The liquid passes through a stainless steel filter to remove suspended solids.
5. Secondary vacuum filtration. A second filtration stage under vacuum removes the remaining fine particles.
6. Intermediate solvent removal. Solvent is stripped from the filtered liquid and recovered for reuse.
7. Evaporation. The evaporator unit concentrates the product under vacuum, leaving the concrete or extract behind.

Why Rotation Improves Yield

Better contact. In a static vessel, material compacts and the solvent finds channels through the bed, leaving pockets barely touched. Rotation prevents that packing, so extraction is more uniform across the whole charge.

High efficiency at moderate cycle times. Rotary extraction sits between the two other methods. It is slower than turbo extraction but considerably faster than static extraction, and it delivers high yield. That balance is what makes it the usual choice for medium and large-scale production.

Higher investment and more demanding maintenance. A rotating vessel carries drive components and seals that a static tank does not. Both the initial cost and the service requirement are higher, and any honest specification should account for that from the start.

Rotary, Static or Turbo?

The right method depends on your production scale, your budget and how much solvent and energy you are prepared to run through the plant. The table below compares the three systems we manufacture.

If your priority is throughput at large volumes and you can carry the investment and the maintenance, rotary extraction is the strongest option. If solvent and energy economy matter more than scale, turbo extraction is worth comparing. If you are starting small with a limited budget, static extraction remains a reliable entry point.

Typical Applications

• Rose concrete from Rosa damascena flowers
• Delicate florals such as jasmine and tuberose, where heat-based methods damage the profile
• Oleoresins from spices and seeds
• Herbal and botanical extracts for the pharmaceutical and cosmetics industries

Where It Fits in the Production Plant

A rotary extractor rarely works alone. It sits between raw material handling and the downstream stages that turn a crude extract into a finished aromatic material. In a complete line it is paired with a condenser column, a solvent recovery circuit and, where the end product is an absolute, an absolute production system for the ethanol washing and chilling stages.

Producers working specifically with roses often combine it with a dedicated rose extraction system, while operations that need faster turnaround on larger volumes may look at turbo extraction systems instead.

Materials and Construction

Extraction vessels are built from stainless steel throughout, since solvents, plant acids and repeated cleaning cycles will find any weakness in a lesser material. Welds are ground and polished so that no residue is trapped at joints, and every connection on a solvent circuit has to be sealed to a standard appropriate for flammable service.

Technical Specifications

The EKS-R series is produced in two standard models. These are standard designs and can be modified to customer requirements.

What a Complete Rotary Extraction Line Includes

The extractor is one station in a closed circuit. A full Dünder Machinery rotary extraction line is delivered with the following equipment.

1. Rotary extractor
2. Extractor cooling heat exchanger
3. Solvent collection tank, horizontal
4. Stainless steel filter
5. Transfer pump
6. Settling tank, horizontal
7. Decanter
8. Distiller
9. Distiller condenser
10. Second solvent collection tank, horizontal
11. Second transfer pump
12. Settling tank, vertical
13. Evaporator unit with its own heat exchanger

Because the solvent circuit is closed, solvent is condensed and returned rather than lost, which is what keeps operating cost per kilogram of raw material under control.

See the System in Operation

Talk to Our Engineers

Every raw material behaves differently, and the right extractor configuration depends on your botanical, your batch volume and the solvent you work with. Tell us what you process and how much, and we will propose a suitable configuration. Contact us to discuss your project.