Extraction Equipment

Continuous Extractor

Mechotech designs and manufactures the Continuous Extractor as turnkey process equipment that runs solid-liquid extraction as a steady, uninterrupted operation rather than the discrete load-extract-discharge cycle of a batch extractor. Fresh feed enters at one end of the extractor while spent marc discharges continuously at the other, with solvent typically moving counter-current to the solids so that the freshest solvent meets the most-exhausted material and the richest miscella meets the freshest feed — giving higher solvent efficiency and steadier throughput than repeated batch cycles can sustain.

In a counter-current continuous extractor, feed material is conveyed progressively through a series of extraction stages — commonly on a moving screen, basket, or auger arrangement — while solvent is pumped in the opposite direction, percolating or immersing the solids at each stage before being drawn off as increasingly concentrated miscella. Because feed-in and discharge-out happen simultaneously and continuously rather than in discrete batches, the extractor sustains a constant production rate without the downtime batch systems lose to charging, holding, and discharging each cycle, and the counter-current solvent path drives a higher concentration gradient at every stage than a single batch soak can achieve. Mechotech fabricates the extraction body, solids-conveying mechanism, solvent distribution system, and miscella collection train in SS 316L (or a process-appropriate grade) with electropolished product-contact surfaces, and controls feed rate, solvent flow, and stage residence time under PLC-based automation, with capacity and stage configuration engineered to the customer's feedstock and target throughput.

Process Flow

Technical Specifications

Technology	Continuous counter-current solid-liquid extraction
Working Principle	Feed and solvent move continuously in opposite directions through multiple extraction stages, maximising concentration-gradient-driven mass transfer
Extraction Mode	Continuous counter-current percolation / immersion (configurable)
Solids Conveying	Moving screen, basket, or auger conveyor mechanism (configurable)
Number of Stages	Multiple sequential extraction stages, configured to feedstock and target yield
Solvent	Water, ethanol, hexane, hydro-alcoholic, or other process-grade solvents (as applicable)
Product-contact Material	SS 316L (or process-appropriate grade), electropolished
Miscella Handling	In-line filtration and clarification ahead of downstream concentration
Solvent Recovery	Integrated recirculation of recovered solvent to the counter-current loop
Automation	PLC-based control of feed rate, solvent flow, and stage residence time
Capacity	Configured to requirement — pilot to high-throughput commercial
Utilities	Power, solvent-handling and recovery utilities, compressed air
Compliance	WHO-GMP, Schedule M hygienic design
Final Output	Concentrated miscella (extract-in-solvent) and continuously discharged spent marc

Plant Capacities

Scale	Typical Duty	Stage Configuration	Conveying Mechanism
Pilot	Continuous-process validation, low-volume feedstock	Fewer stages, shorter extraction body	Screen, basket, or auger (configurable)
Mid-size commercial	Plant-scale continuous production	Multiple sequential stages	Screen, basket, or auger (configurable)
High-throughput commercial	High-volume continuous production line	Extended multi-stage extraction body	Screen, basket, or auger (configurable)

Extraction-body length, number of stages, and conveying mechanism are engineered to the specified feedstock, particle size, and target throughput; exact capacity is confirmed during process design.

Manufacturing Process

Continuous Feed Intake

Prepared feed material is metered into the extractor at a steady rate, entering the first extraction stage without interrupting flow through the rest of the system.

Progressive Solids Conveying

A moving screen, basket, or auger mechanism carries the solids through successive extraction stages at a controlled residence time per stage.

Counter-Current Solvent Contact

Solvent is introduced at the discharge end and flows opposite to the solids' travel, so the leanest solvent meets the most-exhausted marc and the richest solvent meets the freshest feed, maximising the concentration gradient driving mass transfer.

Percolation / Immersion Extraction

At each stage, solvent percolates through or immerses the solid bed, dissolving target compounds progressively as the material advances toward discharge.

Miscella Drawoff

Concentrated solvent-and-extract solution (miscella) is drawn off continuously from the feed-entry end, where it has contacted the freshest material and reached its highest concentration.

Continuous Marc Discharge

Extracted, solvent-wet solids are discharged continuously from the far end of the extractor for downstream desolventising or disposal.

Miscella Filtration & Clarification

Drawn-off miscella passes through in-line filtration to remove fines before being routed to downstream concentration and solvent-recovery stages.

Solvent Recovery & Recirculation

Recovered solvent from downstream evaporation is returned to the extractor's solvent-in stage, sustaining the counter-current loop and reducing fresh-solvent consumption.

Major Plant Equipment

Continuous feed intake and metering system
Multi-stage extraction body
Solids-conveying mechanism (screen, basket, or auger)
Counter-current solvent distribution system
Solvent inlet and spray/immersion headers
Miscella drawoff and collection manifold
In-line miscella filtration
Continuous marc discharge system
Solvent recovery and recirculation interface
Drive system and stage-residence-time control
Instrumentation — flow, level, and temperature sensors
PLC/HMI control panel

Plant Output

Concentrated miscella (extract-in-solvent)Continuously discharged spent marc / de-oiled solids

Applications

High-throughput continuous oilseed and vegetable-oil extraction
Continuous herbal and botanical extraction at commercial production scale
Continuous coffee, tea, and plant-based flavour extraction
Extraction of oleoresins and spice extracts at steady production rates
Continuous extraction of protein-rich meals and de-oiled cake
Large-volume nutraceutical actives extraction requiring uninterrupted throughput
Continuous leaching operations in specialty-chemical processing
Scale-up production lines transitioning from batch to continuous operation

Key Features

Uninterrupted Feed-In / Discharge-Out Operation
Fresh feed enters and spent marc discharges simultaneously and continuously, sustaining a steady production rate without the charge/hold/discharge downtime of batch cycles.
Counter-Current Solvent Efficiency
Solvent flows opposite to the solids' travel, maximising the concentration gradient at every stage and extracting more efficiently per unit of solvent than a single batch soak.
Higher Throughput at Steady State
Continuous operation sustains a constant output rate suited to high-volume production, in contrast to the cyclical, stop-start output of a [Batch Extractor](/products/batch-extractor).
Multi-Stage Progressive Extraction
Feed material passes through a series of extraction stages with controlled residence time at each, giving more consistent and complete extraction than a single-vessel soak.
GMP-Compliant Construction
Electropolished SS 316L product-contact surfaces meet WHO-GMP and Schedule M requirements, with cleaning and sanitation provisions for continuous production runs.
PLC-Based Throughput Control
Feed rate, solvent flow, and stage residence time are coordinated under automated control to hold a consistent extraction yield as the system runs continuously.

Frequently Asked Questions

What is a Continuous Extractor and how does it differ from batch extraction?

A Continuous Extractor processes feed material as an uninterrupted flow — fresh feed enters at one end while spent solids discharge at the other, all while extraction is happening in between. A Batch Extractor, by contrast, loads a fixed charge, extracts it for a set time, then discharges it fully before the next charge begins. Continuous operation sustains a constant output rate and avoids the downtime batch cycles lose to charging and discharging.

What does counter-current solvent flow mean, and why does it matter?

Solvent is introduced at the discharge end of the extractor and flows opposite to the direction the solids travel. That means the freshest, most concentrated solvent gradient always meets the material at the stage where it will do the most good — the leanest solvent finishes off the most-exhausted marc, and the richest miscella is drawn off where it has contacted the freshest feed. This arrangement extracts more efficiently per unit of solvent than a single batch soak.

What throughput can a continuous extractor sustain?

Because feed-in and discharge-out happen simultaneously, throughput is governed by the conveying speed and stage residence time rather than by cycle time, so a properly sized continuous extractor sustains a steady, higher production rate than an equivalent batch system running repeated cycles. Exact throughput is configured to the feedstock, particle size, and required extraction yield.

What feedstocks and solvents suit continuous extraction?

It suits high-volume solid-liquid extraction applications such as oilseed and vegetable-oil extraction, botanical and herbal actives, coffee and tea extracts, oleoresins, and protein meal processing, using solvents ranging from water and ethanol to hexane and hydro-alcoholic blends depending on the target compound.

How does this compare with a Percolation Extractor or Counter-Current Extractor?

Mechotech's Percolation Extractor and Counter-Current Extraction (CCE) both use similar solvent-percolation principles; the Continuous Extractor is the general-purpose, fully continuous configuration of this family, engineered for feed-in/discharge-out operation across multiple stages rather than a single-vessel or specific-format design.

What capacity and stage configuration can Mechotech supply?

Extraction-body length, number of stages, conveying mechanism, and solvent-handling capacity are configured to the feedstock, particle size, and target throughput, from pilot-scale continuous rigs for process validation to high-throughput commercial lines. We recommend validating extraction yield on a pilot system before scaling to full continuous production.

Does Mechotech provide turnkey design, installation, and commissioning?

Yes. Mechotech engineers, fabricates, installs, and commissions the complete extraction body, conveying mechanism, solvent-handling system, and control automation as a single accountable scope, with documentation to support GMP and regulatory qualification.

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Continuous Extractor