Soybean oil is one of the most consumed vegetable oils in the world. But efficient soybean oil extraction starts long before the actual solvent extraction stage. Every step – from raw material selection, pretreatment, to solvent extraction, desolventizing, and then refining and plant integration – directly affects oil yield, oil quality and production costs.
This article will provide you with a complete analysis of the full soybean oil extraction process and introduce the key soybean oil extraction equipment to help you build a safe, efficient and high-return production line.
I. Pretreatment: The Starting Point for Efficient Extraction
High-quality soybean oil extraction begins with scientific raw material preparation.
1. Raw Material Selection
For industrial-scale production, it is recommended to choose soybeans with moisture content of 10%–12% and oil content ≥18% to ensure extraction stability and oil yield.
2. Cleaning
Use mechanical screens and magnetic separators to remove impurities, achieving a cleaning efficiency of up to 99.5%. This step prevents sand and metal from damaging downstream equipment.
3. Crushing
A crusher reduces soybean particle size to about 0.3 mm, greatly increasing the surface area for subsequent solvent penetration.
4. Conditioning
Heat the crushed soybeans in a conditioner to 65–70°C to adjust moisture content in preparation for flaking.
5. Flaking
A flaking mill presses the soybeans into thin flakes of 0.25–0.35 mm thickness. The more uniform the flakes, the better the cell rupture and solvent permeability. Studies show that optimising flake thickness can increase oil yield by up to 2.5%, while improper raw material preparation can reduce extraction efficiency by 4–5%.
> Pretreatment effectiveness directly determines extraction returns. Continuous monitoring of particle size, temperature and moisture is key to ensuring high throughput and stable oil recovery.
II. Solvent Extraction: The Core Oil Recovery Process
The solvent extraction stage determines the core efficiency of soybean oil extraction.
1. Solvent Selection
Industrial production most commonly uses n-hexane as the solvent because of its strong oil solubility, low boiling point (69°C) and easy recovery. Compared with alternatives such as isopropanol or ethanol, n-hexane reduces extraction costs by 10–15% per tonne.
2. Extraction Equipment and Capacity
Modern solvent extraction equipment is designed with energy efficiency and safety in mind. Common continuous extractors include:
| Extractor Type | Typical Capacity (TPD) | Oil Recovery (%) | Solvent Loss (kg/tonne) |
| Rotocel Extractor | 200–600 | 97.5–98.2 | 1.2–1.5 |
| Loop Extractor | 400–1,000 | 98.0–98.5 | 1.0–1.2 |
The extractor maintains a solvent-to-solid ratio of 0.7–0.9:1, ensuring over 98% oil recovery.
3. Desolventizing/Toasting (DT)
The wet meal leaving the extractor enters a desolventizer-toaster (DT), where residual solvent is removed under vacuum at 105–110°C and below 0.3 bar, while preserving protein quality in the soybean meal. Energy integration between the extractor vapour and the DT system can reduce steam consumption by 15–18%.
4. Safety and Automation
Using n-hexane requires explosion-proof design, nitrogen blanketing and a solvent vapour recovery system. Solvent loss should be kept below 0.05% of the circulating solvent volume. Integrated in-line sensors and a Manufacturing Execution System (MES) enable precise tracking of temperature, pressure and flow, reducing unplanned downtime by more than 20%.
> Optimisation tips: Properly control the solvent circulation ratio, reuse condensation heat, and adopt automatic recovery systems – saving up to 30 kWh per tonne and keeping VOC emissions below 20 mg/m³.
III. Desolventizing and Refining: From Crude Soybean Oil to High-Purity Finished Oil
After crude oil separation, it must be refined before consumption.
1. Desolventizing
Residual hexane is removed under vacuum at 105°C, bringing solvent content in the meal to below 300 ppm.
2. Refining Steps
– Degumming: Removes phospholipids. Equipment: degumming tank, centrifuge separator.
– Neutralisation (deacidification): Removes free fatty acids. Equipment: alkali refining kettle or deacidification tower.
– Bleaching (decolorisation): Uses activated bleaching earth (0.8%–1.2% dosage) to adsorb pigments. Equipment: bleaching tank, filter.
– Deodorisation: Carried out at 230–250°C for 1.5–2 hours to remove off-flavours. Equipment: deodoriser tower, vacuum system.
Refined soybean oil has free fatty acid (FFA) content below 0.05% and transparency above 95%, meeting international edible standards. An automatic on-line spectrometer using near-infrared reflectance (NIR) can monitor colour and FFA content in real time, ensuring product consistency.
IV. Plant Design and Integration: Efficient, Safe, Scalable
Efficient plant operation requires not only good extraction equipment but also sound plant design.
– Layout optimisation: Can reduce material handling time by 15–20% and save up to 40 kWh/tonne in total energy consumption.
– Automation systems: Integrate SCADA and MES systems for end-to-end visibility and real-time performance tracking. A centralised control room enhances operator safety and reduces human error.
– Modular design: Supports phased capacity expansion. The Engineering, Procurement and Construction (EPC) model typically shortens project timelines by 25%.
– Predictive maintenance: Using vibration analysis and other techniques to detect extractor bearing wear before failure reduces downtime by up to 30%, while solvent recovery remains above 99%.
V. Core Equipment List (by Process)
| Process | Recommended Equipment |
| Cleaning | Mechanical screens, magnetic separators |
| Crushing | Crusher |
| Conditioning | Conditioner |
| Flaking | Flaking mill |
| Solvent extraction | Rotocel or Loop extractor, evaporator, condenser |
| Desolventizing | Desolventizer-toaster (DT) |
| Refining | Degumming tank, centrifuge, alkali refining kettle, bleaching tank, deodoriser tower, vacuum system |
| Automation | SCADA, MES, on-line spectrometer |
Soybean oil extraction is a systematic process that combines materials science, thermodynamics and plant engineering. From raw material pretreatment and solvent extraction to desolventizing/toasting and refining, every stage requires professional soybean oil extraction equipment. Scientific plant design and automation integration can significantly increase oil yield, reduce energy consumption and ensure production safety.
If you are planning or upgrading a soybean oil extraction line, please contact us. We provide one-stop EPC solutions from single machines to complete plants. Our engineering team can tailor an efficient and safe extraction process based on your capacity, raw materials and budget.