A soybean oil plant is a facility designed for the processing of soybeans into soybean oil and its by-products, including soybean meal or cake. These plants are designed to handle the entire oil extraction process, from the preparation of the soybeans to oil refining, producing high-quality, edible oil for food, industrial, and biofuel applications. A soybean oil plant can be designed for small-scale, medium-scale, or large-scale production depending on the desired capacity and end use.

Main Processes in a Soybean Oil Plant

A typical soybean oil plant is composed of several key stages:

1. Soybean Preparation:
- Cleaning: The first step is cleaning the soybeans to remove impurities like dirt, stones, leaves, and other foreign materials. This ensures the quality of the oil and prevents damage to machinery.
- Cracking/Dehulling: The cleaned soybeans are cracked and dehulled to separate the seed coat from the kernels. Removing the hulls improves the oil yield and makes the pressing process more efficient.
- Flaking: The soybeans are rolled into thin flakes to increase the surface area for oil extraction. This also helps to rupture the oil cells in the soybeans, making it easier to extract oil.

2. Soybean Oil Extraction:
- Mechanical Pressing (Expeller Method): The soybeans are passed through an oil expeller, where mechanical force is applied to crush and press the oil out of the flakes. This method is commonly used for small- and medium-scale oil plants.
- Solvent Extraction: For larger plants, the solvent extraction method is used, which involves using a solvent like hexane to dissolve the oil from the soybean flakes. After extraction, the solvent is evaporated and recovered, leaving behind the crude soybean oil.

3. Crude Soybean Oil Filtration:
- After extraction, the crude oil is filtered to remove solid particles, dust, and other impurities. This prepares the oil for further refining.

4. Soybean Oil Refining:
- Degumming: The first step in refining crude soybean oil is to remove phospholipids (gums). This is done by treating the oil with water or acid, causing the gums to become hydrated and easier to separate.
- Neutralization (Alkali Refining): The crude oil is mixed with an alkali solution (e.g., sodium hydroxide) to neutralize free fatty acids and remove impurities that affect the oil’s quality.
- Bleaching: In this step, the oil is treated with bleaching earth or activated carbon to remove pigments, color compounds, and trace metals. This improves the color and stability of the oil.
- Deodorization: This step removes volatile compounds that cause unpleasant odors and flavors in the oil. The oil is heated under a vacuum, and steam is passed through it to strip off these compounds.
- Winterization (Optional): This process involves cooling the oil to remove waxes and high-melting point triglycerides that cause cloudiness when the oil is stored at low temperatures.

5. Soybean Meal Processing:
- After oil extraction, the solid residue left behind is called soybean meal or soybean cake. This by-product is high in protein and is widely used in animal feed production.

6. Storage and Packaging:
- The refined oil is stored in large tanks before it is packaged for sale or distribution. Soybean oil can be packaged in bottles, drums, or bulk containers depending on the market requirements.