Solvent extraction is an oil-making process that selects an organic solvent capable of dissolving the oil and makes it contacts with the pretreated oilseed, soaking or spraying, so that the oil in the oil is dissolved. The grease leaching process forms a solution of the solvent with the oil it dissolves. This solution is called a mixed oil. The selected solvent is evaporated and stripped with a different boiling point of the oil, and the solvent is distilled off to leave a grease to obtain a hair oil. The vaporized solvent vapor is recovered by condensation and recycled.

●According to the mode of production operation

1. Intermittent type

Intermittent type refers to the discharge of oil into the crucible, and the discharge of the solvent into the mixed oil is carried out in batches, in an intermittent operation mode. If the tank leaching device is leached, it is intermittent leaching.

2. Continuous type

Compared with the batch type, the oil is put into the sputum discharge, and the solvent is put into the mixed oil discharge, which are successively carried out, and are in a continuous operation mode. Such as flat-rotating, crawler-type, ring-type leaching leaching is a continuous leaching.

 
● According to the production process

1. Direct extraction, also known as leaching, refers to the process in which the oil is directly pretreated into the leacher for leaching to obtain grease. The direct leaching process is generally applicable to oil processing with low oil content, such as soybean, rice bran, cottonseed and the like.

2. Pre-pressing extraction, refers to a process in which a portion of the oil is firstly extracted by an oil extraction device after the oil is pretreated, and then the remaining portion of the pressed cake is removed by a leaching method. The pre-extraction leaching process is suitable for oil processing with high oil content, such as rapeseed, peanuts, sunflower seeds and etc.