In solvent extraction, pre-pressing of oilseeds is a crucial pretreatment step, primarily aimed at improving extraction efficiency, optimizing the production process, and enhancing the quality of the final product. Here are some of the main reasons for pre-pressing oilseeds:

First, pre-pressing effectively removes some of the oil from the oilseeds. Through mechanical pressing, free oil is squeezed out, which not only reduces the amount of solvent required for subsequent solvent extraction but also lowers the risk of solvent residue, thereby improving product safety. Furthermore, the pre-pressed oilseed residue (i.e., oil cake) has a lower oil content, which is more conducive to the full penetration and extraction of the solvent.

Second, pre-pressing improves the physical properties of oilseeds, making them more suitable for solvent extraction. During pre-pressing, the oilseeds form a loose cake structure after pressing. This structure increases the specific surface area, allowing for more uniform solvent contact and thus improving extraction efficiency. Simultaneously, the cake structure facilitates solvent penetration and diffusion, accelerating the oil extraction process.

Furthermore, pre-pressing reduces the burden on solvent extraction equipment. Directly feeding untreated oilseeds into the extraction process not only increases solvent consumption but can also lead to equipment blockage or decreased operating efficiency. Pre-pressing reduces the volume and oil content of the feedstock entering the extraction system, thereby lowering the operating pressure on the equipment and improving the stability and economy of the entire production line.

Last, pre-pressing also improves the quality of the final product. Crude oil obtained through mechanical pressing has fewer impurities and is of higher quality, allowing for direct use in refining or other processing applications. Oil extracted through solvent extraction, on the other hand, can be further processed. Combining both methods allows for more comprehensive utilization of raw material resources and maximizes economic benefits.

In short, pre-pressing oilseeds is an indispensable step in solvent extraction. It not only optimizes the production process but also improves economic efficiency and product quality. Therefore, in actual industrial production, pre-pressing has become a widely used standard process.