Extraction

Solvent extraction using hexane is the primary method for recovery of oil from soybeans, although some mechanical extraction is still used. Process improvement in extraction plants has continued with increasing emphasis on energy efficiency, cost reduction, reducing hexane loss, quality of meal and oil, and increased capacity, driven by a six-fold increase in soybean production since 1950 and by an increase in energy costs since 1970. The conventional soybean extraction process consists of four steps; preparation, extraction, solvent recovery from miscella and desolventizing/toasting of meal. Modern soybean processing involves large plants with many operations that must be considered. Transportation, material handling, drying, and milling are similar to other grain processing. Dust explosions and personal injuries from machinery, falls, burns, asphyxiation, and other causes must be considered in developing a comprehensive safety program. An alternative to solvent extraction for extraction of oil from soybeans is the use of mechanical pressing. It is an old practice dating from the original lever and screw presses to more modern hydraulic and continuous screw presses.