How does Solvent Extraction Plant Work

Solvent extraction is employed to separate compounds based on the differences in the relative solubilities in two immiscible liquids. More conveniently, it can be described as the separation/extraction of a substance from a mixture by preferentially dissolving the substance to be extracted in a suitable solvent. It is usually chosen when a soluble compound needs to be separated from an insoluble compound or a complex matrix. LLE or Solvent Extraction is widely used in the production of fine organic compounds, the processing of perfumes, the production of vegetable oils and biodiesel, and in related industries.   Immiscible liquids refers to liquids do not mix and instead separate into layers. These properties are utilized for separation  of  Organic compounds that exhibit  physical property  of greater solubility  in organic solvents, and these solvents are often found to be  immiscible in water. These Organic compounds can be easily be extracted in aqueous form by the addition of benzene, chloroform etc. These are then collected after they settle into two layers and the non-aqueous layer is removed. After distillation   the purified compound is obtained. 

Commonly referred to as Liquid–liquid extraction

(LLE), Solvent Extraction is preferred when substances like edible oils need to be separated or extracted   based on the differences in relative solubilities in two different immiscible liquids. The transfer occurs due to different chemical potentials. This occurs when  the overall system of protons and electrons constituting  the solutes and the solvents have greater  stability of  configuration and exhibit lower free energy after  completion. The solvent thus produced then is obviously enriched in the solute(s) and is referred to as extract. The depleted feed solutions usually termed as the definite. The solvent extraction plants are used where oil is extracted from oil seeds like soybean, sunflower, cottonseed, other oil seeds and oil cakes like mustard cake, groundnut cake and rice bran. In such solvent extraction, it's advantageous to do extraction in successive stages using smaller lots of solvents rather doing extraction once using the entire lot.