What are the separation principles and characteristics of solid-liquid extraction?

Extraction, also known as solvent extraction or liquid-liquid extraction, is a unit operation to separate the mixture by using the solubility of each component in the solvent. That is, the method of transferring solute substances from one solvent to another by using the difference of solubility or distribution coefficient of substances in two mutually insoluble (or slightly soluble) solvents. Widely used in chemical, metallurgical, food and other industries, generally used in petroleum refining industry. In addition, the operation of separating two immiscible liquids after extraction is called liquid separation.

Solid-liquid extraction, also known as leaching, is to separate the components in the solid mixture with solvents, such as leaching sugar from beets with water; Soak soybean oil in soybean with alcohol to increase oil yield; The effective components in traditional Chinese medicine are leached with water to make fluid extract, which is called "leaching" or "leaching".