Mechanical refining, including precipitation, filtration, centrifugal separation, is mainly used to separate mechanical impurities and a part of the gel soluble impurities suspended in the crude oil.
Chemical refining mainly includes acid refining, alkali refining, lipidization, oxidation and so on. Acid refining is treated with acid, which mainly removes pigment, colloidal soluble impurities; Alkali refining is treated with alkali, which mainly removes free fatty acids; Oxidation is mainly used for decolorization.
Physical & Chemical Method
Physical and chemical refining methods mainly include hydration, decolorization, steam distillation and more. Hydration mainly removeS phospholipid, decolorization mainly removeS pigment, steam distillation is to remove odor and free fatty acids.