1.Hydration and degumming. Hydration and degumming is a method that uses the hydrophilicity of colloidal impurities such as phospholipid to add a certain amount of water or dilute electrolyte solution to the crude oil under stirring to make the glue-soluble impurities in crude oil absorb water and expand, condense and remove.

2.Alkali deacidification. There are a certain amount of free fatty acids in all kinds of crude oil without refining. The process of removing free fatty acids in oil is called deacidification. The methods of deacidification include alkali refining, distillation; solvent extraction and esterification.The most widely used methods in industrial production are alkali refining and steam distillation (i.e. physical refining).

3.Decolorization. The third step of the refining process of animal oil refining equipment is the decolorization, it is to use some substances with strong selective adsorption effect on pigment (such as drift soil, active clay, activated carbon, etc.) to adsorb pigment and other impurities in oil under certain conditions, so as to achieve the purpose of decolorization.

4.Deodorization. Deodorization is a process in which odorous substances in oil are distilled by steam under high temperature and high vacuum conditions by taking advantage of the difference between the volatilization of triglyceride and odorous substances in oil.
The principle of deodorization by steam distillation (also known as stripping) is to remove the odorant components by means of water vapor contact with oil containing odor components, vapor-liquid surface, and the water vapor is saturated by the volatile odor components, and escapes according to the ratio of its partial pressure, so as to achieve the purpose of removing odor components.