Generally, n-hexane is directly extracted by Soxhlet extractor or directly refluxed, and then the solvent is concentrated and recovered to obtain crude fat.

Soxhlet extractor consists of three parts: extraction bottle, extraction tube and condenser. Siphons and connecting pipes are arranged on both sides of the extraction pipe. The joints of all parts shall be tight, and there shall be no air leakage. When extracting, wrap the sample to be detected with degreased filter paper and put it into the extraction tube. Add petroleum ether into the extraction bottle, heat the extraction bottle, evaporate the petroleum ether, rise from the connecting pipe to the condenser, and drop the condensate into the extraction pipe to extract the lipid substances in the sample. The liquid level of petroleum ether in the pipeline to be extracted reaches a certain height, and the petroleum ether dissolved with crude fat flows into the extraction bottle through the siphon. The petroleum ether flowing into the extraction bottle is continuously heated, gasified, lifted, condensed, dripped into the extraction tube, and so on until the extraction is completed.