1. Pulverization: Take the roots and stems of licorice, pulverize them in a pulverizer, and pass through a 20-mesh sieve for use.
2. Extraction: take 200kg of the above-mentioned licorice coarse powder, put it into a 2000L enamel reaction kettle, add 1200kg of water, slowly heat to 85-100°C, stir and extract for 2h, filter, add 1000kg of water to the filter residue, and extract twice according to the above method , and combined the 3 filtrates.
3. Concentration: pump the extract into an enamel evaporator for concentration, and filter it while hot when it is concentrated to 1/5 of the original volume.
4. Separation: The filtrate is cooled to room temperature and 95% ethanol is added to make the ethanol content in the extract reach 65%, and it is allowed to stand for 24 hours, and then filtered to remove vegetable protein and polysaccharide.
5. Precipitation: Take licorice filtrate, put it into a sedimentation tank, add concentrated sulfuric acid to adjust pH=3, and glycyrrhizic acid will precipitate out, filter, wash twice with deionized water, and then vacuum dry.
6. Refining: add 3 times the amount of acetone to the glycyrrhizic acid precipitation, heat and reflux for extraction for 3 hours, filter and reflux the residue for 2 times, combine the 3 reflux extracts, filter, and recover acetone to obtain a wet product of glycyrrhizic acid.
7. Drying: Put the dry oxalic acid wet product into the drying room to dry, control the temperature at 45 °C, dry for 1 hour, slowly heat up to 85-95 °C, when it is nearly drying, heat up to 100 °C, and finally bake at 105 °C for 5 minutes .
8. Pulverization: put the dried glycyrrhizic acid in a pulverizer and pulverize, and pass through a 60-80 mesh sieve to obtain glycyrrhizic acid powder.