Method for preparing taurine and method for recovering mother liquor thereof

A method for recovering a taurine mother liquor, comprising:

• A1, providing a taurine mother liquor, and mixing the taurine mother liquor and a treating agent to obtain a solid-containing suspension, wherein the treating agent is a water-soluble organic solvent or a mixture of the water-soluble organic solvent and water;
• A2, filtering the suspension to obtain a first solid product and a first filtrate;
• and
• A3, dissolving the first solid product with an ammonia source to obtain a first mixture, and then filtering the first mixture to obtain a second solid product and a second filtrate,
• wherein the taurine mother liquor is a solution containing impurities comprising taurine, sodium taurate, sodium ditaurate, sodium tritaurate, sodium isethionate, organic impurities and inorganic impurities,
• the organic impurities comprise ethanediol, polyethylene glycol, and polyether, and the inorganic impurities comprise sulfates,
• in step A3, before dissolving the first solid product in the ammonia source, the method further comprises:
• drying the first solid product to make a mass fraction of the organic solvent in the first solid product less than or equal to 2%,
• the ammonia source in step A3 comprises a saturated ammonium hydroxide, and
• in step A3, the mass of the ammonia source is 4 times to 15 times of a mass of the dried first solid product.