The invention relates to a recrystallization method of long-chain
dibasic acid, which comprises the following steps: by taking a
mixed solution of ethers and at least one selected from water and low-carbon
alcohol as a
solvent of the long-chain
dibasic acid and a to-be-treated material with the concentration of the long-chain
dibasic acid in the to-be-treated material being 15-50g / 100g
solvent, putting the to-be-treated material in a crystallizer, preserving heat at the temperature of 80-95 DEG C, reducing the pressure, keeping the vacuum degree, extracting part of the
solvent to reduce the volume of the to-be-treated material by 0.5-10%, then increasing the pressure to maintain
positive pressure, and cooling to crystallize and separate out the long-chain dibasic acid, thereby completing the recrystallization of the long-chain dibasic acid. According to the invention, seed crystals do not need to be added, the
solubility of the dibasic acid can be greatly improved by adding the low-carbon alcohols, then the dibasic acid is discharged through
pressure reduction, so that the
solubility of the dibasic acid is greatly reduced, crystals are separated out, the dibasic acid explodes in a solvent to spontaneously nucleate in the subsequent cooling
crystallization process, and compared with seed crystals added in an original process, the method has the advantages that the number of
crystal nucleuses is larger, and the
crystal tends to grow on a
crystal nucleus rather than being separated out along a wall, so that the problem of cold wall separation is avoided.