A method for the purification of benzoic acid

摘要

Crystals of crude benzoic acid whose volume density is not less than 0.2 g/cm3 and whose average particle diameter is not less than 0.3 mm are put from above into a continuous crystallizer having a stirrer and a heating means and the crude benzoic acid crystals which descend inside the crystallizer and melt produced by the heat of the heating means are brought into counterflow contact with each other for refining. The refined benzoic acid is drained out of the bottom of the crystallizer as melt, and the mother liquor is taken out of the top of the crystallizer to obtain refined benzoic acid with a purity of not less than 99.9 % continuously. In such a way, high purity benzoic acid can be continuously obtained with high efficiency and with relatively simple apparatus.