Process for preparing aromatic hydroxycarboxylic acids

Aromatic hydroxycarboxylic acids are prepared by reacting an alkali metal salt of an aromatic hydroxy compound in solid phase with carbon dioxide, by reacting an alkali metal salt of an aromatic hydroxy compound in the form of granules in a fluidized bed with carbon dioxide, if desired under elevated pressure, at first at temperatures of 20 DEG to 130 DEG C. until at least 40% of the hydroxy compound has been converted into the corresponding carbonate, then completing the reaction at temperatures of 135 DEG to 300 DEG C., and then converting the reaction product obtained into the free acid.