Abstract: Particulate material is discharged continuously from fluidized bed reactors by passing the material emerging at the lowest point of the fluidized bed through a zone which is narrower than the fluidized bed and in which a gas stream flows counter-current to the material, the pressure of the gas stream being above the pressure of the fluidized zone.

Abstract: A new process for continuously preparing granules having narrow grain size distribution, comprisinga. spraying the product to be granulated in liquid form into a fluidized bed,b. separating the proportions of fine material escaping from the fluidized bed from the off-gas and returning said fine material to the fluidized bed as nuclei for granule formation,c. setting the fluidizing gas flow such that granules are formed which are of a predetermined size, andd. removing the completed granules solely by way of at least one countercurrent gravity classifier inserted into the outflow bottom of the fluidized-bed vessel.A new apparatus for carrying out the process according to the invention and new granules.

Abstract: 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.degree. to 130.degree. C. until at least 40% of the hydroxy compound has been converted into the corresponding carbonate, then completing the reaction at temperatures of 135.degree. to 300.degree. C., and then converting the reaction product obtained into the free acid.

Abstract: Aromatic hydroxycarboxylic acids are prepared by reacting alkali metal salts of aromatic hydroxy compounds in the solid phase with carbon dioxide in a process in which the alkali metal salt of the aromatic hydroxy compound is reacted at temperatures of 120.degree. to 300.degree. C., in the form of granules, in a fluidized bed with carbon dioxide, if appropriate under elevated pressure and, if appropriate, in the presence of the aromatic hydroxy compound in the form of vapor, with continuous removal, by means of excess carbon dioxide, of the aromatic hydroxy compound which is formed, until at least 40% of the hydroxy compound have been converted into the alkali metal salt of the corresponding hydroxycarboxylic acid, and, if appropriate, the resulting alkali metal salt of the hydroxycarboxylic acid is reacted further in a subsequent stage at temperatures of 150.degree. to 300.degree. C.