Preparation of granules by making nuclei grow, in a fluidized bed, by causing a liquid material to solidify thereon. The liquid material is sprayed in the bed upwards, with the aid of a spraying device provided with a central channel through which the liquid material is supplied, and a channel concentric therewith carrying a powerful gas stream, with the liquid material contacting the gas stream and being carried with the gas stream to a dilute zone where the growth of the nuclei takes place, which zone is created by the gas stream and is completely within the fluidized bed. The liquid material is made to come out of the central channel as a virtually closed, conical film, with a thrust exceeding the thrust
of the gas stream, and this film is nebulized to very fine droplets with the aid of the gas stream.In this process a very small amount of high-energetic gas is needed, while no agglomeration occurs in the bed.