FREMGANGSMAADE TIL KONTINUERLIG FREMSTILING AF NATRIUMPERBORATGRANULATER

Spray-drying of a solution containing hydrogen peroxide and sodium metaborate is known per se; these products are very fine and amorphous, and they show an unsatisfactory storage stability. According to the invention, these disadvantages are eliminated, if the primary particles obtained by spray-drying are, immediately after they have left the drying zone, fed to a granulator device and granulated in the presence of free water and/or water of crystallisation of the perborate and, if necessary, the granules are dried. The generally amorphous primary particles are converted into granules having an at least partially crystalline structure and a significantly improved storage stability. Advantageously, the process is carried out in a spray drier with integrated fluidised bed or in a compacting granulator device. The process is suitable for producing perborate granules with more than 10 % by weight, especially perborate monohydrate granules with 14 - 16 % by weight, of active oxygen.